Quadplane transition is too fast - How do I slow it down?

I am trying to slow down my quadplane transition because I am towing a sensor and it needs time to “follow” the aircraft. I am using an orange cube and ArduPlane v4.0.9. I have tried multiple different parameters but can’t get the transition to slow down. Q_TANSITION_MS, THR_SLEW & TKOFF_THR_SLEW are the main parameters that I have been concentrating on. Even with THR_SLEW at 30 (30% throttle per second) It still ramps up to THR_MAX within around 1.5 seconds. Any help would be greatly appreciated.
Kind Regards,
Perry

I will attach the Bin file as soon as it has finished uploading (very slow internet)

These graphs above are of the RCOUT_CH3 (SERVO3) for the throttle during the transition. The gradient is all the same as far as I can see but I expected them to change when changing throttle slew rates. The first graph is THR_SLEW at 50 then the subsequent ones are at 30 while changing other parameters.
Kind Regards,
Perry

BIN file
https://drive.google.com/file/d/1m_siRxDpf3QQtR8bGSoHe7qEA_yguSau/view?usp=sharing

@Hawk_Airborne unfortunately the throttle slew limit is done with integer maths, and to ensure progress is made it is at least 1us per loop, which means 300us/second for a quadplane with SCHED_LOOP_RATE=300.
As your SERVO3_MIN and MAX are 1100 and 1900, that means 100*300/800 percentage per second, which is 37.5 percent. So any THR_SLEW_RATE below 38 will give 37.5%, which is clearly not enough for your setup.
@iampete has a PR that converts the library to float which has the potential to fix this:

it needs some more work though

Tridge,

Thanks so much for looking at my issue. I will keep my eye on that PR and hope that we can get a solution soon.

Kind Regards,

Perry

I’ve also opened a PR to apply the takeoff throttle slew limit to fwd transitions in quadplanes:

note that you could fix this in 4.1.x with a lua script. You’d change SERVO3_FUNCTION to 94 (SCRIPTING1), and make a small lua script that copies the throttle output to function 94 with an extra slew limit applied

Tridge,

Great, thanks for thinking that through. I better start learning LUA and developing my parameters on 4.1 (then testing in SiTL)

Just on SiTL, is there any way to use Plane v4.1 instead of the development firmware?

Kind Regards,

Perry

yes, though the method depends if you are on linux or windows. Jump on discord voice sometime and I’ll walk you through it