This project was started in , electronics and control loops. Because I always need a cool project to learn new things, it was clear that something that can fly had to be built.
The project started as a "tricopter-only" project, but as I wanted to build smaller vehicles with more payload capacity, I decided to make some quadrotor, hexacopter and Y6 hexacopter firmwares too. My main interest is to build very small MAVs that fly as good as larger ones (or even better) and that can be controlled by wireless video link. I also experimented with autonomous flight in GPS-denied areas (video), and with GPS assisted autonomous hover (video).
-- William

Contact: Shrediquette @ g m x . d e --- All content published under CC Attribution-Noncommercial-Share Alike 3.0 Germany

125mm, 125g mini brushless copter

Currently, I love to fly with my latest design, called "RECOIL": It is a very small brushless copter (125mm MTM) with a total weight (including 3S 450 mAh lipo) of 125g. It however flies like a large copter and is a lot of fun!

Emax F3 femto
RCX H1105 5000 kV
Racerstar 6A
3x2" props
3S 450 mAh

Some brushed action for the winter

It has been a while since I posted something here. It is not because my project is dead, it is more because I spent my hobby time with flying and not with making new things. The derbe evo is almost perfect and I am very happy with it, so I don't see the need to design a new frame currently. But I am currently rewriting my flightcontroller code in order to achieve a faster control loop frequency. 1000 Hz should be possible on my 8bit ATXmega32A4. I will achieve this by using integers instead of floating point variables, and by removing every unnecessary line of code.

But recently, I bought an Eachine QX90 (always wanted to adapt my own flight controller for a small brushed copter, but there was not enough time...). And it flies great. I however changed it a bit, here is my setup:
  • QX90 original FC (stock firmware, see settings in the pictures below)
  • Standard motors
  • Gemfan 65mm propellers
  • Custom frame (weight: 5.5g, see pictures below)
  • Eachine TX01 cam with dipole antenna
  • Turnigy graphene 1S 600 mAh lipo (see picture)
  • Spektrum satellite receiver (the original FRSky receiver only had 50m range, now I have >500m)
Have a look at these videos for the flight performance:

Some pictures of the frame and the cleanflight settings:

Derbe evo available on

Hey, I decided to make the derbe evo v2 available on So I don't have to send the files manually by e-mail. You can download or order using this URL:

The fleet...

Derbe evo - Version 2

I've been flying the derbe evo for a while now, and it is very agile and fast. I had to reduce the PD parameters by 30%. This is due to the fact that the mass is closer to the centre of the copter, and that reduces the moment of inertia. I was flying a competition with the derbe evo already (Hannover Cebit FPV Cup, here's a video). Unfortunately, the derbe evo crashed very hard during the qualifying (the gates were made out of massive steel, and the video reception was very poor). I think, I was frontally hitting a metal tube, and the 3D printed frame broke (two Cobra motors also have a bent shaft - I had to replace them as I do not manage to remove the shafts).
I implemented some modifications in the new version. The camera angle (wide angle lens) is now 35° (instead of 25°) to allow for higher pitch props. The 3D printed frame is thicker. And the power conncetor is now integrated in the frame. Additionally, I added a small button for the TBS unify pro to change channels comfortably.

There are many competitions this year that I am planning to attend, therefore I will most likely make another derbe evo frame as backup.

  • Flying Fischkopp vs. Kloppokopter vs. FPV Nutz (16. April 2016)
  • FPV Drone Master (30. April 2016)
  • FPV Race Friedewalde (07. May 2016)
  • Copter Clash Hannover (28. May 2016)
  • Bexbach German Master (27. August 2016)
RGB LEDs are mandatory on some events...

Increased camera angle. The ultra-large capacitors
might keep my ESCs and motors from dying all the time
(I lost 4 motors due to ESC malfunction already). I also added a
pull-down resistor (10k) to the signal wire of each ESC.

Pushbutton for channel selection & integrated power plug.

'Last christmas, I gave you my....'

First flight - derbe evo

The copter had its first flight yesterday. With the 5.5" Graupner Race-Props, the speed is absolutely amazing - I still need to learn how to control such a fast device properly.

Here is a quick + dirty video: 

And Shrediquette is still open source of course, so here are the 3D files:

The arms are from the Claerials HUMs quadrotor:

Shrediquette derbe evo progress

Some images of the assembly process...:

There is not much space inside the frame, but everything fits. The assembly also went quicker than I thought. I just need to replace all the motor shafts of the Graupner Ultra 2806 2300 kV motors (due to a hard crash), and then I am ready to go.

The take-off weight is just 447 grams.

derbe evo FPV racing quad

I think I now have all the parts that I need to start assembly. The frame weight is 77 grams (without electronics).

Here is the latest teaser:

My next FPV racing machine...

Here are some renderings of my latest frame concept. It has a very small frontal area and should reach high speeds. The diagonal motor distance is 210 mm and I will use 5.5 inch propellers (Graupner Race-Prop or C-prop).