Here is a video and a 3-views drawing explaining the mechanism of a new tilted coaxial system.

The machine has a frame, and a motor comprising a lower output shaft and an upper output shaft. A lower assembly of blades is fixed to the lower output shaft, and an upper assembly of blades is fixed to the upper output shaft. An orientation module is mounted on the frame, and the motor is fixed on the module. The module includes an orientation unit to pivot the motor around a pitch axis and a rolling axis. The orientation unit comprises a plate mounted on the frame via a pivot link around the pitch axis.


Components embedded in the drone:

- Camera Fatshark Pilot HD

- 200mw 5.8Ghz Tx with Spironet antenna

- 2 JR DS385 sub-micro digital servos

- 1 contrarotating bruhsless motor Maxxprod CR 2805

- 2 ESC brushless 10A

- 1 Lipo Battery 3S 2200 mah

- 1 flight controller uPilot32 (VGR-Systems)

- 1 Graupner Rx for command input


Weight: about 500g

Flight time: 10-11 minutes


The main advantage of the system is the size: features of a big quadcopter but ccarried in a bag pocket.


Views: 4478

Comment by Gary Mortimer on August 26, 2015 at 10:33pm

What is worth a patent?  This has been done loads of times. Looks very neat though.

Comment by Gary Mortimer on August 26, 2015 at 10:41pm

Here's vector control of a contra on a kite 


Comment by VGR-Systems on August 26, 2015 at 10:54pm
The patent is the use of this system for stabilizing et controlling a vtol aircraft in the 3 axes. Not just to replace the governs of a plane.

Thank you for the "neat"!
Comment by Ouroboros on August 27, 2015 at 12:28am

So I guess the two sub-motors in the motor assembly can be controlled seperately to provide yaw via differential torque from the rotors?

This has the feeling of an FPV specific kickstarter in the making, if you can effectively pitch very far forward as a monocopter tiltrotor aggressive forward flight mode. Though that would probably require splitting the battery into two mounted side saddle on the frame closer to the pivot to shift the center of gravity, and shift the camera module down and to the rear to provide more clearance for the lower propeller when the motor assembly is pitched far forward. Not too far forward though, since you lose yaw authority as motor torque merges with motor assembly roll servo movement.

Comment by VGR-Systems on August 27, 2015 at 1:23am

Ourobos, you're right, yaw control is applied on motors.

Still need some work on the pid to test it but you can tilt the entire frame even with the battery below, particularly if your integral term is based on error(stick command - real angle). Then, you keep the power of motors aligned with the frame and the yaw applied in a good way. in this way, you can have a very agressive pitch (and roll) flight.

The other solution i tried is to keep the center of gravity very low. In this way, you keep the camera always leveled and you don't need any gimbal to stabilize during translation. in the pid loop, the integral term is based on error(real angle) to stay leveled. Nevertheless, the drone is slower during translation than the first solution.

Comment by Hans H. on August 27, 2015 at 3:15am
Nice build, but not new. In addition to all the research the past 50-60 years, there is also complete kits you can buy. Here is one of them.

Comment by hovercycle on August 27, 2015 at 3:16am

Really cool design. I'm going to build one too :)

Comment by R. D. Starwalt on August 27, 2015 at 3:56am

Nice to see it fly, even if for a brief period. Your efforts at miniaturizing the coax control system looks simple. I suspect the accelerometers are the feedback for the positional variations of the coax assembly. Small encoders might be tough to use in the vibration prone environment.

This airframe type might be a tool for law enforcement or other tactical uses if the propeller noise can be reduced.


Comment by VGR-Systems on August 27, 2015 at 3:57am


The coaxial birotor has been invented and patented for years you're right !!! (ex Kamov52)

Your exemple is a simple coax birotor and this technology is used by tons of toys all around the world but it is not the same system as presented here (rigid props, tilted plates, 1 motor, etc.)

Comment by JB on August 27, 2015 at 4:19am

That thing looks cool! It looks pretty stable as well, but accurate balancing will likely be needed for good control.

Is it true you only have one motor or do with CR-Motor do you mean a counter rotating motor? Is that different from two separate motors and can you still use torque differential for yaw control?


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