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H: Empty Cells on LiPo - Balance Charger or Battery Problem? I recently opened up a box of 5 year old 3S LiPos which I had in storage. When I hooked them up to my Turnigy Accucel 6 80w balance charger, they mostly measured total voltages around 11v~. However, upon connecting the balance leads, the charger is saying that all of the old batteries have only 2 out of 3 cells carrying voltage (and one was at only 1 of 3). Similarly, when I try to balance charge these batteries, I get a "cell error". It's possible the batteries are bad, but it seems weird for them all to be bad in exactly the same way. For example, on one of the 3S batteries, voltage reported is: 0.00 6.07 3.87 0.00 0.00 0.00 This shouldn't even be possible, there's no way I have 6.07V in one cell. I proceeded to test the voltage of these batteries directly with a multimeter (followed this guide) and I'm seeing voltages on all three cells. What's a little odd is on the one I tested, they all seem to report the exact same voltage (3.72V). Testing the main power lead directly, I get 11.16V (3.72V x 3). It seems reasonable to assume there's something wrong with the balance charger, but I wanted a second opinion. I was able to use the balance charger to successfully charge some new 4S batteries, but I don't have any new 3S batteries handy. Is it possible I just have a problem with the circuitry for the 3S balance connection? AI: It sounds like the balance lead for the first cell isn't connected somewhere. The wire may have come off inside the charger, or it could be the balance plug, the wire, or an external parallel board (if you're using one). I'd open up the charger and test the voltage at the back of the balance plug, and see if you can spot any broken solder joints.
H: Report a lost drone in the UK? I recently lost my drone in the UK, it is quite big and sure someone must have picked it up. Is there any way to try and recover it, an online lost drone database? What steps can be taken in the future so if my drone is lost it can be returned to me? AI: There is a CAA run scheme to help return lost drones to their owners called ‘drones reunited’, however you have to have registered your drone with the CAA to use it. If you have, then you may find their website helpful. There are also other ways in which you can try to locate your drone: Firstly, have a look around the Facebook groups local to your area in case anyone has posted about it, and if they haven’t then you can put out a post asking if anyone has found it. You can also put up posters offering a reward if someone finds your drone and returns it to you (assuming you get the appropriate permissions). There are also several lost and found schemes across the UK, one of which is the Metropolitan Police Lost and Found scheme. If this is the S49 you posted about, it may have flown for a few minutes after it started to fly away (assuming you had already run down the battery a bit). You can look on Google Maps and form a search pattern to cover the area around where you lost your quad - if you can remember the direction it flew then that is especially helpful. Finally, try to learn from the flyaway to make sure it never happens again. Many environmental factors, such as power lines, can disrupt your control of the aircraft, so always scout where you are going to fly to make sure it is safe to do so. I also put my contact details and the phrase ‘reward if found’ on my drone so if it is lost, the finder can easily contact me to return it.
H: Spray painting a drone, what to look out for? I don't really like the colours on my drone and found a few bright spray paint colours around my house. I would like to spray paint my drone, but I obviously do not want to damage any parts of my drone (motors, electrical components etc.) Is it safe to do this? What should I look out for when painting? Any specific areas of the drone I should avoid touching? How can I get the paint to not wash off it the drone crashes etc.? Anything I can apply to it? AI: If you have the technical know how, I would suggest you remove the shell from the drone and spray paint that separately to avoid contamination any of the electronics or mechanical components. If you aren’t able to do that, then apply masking tape and/or plastic or any other protective layer over any exposed electronics, cameras, ports, motors etc. Basically anything functional. Also make sure not to point the propellers as this could lead to them being unbalanced. Before you paint the drones, you may want to scuff the surface with some sand paper. This will provide better adhesion for the paint - if you’ve ever tried writing in marker on a smooth surface, you know how difficult it is to stick. After you have applied your paint, you can add a clear coat and a fixative to protect the paint. Here is a video showing how to spray paint a drone: https://youtu.be/5aSsd3tCJ-c, notice how the person completely disassembles the drone before applying the paint. You may also want to consider a vinyl wrap of hydro dipping as decent alternatives to spray paint. Here is another example of how to spray paint a more premium drone: https://youtu.be/mP4oyjipwhQ
H: Why do drone propellers have blades with thin chords? Almost all propellers used for drones have very thin chord length compared to the propellers used for things like table fans or boats which seem to have blades with much longer chord length. What is the reason that drones most often use propellers with blades that have thinner chord length? Common drone propeller shape: Common table fan or boat propeller shape: AI: Overview The most efficient propeller is single bladed, has infinitely narrow chord, has infinitely thin airfoil, has an infinitely long blade, spins infinitely slowly, and requires infinite torque. So at the risk of stating the obvious, propeller design is a study of the tradeoffs and compromises required to make something practical. Here's a list of some compromises: length: landing gear height (or water depth) restricts how long a blade can be. material constraints: thicker airfoils resist forces better. Stronger materials allow for thinner airfoils while still meeting required blade strength power-plant constraints: the torque required to spin the propeller should match the motor/engine's efficiency and power curves. number of blades: more blades equal more thrust for a same diameter increased activity factor (aka blade width): wider blades produce more thrust for the same diameter balancing: one prop is very hard to balance without causing lots of drag by the opposing mass. vibration: three props give fewer vibrations than two sound pollution: smaller props spinning more slowly are more pleasing on the ear consumer perception: consumers like to see big blades in their fans, regardless of real-world efficiency and performance. density of the fluid: dense fluids such as water can cause cavitation, which can quickly damage the propeller. One solution is to change tip shape so as to minimize cavitation likelihood. on the opposite scale, with low-density fluids such as air, the blade tip can spin so quickly it stalls. As it relates to drones Rotorcraft are a little special, so let's break out by type: Vertical propulsion Multirotor drones and helicopters have tons of space compared to boats, and so don't particularly need to restrict their diameter. They choose their rotors based primarily on power-plant performance. Longitudinal propulsion Fixed-wing drones with landing gear obey the same rules as full-scale aircraft. If the prop is going to hit the ground on takeoff it's not very useful! Fixed-wing drones without landing gear, e.g. hand-launch gliders, can use very large folding propellers. These are chosen similarly to multirotors, where it's about efficient power-plant matching. As pointed out by @RobinBennett, "You don't want it stalled when the aircraft is stationary, so there's a maximum pitch angle - and that sets the maximum speed. If you want to go faster you need to spin the prop faster, and if you've got a fixed amount of power, you need a smaller prop just to spin it faster."
H: How to prevent a 5V supply from sagging to 4.6V when the FPV camera is on? I have issues with my FPV camera. My camera is a RunCam split 2S (concept is similar to Caddx turtle). This camera turns off almost instantly after I have plugged in my battery. When I probe the voltage between 5V and ground, I can see the voltage drop from 4.9V to 4.6V as soon as the camera starts recording (which it does automatically when powering it). Then, when the camera shuts completely off, the voltage goes up again. Also, I can press a button and the camera will turn on but also back off again Hooking up a phone charger to the camera gets the voltage up again (and makes the camera run stably), but I obviously don't want to fly around with a power bank attached to my drone. Unfortunately, the VTX is also wired to the flight controller's 5V converter instead of its own. TL;DR: The issue is not that the voltage has too much ripple. The issue is that the voltage converter on my FC is not strong enough. Would a capacitor at the input (XT60 connector) make any sense? If yes, which size should it be? I have 220µF and 1000µF electrolytic caps. Links to the mentioned parts: Flight controller, Camera, VTX EDIT short answer for future people: additional, external voltage converter/BEC; use all available voltage converters (VTX, FC, (PDB)); do not make them parallel! long answer: see accepted answer AI: I've pulled a few specs together from the parts you linked to: Flight controller: Input: 2S to 6S LiPo (7V to 20V) Output: 5V 3A VTX: Input: 7V to 24V Output: 5V 0.3A Camera: Input: 5V 0.65A --OR-- 12V 0.27A You don't mention what size battery you are using, but I will assume it is in the FCs range of 2S to 6S. The camera needs too much current (0.65A) to get it's 5V from the VTX (max 0.3A) The VTX should be connected to the battery The FC should be connected to the battery The camera should be connected to the FC 5V supply This wiring should work, if you have no other large 5V loads connected to the FC. ╔══════════════════╗ ╭───────╮ ║ LiPo Battery ╟──┤ 7-20V ├────┬──────────┐ ╚══════════════════╝ ╰───────╯╔═══╧═══╗ ╔═══╧═══╗ ╭────╮ ║ VTX ║ ║ FC ╟──┤ 5V ├────┐ ╚═══════╝ ╚═══════╝ ╰────╯╔═══╧═══╗ ║ Cam ║ ╚═══════╝ Alternatively you will need a separate DC-DC converter or regulator to supply the 5V. A capacitor is great for smoothing out surges in demand, but won't hold up the 5V rail if the load is constantly too large.
H: How do laterally folding propellers affect multirotor flight? There are a number of multirotors on the market which have propellers which fold at the hub, primarily to make storage and transport easier. Centrifugal force keeps the blade extended when the motor is spinning. However, there is still a flexible coupling between the blade and the hub; what effect does this have on the aircraft during flight? AI: In theory, you can't accelerate and decelerate the props as quickly. If the motor accelerates, the props lower angular velocity keeps it from accelerating too quickly. Same for deceleration: if the motor decelerates, the prop's momentum makes it want to stay fast. It is only when the prop's position exceeds the motor's position, that the centrifugal force will slow it down. But you have to consider that the angular velocity is quite a lot - therefore the centrifugal force is very high and the prop will only slightly move in its mount, thus not really affecting the flight all that much. Especially, when you consider that most drones with foldable props (e.g. DJI Mavic series) are "smart drones": They probably considered that during development and made it so that the motor speed is only raised and lowered slowly, so the effect isn't too noticeable. Plus, these drones are quite heavy so a tiny little change in prop speed will probably not have a big impact on the position in the air. As you can see below, the propellers have different angles relative to the motor position. Obviously, propellers can only be designed for one direction of movement. Since the direction changes however, depending on whether it is accelerating or decelerating or at a constant speed, the uplift will be slightly reduced during speed changes of the props.
H: How to determine the largest LiPo I can use in a quadcopter? Multirotors can usually operate with a larger battery than recommended for longer flight times but slightly less performance. However, there is a point of diminishing returns at which increasing the battery size will just make a drone so heavy that it uses more power to stay in the air than the added battery size provides. How do I know when a battery will be too big and won't provide significantly more flight time? Is there some way to calculate the diminishing returns of increasing the battery size for a freestyle quadcopter? My goal is to get the longest flight time that I can while only losing the upper-end performance which I don't use anyways. AI: Short of very complicated maths, here is what I would do, and may very well help you: You need to know the specifications of your motor - how much power do they consume for a given amount of thrust? You can find this out either by looking at the spec sheet, or I would just add masses in 25g increments and take a look at the black box recording. Once you know this, you can know how much power it will take to lift the extra mass of the battery, you can use P=IV to figure out the extra energy stored in the battery itself and see if it is enough to counteract the extra mass. This is obviously very rough - you would need a large sample size and to operate in lots of different conditions, but it would give you a good idea of if it is worth it before you even buy the larger battery. Disclaimer: don’t overload your quad and risk burning out your gear - do this at your own risk.
H: Would I be able to program a smartphone app to control a smartphone-controlled drone? I want to buy my first drone, I have no prior experience. I'm interesting in getting a cheap drone with a camera that can be controlled from a smartphone app. Something like the Tello Ryze would be at the higher end of my price range. I have experience programming (including smartphone apps). I noticed the Tello Ryze specifically has an SDK. Would it be possible to use this SDK from an Android app I wrote? And is it usually possible to program drones that are controllable from a smartphone yourself (I am finding it difficult to Google good information about this)? To clarify, what I would like to access in my program: Video stream from the drone to my smartphone app Send commands from my smartphone app to the drone to control it AI: This certainly seems doable. The SDK documentation is not very clear but basically it's a simple string command over UDP. So it looks like the drone creates a WiFi access point which you connect to with your phone and you have a dedicated IP address/port number to send commands to the drone. There is a simple python application linked in their SDK document that shows the basics. And there is a github repository that also has a python program that shows how to get the video feed from the drone over the command API described in the SDK. Given the SDK and the example projects in the github repository I think it would be a feasible project by someone with some Android development skills.
H: How does frame stiffness affect a quadcopter? When choosing a frame for a drone, something I hear mentioned occasionally is how flexible the carbon fiber is. It seems that the general opinion is: more flex in a frame is worse. How would having a frame with flex in it be bad for a high-powered quadcopter? Would it impact the efficiency and performance of the quadcopter? AI: Background Stiffness, oscillation, and vibration damping are separate concepts but all somewhat relevant to the question. Each affects flight dynamics, and each is (somewhat) a function of material choice. For example, titanium is very stiff, and it rings like a bell. CF is very stiff, but it rings like mud. Aluminum is in between. Stiffness Stiffness is a good thing when you don't want your structure to be compliant[]. Stiffness means that the frame isn't deflecting, which is important for the presumed laws of motion. Put another way, a quadcopter's autopilot assumes that all the motors are pointed in a fixed direction[]. If those directions change, i.e. because of flexing, then the most fundamental assumptions of its flight dynamics are false. It's no surprise flight flight performance degrades! Of course, any structure will bend/deflect/twist under load, no matter how stiff. What's important is whether it does any of these sufficiently enough to compromise your flight goal. If you're trying to do telescopic videography then a little bit of error is immediately visible in the results. If you're learning to fly, then so long as the autopilot keeps things sunny-side up you're fine. Oscillation Oscillation, such as control-surface flutter, occur when the entire structure starts deforming like a spring. This can dramatically build up and quickly rip the airframe to shreds. (It really is that fast, that violent, and that scary.) If a quad's arms are insufficiently damped, oscillations can occur. Most frequently, it will occur as a twist about the arm axis, but I've also seen it happen in the flapping direction. Because of differences in dynamics between a multirotor and a fixed-wing, it's unlikely that your quad will suffer inflight failure but it's also very hard to keep control, both for you and the autopilot. The closer you get to instability, the more energy you have to expend to keep things stable. In the case of a multi, at the very least this translates into decreased flight time. The more powerful your input (e.g. a powerful quadcopter), the easier it is to drive a system past a critical damping threshold. The Tacoma Narrows Bridge was famous for this when the wind was blowing and the bridge was slightly wet. More recently, these out of control harmonic oscillations have famously been seen on the Millennium Bridge in London (surprisingly due to human footfall) and the Humen Perl River Bridge in China (heavy winds). A full discussion of how to control oscillation is outside the scope of this answer. However, it is relevant to note that some materials are springier than others, and these materials are the ones more likely to have pathological oscillation. Vibration Vibration is a form of oscillation, but I'm breaking it out so I can specifically address how it affects sensor data. Vibration is an issue when it causes signal integrity issues with the IMU (i.e. accelerometer + gyrometer)[*]. This can confuse the autopilot, leading it to make incorrect estimations of the aircraft's roll-pitch-yaw, and as a result respond inappropriately. This can and does cause crashes. Again, a full discussion of how to control vibration is outside the scope of this answer. And once again, the springier the material is, the more it is likely to have pathological vibration. Composites vs. metals Composites (e.g. carbon fiber, fiberglass, kevlar, ...) have what are called anisotropic properties. This means that they don't have the same properties in all directions. Consider a square sheet of aluminum. No matter which axis you pull it on, it has the same strength, stiffness, heat transfer, etc... This is isotropic. Now consider the same sheet made out of unidirectional carbon fiber. Along the carbon fiber axis it's incredibly strong. But turned 90 degrees, where the only thing holding it together is the glue, you'll find that it has no strength whatsoever. You would be correct in assuming that this difference in properties extends to oscillation and vibration. The upshot is that composites can be tricky to chose because two seemingly similar structures (e.g. a tube) can have very different properties. [] Able to move and bend, like the Goshawk. [] See math in https://drones.stackexchange.com/a/323/46. [*] For example, aliasing and clipping.
H: Is it a good practice to use a throttle limit of 90% for racing builds? I had read somewhere that it's a good idea to set a throttle limit of 90% for racing. The reason given was that, in the last 10% of the throttle, the cost/benefit ratio for power to thrust would not be worth it. Is there any truth to this? If so, what is the recommended throttle limit for any build/all builds? AI: The reason why this is recommended for racers is likely due to the fact that during these high-throttle punches, the voltage of the battery sags from the load and so more current is pulled from the battery to increase the motor RPM. Power is equal to VI when V is voltage and I is current, which can be rewritten (by substitution of Ohm's law V = IR in for V) as I^2 * R. This means that if more current is drawn to compensate for a voltage sag, the power consumed by the motors increases by a greater amount because the resistance of the circuit is constant. (for all intents and purposes) For example, in the hypothetical scenareo that twice the current is drawn, four times the power would be consumed. This results in quicker battery drain. The 10% figure that you've heard isn't a hard line, but rather just a suggestion based on experience with miniquad hardware and its capabilities. This recommendation isn't just specific to racing; all quads would benefit from the efficency (energy extraction from the battery) boost from rarely using the top XX% of the throttle range. However, this is often more important in racing scenareos where it is often necessary to make the most of the energy in the battery pack you're using because you've selected the smallest and lightest one possible and need as much energy as you can get to complete the course in record time.
H: "Rogallo wing" balsa rubber-band model plan - do you have one? Several decades ago - 4 or 5 at least - I saw a plan in a model aircraft magazine for a very simple rubber-band driven plane that used a piece of a dry cleaner bag (thin plastic wrap style) as a Rogallo wing. Wingspan was maybe 2 feet. Wing spars were simple 3/16" (approx balsa sticks), the body was simple balsa too. Flew great - I built several back then! Now, I'd like to experiment with that again and would really like to have some tips - the original plans would be great if someone has a stash or online scan of it in whichever model aircraft magazine it was ... but any information on model-scale Rogallo wings would be useful to get me started. AI: I found this plan online, which might be similar to what you want. The wingspan is about right, it uses a Rogallo wing and the text in the bottom-right suggests it was in a magazine called the "American Aircraft Modeler", if that rings any bells? (Your profile indicates America, so it sounded promising.)
