Using Throttle curve instead of governor mode


Following a previous thread in this forum:

I have exactly the same problem. I am using the Align ESC RCE-BL15P to control my T-rex helicopter. As suggested in other posts in this forum, I tried to use the ESC in governor mode (to 80% of total velocity) to care just about collective pitch when flying. The problem is that I get tail wag in the helicopter and very little control over tail, I barely can keep it without rotation (counterclocwise, from top view) when I move full stick to the right with the radio.

So I called the technician from the official page of align ( and he told me that their ESC simply doesn’t work good in governor mode, so he suggested me to use flat throttle curve instead to fly (maybe 0-70-80-80-80).

The question is: Can I use the throttle curve instead of governor mode to fly the helicopter? or it will bring some problems when switching to alt_hold or loiter mode (I am flying in stable mode yet)?

I attach the picture of the throttle curve I want to use for the helicopter. That one match the throttle curve suggested in the manual of the T-rex helicopter. It would correspond to collective pitch: -2 (min) +5( mid point) +12 (max) degrees of angle of attack.


I use a curve on mine as my ESC doesn’t have governor mode (trex 450 and turnigy 9XR radio) i use a 10 point curve that is similar to yours but first point is 0% throttle then point 2 is up to about 85% then center stick is about 80 then full stick is about 85 (im not sure of exact numbers as i dont have my radio with me). im still fine tuning mine but have successfully done alt hold, loiter and RTL. looking at yours i would up your first point to at least 80 because if you are flying alt hold or loiter you have your stick in the center to hold altitude and your throttle curve will be at about 50-60% looking at your picture, and if you want to loose altitude in these modes you put your stick to maybe 1/4 which your throttle will be at around 20% (which you will loose control). i have accidently cut power to the motor while flying alt hold because i went too low with my throttle/pitch stick trying to bring it down but i reacted quickly and it was fine. I hope i haven’t confused you with my answer and i am by no means an expert on this but these are my findings and only having a 5 point curve will make it harder for you. ill try post a pic of my throttle curve 2mrw.


here is my throttle curve

When you say “use a throttle curve”, you mean to plug the ESC directly into the RX?

Yes, you can do this, but it will not work well when in Alt_Hold, Loiter, Auto, etc. And you won’t be able to use transmitter failsafe, etc.

no it is still running through APM so the motor wont start when the APM isnt armed.

No, as Ask K said, I meant to connect the throttle signal from RX to Ch8 input of APM and the output to ESC.

By the way, is there any suitable altitude to test Alt_hold mode?, I am planning to fly the heli at 2 meters from the ground but this might not be good enough for the barometer.

Thanks for the replies, I will make some test this weekend and let you know the results.

2 meters is high enough for the barometer. Do yourself a favor and test it at 10. Altitude is your friend . I have hovered a meter off the ground in Altitude Hold with out a problem and frequently land with it.

David R. Boulanger

I hovered at about 1.5~2M and it worked fine for me it may move up and down maybe 10cm give or take up and down. but as im sure you have read be ready to flick it straight to stab at a moments notice if it does something your not expecting. I used a training frame for the first few just for insurance but i didnt have any issues

Once Alt Hold is tuned in, you can use it to hover at low altitude no problem. However, you should be about 10 meters up the first time you try it on a new airframe, because if it’s not working right, you need need altitude to recover. 10 meters should be fine as long as you’re ready to flip back to Stab.