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Setting up a new Fixed Wing Vector Tricopter

Hey all,

It’s about time I started a thread about my project. I imagine some of you will have seen this work on the ardupilot facebook group, my project page, or eve my Linkedin account. I apologise for the repetition!

My project is a VTOL fixed wing hybrid tri-copter (initially) with a MAUW of around 11kg, of which 1kg at least is payload. The aircraft is approximately 2m long with a wingspan of 3m.

Whilst I plan to sell this aircraft as my main business, I’ve tried to keep a community focus sharing what I’m doing and why. This is a 2yr long project along side my day job, with a few years of exploration before that.

I’m going to keep on with the community focus by sharing my experiences with flight testing the airframe.

I’ve read around the set-up of these configurations, including Greg’s excellent thread here. Obviously the high level configuration is similar to the Nimbus VTOL, but I won’t be able to use their parameters because of the difference in size (and, I don’t want to just copy their param lists - no learning in that / it’s just cheating).

My intention is to take a fairly cautious approach to the flight testing. Something along these lines:

Under operator control (Qstab?):

  1. Simple vertical hop up and down
  2. Vertical take off and rotation about vertical axis
  3. Vertical take off and translations in the horizontal plane

Each time checking control authority and stabilisation. From here I’ll move on to more complex tests, which we’ll cover as they come up. This will lead to some repetition but, that’s expected, and allows me to compare results with known data when I change/add something.

At the moment the aircraft has power on, and the next task is reinforcement of the inboard wings. The tilt rotor mechanisms are out being made and are likely to be the limiting factor for when first flight can be achieved.

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Hi Phill,

I am glad to see you post your project here as I do not visit Facebook. Your approach looks good and is very pragmatic. One thing to consider is that before testing transitions to forward flight, you first test the BARO and GPS sensors; QSTABILIZE, QHOVER, and QLOITER. In this manner, your emergency fall-back mode becomes QHOVER or QLOITER (instead of MANUAL) in case you have a failure in forward flight.

So on a normal APM Plane setup, we use MANUAL as our emergency fall-back mode. On VTOLs, we use one of the Q modes. I don’t even have the MANUAL mode as an option on my VTOLs.

Good luck! I am looking forward to your progress…

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Thanks Greg, that’s good advice. There’s a fair amount at risk here in terms of time, effort and to a lesser extent money, so I’m very happy to take all advice.

At the moment, I’m going through and setting up Parameters to suit the configuration. Lots to look at but mostly is sensible when I go back to the quadplane documentation. I’m using servo outputs 1,2 and 4 for the ESCs so I think I will have to change the standard settings if I’ve understood Q_ENABLE correctly. I need to get my head around bitmasks too!

Update: I think I’m ready for first (hovering) flight now. Bench set-up seems to work as intended, and the only way to know if I have the control authority I need is to go out and do it.

I’ve taken Gregs advice and have Qstab/Qhov/Qloit as my flight modes for now. I have gone through the transition with FBWA and there is an interesting behaviour that I hope never happens in flight:

If I go from QHOVER to FBWA the aircraft attempts transition and then fails because its on my bench without props. It signals failed transition to me on QGC and then goes back to QHOVER. Then the aircraft disarms itself rather than staying in the Q mode! Is this something to do with QGC or a parameter I haven’t set correctly?

I would upload a picture but the forum won’t take a 2mb png?!

Hi Phill,

Do this transition testing on the bench while disarmed. If you arm the plane and try to transition to FBWA, the speed estimator will not like it.

Reduce your image size to below 1mb before posting.

Good luck!

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