H: What is the purpose of adjusting the thrust angle for model aircraft? I have a few model aircraft and know that the motor is often slightly offset. I have heard conflicting reasons as to why this is done. Some people claim it is because of motor torque and other people say that it is done because of other things, and not really because of torque. What is the most significant reason that the thrust angle is usually adjusted on model aircraft? AI: Typically the motor will point down and to the right. There can be various reasons for this. I've included a plans excerpt from https://aerofred.com/details.php?image_id=91062 Downward angle Sometimes it's to align the motor with the true flight direction, because the wings need some AOA (Angle Of AttacK) greater than 0. In the excerpt above, you can see that there's a 3 degree downward tilt. If you look at the original plan, the wings are mounted flat to the fuselage. A 3 degree AOA is pretty normal for cruise flight, so this motor is mounted so that it's pointed in the direction of movement. If it were not pointing downward, then when you changed thrust it would have a tendency to momentarily sink/climb. Another advantage of pointing down is that it increases pitch down tendency (or decreases pitch up tendency) when power is applied. Pitching down is safer since it drives you away from stall, instead of toward it. This is especially valuable in the case of positive pitch stability craft where there is a natural tendency to pitch up as airspeed increases. You'll find that full-scale aircraft have the motor aligned with the fuselage, but their wings mounted at a 2-3 degree incidence angle so that the fuselage is level while the plane is flying forward. It turns out that the squishy humans seated inside prefer not to be seated on a slope. Pointing to the right In some models, the motor can be turned to the right so that its thrust counteracts the p-factor, which tends to turn the plane to the left. This makes the plane easier to handle when under high power at slower speeds when the rudder is less effective.
H: How to identify and address multirotor motor overheating When flying my drone, I often notice my drone motors getting hot after a flight and am concerned that it could explode/blow up. What does a hot drone motor mean? Is this something to be concerned about? What could be done to prevent overheating? AI: Assuming that you've spec'ed a good propeller-motor match and the heat isn't generated by a tiny motor being forced to drive a giant propeller, the heat generation is likely due to a physical issue with the drone, mistaken filter settings, or a tight PID tune. First of all, it's a good idea to determine whether your motors are actually hot enough to matter. A good rule of thumb I've heard commonly thrown around is that if your motors are SO hot to the touch that you want to take your fingers off after a few seconds, then that's too hot. If you feel like you could keep them there forever, then it's probably not something that will ever be a problem. Physical Causes It's possible that you have a mechanical connection issue somewhere on your drone which is causing problems, like if one of the motor fastener screws is protruding into the motor casing and making contact with the windings like in this video from Joshua Bardwell which also goes through troubleshooting steps and how to rectify the issue. Other physical causes can include locations on the drone where parts or wires (like motor phase wires) that are touching conductive things they shouldn't be. Giving your drone a look over to make sure any of these aren't the problem is worth a try. Also, make sure that the hot motor is still balanced. If the motor has been damaged, that is almost certainly the cause of the elevated temperature of the motor. Filtering Issues If you ever went into the configurator for your flight controller firmware (e.g. Betaflight, Cleanflight, Raceflight, iNav, etc.) and disabled or restricted the default gyroscope filtering settings, it's possible that these are the culprits. Insufficient filtering on the noisy gyroscope signals can result in hot motors because the flight controller tries to respond to the noise it sees in the gyroscope data and not just the pilot's inputs. The inconsistent nature of the gyro noise means that motor commands would be constantly changing up and down, which can be a cause of hot motors. If you ever tweaked the filtering settings to try and improve their latency, it's possible that any crashes you've since experienced have beat up the drone sufficiently that there is now extra noise that wasn't there before when you adjusted the filters, causing hot motors. In that case, I'd recommend raising the filter sensitivity. The Betaflight Configurator for >4.0 versions of Betaflight makes this super easy with a slider that you could push towards increased filtering. PID Tuning Factors As noted in this (admittedly old, for Betaflight <2.x) Betaflight Tuning Guide, motors will start getting hot if your D-gains are too high. I would recommend checking all of the previous situations before pursuing this case because issues with the PID gains are often more subtle and difficult to track down, but a solution here would be to slowly back off on the D-gains in your PID controller until the motors cool down sufficiently. The D term in the PID controller tries to look ahead into the future and consider if the controller is trying to reach the pilot's input commands quickly enough, attempting to slow the reaction time or speed it up as necessary to minimize overshoot. This system can be completely screwed up if excess noise enters, so checking the filtering settings to make sure nothing is wrong there first is a good idea.
H: How does the center of gravity affect a quadcopter? I have heard a lot about center of gravity for fixed wings, but very little about the CG in quadcopters. How does moving the CG forward or backward impact the flight characteristics of a quadcopter? For example, if I had a 5 inch drone, how different would it perform if I moved the CG from the center to a position right behind the front two motors? AI: Altering the location of the CG (center of gravity) also changes the CM(center of mass) because the force of gravity acts roughly on the CM. Normally, the motor arms are equally sized so that all motors have equal control authority and all contribute equally to providing thrust while in level flight when the CM is close to the center of the multirotor. Another way to say this is that multirotor frames are constructed so that the CG, CM, and CL (center of lift/thrust) are all as close as possible to one another. However, this is no longer the case because now each of the motors now has a slightly different lever arm distance to the CM of the multirotor. Consequently, not all of the motors have the same control authority and some of the motors will have to remain at higher/lower throttle than others while in level flight. This will manifest itself in diminished flight performance. If all motors are running at the same throttle, the multirotor will naturally begin rotating with the longer lever arm(s) going upward and the shorter one(s) going down. If the distance between the CG/CM and CL isn't too great so as to not make the multirotor immediately flip over after raising the throttle, the I term in the PID controller of your flight controller should be able to account for the discrepancy after takeoff. The ability to pitch/roll in different directions will be different due to the asymmetric thrust distribution around the CG/CM. Even so, it isn't ever recommended to fly with a significant distance between the CG/CM and CL. All (half-decent) frames are designed to minimize the risk that component placement will move the three far from one another, but this is an important consideration for scratch-built frames. In the example from the OP, a case where the CG/CM was moved from the center to a location right behind the front two motors, the effects would be quite severe indeed. It's difficult for me to come up with a practical setup to create such a situation, but this is a good example of a worst-case situation, with the CG/CM to CL distance being close to 2/3 the arm length. (depending on the angle between the arms on the frame)
H: At what point does drone insurance become worth it? Should the average enthusiast buy drone insurance? I'm expecting it to be essential for commercial use, or if the drone was used in a busy area, but what if the drone was a collaboration between multiple people? AI: This is a personal approach, so like all financial advice it's only worth what you paid for it. If you have worked with the insurance industry in the past, you will likely have learned that good insurance companies pay out almost (if not more) money than they take in. This is because what the insurer is doing is taking the premiums and lending them out, much like a bank. So when you spend \$100/yr across 10 years, and you get back a $1000 payout in the tenth year, the entire time the insurance company has been earning interest on the money you gave them. This 5-10% overhead is quite profitable when you have tens and hundreds of billions of dollars stockpiled. The upshot is that insurance won't save you any money in the long-term, it only spreads the financial pressure of a decision across time. I only consider insurance worthwhile when the cost of throwing my hands up and walking away is unacceptably high. Put another way, I only get insurance when either required by contract or law (e.g. renters insurance or auto insurance), or when I cannot afford the consequences of not having the thing which is insured. Worthwhile: I have a pet, and I don't want to have a financial consideration enter into whether life-saving surgery is an option. Not worthwhile: I have a television which I don't really watch and wouldn't miss it if it weren't there anymore. You'll have to decide for yourself the impact of losing your drone. If it's just a toy and you don't think you'll fly it again if you lose it, then maybe it's not worth the cost of insurance. If it's your livelihood and you can't afford to buy another one then insurance is a guarantee against catastrophic business failure. Or if the amount of damage you could do with your drone could cause you to be personally liable for a ruinous amount, then you might want to protect yourself with insurance. P.S. Drop a comment when you decide, I'd love to know how your reasoning went.
H: Putting decorations onto a drone? I want to jazz my quadcopter up a bit, maybe put some stickers or little sequins. Will these affect the flying capability of the drone, even though they aren’t that heavy? Will this affect balance? AI: So long as your additions are very lightweight compared to the drone - like stickers or paint - this should not have a significant effect the balance of your drone. However, you want to make sure that you do not cover any ventilation holes or heat transfer surfaces as this might affect the lifespan of those parts. In the case of metallic additions (shiny stickers, sequins) it is good practice to keep these clear of the antenna as they may affect the radio performance. You should avoid adding anything to the propellers or motors as these do need to be precisely balanced.
H: How to measure the RPM of a drone motor using Betaflight? I am interested in finding out the RPM of the motors on my drone with certain amounts of load and without load. Is there some way to measure the RPM of a drone motor using BetaFlight? If not, is there another way? Not sure if it matters, but I am using the SucceX-E 45A 2-6S BLHeli_S Dshot600 4-in-1 ESC and some Xing-E 2207 2750kv motors. AI: Bi-directional DShot can help you here. After updating the BLHeli firmware on your BLHeli_32 ESCs to the latest version (support was added only recently) and the firmware on your flight controller to Betaflight >4.0 (PR on Github), you can go into the Betaflight Configurator app and enable Bi-directional DShot under the Configuration tab. It must be said that the easy BLHeli ESC firmware upgrade is only available for BLHeli_32 ESCs. There are ways to get support for bi-directional DShot on BLHeli_S ESCs, but they're more complicated. Instructions are linked to on the Betaflight Wiki page. Motors tab in Betaflight Configurator The ESC-reported motor RPM values will then be displayed under the R label next to each motor in the Motors tab. OSD Widget There is also an OSD widget for viewing motor RPMs, called OSD_ESC_RPM in the code, which can be enabled under the OSD tab. BlackBox As @BenWilson points out in his comment on this answer, you can also set the BlackBox debug mode to DSHOT_RPM_TELEMETRY and get motor RPM values recorded in your BlackBox log The implementation is described on the Betaflight Wiki here.
H: Flying a UAV with a banner? I want to attach a banner to a UAV like this: I have two questions: Firstly, is it even possible to fly a UAV like this with the banner visible? What sort of design considerations would I have to take into account when attaching a banner to a UAV? Briefly sketching forces that act on the banner, we can see that there needs to be two strings connecting to the aircraft at A. There's also no force that directly counters the weight of the banner, but aircraft tend to solve this problem by simply increasing the length of the banner and having the power to overcome the added air resistance. AI: It should be possible so long as the aircraft has enough spare thrust and lift to counteract the drag and weight. Many model aircraft have good power-to-weight compared to their full size equivalent. For the banner attachment, you need a secure point to attach it to the aircraft, well away from any propellers or control surfaces. Usually this is on the bottom rear of the fuselage. It is a good idea to include a 'weak link', which will break if the banner snags; this leaves the banner behind, but saves the aircraft being pulled from the sky. You will also need to weight the banner to hang in the correct orientation - making the vertical part of the banner support bottom heavy should suffice. You can fly banners from both fixed-wing or rotary wing aircraft, in slightly different ways. Fixed wing banner extends behing the aircraft, whereas on a helicopter or multirotor the banner hangs below. Image source
H: Is it possible to control an RC plane using reaction wheels? I recently had an idea involving reaction wheels and a model airplane. Would it be possible to control an RC plane using reaction wheels rather that servos and control surfaces? Would a reaction wheel controlled plane be able to function similarly to a "normal" model airplane and would this be practical at all? AI: Yes, it would! A YouTuber, Thomas Stanton, has actually built a helicopter controlled with reaction wheels in this video! However, for a fixed wing aircraft, you would also have to consider the location of the reaction wheels relative to the centre of mass, and you would most likely want to house the reaction wheels internally to avoid adding extra drag. You would also have to have a reaction wheel for each axis. However, this should be relatively simple, so the answer to your question is yes, it is possible. In answer to your other question of practicality, as far as I am aware there have not been enough studies in the RC sector to say for certain, but my personal opinion is no, it would not be practical due to the added mass and the problem of weight distribution, plus the limited space inside an RC aircraft and the advantageous torque traditional control surfaces give.
H: How do ducted fans impact drone performance? There are many drones available which use ducted fans as opposed to open propellers. How does a ducted fan quadcopter differ in performance from an open-prop quadcopter? Note: the other question asking about shrouded propellers is different and its answers do not answer this question because it asks specifically about the impact the shroud has on the production of yaw by the torque produced by the propellers. AI: There are a number of performance differences between open-blade quadcopters and ducted fan quadcopters and they may depend on the shape of the ducts. In theory, the most notable difference in performance is the increase in either hovering efficiency or increase in thrust. When a drone has the ideal shape of ducted fan, it could decrease battery consumption by up to 60% or almost double the thrust. However, many drones that use ducted fans don't have a duct with optimal shape or have heavy ducts and thus won't get as significant advantages. An optimal duct for hovering would look something like this: Also, for larger quadcopters, creating a ducted fan with tight tolerances would probably add a lot of weight which would diminish the usefulness of the duct and if a duct is severely limiting the prop size, it can limit the quadcopter's efficiency because larger props tend to be more efficient. Another impact on performance that can be caused from using ducts, (especially for high performance or fast quadcopters), is ducts can cause the drone to react strangely when performing aerobatic maneuvers because the ducts can catch the wind and push the quadcopter off course. The ducts can also add more drag when the quadcopter moves fast. An open-blade quadcopter is generally smoother when performing fast movements or maneuvers. In the end, If a drone has ducts with tight tolerances that don't add too much weight and has the "optimal" duct shape, it will probably be more efficient and get better flight time than a similar open-blade quadcopter but it may be less smooth and efficient when performing fast aerobatic maneuvers. Source of information about efficiency: The ideal shape for a multirotor ducted-fan
H: Disposing of a drone safely Related: How do I safely dispose of my LiPo batteries? If my drone crashes and I want to dispose of it, how can I do so safely? Is it necessary to disassemble the drone into different parts: motors, batteries, propellers, shell etc. ? AI: In the UK a drone would almost certainly be considered WEEE waste (Waste Electrical and Electronic Equipment.) You can take WEEE waste to your local waste handling/recycling facility; alternatively, there are "Take back Schemes" where some distributors will accept WEEE waste. This is often geared more towards white goods (fridges, washing machines, etc.); unfortunately you will need to check locally.
H: What mission planner should I be using for INav? I'm new to the quadcopter community and am looking to plan my first mission for my drone. As far as I can tell, the recommended mission planner is an Android app? I am hoping there is a good alternative to this for INav. I just want to check it can leave the ground with a simple hover at 1m and land? AI: This is the official recommended mission planner for INav on the Google Play Store: https://play.google.com/store/apps/details?id=com.eziosoft.ezgui.inav&hl=en From the official GitHub repo: Mission Planner for INAV can be downloaded from the Google Play Store. There is a free version which limits number of waypoints to 5 and (very reasonably priced) paid-for version with additional functionality. The application is not open source. For questions and help the RCG "Mission Planner for INAV" thread can be used: RC Groups support forum. There used to be an app for iOS as well, but this is no longer available on the app store. Another app for Android is Droid Planner 2: Droid Planner 2 can also be downloaded from the GitHub. It is free and released under GNU Public License v3. Droid Planner only supports iNav's one-way MAVLink protocol. The following telemetry data is displayed: Vehicle position on map, active flight mode, heading, altitude, speed. A broken connection recovers once restored after any amount of time. The flight track remains on screen even when data link is broken -> lost model recovery. Log files can be opened in PC software Mission Planner. More options can be found in the GitHub repo.
H: How hot is too hot for a VTX? I have heard that when a VTX gets too hot, it can cause irreversible damage to the VTX. I have sometimes noticed that the VTX on my 5-inch drone gets very hot to the touch. How hot is too hot for a VTX and what are some signs that the VTX on my drone might be getting too hot? AI: Transistor junction temperature (aka junction temperature or Tjunction) is the rated maximum operating temperature for a semiconductor before it will either permanently fail or produce possibly damaging outputs to other components in the circuit. Desktop computer CPUs often have a Tjunction of ~100 °C, and this site claims that most commercial-grade semiconductor parts have a max operating temperature of ~70 °C. (cit. ROC = Recommended Operating Conditions and AMR = Absolute Maximum Rating) Abiding by the manufacturer's specs for thermal limits is usually a good idea assuming they're published, but staying below 70-80 °C is always good. Redlining temperatures in between the ROC and AMR will result in decreased efficiency and abnormal behaviors of the transistors in the ICs and switching components in the VTX, like the power regulators (most of which use inefficient linear regulators which dump a lot of wasted energy as heat) and signal processors. Some of these abnormal behaviors may cause the kind of irrevocable damage to the VTX mentioned in the OP and will for sure decrease the VTX's power efficiency. This can cause the VTX to fail mid-flight and leave you high and dry without a video feed. High VTX temperatures could also have adverse effects on other parts of your drone if in close proximity by heating them up as well. Possible solutions As Oscar Liang points out, you could try: Replacing the (usually metal block) heat sink on the VTX with something better Take load off of the voltage regulator in the VTX by installing a more efficient switching regulator to step down Vbattery before it gets to the VTX. Move the VTX to a location where it sees more airflow. Try replacing the VTX; it could be dead/dying.
