Motor RPM overshoots on spoolup only when AR bank is enabled

I see an interesting issue which I can faithfully reproduce every time. At first I did not have the AR bank enabled and the spoolup was perfect. After a few flights, I enabled the AR bank because I needed to lower the tail gain during autorotation. Immediately on that very flight I noticed during spoolup the headspeed would surge to a high value for a few seconds before coming back down to the set RPM. If I disable the AR bank, this problem immediately goes away. How can enabling/disabling of AR bank affect spoolup?

We can also see this in the graph. The first image is with AR bank disabled. The ESC output smoothly ramps up to ~65. The second image is with AR bank enabled. The ESC output overshoots to ~90 and then settles back down to ~65. I was able to reduce the amount of overshoot by reducing the "runup limit" from 3 to 2. But this will affect how fast my bailout speed is, so I don't want to do that.

My setup is:
VBC touch (firmware updated within last 3 weeks)
Vbar Neo Pro (firmware updated within last 3 weeks)
Vbar governor
Hobbywing 180A v5 ESC
Sunnysky 4530-518kv motor
Brand new SMC 12s battery
OMP M7 airframe
Theta Servos



2 mal bearbeitet. Zuletzt am 10.09.2024 07:58 von P@reez.

How much AR Throttle is set?

regards (EN) / Gruss (DE)

Rainer Vetter

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

Für Posts und Antworten bitte einen PC und eine richtige Taststaur benutzen sowie alle Fragen vollständig abarbeiten. Nehmt Euch Zeit, beantwortet Rückfragen in Ruhe und vollständig.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Für Einzelkommunikation bitte ausschließlich Email verwenden! - PN, Messenger, Chat usw. werden nicht bearbeitet.
For single user communication please send a email only! PM, Messenger, Chat etc. won't be read.

AR throttle is set to 40 in both cases (when AR bank is enabled vs disabled). I keep it this high to practice autorotations. It gives me about 1000rpm of headspeed to prevent the heli from landing in the event of a bad auto.

If I remember correctly, I did try to reduce AR throttle to 10 and the issue went away. But ofcourse, I hope this is not a solution, since I really do want to keep my AR throttle at 40 to practice autos

This is the solution.

The AR throttle is meant to be set in a value which keeps the motor slowly spinning not to loose its timing for a fast restart. Usually somewhat between 10 and 15% is enough.

It is not meant to be used as "AR helpercheatthrottle" ;-)

regards (EN) / Gruss (DE)

Rainer Vetter

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

Für Posts und Antworten bitte einen PC und eine richtige Taststaur benutzen sowie alle Fragen vollständig abarbeiten. Nehmt Euch Zeit, beantwortet Rückfragen in Ruhe und vollständig.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Für Einzelkommunikation bitte ausschließlich Email verwenden! - PN, Messenger, Chat usw. werden nicht bearbeitet.
For single user communication please send a email only! PM, Messenger, Chat etc. won't be read.

Sorry RV, but the higher AR throttle of 40 causes no problem of overshoot during initial spoolup when the AR bank is not enabled. Don't you agree there is something strange about the issue? If merely enabling the AR bank causes a overshoot on spool up, but disabling the AR bank causes no overshoot on spoolup. Please note, when I say "enabling the AR bank" I don't mean that I am putting the motor switch to the idle position. Instead, I'm referring to the act of going into "Model Tools"->"Bank management" and then I check the box that says "AR bank". Which then allows me to set different tail gains for the AR bank.

So how can merely checking that box for AR bank cause different behavior (overshoot) at initial spoolup? If I were to make a guess, when the motor is off, the system is in the Bank4 (AR bank) and all the gains from that bank are active. Then when the motor switch goes to idle, then to on, the system should immediately be in either Bank1,2or3 whichever is selected by the bank switch. And somehow during this transition, either it is delayed or something else, causes the overshoot. Sorry, I'm just hypothesizing here and trying to help, but I think there is some genuine issue worth looking into.

We have been investigating in exactly this issue with YGE and VBar EVO a few days ago. So i am very familiar with this part of the governor right now. But as this had only effect on the high frame rates - the result can't be used on a VBar NEO.

But - I'll try to shoot some graphs here with my BO105 and the HW180A next time flying. My only difference is - i have a VBar EVO on board, probably need to set it to 72Hz at the output first.

What i can tell from my observations until yet - the 180A HW climbs steeper on the spoolup than the previously installed Scorpion 300A did on this heli. So there is some difference in the ESCs too.

regards (EN) / Gruss (DE)

Rainer Vetter

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

Für Posts und Antworten bitte einen PC und eine richtige Taststaur benutzen sowie alle Fragen vollständig abarbeiten. Nehmt Euch Zeit, beantwortet Rückfragen in Ruhe und vollständig.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Für Einzelkommunikation bitte ausschließlich Email verwenden! - PN, Messenger, Chat usw. werden nicht bearbeitet.
For single user communication please send a email only! PM, Messenger, Chat etc. won't be read.



1 mal bearbeitet. Zuletzt am 11.09.2024 08:09 von RV.

RV, I found a much more reliable way to workaround the problem, which doesn't require me to change the run up limit.

Here is how I spoolup the helicopter to workaround the problem:

1) Make sure motor safety switch is on
2) Flip the Motor switch to the ON position (Motor will NOT spool up because safety switch is still on)
3) Flip the safety switch to the off position
4) Motor now spools up smoothly to the set RPM without overshooting

If I do it the other way, where safety switch is flipped off first, and then motor switch is flipped on, then the motor will overshoot the set RPM before settling back down.