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New TriCopter-Quadplane Concept

#1

Hi guys

Thought I’d start a thread based on a new concept I’m working on. Basically, this is a reverse tricopter using the QuadPlane code with a twist. At the centre of the frame, I’m adding a EDF unit at the centre (C.G) that will provide (some) vertical thrust in QHOVER and then rotate to horizontal position for foward flight.

I have succeeded in getting the tricopter to hover (with tail rotor facing forward). The question I have for the Dev team, how can I drive the EDF in hover so that some thrust is derived from throttle position and then rotate the EDF when switching into forward flight? The EDF will provide forward thrust in cruise. Wings not shown in image.

Thanks!

mytri
mytri.jpg800×600 208 KB

Fanman

Getting Flight Mode and Throttle/Power Level via MAVLink for VTOL
#2

using plane throttle output may work, if not will require some small code changes

#3

Thanks Peter. My understanding is that plane throttle is inactive when in QHOVER mode? Is there a setting to link plane throttle to assist with lift?

#4

Hey, just saw this… http://ardupilot.org/copter/docs/booster-motor.html#booster-motor

Only question is how can I link boost motor SERVOx_FUNCTION = 81 to plane throttle in forward flight?

cheers

Fanman

#5

it will need a small code change i think

#6

As far as I know you might need a small chage in the code.

#7

Thanks guys. I’m not really a software engineer so some guidance would be appreciated.

From what I can see,

  1. In QHOVER -> SERVOx_FUNCTION = 81
  2. In FBWA or Auto -> SERVOx_FUNCTION = 70

Help please :slight_smile:

#8

Hi Dev Team

I have setup the ArduPilot dev environment on my PC in hope to modify code. I’m seeking advice from the community as to the entry point into the code to make the correct changes.

On the surfcae it would appear that all I need to do is to change the servo assignments between BOOST and Plane Throttle between flight modes. After reviewing the documentation online regarding RC_Channel, now I’m not so sure.

I’m keen to figure this out, I just need some guidance as to the correct entry points in the code and best approach.

regards

Fanman

#9

realflight SITL is great for testing this stuff.

Boost motor is a sensible way to go, first thing to do is check that it works for quadplanes in hover. Then assign it to just be throttle pashtough for forward flight.

probably here would be a good place, something like:

SRV_Channels::set_output_scaled(SRV_Channel::k_boost, tilt.current_throttle);

there might be one or two other thing to do but that should be a good start

#10

Hey thanks for the advice Peter I’ll give it a go. :grinning:

I plan to rig up an EDF and test booster first. I’m hoping there’s nil torque from the EDF to worry about so should work OK with the tricopter config.

The other thing I noticed in the code is that k_boost_throttle has a scale factor applied to it, so if I was to map it to k_throttle in forward flight, I’ll need to set scale factor = 1.

cheers

Fanman

#11

the boost output in multiopter mode is done here,

ie the scaling is not inherent in the output function, you can pass it whatever you like.

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