H: At what voltage per cell should I store a LiPo? Some sources say you should store your batteries at 3.85V per cell, other says it should be 3.7V. My charger (ISDT Q6 Lite) on the "Storage" mode has a thumbs-up mark at 3.7V, probably indicating that it's the best voltage, at the same time when I ordered some CNHL LiPos, they came charged to ≈3.85V per cell. Are there any papers/experiments about storage voltage or maybe this difference is neglectable? AI: This question seems to be quite the debate in many places. However, the general consensus falls between 3.7 and 3.85v per cell. You can find a similar inquiry here: Storing at 3.7 or 3.85v and here: LiPo storage voltage It seems that generally, the difference between storage charging to 3.7v, 3.8v, or 3.85v is negligible for most people. However, I would recommend 3.7-3.8v per cell. I store my LiPos at 3.8v per cell and all of my year-old LiPos perform almost like they are brand new. The exact voltage you storage charge LiPos is important, but it is even more important that you just take good care of them and do storage charge them. It's better to storage charge LiPos to a close enough voltage than to not storage charge them at all. Here is a pretty useful guide to LiPo batteries: Guide to understanding LiPo batteries
H: Determining the mAh of 4S battery for a 3 inch drone I have a 3" drone frame, flight controller that can take 3S or 4S LiPo, and 1507 4200KV motors. How do I find the right capacity of battery to purchase? Should I purchase 4S 850mAh or 4S 1500mAh? And why? AI: As @JacobB suggested in his comment, first check all the parts of your aircraft that connect directly to the battery can accept 3S or 4S voltages (usually the flight-controller and esc.) This may immediately constrain your choice. First you need to calculate the maximum weight your drone can lift; you can work backwards from this question: Get the thrust per motor for your drone Multiply this by the number of motors Divide by two Weigh the drone without the battery and subtract from number above This will give you a target maximum weight for your battery. You can then choose the highest capacity battery that falls in this range. More expensive batteries will give slightly higher mAh ratings at slightly lower weights - to work out what is good cost/flight time balance in your situation, you can estimate the flight time for a given mAh rating with the following formula: $$Endurance = \frac{ 0.8 * Ah }{ AverageAmpsDraw } * 60 $$ [source] Note - if your battery is labelled in mAh, divide by 1000 for Ah
H: How to measure the pitch of a propeller? I have some random drone propellers which I don't have any information on. I looking to find a way to measure the pitch of the propellers to figure out if they will be well suited to a 5-inch drone I have. Is there any way to go about measuring prop pitch? (at least somewhat accurately) AI: Theoretically the pitch of a prop is supposed to be the distance it would move in a full rotation (in an ideal world). As most modern props vary pitch along their length, a single number is almost impossible to measure. Manufacturers tend to give a number which is an indication of how the user would expect the prop to perform. Most propellers will work on any 5" drone, they usually have the pitch printed on the upper surface of the blade near the leading edge.
H: Why are quadcopters inherently unstable? I have heard it mentioned that quadcopters are inherently unstable and only become stable due to control. What does inherently unstable mean in this context, and why are quadcopters inherently unstable? AI: A stable system is one where there's a force that pushes the system back towards it's original state when the system is moved from its balance point. For example, when the driver gets into a car, there's more weight on one side of the car than the other but the car doesn't flip over. The springs on that side of the car compress and push harder on the wheels. The tyres push harder on the ground and the ground pushes back. The extra force from the ground exactly balances the extra weight and (after possibly bouncing for a moment) the car stops moving. In an unstable system, say a broom balanced vertically, once it moves from the perfect balance point gravity will pull it further away and it accelerates. For a quadcopter, there is no force that returns it to its original location, holding it horizontal, or even preventing a gradual roll. Even if the thrust from each motor was exactly the same, and the weight was perfectly balanced, it's very unlikely to be perfectly stationary. If there's even the slight amount of pitch or roll, the angle from horizontal will gradually increase. As the angle increases, the sideways thrust increases and the drone accelerates. So the roll rate is constant, the angle and acceleration increase linearly, the horizontal speed increases faster as the acceleration builds, and the distance from the starting position increases even faster as the speed builds. To the pilot, it looks like the drone is accelerating away from its original position much like the broom falling over. To a systems engineer, the rotation of the drone is neutrally stable - there are no forces increasing or decreasing the rotation rate. However the speed and position are unstable - once it starts moving, it accelerates. I should mention that there are second-order (i.e. relatively minor) forces too. If you had a large fin on top of the drone, aerodynamic drag on the fin would return the drone to upright as the speed builds and limit the maximum speed - in practice this isn't useful as it doesn't return the drone to its original position.
H: Does the sharpness of a propeller blade affect efficiency? Some of the propellers I have used on drones have sharp edges (sharp enough that they have cut me) and others have comparatively dull edges. Does the sharpness of the leading edge of a propeller impact the efficiency of a quadcopter at all? Would it be better to use propellers with sharp or dull leading edges for race drones? AI: Rounded leading edges are better for subsonic aerofoils. Props and wings have to work at a range of angles of attack. The airflow has to split to pass either side of the aerofoil, and a rounded leading edge allows the separation point to move smoothly. Sharp leading edges cause a lot of drag at extreme angles of attack when air has to flow across the sharp edge. That said, the sharp edge on some props is just mould flash and can be sanded off with fine sand paper. Sharp trailing edges are OK aerodynamically but easily damaged, and dings in thin plastic can cause drag, so there's a practical limit to the sharpness of a trailing edge.
H: How do thrust requirements change as a multirotor leaves ground effect? Assuming either a quadcopter or a hexacopter, is there any published data on how much more energy is expended to escape the ground effect? Is it a function of the thrust being produced to lift the multirotor? And is it different for a quadcopter than for a hexacopter? Is the requirement lower when the props are higher off the ground? AI: To fly above ground effect, you need thrust equal to the weight of the aircraft (or slightly more, as you want to climb). Ground effect doesn't hold aircraft down, it just makes it easier to fly when they are close to the ground. The exact amount varies quite widely depending on exactly how close the wing/rotor is to the ground. For a plane or helicopter it may only be 10% extra lift, but a vehicle designed to maximise ground effect (like a hovercraft) can fly with vastly less power than would be required to fly without ground effect. Ground effect is particularly noticeable if you hover a model helicopter inverted over a smooth surface. As it descends towards the floor, it looks as if it lands in a big soft cushion - decelerating and bobbing around at about half to a third of rotor diameter. You can hover without the constant adjustments in collective pitch that are normally required, and need to drastically reduce thrust to go lower. When you're half an inch or less off the floor, it's probably only using 10-20% of the pitch required for normal hovering, and there's a self-levelling effect so it's much easier than it looks! For a typical FPV quadcopter with 5" props on top of the motors, you almost can't feel ground effect if you put the battery under the frame. With the battery on top you can feel a noticeable cushion and you can find a throttle setting that holds the quad off the ground but won't climb out of ground effect. I'd estimate that it's flying at about 80-90% of normal power. While the power may be reduced, it can be harder to hold a multi-rotor or helicopter in place when in ground effect. The bubble of higher pressure tries to escape out from underneath the aircraft, pushing it in the opposite direction. A general rule of thumb is that the reduction in power due to ground effect starts to be noticeable when the altitude is less than around half or a third of the wing span or rotor diameter. The 'air bubble' effect on position holding while hovering is noticeable one or two diameters above the ground. Both tail off gradually so there's no hard limit. See also: * What is ground effect? * How high does the ground effect last? * Does ground effect scale 1:1 with wingspan? and lots more, over at the Aviation stack-exchange. Also this excellent academic paper: Characterization of the Aerodynamic Ground Effect and Its Influence in Multirotor Control
H: Do propellers layered on top of each other have twice the thrust of one propeller? If you had two of the same propellers layered on top of each other going at the same RPM, with some space in between, would the thrust be double the amount of a single propeller at the same RPM? If not, what factors affect this? The propellers are pushing down on the ground by the way. AI: At least at the small/model scale, the answer is no. There is significant efficiency loss due to the stacked propellers not receiving the same clean air as they would if they were horizontally separated. This is demonstrated experimentally in a Youtube video by rctestflight which compares the efficiency/thrust production of three different propeller configurations sharing the same propeller type and motor type: Coaxial — What you're talking about where two props are stacked vertically so that they share the same rotational axis. Overlapping — Where two props' discs overlap each other by roughly half a prop diameter Normal — Where two props are positioned side-by-side without any overlap To quote Daniel from rctestflight in his video: Any prop overlap is significant in efficiency loss. Traditional side-by-side motors are 25% more efficient than coaxial and 8.4% more efficient than overlapping props. To me, losing 25% efficiency is not worth the small form-factor and increased ease of transportability that a coaxial system produces.
H: Where to find model aircraft with moving parts? I came across a model F22 raptor here and here but I am looking for a place where I can get one with moving parts, e.g retractable landing gear, canopy and the likes with a sizable scale, maybe 1:48 or thereabouts. I have had no such luck online, do such models exist without having to get RC models? AI: I don't have any models from this site, but it appears from their product descriptions that they have what you're looking for on themotorpool.net. They have a plethora of models of all nationalities, classes, and time periods. For example, their Bf 110E-2 model is described as having "spinning propellers" and the "ability to display the model with landing gear in either extended or retracted mode". From what I can tell, almost all of their models have movable parts of some sort.
H: Do flexible propellers affect multirotor efficiency? There are a wide variety of materials and methods for making the propellers used on drones. This leads to certain propellers having different characteristics than others. Some propellers are more flexible than others and I am wondering how that would impact the efficiency of a drone? AI: It's really a challenging question to answer because flexible and stiff propellers both have their advantages and disadvantages in terms of efficiency. Flexible propellers are typically lighter than stiff propellers, so they spin-up more efficiently than stiff propellers. On the other hand, when a propeller is spinning at higher speed, a flexible propeller will have a tendency to flex upward and flatten out vs a stiff propeller that is designed to resist flexing (stiff propellers will still flex, but not as much as a flexible propeller). With a flexible propeller, this could result in a scenario where you have more throttle to give, but the drone won't go any faster. To some degree, you might also notice that the drone is less controllable - might not take a corner as well as a stiff propeller would. If you have a lower powered motor, a flexible (lighter) propeller might be your best option because you may never reach the point where efficiency is an issue. However, if you have powerful motors, and your desire is for speed, then a stiff propeller will probably be more efficient at higher speeds than a flexible one.
H: Does frequently changing the amount of power to a bldc motor wear it out? If you had a brushless dc motor and kept it running but changing the power input every few seconds/minutes would it wear it out? I ask because for a drone like aircraft I'm designing, making turns requires change in rpm and input power. If it helps, the motors are large and 167kv bldc motor with 100cc. AI: No, changes in speed should have little effect. The only wearing part of a brushless motor is the bearings, which are generally rated for a certain number of rotations and a certain load (and are reasonably easy to replace). With IC engines there are complex issues piston and bore temperature, expansion, lubrication and heat cycling - but electric motors are much simpler.
H: Do propellers at different angles work the same? And do intersecting flows of air work the same? Say a propeller pushing thrust downwards generates 70 lbs of force. If you tilted the angle of the system to 45 degrees would it generate the same thrust? If you had each rotor angled inwards of a system like this, assuming that the system is on the ground, would the airflow be the same or cancel each other out a bit? (the arrows is airflow direction) Thanks AI: The motors would still generate the same amount of thrust, however it would be aimed in a different direction. Think of the thrust as horizontal and vertical vectors. You can work out the ratio of these vectors using trigonometry to work out how much of that thrust is going to be effective in the downwards direction and how much will be horizontal.
H: Why is 900 MHz better for long range than 2.4 GHz? There are various transmitter modules like the FrSky R9M system which operate at around 900MHz rather than the more commonly seen 2.4GHz. Why is 900MHz better for long range drones, and why is 2.4GHz so common if 900MHz can provide better range? AI: The strength of an electromagnetic signal will attenuate (decrease in strength) over long distances between the receiver and the transmitter due to the inverse square law, but this phenomenon applies equally to all wavelengths/frequencies. The main difference in transmission distance capability between long-range RC systems like TBS Crossfire and FrSky R9M (which use the 900 MHz ISM band) and run-of-the-mill RX systems that use the 2.4 GHz band is due to the diffraction (and reflection) of the signal by obstructions in and around the line of sight between the transmitter and receiver. This process is explained well in this Electronics.SE answer. Essentially, lower frequency (longer wavelength) signals are less susceptible to signal strength losses by reflection and diffraction because they require larger objects to affect the signal in the same way. As the Electronics.SE answer points out, this becomes easier to conceptualize if you look at two different frequencies like 1 MHz (wavelength of 300 m) and 100 MHz (wavelength of only 3 m). If there's, for example, a house or other large object in the vicinity of the path between the transmitter and receiver, the 1 MHz signal with a wavelength of 300 m will find it a lot easier to avoid being disturbed and reflected than the 100 MHz signal with a wavelength of 3 m for the simple reason that it is just so much larger in comparison to the house. At extremely long ranges (like over the horizon), other effects also come into play like the ability of lower frequency signals to more easily reflect off the curved surface of the earth and the ionosphere, but these kinds of transmission distances aren't an issue for RC aviation for more practical reasons. :) 2.4 GHz RC solutions are far more ubiquitous because the antennae required to transmit and receive signals at a frequency of 2.4 GHz are far smaller than those required for 900 MHz. This is due to the change in wavelength between the two frequencies and is evident in the size difference between 2.4 GHz receiver antennae and those for 900 MHz: TBS Crossfire Immortal-T antenna: (The active section runs horizontally in the picture) Futaba 2.4 GHz receiver and antenna: (The active section is silver/white in the picture)
H: Do aerodynamics scale for model aircraft? If I wanted to make a scale model plane that looked like a real aircraft, could I just scale down all of the measurements of the actual aircraft to make a model aircraft with similar flight characteristics? If not, what is the reason? AI: Aircraft do not scale linearly, for a number of reasons. Most aerodynamic equations include a speed squared term. If you halve the speed, you only get a quarter of the lift and drag, so models tend to be lighter and less powerful than you'd expect. If you make a plane with half the wing span, it only has a quarter of the wing area. So now a half size model flying at half speed only has one sixteenth of the lift. Reynolds number - air flowing over a surface will start with laminar flow but turn turbulent after a while, depending on the speed (and density and viscosity but we can ignore those). A smaller, slower model will see more laminar flow than the full size aircraft. In practice, this is a relatively small effect compared to the previous factors but it's an important consideration for high performance models. Example A full size Spitfire had a wing span of 36 ft 10 in (11.23 m), a weight of 5-6000lbs (2-3,000kg) and between 1000hp and 2000hp depending on the variant, with a maximum speed of around 400mph. If you scaled it linearly, a 1/10th scale model would have a 1.1m span, weigh 200kg, have 100hp and fly at 40mph! If (as Phil suggests) you scale weight and power by 1000 (10 cubed) it would weigh 5-6lbs and have 1-2hp, which is close but still heavier and more powerful than real models: A 72" model (1/6th scale) might weigh 15lbs and have 2.5-3KW (4hp) and fly at 100mph. A 44" model (1/10th scale) might weigh 2-3lb and have 2-300W (1/2hp) and fly at 60mph. A 36" model (1/12th scale) might weigh about 1lb and have 100W (1/7th hp) and fly at 50mph
H: How to prevent an ESC from overheating? I have a 5-inch drone with individual ESCs on the arms of the frame. The ESCs tend to get very hot (somewhere around 70°C) and I'm not sure what is causing this and how to keep them cooler. Are there any ways to keep the ESCs cooler without adding too much weight to the quadcopter? Or is there anything I can do in the tuning to keep them cooler? There is enough room to add things like heat sinks. (although I don't want to add too much weight) AI: Under normal conditions operating on the arms of a multirotor, ESC temperature should be well-controlled by the airflow passing over them from the propeller exhaust. It isn't a good sign that your ESCs are reaching dramatically higher temperatures like 70° C, given that you should be expecting to see ~30-40° C on a regular basis. One of three things is likely to be happening here: The ESCs are undersized for the motors/propellers you have them driving The ESCs are broken and showing signs of wear The design of the ESCs is bad Your PID/filter tuning settings are bad Without knowing the exact details of your multirotor setup, it could be the first case due to the ease of accidentally picking too small an ESC to pair with power-thirsty motors and propellers. If this is true, then you should replace the ESCs with properly sized units, because there is a possibility that the overworked ESCs could catch fire or spontaneously die on you. (not to mention the fact that the efficency of the ESC will be decreased at higher temperatures) However, the likely causes change because you're running a smaller multirotor, as @QuadMcFly said in his comment below: (emphasis mine) I would add for a 5" inch drone it is extremely unlikely that the issue is related to the ESC. I have run even tiny 20A ESCs on some ridiculously overpowered setups and they come down cool when tuned properly. In the vast majority of cases, hot ESCs come from bad tuning or bad hardware, either in the FC or the ESC. The first place I would look is at flight logs of the gyro and motor output data. That will tell you right away if it's a tuning issue. Mitigation of ESC Related Thermal Issues The heat you see generated by the ESCs is likely related to the power losses in the MOSFETs (metal–oxide–semiconductor field-effect transistors) used by most all ESCs to switch the power and off between the three phases of the BLDC motor. There are calculable power losses that occur while the MOSFET is conducting electricity and when it switches state between on and off, both of which contribute to heat generation. The most direct solution to the issue is to add a decently-sized heatsink to the top surface of the MOSFET transistors and capacitors on the ESCs. You'd likely have to remove the plastic insulation for the best heat transfer between the MOSFET casings and heatsink. Something like this, although with the insulation removed: (cit.) When you re-affix the ESC to the frame arm, it would be best if you also put down some kind of electrical insulation like electrical tape on the surface of the arm between it and the ESC so that there isn't a risk of the frame shorting out an ESC component.
