Heli question: governor mode

[NormMonkey]

So I'm getting ready to put an Align 450SE together and I have a question about governor mode. My understanding is that in this mode the speed control always strives to keep the rotor head at the same, optimal RPM (please correct me if I'm wrong).

Here's my question: the manual for the Align ESC I'm getting says that the throttle signal should be between 75-85% for governor mode. What does the ESC do with a throttle signal >85%? Why isn't governor mode active whenever the throttle signal is, say, 75-100%?

My guess would be that >85% is there for stunt fliers who need absolute maximum crazygonuts full power, but I'm having a hard time imagining what scenario that might be. Of course I can barely hover and manoeuvre so that's not surprising :D

[cgroves]

For electrics in governer mode the ESC usually translates a given throttle setting to a given RPM. This number may vary for some motors and different pinion sizes but for a given motor and pinion the ESC will always try to maintain the same speed for the same throttle setting. As a result you can build a table sort of like this:
60% 1150 RPM
70% 1550 RPM
80% 1950 RPM
90% 2350 RPM
100% 2750 RPM

Setting it higher than the recommended range may result in a higher than safe headspeed and a tendency to bog as the ESC/Battery may not be able to supply enough power to keep the head spinning at the higher speed. Or in the worst case with no current limiting you may release the magic smoke from the ESC.;)

Note, nitros have a completely different approach to governers.

[Soclarke]

It may also have to do with effeciency. Different motors and ESCs generate their most effecient power at different points through the throttle range. So in the case of the Align ESC it may be most effecient at the throttle settings indicated and operating it for extended periods outside that range may result in excessive heat or rapid drain on your batteries.

Ideally you want to look at the headspeed you'd like to acheive and then work backwards to calculate the proper gear ratio required to keep the ESC and motor operating at their maximum effeciency.

[NormMonkey]

Aah,

So given that the throttle signal corresponds to RPM, when setting the beast up I should experiment with the throttle signal to find which one gives the ideal head RPM (at 0 or slightly neg. pitch, I guess).

Then once I find the throttle signal that corresponds to the ideal RPM, use that in my throttle curves on the transmitter. Finally, if this ideal throttle signal value is outside of 75%-85% then something is wrong (perhaps gear ratio).

Does that sound reasonable?

[Soclarke]

Yep you're on the right track.