I have a Sonicmodell ARWing running Ardupilot/Arduplane. It generally works great. I do not have an airspeed sensor.
Problem: In Cruise mode, it goes too fast. It pulls a lot of amps, and shortens my flight times. I set THROTTLE_TRIM = 35 (the percentage of throttle that I like in ACRO mode) which gets me about 35 mph in ACRO. I also have THROTTLE_NUDGE = 1
Instead it runs at 50-60% throttle, sometimes more, goes 50+ mph, and it ignores the position of the throttle stick, so I can’t “nudge” it down.
I’m misunderstanding something. Can someone help me out?
Thanks.
Hello Glen,
what happens if you put THROTTLE_NUDGE = 0 and center the throttle stick on your transmitter during cruise.
How is your RC_TRIM set of your Throttle Channel.
Best is if You can present a log file
Thanks for the reply. I don’t know what happens if I set THROTTLE_NUDGE = 0 and try Cruise. I’m going to the field tomorrow. I’ll set it and find out.
RC3_TRIM is 987. (Hmmm, I have a feeling that’s the problem. Does it use this to determine the stick midpoint? If so, then it doesn’t know mid-stick position is actually about 1500. I never get below 987 “midpoint” so I can’t nudge the throttle down. Correct?) RC3_MIN is also 987. RC3_MAX is 2011. RC3_DZ is 30.
Should I set RC3_TRIM to 1500 and turn nudge back on?
STOP!
Do not change the RC3_TRIM (Throttle) value manually under any circumstances!
Do a radio calibration via Mission Planner instead. I assume you did, because 987 is the typical CRSF default on EdgeTX and the like.
Before mangling with TRIM_THROTTLE, you need have PTCH_TRIM_DEG dialed in and some TECS tuning must be done.
If it’s an AR PRO, I would be interested in the launch method. I was not yet able to get mine into the air. Crashed the first hard onto the tarmac and swapped to another kit in the aftermath.
Ok, I will not change it manually. It’s been a while, but yes, I assume I did a radio cal in Mission Planner. And correct, it’s ELRS on EdgeTX. OK, I’ll look at TECS tuning again. I know I’ve read thru it, but don’t recall what I did.
It’s an original 900mm AR Wing. I had problems hand launching it (and other planes) so I designed a launcher. The AR Wing Pro would work fine on the launcher. It launched a GoDiscover, which was probably 2kg.
I’ll try to give a brief explanation on how throttle output comes out of TECS in automatic modes.
Level Flight in the attempt to hold altitude yields a pitch value. That pitch value minus PTCH_TRIM_DEG is zero pitch how TECS sees it and it will use TRIM_THROTTLE for that pitch value. The other point is TECS_PITCH_MAX and THR_MAX. Anything between there will be linear interpolated.
It can be changed by using battery voltage correction but it requires the values to be set correctly.
If you see 50% Throttle while TRIM_THROTTLE is 35%, you could have values set like TECS_PITCH_MAX=20deg
PTCH_TRIM_DEG=0deg
but you need 5deg pitch to fly level, just as an example.
If you happen to have a measurement in cruise mode while flying level, set PTCH_TRIM_DEG to that value. IIRC Inav uses a similar value named “board pitch alignment”.
I’m at the field, and it’s raining, so I’ll update. For whatever reason, Ardupilot was suddenly unhappy with the compass and the accelerometers, so I had to re-do setup those. I also recalibrated the radio. (Didn’t see much change there.) As an experiment I decided to put 3 deg in PTCH_TRIM_DEG. I left THROTTLE_NUDGE = 1. And I did a flight. It was much better. It cruised at 35-40% throttle (same with missions) and nudge worked. So dumb luck, maybe, but it’s better. Weather permitting, I’ll try to take a more procedural approach to tuning this. I’m assuming the Pitch trim change, and the re-leveling of the FC, were the important factors. Thanks for everyone’s input.