H: How to reset connection between drone and RC for MAVIC Air 2 My new dji Mavic Air 2 arrived, but it was not connected to the remote control as it is supposed to be connected upon arrival. I then tried connecting it manually following the on-screen instructions of the DJI Fly App, but the Mavic Air 2 doesn't go into the pairing mode when I press the on/off button for 4 seconds or more. The connection between the App and RC works. The drone is turned on, it does its self-test and briefly beeps. The 4 LEDs are constantly on. Holding down the power button makes it flash slowly, but there is no beep and the LEDs will stop flashing when I release the button. Is there any other way to reset / pair the drone to the remote control? AI: In this case there is no way to reset the connection. It is a defective unit. I sent it back and ordered a new one. Result of chat discussion with @Daniil: I couldn't connect the drone to the RC nor to a PC/Mac (it never showed up in the DJI Assistant for Mavic nor in the usb device list), and therefore not reset or update the drones firmware. @Daniil and me concluded, the drone is defect. I sent it back to Amazon and ordered a new one. I also opened a support ticket at DJI, describing the problem. So far I got no response, but hope they use this feedback to fix the bug and improve their QA.
H: How to clean dirt out of my miniquad motors? I accidentally crashed my 250 class quadcopter into the dirt today and got dirt all over it, including into the motors. I managed to clean the dirt off of the frame and electronics, but I have no idea how to go about dealing with the dirt inside the motors. Do I have to take apart my motors in order to clean them? If so, how could I do that and what tools/cleaning supplies should I have to do this well. AI: There are several steps to cleaning the motor: Clean the chassis and speed control An air compressor can be used to blow off the dust and dirt that has accumulated on the chassis and speed control. It’s best to work with a clean car and workspace to prevent crud from getting into the motor. If necessary, use an old toothbrush to remove stubborn dirt deposits. Inspect the wiring Check the speed control for frayed wires and damaged insulation; these can lead to radio interference and, worse, short-circuiting, which can burn up the motor and speed control. Repair damaged wires with heat-shrink tubing or liquid electrical tape. Remove the motor You do not need to unsolder the motor’s power leads or unplug the sensor harness, but doing so will give you more freedom to work. After removing the motor, wipe it with a rag to remove dust and dirt. Disassemble the motor Take the motor apart (this is quite easy to do) then you can wipe the individual parts of the motor. Clean the bearings Remove the rear bearing from the motor for cleaning. The front bearing on Novak brushless motors is glued to the front endbell and cannot be removed; leave the front bearing in place, and give it a good dousing with motor spray. (Steps adapted from this link) How to take the motor apart: (added per OP's request) IMPORTANT: Before disassembling the motor, if your item carries a warranty, opening and attempting your own repair, will void whatever warranty you have. First, get to know the parts of your brushless motor: (Image Source) The parts needed/recommended for disassembly: (Image Source) Step 1: The first step involves in removing the circlip (E-ring), followed by the collar ring from the rear shaft using the pliers. Be cautious when removing the circlip because it might spring out. If you do not have any spares, do not lose it or bend it out of shape. (Image Source) Step 2: The second step is to pull and remove the rotor (the bell) from the stator (the body). (Image Source) Step 3: Notice that there are two bearings attached to the rear end and front end of the stator. The next step is to remove the bearings from the stator. Sometimes, the bearings are easy to remove, and some have a tight fit. Remove one of the bearings using barbeque skewer or any wooden stick to plug out the bearing from the stator. Usually, the front end bearing is easier to remove. (Image Source) (Image Source) Step 4: After you have managed to remove one of the bearings, use a pin punch tool to push the other bearing out from the stator. (Image Source) Step 5: Place the stator on the plastic wire spool / solder bobbin and carefully tap the pin punch tool using the hammer until the bearing drops out from the stator. (Image Source) (Image Source) Step 6: The next procedure is to remove the shaft from the rotor (the bell). Use the allen key to remove the set screw on the rotor. (Image Source) (Image Source) Step 7: The final step is to push the shaft out from the rotor using the similar pin punch tool technique implemented previously to remove the bearings. (Image Source) (Image Source) Motor disassembly steps adapted from this article.
H: How useful is knowing the torque generated by a motor prop combination? I'm designing a series of small drones for use in a swarm configuration in combination with terrestrial / marine / submarine robots. As part of the process, I've designed a test rig to measure the thrust performance of various motor / propeller combinations. The general layout of the rig is shown in the Sketchup diagram below: (click to enlarge) The motor mount is attached to a plate, which is bolted to a MGN12C linear bearing block mounted on a 100mm rail. (If anyone is interested, the details of the MG series linear bearings can be downloaded here). This particular bearing was just one I happened to have available. At the other end of the plate, a load cell protrudes through a slot, and this is used to measure the thrust force generated by the motor / propeller combination. The mount is designed to allow the load cell to be easily changed (I have quite a few 1kg, 3kg, 5kg, and 10kg load cells). The data, together with temperature and vibration measurements from an accelerometer, will be gathered using an Arduino (or possibly a Raspberry Pi if I decide to integrate the rig with other test gear). The length of the plate means there is ample room to mount the ESC between the motor mount and the load cell. It occurs to me that it would be fairly straightforward to modify the rig to allow the twisting force, or torque, generated by the motor / propeller combination to be measured. Probably the simplest way with the parts I have available now would be a pair of load cells fitted between a modified motor mount and the plate attached to the linear bearing as shown here: (Click to enlarge) Minimal modification to the electronics would be required to add this to the design, and I have more than enough load cells available to add this to the rig. We had to re-design arms in a previous model when we found the forces generated by the motors caused them to deform while testing the unit on a static rig, which is why this modification appeals to me. However, I wonder whether anyone else has any experience of using this kind of data in drone design. So, how useful is it to know the torque generated by a motor prop combination when designing multi-rotor drones? AI: I am a fan of "More information is better". I believe that torque can be used to calculate system efficiency. I just do not know what those calculations are. I have seen one commercial thrust stand like your concept/design that includes one or two load cells that measure torque. I do not believe that measuring torque would be included in that thrust stand if there was no merit in it. Look at this similar thrust stand which also comes with data collection and reporting software. It is linked to a computer through a USB: RC Benchmark Thrust Stand It does not use a linear bearing. I like your concept very much. I encourage you in your quest for a deeper understanding of the entire performance characteristics of your drone design. I would have a use for a sophisticated thrust stand like yours.
H: Does FPV transmitter antenna need to match the goggle receiver antenna? So for a Fatshark, do I need to have both FPV transmitter and receiver antennas to be of the same brand and same specs? What about for a DJI goggle? AI: No, specific brand and specs don't matter for interoperability (aside from making sure that both antennae are built to transmit/receive the same frequency). Specific specifications about an antenna can help you figure out which will work best for your use case, like the antenna's gain, but mixing brands and types is fine. However, there are certain mixes of antenna polarizations that will work better than others. You can learn more about this in Can circularly and linearly polarized antennae be used together for FPV? and about what antenna polarization is in What is circular polarization in antennae?.
H: DJI FPV Goggles Max Power option not available. Location: USA I have a set of DJI FPV goggles but cannot change the Max Power option. It shows on the menu under the device section but I cannot select it. I am in the USA updated to latest firmware: V01.00.0500 2S 3000mAh battery .txt file on sd card narco_pwr.txt with pwr_2 attribute in txt file I have not powered or setup my Caddx Vista. Max Power is set to 25mW and I cannot change it. AI: You won't know if the "hack" has worked until you also have a Vista or Air unit bound to the goggles. As a quick test, I powered up my goggles and left everything else off. If I go to where you can adjust the power output it only shows 25mw and is grayed out. As soon as I power up the rest of the system and the goggles connect to my air unit, I can change power output and other settings. There are a number of options that require the air unit or vista to be powered on before you can change them. I assume that information must be stored on the air unit side, not in the goggles.
H: In what direction should I orient the dipole antenna on my 2.4 GHz RC transmitter? My RC transmitter has a movable antenna that allows me to change its orientation, like this one: In what direction should I point my 2.4 GHz RC transmitter antenna for best range and signal penetration? AI: The antenna should be aligned to match the orientation of the antenna on your aircraft; generally this will be vertical, but for more acrobatic aircraft a compromise of 45° might be appropriate for greater reliability but lower performance. For more detail see this question. Some manufacturers of off-the-shelf equipment will recommend an orientation in their user manuals - in this case, follow the instructions they give.
H: What LiPo C-rating is best for a small 65mm quad? I have a small 65mm quadcopter which uses 2s batteries. Is there a recommended LiPo C-rating to get for a drone like this? Or is there some way to figure out what C-rating I should get? AI: C rating is very much a non-science. There’s no real way to compare between brands, so just go off the idea that the higher the C value, the better. If you want to do it a little more mathematically (though it still won’t be completely accurate), find out the maximum current draw of each of your motors and other electronics, add them up and then add a bit (maybe 20%) for some extra safety, and this will be your maximum current draw. Divide this by the capacity of your battery in amp-hours (so 0.45 for a 450mAh battery) and this will give you your ideal C rating.
H: How to build a buddy box cable for FlySky FS-i6X RC transmitters? I have a couple of FlySky FS-i6X RC transmitters that I'd like to use to teach my brother how to fly. I've seen other people use "buddy box" cables that connect two transmitters and allow one person to temporarily give the other control of the aircraft while in flight. The back of the transmitter has a port that looks like an old S-video receptacle. Can I use that to make a buddy box cable? AI: Yes, on both counts! That is an S-video (aka. Mini-DIN-4) connector, and you can use it to make a buddy box cable. The port carries a 4-channel CPPM signal that can be used by cheap USB adapters as a joystick HID input to your computer or for buddy box mode, which FlySky calls "Trainer mode". I've made one for my own use, following the specifications laid out by the user gcartled on the RCGroups forum. Making the Cable It appears that there are sellers with listings for ready-made FlySky trainer cables, like this one on eBay, but I haven't tested them to confirm that they work. Note that @JohnRix in the comments has mentioned that the adapter he purchased for the i6 was incompatible with the i6x. After obtaining a spare S-video cable (or creating your own from Mini-DIN-4 male terminations), chop it somewhere in the middle and reorder the connections for the 4 internal wires such that the pins 1 and 2 are connected to the opposite number on the other end of the cable. i.e.: pin 1 → pin 2 pin 2 → pin 1 pin 3 → pin 3 pin 4 → pin 4 metal housing → metal housing (cit.) This creates a crossover cable that allows the CPPM signals from the "slave"/trainee transmitter to be received by the "master"/trainer transmitter. Configuring the Trainer Transmitter to Enable "Trainer Mode" In order to use trainer/trainee functionality, the appropriate settings must be configured on the trainer's transmitter so that it knows what switch will be used to toggle on/off control inputs from the trainee's transmitter. In this setup, the trainer's radio is the only one bound to the aircraft. These instructions are confirmed functional for the FS-i6X transmitter, but it is likely to also work with the FS-i6 and other derivatives: Turn on the transmitter. Hold the OK key to open up the menu. Scroll to System Setup and select with the OK key. Scroll down to Trainer mode and select with the OK key. Scroll using the OK key so that the horizontal arrow points to Mode and then use the UP key to change from Off to On. If you want to disable buddy box functionality in the future, come back here and change the Mode back to Off. Scroll using the OK key so that the horizontal arrow points to Switch and then use the UP and DOWN keys to select the switch that you'd like to use to enable/disable buddy box functionality. (WARNING: you shouldn't have this switch bound to anything on your aircraft, as this could cause issues inflight when something is accidentally triggered in the process of enabling/disabling the biddy box) Note the position of the switch you selected that changes the text Inactive to Active at the bottom of the screen. The Active position enables the buddy box and vice versa. Hold the CANCEL key until you hear a beep to save the changes and then press CANCEL twice more to escape the menus all together. Now, go and fly!
H: Holy Stone HS110D Drone PCB Wiring - What does the circled wire in the picture do? Total drone noob here so please bear with me. I bought my first cheap drone and I crashed it while flying indoor and one of the rotors stopped working so I took it apart to replace the rotor. But then I saw this black wire (please refer to the red circle in the attached picture) sticking out and one end of this wire not soldered to anything on the PCB. So my conclusion was either one end of soldering came off while I was taking the PCB apart or it wasn't connected to anything to begin with! So I would like to know the purpose of this wire and which one of my conclusion is right? And if it was soldered to something please guide me where to solder it back. Thanks for your time in advance. I would really appreciate the help! AI: That is almost certainly the antenna and one end is supposed to be free. This is increasingly likely as the square black chip next to it (labelled PAN159CY) is the wireless transciever (radio) - and I can't see another antenna candidate or connector.
H: Grinding sound on FPV motor but no apparent damage I have been testing a new brushless motor for an RC plane. It is a 2200KV motor controlled by a 30A BLDC ESC. I heard a grinding noise coming from my motor, as demonstrated in the following video: Video Here I have not been able to find a video where someone's motor produced a similar sound. I feel like I have checked many of the usual troubleshooting issues. This is a new product and has never been crashed. I checked for damage from manufacturing and there aren't any dents or deformations. Magnets on rotor seem to be level and secure Unsure about state of bearings. I thought one seemed to be spinning strangely (as if misaligned) but when I reevaluated it seemed fine. Shaft is straight A few coils are every so slightly loose... doesn't seem like it would be enough to cause problems Screws for mounting clear both the stator and rotor. Seem to be magnetically attracted to rotor, but when I removed the screws then the same sound was produced. I would like to believe it's just the cause of a bad bearing, but there were a couple times where the motor spun just fine after I had reassembled it, which leads me to believe something else is awry. I'm just a rookie at RC, so I'd like to get the opinion of some more experienced ears. Is it possibly an issue with the ESC? I did solder the ends of the power wires. I was careful not to overheat, but possibly not careful enough? AI: It looks like a bad phase to me. Check the resistance of each phase, wire 1 to wire 2, wire 2 to wire 3, and wire 1 to wire 3. If one of those is much higher resistance or shows no continuity, then you've got a bad phase. I suspect this is the issue. Also try swapping the motor to a different arm. This will eliminate the ESC as the issue. If the problem follows the motor to the new arm, then the the issue is the motor, if it stays put then it's the ESC. A bad FET or gate driver in one phase on the ESC can cause the same symptoms as a damaged phase in the motor.
H: Why do LiPo batteries get puffy? I have used many liPo batteries with my drones and other RCs over the years and have had a few of them puff up. What are the main reasons that LiPo batteries puff up? And are there ways to avoid LiPo batteries getting like this? AI: All LiPo batteries face a process called electrolyte decomposition. This means that all LiPo batteries will produce oxygen, some carbon dioxide, and some carbon monoxide through normal use. This process, however, is greatly sped up when certain things happen to a LiPo. These are the things that will cause noticeable "puffiness" in LiPo batteries: Over-Discharge. Don't let a LiPo go below the minimum safe voltage (Example: if you fly your drone too long and the battery gets below ~3.3v per cell) and don't pull too much current from the LiPo. (Example: using a low C-rating LiPo, like 20c, on a high performance race drone.) Make sure you pay attention to battery voltage when flying and make sure you have suitable C-rating. Overheat. Exposure to heat can cause battery puffiness. Make sure to let LiPo batteries cool off before charging and don't fly when it is too hot. Also, make sure to store LiPos in a cool location. Overcharging. If a LiPo is charged higher than 4.2v per cell, it can cause puffiness. Make sure you use a good balance charger to avoid this. Improper storage. Storing LiPos at full capacity is a major cause of puffiness. Make sure to storage charge LiPos before putting them away for any significant time. If you have a good charger, storage charge is one of the options. Also make sure to store LiPos in a cool/cold area. More in-depth information here.
H: Will LiPo batteries deteriorate outside with the temperature changes due to day-night cycle? I am new to the hobby and I'm concerned about LiPo batteries. I live in an apartment (this is Europe, blocks of apartments are the norm in my country) so I can not put the batteries in a dedicated room or garage. Finding a spot in the house where I can put the LiPos 1 meter away from any flammable material seems impossible. I do have, however, a convenient small balcony in which I could put a box with the batteries for safe(st) storage, something like a bat-safe, ammo or metal tool box, which have kind of proven they can withstand a LiPo fire; in a small plastic closet to protect them from rain insulating the metal box from the plastic closet with some drywall and maybe some sand. The balcony does not receive direct sunlight, but temperatures vary from ~ 15C/59F (min) ~ 35C/95F (max) in summer and ~0C/32F (min) ~ 15C/59F in winter. Temperatures could very exceptionally reach a maximum of 45°C a couple of days at peak hours. From what I have read batteries can bare these ranges of temperatures without too much of a problem but, Will they suffer from the everyday variation of temperatures and humidity and will this increase the risk of them exploding? The idea here is to maximize safety, I do not really care that much if their performance deteriorates or if I have to renew them more often, as long as this does not come with a higher risk. Note: The batteries I have ordered are two AHTECH Infinity 4S 14.8V 1300mAh 85C Graphene. AI: The typical temperatures experienced across Europe shouldn't be a problem for LiPo storage; although depending on exactly where you are you may also want to check out this question: Do low temperatures damage LiPo batteries? If your storage location may be subject to direct sun then this could cause extra heating which may be harmful - think of a dark colour car on a hot day. Having a light (e.g. white) box or keeping it in shade would help here. Also, you do want to avoid condensation wherever possible as the moisture may cause corrosion or (if it pools/collects) may short the battery connectors. Many LiPo storage containers have vents to let pressure out if a battery fails and you don't want to seal these, so add the waterproof layer inside - something as simple as putting each battery in a zip-lock bag would work, for example. Finally, storing the batteries at the appropriate storage charge level will help maximise their life wherever you store them - see At what voltage per cell should I store a LiPo?
H: Drone simulators for designing and flying aircraft? Is there any free software that can design drones/aircraft and test fly them? Thank you. I’m looking for a software with no controller needed, just to test if the aircraft/drone can hover with stability. AI: I am not quite sure what kind of drone you'd like to build. However, here are the ones I use for a variety of multirotor and fixed-wing drones: I love CoppeliaSim (formerly V-REP) for multitorotors. It makes it very easy to make certain assumptions about forces and torques, and to see the results in real-time. X-Plane is great for fixed-wing drones. X-Plane simulates flight dynamics on a fluid-dynamics level so it's actually simulating the plane as it would fly based on its geometry.
