Rudder Mixing in Manual vs FBWA

Hi, I am close to doing the maiden flight with my Volantex Ranger 2000 running Arduplane on a Matek H743. Everything seems to be working fine, but I noticed a rudder mixing issue that I can’t resolve.

If I set a 10% Rudder to Aileron mix on the transmitter, I get a 10% response in Manual Flight Mode when I move the ailerons. All good. However, when I switch to FBWA mode, I get a 100% response of the rudder when I move the ailerons.

Is there an Arduplane parameter that is working to override my transmitter? Sorry if this is a newb question.

See here about rudder mixing and turn coordination. Though I’m not much of a Plane user, it’s my understanding that transmitter mixing is generally discouraged in any mode other than MANUAL.

@Yuri_Rage is correct, do not use any mixing (or trims) on the radio.

Modes like FBWA will automatically handle rudder mixing for you when you enter in a roll. It helps to think of FBWA differently, in so much that you aren’t requesting a roll when you move the stick sideways, but really you’re asking Arduplane to turn the plane. Arduplane will apply rudder based on your configuration.

This means that manual mode is left to be somewhat raw. No radio mixes, rates, expo or trim. Just leave your radio 100% travel, AETR (or whatever setup you’re using).

Set SERVO_AUTO_TRIM,1 and it will trim your servos after a few minutes of stable flight in FBWA.

Side note: There is MAN_EXPO_ROLL (and ptich) to setup some expo for manual modes.

Thanks, Yuri and Allister, that makes sense. I guess that really impresses me that Arduplane in FBWA can “figure this out”. Yes, I have SERVO_AUTO_TRIM = 1 set.

So, I currently have my aileron expo set and dual rates set on a switch. Should I delete them and just leave A, E, and R set to 100%, no other modifications? What happens when I need to switch to Manual flight mode?

Yup, leave AETR at 100%. Your servo travel is set in servo configuration so no need to adjust that on the radio.

Personally, I find in FBWA you don’t need expo or rates. It’s a different kind of flying compared to manual mode.

If you feel you need rates in manual mode, then depending on your radio, you can set it so the switch that turns on manual mode also turns on some kind of rates. I do that in EdgeTX on some of my planes that I use manual. But be absolutely certain that the rates don’t effect FBWA or any other mode. If you have dual rates on in FBWA you could be missing a lot of control authority and depending on your RC plane skills that could be an issue.

Leave the expo out of your transmitter and see here for manual mode.

As for manual mode rudder mixing, I think the expectation is that the pilot will manage it entirely. Depending on your transmitter, you could get a little fancy and have a mix that applies only to manual mode (if you’re using something like EdgeTX or OpenTX).

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OK, thanks, I do fly with EdgeTx, so I’ll research mixes just for Manual mode, on a switch.

Last question: If you were hand launching this plane for it’s maiden, would you:

  1. Launch on Manual, then switch to FBWA
  2. Launch with FBWA with a bit of elevator
  3. Use TAKE_OFF mode

Been reading too much research, and getting mixed advice…
Thanks, guys!

Depends on your RC plane skills.

If you’re comfortable with manual flying then this is safe and easy. If you aren’t then this could be asking a lot.

Admittedly I’ve done this a lot, but be sure that you have all the controls and stabilization corrections going in the right direction. If you have got one of the corrections backwards (ie: manual is correct but the FBWA stabilization is moving a control in the wrong direction) then you can only recover by going into manual mode, and after take off you don’t have a lot of time for that kind of trouble shooting. So yes, this works, but take your time with the setup and double check that everything is working right.

Not recommended on a maiden. That’s asking a lot on a new setup and some simple mistakes or tuning could end badly.

All that said, I’ve build a Volantex Ranger on Ardupilot in the past, and it flew just fine. Didn’t need a lot of tuning and just cruised along. I remember on the maiden I had a hard time landing it because it just kept floating and wouldn’t come down. Had to think more like a glider to get it back.

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Duly noted! I was leaning toward FBWA with elevator, but ready to switch to Manual.

I haven’t connected the Ranger flaps…maybe I should based on your landing experience.

Good choice. As long as you have the controls correct, you probably won’t need manual for the Ranger.

I didn’t connect the flaps on the Ranger, but I think if I kept flying it I probably would have. Where I was flying it I had plenty of space so I never got too worried.

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