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Tiltrotor support for plane

H all,

I bring back this dicussion because I don’t really get how the Q_parameters work and how to assign the outputs :confused:

I have a project of building a quadplane with a servo to control the angle of the 4 motors.

Here is the params I started to configure but that’s just the beginning and nothing is pluged on my Pixhawk except the RCIN and some servos to see how the outputs are answering :wink:
15-09 Param list beginning Quadplane bis.param (12.6 KB)

The Parameters I Changed are :
_ Q_ENABLE = 1
_ Q_TILT_MASK = 15 (1111) in binary (because my 4 motors are tilting)
_ BRD_PWM_COUNT = 6 (to have the AUX5 ;))
_ V_TAIL_OUTPUT = 3 (Because I have a V-tail)
For the RC _FUNCTION I chenged them so I get this configuration :
MAIN1: Aileron
MAIN2: Elevator
MAIN3: Unused
MAIN4: Rudder
MAIN5: Front right motor, CCW : RC5_FUNCTION–> 33
MAIN6: Back left motor, CCW : RC6_FUNCTION–> 34
MAIN7: Front left motor, CW : RC7_FUNCTION–> 35
MAIN8: Back right motor, CW : RC8_FUNCTION–> 36
AUX4: Servo for motor tilt angle : RC12_FUNCTION–> 41
AUX5: Servo for motor tilt angle reversed : RC13_FUNCTION–> 41, RC13_REV–> -1

I’d like to set my own PWM for the tilting angle and also have a transient mode with a 15°degree angle for exemple.
I don’t understand exactly how the “tiltrotor_slew(float newtilt);” is working in quadplane.

Can I create a QHover15deg mode that could be the same as QHover but with tilting motor angle at 15 degree ?

Hope you guys can help me

@GregCovey I’ve been feeling guilty about not following up on this thread. I thought I would have more time before the OBC started, but I’m leaving for OBC in the morning and still haven’t had time to work on tiltrotor some more. Darn!
Anyway, I think I know what is causing the motor “pop”. The PWM value is just changing too fast. It needs some slew rate code to prevent it going from nothing to full throttle in zero time.
I still haven’t setup my Cl-84 for flight. I hope to do that when I get back from OBC in early October. I’d really like to give it a test flight.
Also, you’re right about MANUAL mode. As soon as you switch to MANUAL all quad stabilisation is disabled. The intention is users would switch to a mode like FBWA first, but we need to fix the pop issue before that becomes workable for the CL-84.

Hi Tridge,

No problem. I have converted my CL-84 back to the stock FC and it flies great as is. My QuadPlane projects are keeping me busy now. My goal is to compare the QuadPlane concept for mapping against other more expensive solutions currently in the UAV commercial market.

I wish you the best of luck in this year’s OBC!


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I have been flying my CL-84 for some time. My focus has changed from tilt wing to tilt rotor. Havent seen any posts here about tilt rotor with Pixhawk hardware and Mission Planner. I am currently using
a KK2 board on my DIY Osprey, that works after a fashion. I would really like to used the functions of the Pixhawk to control my Osprey. Any developments in this area that I have missed?

We have mounted larger wings, improved the tilt-mechanics, installed tridges code and done the first copterflight succesfull:

The next steps will be testing the transition.


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The first part of the forward transition was successful. We chose 30 degrees as initial tilt angle, because the ratio of lift force (85%) and forward thrust (50%) seemes to us to be optimal. The plane accelerated quickly, stable as on rails and without any change in altitude. Thanks to Tridge for this firmware-version. Before complete switching to the FBW-A flight, I intentionally terminated the transition to see to see how the copter behaves at higher forward speed: In the attempt to slow down speed in copter mode, he still juggles up. We will have to adjust the PIDs even more sharply before the first complete transition.



Hi Rolf, what outputs did you use for the front ESC’s/motors and servos? And what for the servo on the rear motor/ESC?

I would like to use the front motors for yaw and have a fixed rear motor and am trying to figure out the wiring details.

Hi Rolf,
Great to see first tiltrotor transition, even if it was partial!
Based on simulation my main concern with the code as it is now is not the forward transition, but the reverse transition from fixed wing to hover when the aircraft is flying at high speeds. I’d suggest that for first flights doing a fixed wing to hover transition that you let the plane slow down to just above stall before switching to QHOVER or QSTABILIZE.
Cheers, Tridge

I published a 3D printable tilting motor mount on Thingiverse which I’ll be using on my VTOL tricopter. Still a work-in-progress.