H: Determing the frame's hole mount length, for the right mount size motors How do you find out the frame's motor mount mm length? And what motors are generally for 3 inch frames and 5 inch frames? Example: 3inch frames are generally for 1206 or 11XX motors? 5inch frame are generally for 2306 or 22xx motors? Does 23xx or 22xx motor number stand for an identifier? AI: This blog post by Oscar Liang has a table identifying the type of motor that is used for each frame on 4S (other voltages would only affect the KV). Here is a screenshot of it: And yes, 22XX means any motor with a stator diameter of 22mm and with any height, as it is the stator diameter that will determine the mounting pattern.
H: Control opentx transmitter from pc? is a standard way to control a physical aircraft by connecting a frsky transmitter to a PC? I do NOT want to use the transmitter to control a flight Sim etc. I'd like to write autopilot software myself, and have it running on a PC. Id like to connect the PC to the transmitter, and have it send inputs to the aircraft, and also send telemetry back. I'd rather not use an ardupilot. Anyone have a link to details of someone doing this before? Tldr: can I use a keyboard to control an aircraft with a frsky transmitter? AI: OpenTX can be built from source for your receiver using various compile options which may be useful. Enabling USB_SERIAL and CLI will allow connection to your pc using a serial connection, which you can use for bidirectional communication. You will need to add code to the OpenTX firmware to accept commands from the pc, to control the radio. It may be simplest to utilize the trainer variables to control the outputs. The changes required are: in cli.cpp, connect the serial to the trainer variables: int cliSet(const char ** argv) { if (!strcmp(argv[1], "trainer")) { int thr; int chan; if ( (toInt(argv, 2, &chan) > 0) &&(toInt(argv, 3, &thr) > 0)) { ppmInput[chan] = thr; ppmInputValidityTimer = 240;//PPM_IN_VALID_TIMEOUT; serialPrint("!"); } } ...cliSet continues } in mixer.cpp, enable all trainer channels by default: // comment out this check // && isFunctionActive(FUNCTION_TRAINER_STICK1+ch) in trainer.cpp, clear all trainer signals after timeout: void checkTrainerSignalWarning() { ... else if (!ppmInputValidityTimer && (ppmInputValidState == PPM_IN_IS_VALID)) { ppmInputValidState = PPM_IN_INVALID; AUDIO_TRAINER_LOST(); memset(ppmInput, 0, sizeof(ppmInput)); //clear all trainer inputs } ... } You should then be able to use commands over serial such as: set trainer 1 500 to control channel 1 to a value of 500
H: What does the full scale range in a IMU MPU9250 datasheet signify? I have MPU9250 IMU, which I am working on to get orientations from the sensor output data. While exploring the MPU9250 (also other sensor such as BNO055) datasheet I came across the full scale range for accel & gyro given as ±2 ±4 ±8 ±16 (g) and ±250 ±500 ±1000 ±2000 (deg/s). I did not understand what it signifies, but seems important. I tried searching online related to full scale range but did not get explanation regarding it. I request if someone could help me in understanding by providing good explanation or a source which I can go through, I'd really appreciate that. Also which one would be better to use? I have asked the same question on Stack Overflow. I really need help on this. Thanks. AI: TL;DR: The configurable scale ranges for the accelerometer, gyroscope, and magnetometer on the MPU-9250 IMU affect the maximum resolution and range of the reported values. As you increase the full-scale range setting, the maximum value/rate that can be reported by the IMU before the IMU is saturated increases, but the resolution of the value/rate decreases. Section 3.1 of the datasheet for the Invensense MPU-9250 has a table that states the "Gyroscope ADC Word Length", which represents how large the values reported over the I2C or SPI interfaces are. In this case, the gyro word length is 16 bits. A 16 bit two's complement binary number (explained wonderfully in this video by Ben Eater) can range from -32768 to +32767. Take the example of the ±500 °/s full-scale range. The unit resolution of the two's complement value reported by the gyro (aka Least Significant Bit/LSB resolution) in the ±500 °/s full-scale range is: $\frac{32767}{500} = 65.534$ LSB/(°/s) (degrees per second per LSB). This is not coincidentally labeled in the graph as the "Sensitivity Scale Factor" for the FS_SEL=1 condition.
H: 4 in 1 ESC and FC won't turn on when connected together After crashing my drone recently, my ESC and flight controller won't turn on (the power led lights up on the FC, but nothing else works either it doesn't anymore, or I was wrong before) any more when they are connected together. When I disconnect the ribbon cable between the FC and the ESC, the ESC turns on as it should (Beeps when the battery is connected), and the FC turns on when I connect it to USB, and it seems to function correctly. I have measured the connections going between the two, and all of them appears to be okay, except that 5 V from the ESC drops to about 0.5 V when the flight controller is connected. If I connect both the ribbon cable and a USB cable, the FC turns on and the video feed goes from showing black (no OSD) to show the actual video. The ESC still won't turn on though. I noticed that the capacitor had come loose from one terminal, but it seems unlikely that that caused these problems. Unless it caused voltage spikes that damaged something? My FC is a HobbyWing FC F4 G2 and the ESC is a HobbyWing XRotor Micro 60A 4in1. Any help is appreciated, I can't even figure out which board causes the problems. AI: Your description of the dramatic voltage drop (from 5V to 0.5V) upon the connection between the flight controller (FC) and 4-in-1 ESC makes me think that the issue you're seeing is most likely due to a short or low resistance path to ground. There are other possible failure modes that could cause this, but a ground fault sounds most probable here. Why? When a ground fault is created in one of the components attached to the 5V power rail generated by the ESC's BEC (Battery Eliminator Circuit), a substantial current greater than the BEC's rating for continuous power delivery flows. This is due to Ohm's law, $I = \frac{V}{R}$ which states that a large current (I) will flow if the circuit resistance (R) is tiny. The usual mode of operation for power supplies when they experience surges in power demand is to drop their output voltage in an attempt to prevent catastrophic failures of themselves or downstream components by decreasing the power output. (Power $P = \frac{V}{I}$) This is a near-ubiquitous safety feature. Confirming a Diagnosis of a Ground Fault Since ground faults manifest themselves as low-resistance paths between the power rails, the way to test for the existence of one is to (use a multimeter) measure the resistance between the +5V and GND lines on the FC and the 4-in-1 ESC independently. It would be best if you could fully disconnect all peripherals from the FC before measuring for a ground fault, as it is possible that the issue is with one of them and not the FC, but this can also be done once a problem with the ESC is eliminated to possibly avoid desoldering and resoldering the components back together. NOTE: remember to take resistance measurements with no power attached to the device being measured! If the measured resistance for the FC isn't high (the exact threshold differs between circuits, but the difference between a ground fault and a safe circuit is significant and should be noticeable), then there is a ground fault somewhere inside the FC. Likewise, if the measured resistance for the ESC isn't high, then there is a ground fault somewhere inside the FC. If both components have low resistance paths between the power rails, then they both have ground faults. Resolution You could either attempt to correct the ground fault in the affected component(s) or replace them. Sometimes the cause of the ground fault is some SMD (Surface Mount Device) component that is too small for you to comfortably work on or broken solder mask in the PCB, in which case fixing it may be more trouble than it's worth. However, the only cost of trying to fix and not buy new is your time. And hey, you never know when a troubleshooting venture like this will teach you something new about electronics!
H: Can I mount my RX and VTX antennae next to one another? I've heard that it is bad practice to mount a 2.4 GHz RC receiver antenna next to a 5.8 GHz FPV VTX antenna because the transmitting antenna will negatively impact the receiving antenna's reception. For example, this is said to be true in this Rotor Riot video at 1:40. Is this true? If so, how close is too close and how can I mount the two antennae to minimize the interference between the antennae? AI: The distance is dependent on the wavelength of the lowest frequency. You can calculate the wavelength $\lambda$ (m) from $\lambda = c \div f$, where $c$ is the speed of light in a vacuum (ms-1) and $f$ is the frequency (Hz.) Taking the centre frequencies of the ISM bands we get: 2.4 GHz: $$\frac{299 792 458 }{ 2 450 000 000 } ≈ 0.12 = 12 cm$$ 5.8 GHz: $$\frac{299 792 458 }{ 5 800 000 000 } ≈ 0.05 = 5 cm$$ (Quick 'sanity check' tip: 5.8 GHz is about twice 2.4 GHz, so we expect the wavelength to be about half; looks good.) The smallest separation is usually recommended as a quarter of the longest wavelength, which for 2.4 GHz is only 3cm - quite manageable. That said, greater separation helps so put them as far apart as your frame practically allows.
H: FrSky receiver snap-on connection problem The snap connector thingy (picture included) on the xm+ receiver (although it is the same with nearly every other receiver) I have stupidly disfigured, as well as the antenna end. Is it possible to fix this or solder the wires on directly? Do you have to get a new receiver because of some tiny connector which has been slightly (ok, fine, quite a lot) bent? P.S.: Yes, I know this was very stupid and I will not make this mistake again! AI: This type of connector is called a U.FL connector. Replacing the connectors will be super fiddly, but is possible if you are skilled with a soldering iron. The cable side is the more difficult bit but also cheaper, so you might try a new antenna and replace just the PCB connector. You may be able to use something small, like a pin, to carefully nudge the connector back into shape - it may make it worse, but if it doesn't work anyway what's to lose?! Finally, you could unsolder the connector from the board, cut the wire and solder it directly. The wire will be a coaxial cable, so you need to take care not to short the inner to the outer - especially when soldering as you may melt the insulator away. The inner goes to the centre pin on the connector; the outer part to ground (the circle of the U.FL connector is connected to ground so you can use this pad). Before you trust the receiver again you should do some range tests. You can put the transmitter in the range testing mode and check what kind of range you get.
H: How can I know the laws of a specific country regarding drones? Reworded from: https://travel.stackexchange.com/q/112261/ If travelling to a few countries, I was wondering if there is one source for all the drone rules/laws of the countries I am travelling to instead of doing a specific search for each country. Does such a source exist? AI: There are a large number of websites which collate drone rules in different countries; to list a few: Dronegenuity UAV Coach Drone Rush UAV Systems International However, due to the rapidly evolving nature of drone rules these could quickly become out of date - in fact, at time of writing, some of the sites already contain old (now incorrect) information. The safest option is to check the website of the country's aviation regulator before you travel.
H: Wired drone using very high voltage? For those of you who don't know: electricity can be "stepped up" to carry the same amount of power over a thinner wire, over much longer distances with minimal losses. Once the power reaches the destination (like your home), the power is stepped down to a much safer voltage. Here's what I'm thinking: A quadcopter being powered by a super thin, high-voltage line to continuously hover in a single location indefinitely. The power cable would be very thin, like 1 mm in diameter. The voltage would be static-electricity range (very high), but the amperage would be harmlessly low. When the power reaches the quadcopter, it is stepped down to a normal DC current. No, I have no plans to actually do this, but how well would this concept work in theory? AI: Let's work out some numbers. Picking a DJI Phantom 4 as a 'typical photo drone' example, it's battery is 4s 5350mAh and weighs about 500g, and provides about 20 minutes of flight time. That implies that the motors are using (5350/1000)x(60/20)=15amps (converting mAh to Ah, and minutes to hours). At 15v that is 225W for flight. The question talks about using 'static electricity high voltages' - but the most noticeable feature of static electricity is that it can spark across gaps. 10,000v will jump 3mm or so in dry air, and 3000v will jump 0.5mm. However I don't think we need to go that high. Stepping the voltage up 100 times to 1500v would reduce our current to 0.15a. That means we could use 29AWG wire, which is 0.3mm diameter - at that point the insulation may be heavier than the wire. According to that chart, 29AWG has a breaking strain of 3.6lbs, which is much more than the weight we have saved from the battery so we don't need to worry about the wire breaking under its own weight. So how long could the tether be? 29AWG weighs 0.3863 lbs per 1000ft (or 175g for 300m). We will need two strands (350g), so 1000ft (300m) of cable uses up most the weight we've saved by eliminating the battery, before adding any insulation or the transformer. 1500ft of wire would be heavier than the battery. TL;DR: * yes, you could hover at normal photography drone heights for an unlimited time using a tether. * The weight of the wire prevents you going much higher than 1500ft. * The weight of the insulation prevents you using lighter wire.
H: What can I do with a LiPo whose balance lead has been destroyed? I'm starting a bit of a collection of batteries which have been ejected during a crash and ended up with a destroyed balance lead. Is there anything other than disposing of them that I can do, assuming the cells are still in good condition? AI: If you're up for it, the fix you're looking for is to repair the connector with a new housing and new crimps (if the current ones are broken). Joshua Bardwell has an excellent YouTube video documenting how to do this, but I'll summarize here. Most LiPo balance leads are terminated with the JST-XH connector: (cit.) In the above picture, the balance lead is configured such that the left-most pin is ground/GND and then are in ascending order of voltage from left to right when the flat surface of the connector housing is facing upwards. For example, a correctly made 4s LiPo balance plug would be wired up like so from left to right: GND Cell 1 (4.2 V when fully charged) Cell 2 (8.4 V when fully charged) Cell 3 (12.6 V when fully charged) Cell 4 (16.8 V when fully charged) Repair instructions: Purchase a JST-XH connector kit like this one on Amazon and a JST-XH crimper tool like the Engineers PA-09 on Amazon if you know or anticipate you'll need to replace the crimped pins (there are cheaper crimpers available, but I've had little trouble crimping JST-XH with this one and it's a nice-feeling tool) Pick out a new connector housing that's the same size as the broken one Remove the lowest voltage pin (left-most pin in the above picture) from the broken housing using a pointy tool to lightly press down on the edge of the silver retention tab If the pin is broken/bent/deformed, cut/pull off the JST-XH crimp and re-crimp a new one on Insert the pin into the new housing with the little retention tab facing upward until the retention tab on the pin clicks into place Repeat steps 3-5 for each other pin in order of ascending voltage I'd recommend only having one pin free of either connector housing for as much of the process as possible to avoid inserting them in the wrong order or accidentally letting two of the pins tough each other, which would short the cells together (be bad). Afterward, you should check your work by using a multimeter to confirm that the voltages between GND and each pin are in ascending order from left to right.
H: Cannot configure ESC: BLHeli-Configuator connects but with blank screen ESC: GEPRC STABLE PRO F7 ESC BL32 2-6S 4in1 Specs：35A BLheli_32 ESC Steps to connect to BLHeli-Configurator: Connect to flight control (GEPRC STABLE PRO F7 35A) via mini usb Connect Lipo Battery to drone Open BLHeli-Configurator from my Windows 10 laptop Click Connect on the top right corner of BLheli-Configurator. Note, COMM is being read by the configurator Click Read Setup on the bottom right corner. On logs, it states: "2020-06-14 @ 13:30:59 -- Reading setup. 2020-06-14 @ 13:31:00 -- Reading setup finished." Screen is still blank and can't access the ESC items. Beta flight is not opened while going through this process. Experienced this on two drones with the same ESC(built two drones in my life). Trying to change the spin on my motors, any help would be appreciated AI: Try using BLHeliSuite32 instead, since it is a BLHeli_32. I don't think BLHeli configurator works with 32 bit ESC:s, correct me if I'm wrong. If that does not work, try having Betaflight configurator open WITHOUT connecting. This has helped me sometimes. If it still does not work, you might need to connect to the ESC without using passthrough (if possible) and try to reflash it with a newer BLHeli_32 version.
H: DJI Mavic 2 Pro send still images to a laptop in real-time Is it possible to send photos captured by a DJI Mavic 2 Pro to a laptop in real time? AI: I do not believe it is possible to send still images in real-time to a laptop. For devices that take full size SD cards, you can get WiFi enabled SD cards but I can't find a source for micro SD devices like the Mavic 2. If you have a controller with HDMI-out, you could use an HDMI capture card on the laptop to receive live video from the drone and use an application on the laptop to capture stills from this. The quality would be lower (limited by video transmission settings) but you would get the instant images; if you also take a picture with the aircraft you could get the full resolution image once you landing.
H: Taranis X9D Plus 2019: Switches SE,SF,SG,SH, and SI are not working/responding on Betaflight So switches SA,SB,SC, and SD work on Betaflight. Aux channels 1 through 4. But switches SE,SF,SG,SH, and SI are not working/responding on Betaflight. Aux channel 5 through 9, I believe I am using TBS Crossfire lite, with crossfire nano receiver. On my Taranis I have already setup Mixers to activate all switches and nobs. When I first binded to my reciever I did not set up the rear switches(SE,SF,SG,SH, and SI), but I already setup 3 of the front switches(SA,SB, and SC) before binding to my model. Things I have tried: Connected Taranis via usb mini, opened Devices and Printers on windows and ran through the wizard to re-setup my Taranis Reconfigured my Input and Mixer page on my defined model. Simply defined each switch in order in the Inputs page, and then on Mixer page defined the channels Rebinded my crossfire transmitter receiver by holding down the button and plugging in my battery to the quad. Releasing the button on the receiver and pressed and held the button till it binded again and updated again. This time my model was setup but same results On Taranis, long pressed MENU and went to page HARDWARE: ran calibration and also Debuged switches. Everything seems normal Considerations: I have the latest Betaflight-configurator and I am using the latest Beta-flight firmware on my quad Flight Controller: STABLE PRO F7, Model:STABLE PRO F7 35A Transmitter Receiver: TBS crossfire nano Everything else works as expected This is occurring with two of my first-build quads Followed this reference to solder and config the transmitter receiver: https://geprc.com/download/en/GEPRC-STABLE-PRO-F7-DUAL-MANUAL-V1_0.pdf Taranis is in 1-16 channel mode. Also I am not missing switches, all are activated, I checked in the HARDWARE's page Taranis Firmware: opentx-x9d+2019, version: 2.3.6 How my Mixer is setup: CH1 Rud CH2 Ele CH3 Ail CH4 Thr CH5 SA CH6 SB CH7 SC CH8 SD CH9 SE CH10 SF CH11 SG CH12 SH CH13 SI CH14 S1 CH15 S2 CH16 LS CH17 LR Any suggestions would be much appreciated. AI: The issue was on my Crossfire Nano receiver. I had to change the operation mode from 8 channel to 12 channel. Now switches from SE - SH work. Even though I defined all my knobs, switches, and button on my Taranis, I am limited to 12 channels from my crossfire nano receiver(4 channels for the sticks, 4 for front switchers, and 4 for top switches).
