I just built my first wing a S800 Reptile V2 using a Matek F411 Wing flight controller.

Here is the video of the behavior:


I just checked that my Servos are well trimmed and calibrated so when turned my Radio transmitter on both of them are in a 90 degre angle so my flaps are flat. If I have horizon mode enabled and I angle the the wing to the right or left I can see a small compensation of each servos so that’s also good. Also the sticks of my transmitter moves the servos in the right position, already checked that.

I wanted to test Autolaunch without the propeller installed. So I waited for the gps to get enough sats and then I armed and push throttle up and then grabbed the wing with my hand and simulate a launch and I could get the motor spin fast. So all that working flawlessly. The only thing that I noticed is that when I simulate launch by moving fast the wing is that right flap had a bigger angle than my left one, even if keep the plane with my hands completely horizontal with no tilt I could see that.

So don’t know if this is a normal behavior because I didn’t throw the wing in real life and then GPS is not updating altitude or maybe other thing.

Any clue? Does simulating autolaunch without throwing the wing could result in flaps not getting the right position becuase the wing is not in real air? Because what I was expecting is that when launching both of flaps went into up position having the wing prefectly horizontal.

Appreciate any feedback

  • 1
    $\begingroup$ I suggest getting someone else to throw it the first time, so you can be ready to switch it back into manual mode - or launch over long grass, so it doesn't matter if it crashes. $\endgroup$ Nov 16, 2020 at 9:07

1 Answer 1


A possible explanation is the flight controller compensating for propeller torque.

When a propeller spins, there is a counter-rotation applied to the aircraft (Newton's third law.) Assuming your propeller spins clockwise (viewed from behind the aircraft) this would be corrected in the air with a small amount of right roll - which is what is shown in your video. The amount of surface deflection will vary by airframe, so it is hard to judge from a video if the amount of movement is correct.

More info: http://ffden-2.phys.uaf.edu/webproj/211_fall_2016/Collin_Lasley/collin_lasley/torque.htm

  • $\begingroup$ Woow you just explain it as my Engineering classes at college. love it!! Yeah that makes a lot of sense and because I was testing holding the wing without a propeller then its difficult to see without throwing the wing in real life right? $\endgroup$
    – VAAA
    Nov 16, 2020 at 19:23

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