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I’ve been following this for awhile and have a question. I’ve been flying an experimental Tri with Copter in a Pixhawk 2.4.8 with a wing on it, static mounted at 15 deg AoA, in an attempt to get an hour of flight time from it. It would be trivial to put tilt rotors on the wing and add ailerons to it:

My question is, if I try this experimental ArduPlane code in the 'hawk with tilt rotors, does the current implementation of the code leave the tail rotor active for pitch and yaw control in horizontal flight? Or would it require the addition of horizontal and vertical stab’s with control surfaces? I have experimented with taking it up to 120 meters altitude and cutting power and let it glide. I have perfectly acceptable yaw control from tail rotor drag with no power to the tail rotor in a glide. But no pitch or roll control. I kept adjusting the CG forward until it glides with no power, and have bigger motors and props on the wing vs the tail. Just bringing the throttle back up recovers it nicely from a glide.

Even if I could tilt the wing rotors ahead ~30 degrees I think it would greatly enhance efficiency and forward flight speed. Just wondering about the tail.

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no, it doesn’t. Possible to add of course, but for now it would need fixed wing control surfaces

Tridge, do you have the channel out assignments for a tilt rotor plane (front motors tilt, rear static)? I’ve only seen the ones for the quadplane in the wiki

I have AUAV-X1 & X2 flight controllers, do you know if their extra channel outputs are active otherwise I’ll have to source a Pixhawk?

thanks tridge. I think my idea is too far off from the current QuadPlane project to be useful. My thoughts were that conventional fixed wing controls are redundant and amount to what is essentially dead weight for VTOL. And the VTOL components become dead weight in horizontal flight. Thereby limiting useful payload and increasing complexity of the redundant systems.

So I had a totally different idea of adding differential tilt capability to the wing rotors on a couple output channels. And still use the tail rotor for greater payload capability, and wider range of CG, in VTOL. But also use it in horizontal flight to reduce the number of redundant flight control systems. With differential wing rotor tilt I can also eliminate the need for ailerons. I’m pretty sure this has already been done with both ArduCopter on APM (a couple years ago I think I saw a fork), and Cleanflight - using vectored thrust on a Tri.

Sorry for the divergence from the main topic. I think my concept is too much different than the QuadPlane implementation of a VTOL airplane. But I have done enough flight testing with this bird with the wing on it to determine it will work with vectored thrust. Just have to figure out how to do it.

Hi Tridge,
we will adjust the PID values as sharply as possible before testing reverse transition. Of course flying at low speed before reverse transitioning.

You need a servo for the rear motor. Wiring details:
Tiltrotor support for plane
( I recommend you to read the whole thread from the beginning)

Regards Rolf

The thread you refer to relates mostly to the CL84 which is a tilt-wing not a tilt-motor and thus the channel assignments are not the same. I want to use the front motors for yaw control and not have the complication of the rear motor having a tricopter like tail mechanism.

I would like to use a setup like this:

The tail has no servo and the front motors are used for yaw control.

I’m modifying an airframe at the moment but if I can sort out the channel assignments first it’ll help a lot.

That’s what I was referring to also. I would like to use differential tilt on the wing motors, which will provide yaw control in VTOL, and roll control in horizontal flight. If the prop rotations are right, like any multi-engine airplane, simply throttling the motors in horizontal flight will provide yaw and roll from differential thrust and torque. Adding differential tilt to the equation in horizontal flight adds very positive roll control, and would totally eliminate the need for conventional fixed wing control surfaces.

The current implementation is using the Tri code for VTOL and transition to plane for horizontal flight. I think there’s a more efficient way to do it that eliminates complexity and weight in the aircraft design.

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Hi Graham,

our plane is flying with the above mentioned assignement. Because it has standard servos, the parameter Q_TILT_TYPE is set to 0 (For HK CL-84 “Binary” type Servo Q_TILT_TYPE=1) .

Hi Rolf,

What is the airplane brand and model name you are using?


Hi Greg,

the airplane is self-constructed (mainly depron), designed and built by an Austrian friend of mine. Since he comes from Salzburg ( ) , the name of the plane is, of course, Mozart :smile:

Greetings Rolf

right now I’m building my first tiltrotor. I did some testing and I wonder how the plane behaves while switching vom hover to stabilize or FBW.
I expected that the tiltable motors tilt forward as I switch from hover to stabilize to gain speed. But right now it seems to be that I have to pitch the copter/plane to gain speed. correct?

You tried the transition already with Mozart. Did you take off with the tilted motors or is 30° tilted your endpoint? Did you already reach transition airspeed?


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