H: Can I use two 2s lipo batteries to power my FPV DJI goggles? The FPV DJI goggles can take 7.4-17.6 Voltage. I am using a 2S 3000mAh LiPo battery. My plan is to buy another of the same liPo battery and attach it with a female to 2 male TX60 connector, making it a 4s lipo battery of 3000mAh(14.8 - 16.8V) . Do I need to consider anything else? AI: Connecting the batteries in series or parallel brings two new issues with it that you need to consider before you start using them and they are both related to batteries that are not on the same charge level. If you put two batteries of a different charge in parallel, the battery with the highest charge will charge the other one and very high currents can flow which can damage your batteries. If you put two batteries of a different charge in series they will both discharge at the same rate during use and the battery with the lowest charge will discharge a lot deeper potentially causing a lot of damage. So if you want to do this always take this into consideration: Parallel connection: Make sure the batteries are at the same charge level. Series connection: Make sure the batteries are at the same charge level AND of the same capacity. So if you want the higher capacity and don't necessary need the higher voltage (in this case you don't): parallel connection is better and safer than in series.
H: Could a drone collect a river sample? I know very little about drones, but I'm trying to learn if collecting river samples is something that could be done autonomously using commercial drones? Is it possible to give the drone some coordinates of the river and have it go and collect without further input? Is it even legal to do such a thing without someone controlling? If it's not possible to do autonomously, how much input would be needed from a controller? AI: Autonomous operation isn't a technical problem. For example, DJI's drones are capable of flying themselves back to the launch point if the signal from the remote control fails. The problem is legality. Most drones are required to be flown within the operator's line of sight. The reason for this isn't because the operator has to be actively controlling the drone -- a fully-autonomous drone is perfectly legal -- but because the operator is responsible for collision avoidance. If you've got an operator watching things, ready to take over if a problem arises, a self-piloting drone is perfectly legal. If, on the other hand, you want something that's completely unattended, you'll need to work with your local regulatory agency to get permission, and that's going to be a difficult thing to do.
H: Stick commands does not register I'm trying to follow this playlist to set up a drone with iNav, but when it comes to calibrating the compass, the stick command doesn't seem to work (the status light on the FC doesn't flash rapidly as described in the video). When trying some other stick commands it doesn't seem to register either. All the endpoint are set to min 1000 and max 2000. Min_check and max_check are 1100 and 1900 respectively. The FC is a Matek f405 std, and the radio is a Taranis qx7s, in case that matters. AI: I figured this out rather quickly when I tried to arm the quad and it said that the throttle was not low. It turned out that throttle and pitch was switched in iNav.... So after changing that, everything worked...
H: Can a receiver get damaged if you power it up without an antenna? My r-xsr receiver short circuited after a crash recently. When investigating the reason, I found two things; The filtering capacitor had come loose, as well as one of the antennae on the r-xsr. Since the reviver can handle up to 10 volts, and it was connected to a 5 V output on the FC, I assume the capacitor isn't the problem. So my question is therefore: can this problem have been caused by the drone being powered up when the antenna came loose? AI: Running a receiver without an antenna should not cause any damage to the receiver, as no RF power is sent to the antenna (if your receiver has an active antenna there may be a DC bias present, but this does not cause problems - you will often see this in GPS receivers.) However, for completeness, it is worth noting that some modern RC receivers actually do transmit, to send telemetry and other data back to the controller; in this case 'receiver' is a misnomer, used to mean "the radio part in the aircraft" - and it is possible for damage to occur. The correct term would be 'transceiver', a portmanteau of 'transmitter' and 'receiver'. The reason a transmitter can be damaged when run without an antenna is because the power sent to the antenna has nowhere to go. When a (matched) antenna is connected, the power is transferred to the antenna but without it the energy is reflected back down the transmission line to the output transistors. These transistors are not designed to handle that much power coming back, and can fail. The likelihood of this happening generally increases with transmit power, but it also depends on the rating of the output transistors so this is just a crude approximation. (Transmission line theory deviates somewhat from the normal models of power transfer, where having nowhere for the power to go would create an open circuit, and no current flows.)
H: First radio transmitter. Taranis X-Lite, X9 Lite or Jumper T8GS? I'm looking for a nice budget radio transmitter to start in the hooby and stay with it for some good time. I'm found these three good options but I'm tottaly newbie so I don't know the pros and cons of each one I would like some radio that could make at lease abou 1-2 Km with no mods by default. And the most versatile about receivers. I read the T8GS supports almost all protocols and it leads at this specification, but whay about the other ones? I intend to some FPV AI: At this point I would recommend the radiomaster TX16S. It goes for about the same price as the other radios you list but has everything you need to get you going for a very long time. FrSky (Taranis) is doing everything it can these days to lock you into their ecosystem and you need to start hacking once you are further in the hobby and want to switch over to crossfire for example. With the TX16S you can use almost all receivers that are on the market. Whatever radio you pick eventually, just make sure it runs openTX. Almost all instruction videos you will find online are based on openTX.
H: Unrecognised ESC motor connector I purchased an ESC and a Speed 400 motor about 17 years ago with the intention of building my first electric powered model plane. Life took its various turns though and my time for R/C modelling dried up soon afterwards. Now that I have 3 boys who are all starting to show interest in the area, I've started to find the time to look at it all again... yay! Part of the reason I never got to build that electric plane originally though was that I had no means of connecting the motor to the plug included on the ESC. I know I could just cut the plug and replace it, but I've been trying to identify the type of plug without success for a while now. Can anybody tell me what the type of the red plug in the image below is? As an aside, I'm a bit mystified by the battery connector, since it has 16 guage wires onto the ESC, but then connected to much smaller guage wires with a JST plug. I don't have any specs on the ESC itself unfortunately, so don't know what the rated current is and consequently whether or not I should be concerned about those wires! AI: That looks like a 4 pin Deans Micro Plug, which goes by WS Deans part number 1242. Regarding your wire thickness, as you say it all depends on the expected current. If you can identify the current rating for the smallest wire in the circuit, you could add a similarly rated fuse and do some bench testing and current measurements - and if the fuse blows, then the wire probably would too and should be replaced.
H: Finding a ready-to-fly Taranis compatible, Eachine compatible, S4 compatible under 200€ drone The question I'm looking for a drone under 200€, preferably 5" (as that's what I'm used to) but other sizes are ok, that can be purchased/delivered to France, is compatible with a Taranis X7 and an Eachine EV800D. It needs to be as plug & play as possible because I'd rather have the opportunity to fly it at least once before spending another 10 hours Macgyvering the thing. I have found some fairly interesting starter deals on getfpv.com: https://www.getfpv.com/iflight-cidora-sl5-e-5-fpv-racing-drone-pnp.html Only problem: according to the description I need to add a receiver which is, if I understood correctly, precisely what I couldn't get to work in my last build https://www.getfpv.com/emax-hawk-sport-5-pnp-brushless-fpv-drone-1700kv.html I can't determine if this one is compatible with the gear I already own. Why not buy a complete package ?: Because I already own the transmitter and the FPV goggles. And from what I understood the gear I got is decent enough, so I'd rather keep using. plus I'm used to flying a sim with the Taranis so I'd rather keep it. The Context, ignore if you don't care why I'm looking for such a plug & play solution: Last year, after watching a few guys flying their quads, I decided to buy one. Having quite some experience with building computers and being pushed by the other guys to custom build it, I ordered a bunch of component (chosen by them) and bought some second hand from said friends. I got started building the drone and it was a mess. I had done soldering work a few years before but never had it required such precision so I messed up and burnt parts of my first FC. Replaced it, managed to solder everything, only to realize halfway through the build that I couldn't for the life of me pair the Taranis to the receiver and have no way to check if the Taranis is at fault for cheap. I did a lot of research, re-soldered using different connections, changed the settings in betaflight ... in the end I changed the receiver. Still the same problem, spent an other half dozen hours on it. I spare you a whole lot more problems and research online... conclusion: after a good 25 hours spent trying to get this drone working I got so frustrated that I put everything in a box and left it there. note: during the year this group dissolved itself and I now have no contact with anyone that knows anything about quads, so I couldn't get help in building/troubleshooting anything. Now, I want to fly, but I'd rather not have to build, flash & setup everything myself while going blind and with nobody to help me if need be. Thus, I'm looking for a ready-to-fly drone. AI: I think the Cidora SL5-E is a very good choice. What you need to look for is the "BNF" suffix in the description which stands for "Bind and Fly". In that case a receiver is already built in. On the iflight website you can select this option. If you have the choice, it's best to select the r-xsr because it comes with telemetry. If you are browsing shops look for these acronyms: BNF: Bind and Fly, you can pair it to your existing remote and goggles PNP: Plug and Play, you install your own receiver RTF: Ready to Fly: a complete kit with everything included such as remote and sometimes goggles.
H: Drone Controller, PID Is Enough, or ODE Modeling Required? I am planning to build a remote controlled dualcopter where I have two propellers, one on top and one on the bottom. The bottom rotor will be gimbal based for thrust vectoring. Something like this, https://www.youtube.com/watch?v=b14_XQ5nd2A I want to build the controller from scratch (the fella in the video used Multiwii Mega flight board controller). Do I need to get into ODEs, differential equations, etc. as the following paper has done? https://andrew.gibiansky.com/downloads/pdf/Quadcopter%20Dynamics,%20Simulation,%20and%20Control.pdf Or is this overkill? Could I simply use a PID based design for a target tilt, adjust control to reach it, and do the same for motor speed, etc? AI: You can certainly use a PID based design and tune it from there. This design is simple enough that if you just have XYZ PID controllers and proper output mixing it should work just fine. I'd recommend doing something similar to his design where the motors are far from the center of mass which will increase the torque generated by tilting the motors. Good luck!
H: Is owning, but not flying, a drone in Germany illegal? I live in Germany but I travel a lot around the world; my new hobby is aerial photography, for this I am considering buying a drone. Since Germany has some rules about drones, can I have a drone in Germany without a "mandatory label marking," "without insurance," etc? I mean, the rules are clear to me IF AND ONLY IF I am flying the drone in Germany, but what if I use it only when on vacation in other countries? Am I breaking any rules? AI: According to the rules you linked to, the only thing you are required to do is stick a label on your drone with your contact details, so stick a label on! All the remaining rules relate to when, where and how you fly, and what certificates you might need to do so. Since you won't be flying, none of these apply. Nowhere is there any prohibition on simply owning a drone. However, since this is your new hobby I find it unlikely that you won't want to fly in your home country. You'd need a 'certificate of knowledge' which doesn't seem to be too hard to get, and permission if your drone is over 5kg. Why not just get what you need and fly in Germany? Note that flying drones in other countries may have rules that are much more stringent than Germany. Don't expect to just rock up on some foreign beach and fly.
H: What is a good 3'' BNF that can be used indoors and outdoors? I am looking to get a new quadcopter that will work in a variety of places. I want it to be a 3'' drone so that I can fly it both outside and inside. I would prefer if it had prop guards or ducts of some sort, but that's not necessary. I want a drone with decent performance and a good analogue FPV system. I already have a good transmitter (Jumper T16 Pro) and good FPV goggles (Skyzone Sky02X) so I am looking for a BNF. I'm looking for a drone that won't break the bank, but will be good quality and will last a long time. AI: Depending on your budget I would look at these two options: Diatone Taycan: this is a cinewhoop style quad that is more than powerful enough to fly outside as well. It will not be as nimble as your typical freestyle quad but if that is not what you are looking for you can't go wrong with this one. HGLRC Sector 132: This option will be cheaper as the Taycan but seems to offer good value for the money. By default there are prop guards that allow you to fly indoors (not ducts) and if you remove them, you can start freestyling outdoors. Just based on the type of build, the Taycan should be more sturdy and last longer than the Sector 132. That being said, this is a hobby where you can destroy any type of quad if you start pushing your limits and try out more challenging moves. Regardless of your choice, it is a good idea to implement throttle scaling when you fly indoors. This can be done on your remote and tied to a switch.
H: How to control a gimbal remotely? Is there a simple way to remotely control the panning of a gimbal (preferably with a separate stick/joystick, controlled by another person)? I'm planning to do a budget cinematography/utility camera drone built out of the ZD550 frame and I don't really need more than a GoPro. I'd probably get a smaller gimbal like this. It'd also be nice if I could adjust the amount of "inertia" the panning has, sensitivity, etc. According to the description of this gimbal controller board, "Each axis could connect analog joystick." Not sure how I would make that remotely controllable though. Something out of Raspberry Pi? Separate tx/rx? Just throwing out ideas. AI: It all depends on what Flight Controller you are using and how you want to control the gimbal. Gimbals in your links use Storm32 firmware which is very versatile. It can be contolled using knobs on your remote controller, MAVLink messages or their own serial protocol. I use a gimbal from your first link which is controlled by a stand alone Windows application using a Joystick. Same application indicates gimbal's attitude ans shows received video from a camera. It did require coding for the application. On the drone side it is all done using already existing software - Pixhawk4 flight controller, Raspberry-pi for Wi-Fi link and camera capture, Mavlink-router running on RPi to route messages to Pixhawk and gimbal. If you are OK waiting a bit, Px4 will soon release gimbal manager integrated into FC, which will simplify things.
H: What are the benefits to different types of frame arrangements? When looking at different frames, there are lots of descriptions for different ways the arms are set up. Are there objective descriptions of how these arrangement change the flight characteristics rather than just "I like the way this one feels"? For example, looking at the iFlight frames, the XL5 and SL5 are almost identical, except one is a "True-X" arrangement while the other is a "Squished-X" arrangement. A few such terms that'd I would really like to see some solid description of the flight characteristics: True-X Squished-X Stretch-X Deadcat AI: As a designer and manufacturer of frames here's my experience (6+ years, 10,000 flights, FPV only, 107 pilot w/HAM) True-X: If you build well and balance your load these will fly in a symmetrical fashion on roll/pitch. If you set your rotation to 900 degree/sec (my normal) then roll and pitch (freestyle) will be similar in duration, stick movement, and hand-eye. Generally the best to learn on as a point of reference. Squished-X: (lateral x) I fly a few of these, they have a "float" and just like the stretch-x they are slightly different - but not much. I use this layout for our high-resolution filming work, great for sliding pans and holding a line. Stretch-X: I don't fly these too much anymore. I found no advantage for my flight style (all freestyle FPV, no racing). Deadcat: Flies like a lateral-x in my opinion. Other factors beyond frame shape influence performance. ESC on arms versus AIO is huge as you move weight around and change the inertial mass (resistance to acceleration). The same is true of distribution of arm mass. Stack hight is also important. If you are a new pilot lean towards pure-x. In general the frame contributes around 10% of the final flight feel. Electronics, tuning, weight, weight distribution, drive train (motor+prop), battery size/type, battery mounting, and your skill in construction are all as important as the frame. I can change KV by 10% and swap props and get 20x different flight than changing out arm ratio. Focusing on pure-x first will attenuate your hand-eye to notice the difference later.
H: Is WiFi drone control protocol standardized? I'm searching for an app to control a Zerotech Doby drone. The official app "DoFun" is no more available, but surprisingly it works with another Chinese app "FlightGo". I wonder if the WiFi protocol used there is somehow well known, and if there are any better, preferably opensource apps. AI: Since no one has answered this question in pretty much a day, I'm gonna spread my half-knowledge now :) I have never heard of a standardized wifi drone control protocol. However, I wouldn't be surprised if both chinese manufacturers inofficially use the same protocol (be it because they have a contract or because they just copy from each other or because they use the same control chips). I encountered this with a lot of LED strips: Most of these strips can be controlled with the same IR remote - across brands and so on. Even though, IR and WiFi are vastly different things, I think this could be the case here as well. As for using the same control chips, this is also often the case with toy RC cars (27 and 40MHz). Most of the time, you can just use your remote to control your friend's car. I discovered that in kindergarden ^^.
H: FPV lag on visuo xs812 I have a visuo xs812 but with a very slow lag. I know that for many people this is a problem, does anyone know a fix? AI: I found some information here which may be helpful to read through. They mentioned the issue of video lag and seemed to find a few potential solutions which were: to use a wifi extender, use a different app (mentioned in the link) to connect to the drone, or adjust settings of your phone like screen resolution and processor power if possible. As I don't own this drone, I'm not sure that these solutions will fix the issue. But if the video lag persists, just know that you really can't expect very low-latency video from a drone this price.
H: Motor size and Kv advice for ZD550? I'm building my first drone out of the ZD550 frame. Most of the extra weight would be from a small gimbal like this (180g) and a gopro hero 4 (83g). What kv/size of motor would be ideal for this config, plus some extra? Some speed would also be nice :D I'm hearing around 600-900 kv, but I have no idea if that range is too vague. Also, shouldn't I be more concerned about torque? I think that's estimated through physical motor size. Thanks! AI: There are a lot variables when it comes to building your own drone, so there will be a variety of motor sizes and Kvs that will work. I think the recommended motor size for the ZD550 is 3508 (like this motor) but that doesn't mean you can't use something different, like a 2814 motor, because a 2814 is fairly similar in stator volume to a 3508. This answer should help you figure out what motors you want. Torque is mostly related to motor size, so you shouldn't have to worry about not having enough torque with either a 3508 or 2814 motor. And these motors should easily be able to carry some extra weight with no problem. As for Kv, the prop size greatly affects the recommended Kv. Here's a good explanation of Kv and how to choose the correct Kv. The ZD550 frame can fit 10''-15'' propellers, so I would recommend lower Kv (~600) for 15'' and higher Kv (~850) for 10''. Also, Kv will greatly depend on what battery you intend to use. Generally a higher voltage battery = lower Kv motor, and vice versa.
