Quadplane with no control surfaces?

Hello I just stumbled over this exciting webpage.
I had the following idea: when building a quadplane with four quad motors for lifting, and one motor for forward flight, could you just leave out all the control surfaces? The quad motors should give full control over all axes. Maybe that does not work at higher speeds though?

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hey emilalbert, i just had the same question. were you able to get any information on this?

Yes I was reading more and I think there was even a similar post somewhere.
The quad motors work well for direction control at low speeds, but they become inefficient at high speeds. For control surfaces it’s the opposite.
So it’s not efficient. But I’m not sure right now if it would still make some sense

Reminds me of this cool poject: A quadcopter with sensored fixed height and a pusher prop for forward thrust: The EjoWerks Speeder

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Nice. Now some wings in the middle and the back, then maybe it could stay flying with the quad fans turned off?

At high speed the quad fans have to work against the wings to change direction. So the quad fans should be placed quite far out, and the wing not too big

Regarding the flight control: from what I read here the Ardupilot controller should control the plane through the quad rotors when kept in the quadplane transition, by setting the ARSPD_FBW_MIN value very high:

https://ardupilot.org/plane/docs/quadplane-transitions.html

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Though in some automatic flight modes it might try to keep the speed above ARSPD_FBW_MIN.
Another option would be to just use a Quadcopter controller, and to control the forward propeller separately. QSTABILIZE mode should allow forward flight and control. QLOITER mode would attempt to keep position. QHOVER would use vertical thrust to keep it at a certain height

https://ardupilot.org/plane/docs/qstabilize-mode.html

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