Ground steering with wheel and rudder on V-tail plane

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1

Hi All,

Our group is building V-tail plane with steering nose wheel. We have wheel ground steering but it’s not so effective on takeoff as both wheel and rudder steering. We could connect nose wheel servo to rudder servo output, but we have V-tail mix and ruddervators’ signals are not suitable for wheel steering. What workaround can we try? Or only coding this feature (wheel and rudder ground steering) will help?

Thanks!

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Hi Sagaris,
See the docs here:
plane.ardupilot.com/wiki/flight- … functions/
you can define a channel as either a “normal rudder” channel, while still having a v-tail, or as a dedicated ground steering channel.
I’ve flown quite a few planes with V-tail and nose-wheel steering.
Cheers, Tridge

3

Thanks Tridge!

It should work for us. But is it desired behavior to steer only by wheel while on the ground?

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It depends on the aircraft, but I generally find it is best to use both rudder and nose-wheel on the ground. As the plane speeds up the nose wheel becomes less effective and the rudder (in your case a v-tail) more effective.
I’d recommend using the normal v-tail setup, plus a servo set to RCn_FUNCTION=21 (ie. setup as a “rudder”) attached to the nose-wheel. Both the v-tail and the nose-wheel will be used for ground steering when below the GROUND_STEER_ALT.
You then need to tune the ground-steering code as described here:
plane.ardupilot.com/wiki/flying/ … r-a-plane/

Ground steering can be quite tricky to tune. Eventually I’d like to build in an automatic tuning system for it, but for now you have to do it manually. I recommend tuning using FBWA mode. You may also like to use the FBWA_TDRAG_CHAN option if you find you need a bit of down elevator to keep the nose wheel on the ground while accelerating.
Cheers, Tridge