H: Can motors be "too big" for any reason? I'm wondering, what would make a certain motor "too powerful/large" for a build? Could software/firmware of FC/ESCs be a problem? The only thing I could come up with is strength of the frame and weight limitations. Just looking for anything a beginner might miss. AI: Power systems should be balanced. If you fit motors that can handle more power than the battery can provide, you're just adding unnecessary weight. That weight will reduce performance in all areas. With electric power systems the battery is the source of the power, and everything else is little more than the transmission. If you want a 3 minute flight from a 4s1500mAh battery, that's an average of 60/3 * 3.74 1500/1000 = 444W, or 111W per motor. There will be higher burst loads but the motors have the mass to handle it. They'll heat up a little in the bursts and cool down in between. If you switched to more aggressive motors or props you could increase performance in the bursts, at the cost of reduced flight time - and you might be pushing your battery too hard. If your battery is hot at the end of the flight, you're reducing its life. If you push really large bursts through a small motor, there's a point where it will be less efficient (something to do with the maximum magnetic flux density of the stator, IIRC) so there is some benefit to larger motors but if your motors are cool at the end of a flight, you probably won't see any benefit from larger motors.
H: Can "toy" drone FC firmware be tweaked? Can the flight controller of cheap "toy" grade quads, such as the Blade Inductrix, be programmed at all? I'd assume that even if it's possible, it wouldn't be practical. I don't have any experience with FC programming (yet). AI: TL;DR: Probably, but you'd likely be spending a lot of time locating a programming interface on the flight controller board and custom-compiling or custom-writing firmware to work on the special board configuration. Some more expensive toy-grade drones may have accompanying smartphone apps that allow you to change some flight parameters, but very few of those exist for a variety of reasons. In general, I wouldn't recommend trying to modify the firmware of cheap toy-grade drones... It's almost certainly a better use of your time and money to begin tinkering with DIY drone parts that are meant to be tweaked. In the case of the OP's example toy drone, the Blade Inductrix FPV RTF, there is some limited good news. From looking at this image of the FC board, it can be discerned that the FC uses an off-the-shelf Atmel processor of some kind: I've tried rotating and zooming the image to find what exact model the chip is, but the image is too coarse to read the finer print. The fact that it uses an Atmel processor means that you could probably use a UART/ISP programmer device to upload new code once you locate and solder thin wires to the appropriate legs of the LQFP package. However, you'd likely run into other challenges when trying to modify or change the existing firmware: Attempting to de-compile the firmware on the FC to change PID constants or alike would be exceedingly difficult The Atmel chip is likely 8-bit, which would require adaptation of open-source FC firmware like Betaflight to work (Betaflight is designed to work with STM32/ARM 32-bit processors) The Atmel chip is almost certainly running at a slower clock speed and has less IPC capability than the chips used for DIY FPV drones and would require firmware with severely slimmed-down feature sets The pinout of the FC board is entirely unknown; you'd have to manually trace out the circuit to find which pins on the processor lead to what parts of the drone, or locate a schematic Critical peripherals like the IMU (accelerometers + gyroscopes), ESCs/H-bridges, RC RX, and FPV TX are likely non-standard components communicating with custom proprietary (or at least unknown) protocols that would require reverse-engineering etc.
H: Is Naze32 capable of autopilot? (Assuming that you have the required telemetry hardware, barometer, etc...) Are any versions of the Naze32 capable of autopilot features, such as altitude hold? How about more advanced things like flying a preset path? If it's relatively simple, how? AI: You'd likely be looking to run a firmware like iNav on your flight controller to enable the path-following features you need like altitude hold and mission/waypoint flying. This is really the most capable and readily available autonomous flight firmware for hobbyists. The Naze32 FC board is based on the older and less capable STM32F103CBT6 processor (cit.), which hasn't been supported in iNav since the 1.7.2 release in July 2017 because the pace of feature development outstripped the computational power of the STM32F1xx processors. Although you wouldn't be receiving feature/bugfix updates for iNav running on the Naze32, you would still have access to the features added prior to the 1.7.3 release that dropped support for F1 boards and almost certainly includes some sort of altitude hold and waypoint following capabilities, even if they're more rudimentary than what is available in the latest versions of the firmware. You can install and configure iNav using the iNav Configurator and by reading the getting started documentation on the iNav wiki pages.
H: Estimate safe ESC curerent for 4108 600kv motors? Is there a way to safely guess what current ESC's will need to be with this motor (or any motor in general)? The motors are rated 23A in the table, but that's only with a 4s; I might use a 6s in the future. If I were to use, say, a 30A ESC, should it be enough to not burn out mid-flight or something tragic? Would I get some kind of fair warning (obvious smoke, buzzer, etc.) before my investment falls out of the sky? Thanks! Edit - I'll be using 1555 props as recommended, and the ZD550 frame with a small gopro gimbal AI: Myriad factors contribute to the current draw of a drone motor including supply voltage, motor kV, the propeller geometry (i.e. diameter, number of blades, pitch), ambient atmospheric conditions, etc. One can make educated guesses and estimations of the current a motor will draw under known conditions, but the best and most accurate/reliable method is to test the desired setup and measure the current draw under the expected operating conditions. If you can, you should try this by assembling the motor and propeller on a thrust stand and powering the motor while measuring the current draw with an ammeter. From the Banggood listing linked to in the OP: The motor of interest here is the 600 kV variant, which appears to be rated for up to 6S voltage, but power draw is only displayed for 4S voltages. If we take the rough assumption that the motor's current draw will increase linearly with the supply voltage (also assuming all other conditions are unchanged), then we can estimate the current draw for the listed propellers running on a 6S batery: $$\begin{align} \text{New Current Draw} &= \frac{\text{New Voltage}}{\text{Old Voltage}} \times \text{Old Current Draw} \\ &= \frac{6s}{4s} \times \text{Old Current Draw} \\ &= 1.5 \times \text{Old Current Draw} \end{align} $$ APC1238 (12" prop, 3.8" pitch): 25.8 A APC1447 (14" prop, 4.7" pitch): 33.75 A 1555CF (15" prop, 5.5" pitch): 34.5 A NOTE: These are incredibly rough estimates. I highly encourage experimentally determining the true current draw of your intended setup. NOTE: These calculations will be irrelevant if you're not using the same propellers as the ones cited in the experimental performance data. As @Kralc mentions in his answer, you should add a roughly 20% safety margin on top of the expected current draw when spec'ing out an ESC to account for any unforeseen situations.
H: How do I test if my DX5e antenna is still good? I have a second hand DX5e tx that I haven't really used a ton yet, just on a little Blade Inductrix, within my house. However, the upper plastic end is broken off and the actual antenna seems pretty beaten up. Is there a way to check the reliability of the antenna before I risk it on a more expensive/larger drone? I hear that replacing this particular antenna is a pain and I'd rather just 3d print the upper cap out of PLA if I can. I have a cheap multimeter, if that helps at all. Thanks! AI: That's probably OK, but you should do a range test. All transmitters have a mode that transmits a much lower power than normal, and if that is sufficient to control the model at 30 paces, full power will be enough to fly further than you can see. From page 9 of the DX5e manual: Face the model with the transmitter in your normal flying position. Pull and hold the trainer switch while toggling the HI/LO Rate Switch four times. The LEDs will flash and the alarm will sound indicating the system is in range check mode. note: The trainer switch must be held the entire time during the range check process; releasing the trainer switch will exit the range check mode. You should have total control of the model with the trainer switch pulled at 30 paces (90 feet/28 meters). Now an Inductrix probably won't have the range of a normal receiver so don't worry if it's a little short, but you should range test every receiver you buy every time you install it in a different model. Ideally from a range of angles to make sure the antenna can't be hidden behind a large metal or carbon-fibre part. Before doing a range test, it's important to either remove the props or ensure that the model will shut down if it loses signal, to prevent it flying away.
H: Can I replace the switches on my taranis qx7s with switches from a X9D? One of the switches on my taranis qx7s recently broke, and when looking at replacement switches I found two alternatives; X9D and X10/X12. The X9D switches are much cheaper than the other, so my question is therefore: are the X9D and qx7s switches the same? AI: Technically speaking, the electrical functionality of all normally-open SPDT (single pole double throw) toggle switches are exactly the same; it's just a matter of the physical dimensions of the part. The important dimensions for matching RC TXs with toggle switches are the diameter and pitch of the threads cut into the cylindrical section, but they're unlikely to differ between radios. (cit.) The kinds of SPDT toggle switches used in RC transmitters and like are so common and standardized that it's unlikely any manufacturer would go out and make their own instead of sourcing standard ones. In regards to possible differences between FrSky Taranis QX7S and Taranis X9D switches, this RCGroups thread seems to indicate that they are interchangeable. I don't have either product, so I can't speak from experience, but the primary plausible difference seems to be between an M6-0.75mm and an 1/4-40 (inch-TPI) thread on the switch. The replacement switches I've purchased for my own transmitters usually come with matching nuts, so I don't think the possible difference thread pitch is really a concern. M6 and 1/4 in diameters are pretty close in size, so I don't think that the diameter difference would pose much of an issue when sticking the new switch into the clearance hole in the transmitter housing.
H: What obstacles are there in making ultra long range model aircraft? As far as I am aware, there have not been any model aircraft that have successfully circumnavigated the Earth without stopping. Few trans-Atlantic attempts have succeeded (see: The Spirit of Butts' Farm). My question is: what makes long-range model aviation so difficult? Is the small size of model aircraft disadvantageous when traveling long distances? Or is success just a question of improving the materials and propulsion, and flying during good weather? AI: So many different issues, I study a lot of the FAA regulations closely but have contemplated this same question a few times. The power and weight of gear is heavy, so to make it all the way around is not going to happen without a lot of hacking. (solar proof of concept or similar notwithstanding) Efficiency of solar (power and weight) is a problem. The square feet of solar needed is quite large and disproportionate to how we conceptualize "RC planes". These vehicles are really flying solar arrays. Data, control, tracking, and safety assurance is much harder half way around the globe, even with satellite assistance Satellite data and connectivity hardware is still big leaving this type of task to the larger military units. From a regulatory perspective FAA would rather cut their hand off than issue BVLOS waiver Patchwork problems internationally exist not only for aviation, but also frequency use . EU radio freqs are very different. When traveling to fly internationally it takes a while to make sure I am legal or have legal gear. Clearing airspace for these attempts is a serious undertaking of budget and politics. Weather is a huge concern for small craft. Variations in the strata of the atmosphere are no joke. Be it thin air at altitude, winds, cold/hot temperature, all of this is hard for a small craft to manage. "At heights of 7 to 16 kilometres, the air in jet streams moves at constant speeds of over 25 metres per second or 90 kilometres an hour." source The US Military is one of a few orgs with advanced programs for this type of use. The U.S. military UAS groups has Tier 2+ with a '3,000-nautical-mile (6,000 km) radius'. These devices range from sub-55 pound to 2+ ton vehicles. For what it is worth, I know some people with ties to a successful cross Atlantic RC plane flight. The stories they tell underscore how hard this task is to pull off. In the end our number one obstacle for extended UAV flight of this type (and in general) is the same problem we have for phones and laptops. Our current battery tech is 20-30 years behind the technology it powers. The physics community engaged with this part of the equation frequently try to move the ball forward but the person to make a lighter and better battery will win the internet. Other fuel types are out there too, for example Hydrogen where the MFD3000 by Bobby Watts is available with a hydrogen fuel cell providing some interesting performance and represents good progress. I think anyone with some expertise in mechanical, electrical, aviation, fuel and power train, etc could stop by and add a few more reasons why this is generally out of reach right now.
H: Is it feasible to use an RC car transmitter/receiver to control an RC plane? I am a beginner to the hobby and I've been constructing chuck gliders out of foam board and card for a few years. I'd like to start making models that I can control, but I don't have much of a budget. I do, however, have a hobby-grade RC car with a receiver/esc/servo combo and matching transmitter. I am planning on removing this unit and using it to control the one channel (pitch) of a foam board glider. Is this a feasible idea? What are some major problems I might come across? AI: Maybe! Let's take a look at what parts from the RC car we might be able to reuse for an RC plane. You haven't shared any specific details about the RC car you're looking to salvage parts from or the RC plane you're trying to build, so I'm not able to make a specific analysis. RC Transmitter and Receiver One major concern is how many analog channels the RC car control system has. analog channels allow you to vary the control signal through its range of motion as opposed to having the channel just be on or off. AFAIK most RC cars only have two channels (throttle and steering) and you'll need 4-6 channels to control an RC plane (ailerons, elevator, rudder, throttle, any aux channels you may need). You probably won't be able to reuse the RC TX/RX if it doesn't have >=4 analog channels. The RC transmitter might also be less than ideal for RC aircraft control. If you have one of the pistol-grip type devices, like this one from Radiolink, you might find that operating the plane becomes cumbersome even if it has enough analog channels. Most RC aircraft controllers are shaped quite differently for ergonomic reasons, like this one: ESC The major factor to consider here is the current rating of the RC car ESC. Depending on the size plane you plan to pair it with, you may need an ESC capable of supplying >20-30 amps of current to the propeller's driving motor. Assuming that the current rating for the ESC is adequate, the chances are good you'll be able to reuse the RC car ESC. BLDC Motor This is something you didn't ask about in your question, but I thought it would be good to mention anyway. It's possible you may be able to reuse the drive motor to power the propeller, although it's difficult to give a more specific answer without knowing more about the RC car and airplane. As @JacobB notes: Most RC cars use comparatively low voltage batteries (2-3s) and have a spur and pinion gear to create the necessary torque. And because many RC cars use brushed motors (and the ones that are brushless have high Kv, like 4000 or 5000), having the motor attached directly to a propeller would likely result in either a severe lack of power and/or extremely inefficient performance. Servos Servos are rated for how much deflection they can provide (e.g. 45°, 90°, 180°, 360°, continuous/infinite rotation) and how much force/torque they can deliver. Again depending on the size of the aircraft you want to control, the servos you find in your RC car may be too small to control the aerodynamic surfaces of your plane. The aerodynamic surfaces on a plane can experience decently strong forces in-flight, so it's important to make sure your servos are appropriately sized and can maintain control.
H: Why don't solutions exist for a 3-axis helicopter flight controller? So I've been searching around for a 3-axis flight controller for my 450-size helicopter. It seems that nearly every flight controller which is sold today is configured for solely the control of quad/hex/octo-copters, and have little options for helicopters. Why don't helicopters have much options for flight controllers? AI: Beta flight has helicopter modes ("Heli 120", "Heli 90", etc. depending on your swashplate layout), as does pretty much every other programmable flight controller software. The outputs from the flight controller are the inputs for the ESCs, which have the same signal protocol as servos. The exception are the flight controllers with integrated ESCs, where the outputs actually drive the motors directly. This also allows most flight controllers to be used in a fixed wing, where most of the outputs drive servos.
H: LiPo battery power maximization I have a 3S1P 2.2A 50C battery for a drone that I build. I have a charger that looks like this: https://www.alibaba.com/product-detail/RC-B3-AC-Lipo-Battery-Charger_60812527463.html At first, when the battery was new, I pulled a solid 15-20 minutes of aggressive flight time but now, only 6 months later, it is getting only 3 minutes! I have charged it for like 5 hours and it reached 12.48 volts which is good but I think the charger doesn't put much current and when it hits 12V it just stops charging. This is just a guess. Can someone please help me with this. I don't have much of a budget so is there is a safe way for me to get more flight time, I am more than happy to hear it! Specs: My drone is an F450 frame with 4 A2212 100kv motors and weighs a total of 4lbs. My props are 1045 props and I have 3S 30A ESCs! I am using an Arduino as a flight controller and the YMFC-AL firmware/code. AI: TL;DR: You probably need to get a new battery pack. Your current one is likely at the end of its life. My guess is that your battery is just old and has reached the end of its useful lifetime. The fully-charged capacity, and by extension flight time, of all batteries decreases over time when charged and discharged repeatedly. This process is sped along by pulling large amounts of current from the battery like what is sometimes necessary for multirotor flight. Your description of the slow charge rate after the battery reaches ~12V points to the battery being degraded. At 12V, a 3S battery pack is sitting at ~4.0V/cell. This means that the charger has likely entered the balance charging phase where it tries to equalize the voltage of all 3 cells in the pack and slowly bring them up to 4.2V/cell. Well-worn batteries will take longer in the balance charging phase because the internal resistances of each cell in the pack (which generally increases during the battery's lifetime at different rates for each cell in the pack) are different, resulting in more energy and time that must be used to fully balance the pack. Tips for Increasing the Lifetime of a LiPo Battery Although you mentioned that you're not really on a tight budget, you're probably interested in how you can make your next battery packs last longer. Here are some of the more common things that cause wear: Sustained and peak current draw: It's generally an excellent idea to avoid drawing excessive amounts of current from a battery. Full throttle punches are fun and sound amazing, but do contribute to accelerating the degradation of the battery, so maybe don't do them as often. :) Charging beyond 4.2V/cell: LiPo batteries shouldn't be charged beyond their full capacity of 4.20V/cell. Aside from increasing the risk of spontaneous combustion, the increased cell voltage puts extra strain on the internals of the battery, which accelerates battery degradation. It's true that some specific variants of LiPo have higher full-capacity voltages, like LiHv with ~4.25V/cell, but the vast majority of LiPo cells shouldn't be charged beyond 4.20V/cell. Not storing packs at ~1/2 capacity (~3.7-2.8V/cell) for extended periods of time: Much like how over-charging LiPo batteries beyond their full charge level increases the internal strain on the pack, the same is true to a lesser extent for lower cell voltages over a long period of time. It's generally accepted that storing LiPo batteries at ~1/2 capacity, which translates to ~3.7-3.8V/cell, is safe and is a happy medium for minimizing battery degradation over a long period. If you plan on not flying your batteries for more than a few days, it's a good idea to run what's often called a "storage charge program" on your balance charger to charge/discharge your battery to ~3.7-3.8V/cell. Then recharge your batteries back to full as soon as is practical before flying. Draining a pack too far: For normal use, permanent damage is caused to the battery if any of the cells drop below 3.0V/cell. Although as I mentioned previously, multirotors demand a lot from our batteries, so it's important that we try to keep the average cell voltage above ~3.4-3.6V during flight. This is because LiPo battery cell voltages drop off quite quickly below ~3.6V/cell, and so it's important to keep some margin to prevent any of the cell voltages from momentarily dipping below 3.0V before we can get the chance to land safely.
