APM with only rudder?

Greetings. New on the forum I just ordered the APM can't wait to get set up. I did search the forum briefly and did not readily see and answer to this question but if I missed it my apologies.  The plane I will be using is an older balsa nitro engine W/ 3 channel trainer. A Sig seniorita to be exact. Very large wing area and extremely low wing loading. It also has the distinct advantage of the fact I already have it. ;} However it does not have alerons. I do see one of the preloaded configurations for the AMP  is the 'easy star' which on looking at the picture seems to not have ailerons?  Does this mean the AMP can in fact be set up for only a 3 channel plane? Would I connect the rudder servo to the aileron spot on the APM? Perhaps this will be address in the set up process but I don't have it yet so cant get that far and was just sort of wanting to know. thx

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  • Okay so the first flight went very very well. Manual was fine. Stabilize was excellent. Auto flew very well too. Back on topic... the 3 channel model flew great with the rudder servo simply connected to the aileron input and output in the APM for roll axis control. Config adjustments were minor. Just engine speed, failsafes, etc. The stock ardupilot setting worked just great.  No specific model settings were downloaded. 

  • The plane flies beautifully without ailerons so it seems APM could be set up to do the same. I have not had time to actually install the APM yet but did connect the rudder out from loose receiver to the aileron input on the APM and then as Soren suggested [ thx ] turned the rudder mix to zero. Moving the apm left or right does move the servo as expected to adjust for roll. I have no idea what the amp would do if it tries to move , say a rudder, then gets no noticeable change in yaw attitude what it does. Does it detect a fault and then RTL or something? But so far it sure seems it can easily work with a 3 channel model. My thinking on connecting the rudder out to the aileron input on the apm is roll is what is mostly required while yaw is far more of a luxury correction with regards to an airplane staying in the air. Will let ya all know how it works out. 

  • Hi,

    I you never used APM or other autopilots before, I'd say better add ailerons to the model. The autopilots are rally mostly designed and tested for models with ailerons.

    An easy Star basic version really has no ailerons, that is correct.

    You should have the rudder servo connected to the rudder output. APM does most maneuvering though ailerons. To channel that to the rudder instead, look at the KFF_RDDRMIX parameter. It adds part of the aileron output to the rudder.

    Also see here. Maybe leave all those yaw parameters at zero to start with, as they (eg yaw damping) may counteract your roll by rudder.



  • Yes, the bixler is pretty popular as well.

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