Originally Posted by saabguyspg
hi guys, here is some info on the throttle with 31AP
First off we must understand that there is no airspeed sensor on board and thus the plane can not know it's airpseed, only ground speed via gps.
Because of the above fact the autopilot can not know if it is about to stall the plane even when maintinaing ground speed.
I am flying with the throttle connected to the AP from the beginning and it has long time been my concern. But I haven't had any problems sofar. I am flying long distances and I am always doing this:
- Set the failsafe throttle to 60%
- Fly early morning or late afternoon when the wind calms down
- Ground speed 60Km/Hr
- Climb and descend rate 20%
The stall speed of my Raptor is less then 30Km/Hr. I think it is important to know your stall speed.so you know at what wind speed you shouldn't fly. But I also noticed, due to the failsafe of 60% throttle (about 11A motor current), the AP never throttles down to zero. My motor current will go down to 7 or 8, but not less. So that means I will always have enough airspeed. I noticed this is correct, as the ground speed in some cases goes up to 90Km/Hr.
But the same is true for throtteling up. It seems the AP only throttles up to about 18A, so that is why I programmed climb and descend rate of 20%. When climbing, my speed goes down to about 35KM/Hr. If I would climb faster, the AP cannot give enough power to the motor.
So from my experience sofar, the FY31AP only affects the throttle within a certain range, in my case from 7 to 18A, with an average of 11A.
I had 1 occasion where I changed my receiver and forgot to set the failsafe while binding, which resulted in a stall and a landing in a lake. Since then, I always do as follows: My first 2 waypoints are control waypoints where I can still see and control my plane. I bring my plane up, and switch on NAV. At reaching waypoint 1, I switch off my transmitter and observe my plane reaching waypoint 2. Then I know all is OK and enjoy my flight. If there is any strange behavior up to waypoint 2, I take back control and land.
This is what happens if you forget to set the failsafe:
and this is one of my last very nice flights:
Many things I had to learn the hard way, as here in Thailand FPV is still relatively unknown and only forums like this can help me to sort out things.
I just recently bought a good onboard camera and can now enjoy HD recordings:
Thanks for this thread and all the inputs.