H: Where can I find a list of all the model aircraft flying fields in the USA? Is there a comprehensive list of model flying fields that have operated or have been developed in the United States? I assume the AMA has some of this data, but I am curious if there is a larger list that designates all places to fly both past and present? Present is fine if past is too big an ask. AI: Does not exist, a few reasons. AMA lists most of their fields, but that information is spotty and I have almost been arrested trying to fly at listed AMA sites that are not valid. FAA has this list, but they have openly admitted that infrastructure and management problems have led to this data being in decay and not very useful. This problem was exposed as 107 was coming into law and many commercial pilots raised a stink because airports on flight maps were never (EVER) updated, this led to LAANC and the apps becoming more of an authority. No one shares spots. There have been several apps that try to get people to share and they all went belly up real fast. This information ALL exists in the FAA, but their data is horrible (I work with this info, total nightmare). Most of the good fields are private and invite only in my world. We run a few spots and you will be shot dead if you fly there with out permission (not an exaggeration, I often carry when flying). Airmap and Kittyhawk will have reasonably good current AMA type fields. That data is the best for "free". You may want to check with Snowflake, but their data feed (last time I was involved) starts at $5k/year. It should be noted that the FAAn NTSB, FBI, and other orgs all recognize the unstructured, uncoordinated, and non-unified nature of RC flight and use this to control airspace. I mention this because there is considerable history on the record of the FAA trying to wipe all drone use from NAS and this is a declared strategy and we have seen it in action. Dig into the DC restrictions of 2014-15 to understand why the FAA is an advisory and not an ally.
H: Transmit video from drone to laptop via WiFi I recently decided to build my first drone and bought Eachine Tyro 129 KIT. It has a 5.8GHz video transmitter - xf5804 which is supposed to send video to 5.8GHz goggles. I don't have goggles and I'm not sure I want to buy it. My laptop (Debian10 Linux) has WiFi that can operate on 5.8GHz frequency. How can I transmit video from the drone to the laptop directly? Which extra software and/or hardware do I need? What maximal distance can I get with the video transmitter operating in the 600mW mode? AI: This is not possible, at least directly. Although the two technologies use the same frequency range, they are very different communication protocols. A possible solution would be to buy a compatible video receiver (which might be the goggles) which has a video output - typically composite, for analogue systems - and a USB video capture card for your laptop. Regarding signal range, the product page you linked to indicates ≥2km at 600mW.
H: Streaming FPV over WiFi? I met a guy some time ago running a first person view (FPV) stream over Wifi. He said that the setup didn't use a complete Operations System Interconnect (OSI) network stack and this allowed them to stream video faster then one might over User Datagram Protocol (UDP). I don't recall the details but at the time he said it was a common trick used by Drone flyers, perhaps this was just the group he knew. I was wondering if anyone had any further information on this. I believe he was streaming 4K and was quite surprised. At the time I was messing around with a an early Raspberry PI and trying to stream video myself but I could only achieve a speed/quality that where far inferior by comparison. AI: This is done by placing streaming video data (RTP) directly into the Wi-Fi frames. Checkout https://github.com/svpcom/wifibroadcast/ project for more details.
H: Flysky FS-ia10b output more than 2000 microsecond pulse I just modified a servo to spin 360 degrees by taking out its potentiometer and replacing it with a voltage divider of roughly the same value. So when I use an Arduino, I have to send a pulse of about 2250 for the servo to be controlled. Anything a 1000 microseconds lower and it will just spin and won't respond and same for over a 1000. So what I want to do is to send a pulse from my Flysky receiver of more than 2000 microseconds. Is it possible and if so, how? Receiver: FS-ia10b Transmitter: Flysky FS-i6X AI: I don't think that will be possible. The protocol for analogue radio was a 20ms packet, consisting of up to 9 pulses and a gap. So there were 10 things in a 20ms packet. The receiver would split each packet into 2ms blocks and send each block to a servo. Any pulse longer than 2ms would overlap the pulse for the next channel. Obviously with digital radio, it's entirely possible to exceed this limit but I think it's unlikely that there will be an easy, built-in way to do it. Once you've set the end points as high as they'll go, I think that's all you can do. You could use an Arduino to scale up the pulses you're getting from the receiver to the size you need for the servo. An Arduino Nano is a similar size and price to a servo, and easily able to handle that sort of task. However I think you'd be better to look at why your servo needs such a long pulse. Presumably it worked OK before you modified it, so it should be able to work from a standard pulse. It's possible that you've damaged it during the modification, or that the resistance of your voltage divider is too different to the original potentiometer, or that you've connected it incorrectly.
H: What is this ring attached to the bottom of this rotor shaft? My motor came with a black ring attached to the bottom of the rotor. It spins along with the rotor, and it's not exactly a ring shape since it's open at one end - kind of like an omega symbol or like a stag beetle's horns. What is it called and what is it for? AI: That is a circlip (or C-clip) - it looks like it is used here to prevent the shaft from coming out of the bearing. From the Wikipedia link above: A circlip (a portmanteau of "circle" and "clip"), also known as a C-clip, Seeger ring, snap ring or Jesus clip, is a type of fastener or retaining ring consisting of a semi-flexible metal ring with open ends which can be snapped into place, into a machined groove on a dowel pin or other part to permit rotation but to prevent lateral movement. There are two basic types: internal and external, referring to whether they are fitted into a bore or over a shaft. Circlips are often used to secure pinned connections.
H: Can a lipo battery be charged with more than 0.5 amps? Using ISDT q8 to charge my 1205mAh 6S lipo battery. I'm wondering if I can change the default settings and charge with more amps? Is this recommended or will it degrade the battery much quicker. Any information would be much appreciated. AI: You definitely can charge your 1205 mAh 6S LiPo at a current higher than 0.5A. For most of the LiPos we use on drones, the recommended charge rate is 1C, which for your battery, would be about 1.2Amps. (A 1C charge rate is 1 Amp for every 1000mAh) A 1C charge rate is a good middle ground, but you can use a lower charge rate (~0.5C) for safer but slower charging, or a higher charge rate (~2C) for faster charging at the expense of the battery's longevity (and more risk of fire). And as @ifconfig mentioned, this similar question should also help answer your question.
H: How to secure the screw on a BLDC motor shaft I lost the screw that holds the motor bell to the base of the motor. I replaced it and flew, but it came loose and I lost it again. I used blue thread lock to secure it. Do I need to use red thread lock? What's the trick to keeping the screws on? AI: Use red or better. Blue and sub-red are explicitly designed to loosen with low to medium heat. (in the manual) FWIW, thread lock is little more than an increasingly heat resistance paint, close in composition to latex paint (depending on the brand). I have used latex paint and also nail polish in a pinch (an old trick from a car mechanic). If you want a screw to stay, and are okay with possibly never getting it out again, there are a number of advanced and possibly no bueno tricks. All of these are from decades of mechanic work and caution is advised. Toothpick: Shred it, thin it out, stick it in and screw away and grind the fibers in. Tooth pick with thread lock, glue, or paint. Metal shavings, grind them in Damage the correct end of the screw or thread so you get a fused connection (may never come loose >> aka >> danger zone). In some cases, you can cover the screw with a proper cap to stop it from spinning and falling out, similar in theory to the use of a c-clip. For example, drop solder on the top and let it "cast" into the head, then put electrical tape over it (not recommended, many reasons like motor may be off balance). Copper braid or similar, just jam it up. Re-tap and get a new screw Your problem is most probably a combination of these factors: heat hot/cold expand and contract cycle vibration possible weakened threads (cut wide from friction). The trick is context, experience, knowing the tools and materials, and not buying cheap stuff. Now to the meat of the issue - BLDC motor, that is a broad designation (https://en.wikipedia.org/wiki/Brushless_DC_electric_motor), so you could be using an in- or out-runner. Big/low Kv versus smaller high Kv demands a different solution possibly. Each motor has a unique footprint on vibration, heat, operational range, expand/contract margins, etc. So there are a number of factors that will help you decide what is best, I would contact the company if possible (probably Chinese and ZFG, but always an early consideration if possible).
H: How do I wire up this transmitter and camera I'm a total newbie to FPV and electronics. My son bought the following components as an adventure into FPV for his Remote Control vehicles (cars, planes, drones). Descriptions of the components: Eachine TX805 5.8G 40CH 25/200/600/800mW FPV Transmitter TX LED Display Support OSD/Pitmode/Smart Audio https://www.banggood.com/Eachine-TX805-5_8G-40CH-25-or-200-or-600-or-800mW-FPV-Transmitter-TX-LED-Display-Support-OSD-or-Pitmode-or-Smart-Audio-p-1333984.html RunCam Swift 2 600TVL 1/3 CCD 2.5mm/2.3mm/2.1mm FOV 130/150/165 Degree Mini FPV Camera PAL with MIC Support OSD https://www.banggood.com/RunCam-Swift-2-600TVL-1-or-3-CCD-2_5mm-or-2_3mm-or-2_1mm-FOV-130-or-150-or-165-Degree-Mini-FPV-Camera-PAL-with-MIC-Support-OSD-p-1118948.html Eachine ROTG02 UVC OTG 5.8G 150CH Diversity Audio FPV Receiver for Android Tablet Smartphone https://www.banggood.com/Eachine-ROTG02-UVC-OTG-5_8G-150CH-Diversity-Audio-FPV-Receiver-for-Android-Tablet-Smartphone-p-1242422.html The transmitter says it takes between 7 and 24V - so the first issue is to find a battery to power this that fits the connector it has. I don't know how to describe the connector it has so I don't know how to find a compatible battery. Second, from what I understand the transmitter has 5V out to power the camera, but I don't know how I'm supposed to attach the 2 together. My first objective is to get the transmitter and camera connected, with a battery to power the transmitter - so we can at least get something working. Can anyone help me understand what I need to do? Thanks in advance... AI: These components can be split into two functional groups, one for transmitting a picture and one for receiving it, which aren't connected to one another by wires. The Runcam camera and Eachine VTX are both parts of the transmitting section, while the receiver doesn't need to be soldered to anything else in the receiving part. Required Soldered Connections: You'll need to make the following wire connections between the different components: (splicing together the components' connector pigtails is recommended as opposed to trying to solder directly to the camera) Battery+ → VTX 7-24V wire Battery- → VTX GND wire (there are a total of two available, choose either one) Battery+ or VTX +5V wire → Runcam 5-36V wire Battery- or VTX GND wire → Runcam GND wire (in 5-pin camera connector, not the 2-pin camera controller connector) Runcam Video wire → VTX VIDEO wire Essentially, both the camera and VTX need to be connected to each other for the analog video signal (one wire) and each need to have connections to ground/GND and a positive voltage source within their requirements. Battery Setup: In this setup, the VTX is actually the component that constrains the kind of power sources/batteries you can use. It requires 7-24V to operate, which means you can use 2S-5S LiPo batteries with it. (or another battery pack within the same voltage range) Most drone/RC LiPo batteries these days come with either an XT30 or XT60 connector, but can be purchased with other terminations. See this page for a list of the most common ones. Once you know what your battery's connector is called, you can purchase a set of connectors online and solder them to the VTX and camera as required. It's unlikely you'll be able to match the connectors that come with the parts together. While the connectors are all off-the-shelf parts, their usage is unfortunately not really that standardized between manufacturers. You're probably better off just cutting the cable that came with the camera in half and soldering it together with the pigtail wires that come with the VTX. Once this is done, you can hopefully power on the VTX, camera, and receiver without issues, (remember to screw on the VTX's antenna before powering up so you don't damage it!!!) set the VTX and receiver to the same channel, and view the picture on the connected Android phone/tablet. Did I leave something out? Please let me know if I did and something doesn't make sense...
H: Betaflight - Angle mode - motors spins once I arm the quad I have my quad using Mamba F405 MK2. When I arm my quad the motors start spinning. I also set the pid_at_min_throttle = OFF but same behavior. Don't really know why is having this behavior. Any clue? AI: Airmode is a great feature if you race or fly freestyle. As you found out it spins up the motors at 0% throttle. You usually want this to be enabled since lowering the throttle to 0% would stop the motors and this results in a fast death roll of the quad. But Airmode also helps during fast rolls when certain motors cannot spin faster or slower to get more consistent behaviour independent of the throttle position. The default setting has airmode always actived. But you can disable the permanent airmode and enable it with a switch in the modes tab. I usually do my setup this way: One AUX channel controlls both angle mode and airmode in a way that DOWN enables angle mode and UP enables airmode. I take off and land in angle mode without active airmode. That way the props can stop and do not spin after arming the quad. At the same time this setup ensures that airmode is always active in acro mode.
H: Binding DX5e (or any other hobby controller) to generic "toy" drone - protocol compatability I picked up a really cheap generic drone mostly for the purpose of tinkering and testing with something that I wouldn't mind losing or destroying. However I can't seem to bind to it with any of my controllers. The main one that I use is the DX5e (DSM2, as it says on the front), but I don't think it's working. Is there a standard/universal procedure that I can use to be fairly sure that the drone is incompatible or broken? Does a difference in rx/tx protocol always make it completely incompatible? I have a few other "toy" transmitters that I tried a little as well. It's something like this RCtown SH5 (Wish.com). AI: There are many different communication protocols used for radio controlled models and even for the same vendor the parts/versions are not always compatible. While most use the same chips to build their systems everybody uses a different protocol and so the different parts do not understand each other. Most of the companies do not release official information how the protocols works and are not interested to make their products compatible with a competing vendor. So if a drone claims to be DSM2 compatible there are two options: a genuine spektrum receiver is used or somebody found out how the protocol is working by reverse engineering the system. Most cheap drones do not use genuine receivers since the product costs less than the receiver alone. The drone you linked does not state DSM2 compatiblity so I'd say the problem is that you have no compatible tx. But information on the product page is not sufficient to tell what they are using. You could try to find out what protocol the drone uses and check if the multiprotocol project supports it: https://github.com/pascallanger/DIY-Multiprotocol-TX-Module/blob/master/Protocols_Details.md But even in that case you would need to buy a multiprotocol module and make sure it works with your DX5e.
H: Possible to use Eachine E160 with Futaba T6EX transmitter/receiver set? I've inherited a Futaba T6EX transmitter with a Futaba R6106HFC receiver, and now I'm planning to buy an Eachine E160 RC helicopter (BNF version), to be bound to this Futaba set. However, I'm not sure if the receiver can actually be connected to the motherboard of the E160: I've found a video that shows how to connect a receiver to the E160's motherboard, but I'm afraid that available DSM and SBUS/PPM ports are not suitable for my Futaba receiver. AI: The product page of the helicopter states it is compatible with: FUTABA S-FHSS, expandable satellite receiver, and supports DSMX DSM2 PPM S-SUS Your TX/RX are from Futaba but from the older FASST system so S-FHSS is no option. DSMX and DSM2 are from Spektrum and not compatible with Futaba. There are two options remaining: PPM and S-BUS. Both do basically the same: send the signal of all channels via one cable. As far as I can tell your TX does not support either and only allows to send one channel via one output. S-Bus is also from Futaba so you could try to find a FASST receiver that supports S-Bus output. Frsky also has compatible FASST receivers with PPM output (like FrSKY TFR4-B). Then you could solder a connector from the outputs from the RX to the E160 motherboard. The yellow cable in the picture is the S-BUS/PPM wire, red is 5V and black is ground. To find the correct matching pins on the RX I'd look in the manual. Usually you have some labels on the case. A PPM enconder is also an option. This is a small board that encodes the servo signals to a single ppm stream. The downside is that you still have many cabels between the encoder and the RX and you need space for an additional board.
H: Vertical Flight Paths I've been searching around for software to allow a vertical flight plan. For example I want to flight 50m across a building at 20m AGL. Then drop 1m and fly back 50m. So on and so forth. I've read a bit into DJI, DroneDeploy, and Pix4D, but haven't been able to find anything. I've read something about double grids, but I believe that is for 3D models? I am not trying to capture a 3D model. I know that in at least Drone Deploy you can create multiple flight paths, but you have to land and restart for each altitude drop. I am also not taking any pictures. Looking for just the flight path. This could be done manually, but I'd prefer it to be automated. Does anyone have any suggestions? AI: There is a software called UgCS which I believe should fit your requirements. It allows you to create waypoints with precise location and altitude. There are options like terrain following which allows the UAV to maintain a relatively constant altitude above ground level, a Facade scan tool which allows you to plan a flight path along a vertical plane at a certain distance from a wall, or there is the option to easily create custom waypoints with specific altitudes as shown in this flight path:
H: How to record footage from AcroBee Lite? I have an AcroBee Lite(linked to the site I bought it) that I've gotten okay with, and now I would like to record some footage with it. The only problem is, I can't figure out how to record. Any idea what buttons I have to push to start/stop recording? Where can I find the files after I record them? AI: I just scanned the manual for "record" and nothing. I looked at the build and I see no indication of recording capability. There are 3 options (unless there is more information): Record on goggle. Some goggles have a DVR built in, generally low quality. Record on a dedicated DVR on device, goggle, or another receiver. I have used all of these options, DVR's start at $20. Mod it and put in a recording camera (if possible). This will get you to 1080p fast (if possible). RunCam, Caddx, and Foxeer all have models. I was working on this spreadsheet last week for our sub-250 units researching mounting trends - it is not complete but has a lot of the key players. I know the New Bee guys and they should be able to help you out.

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