I am adding an APM2 to one of my park flyers. It is going to be a lot of work to get the airspeed sensor out of the prop blast. How will it fly if I don’t have an airspeed sensor?
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Hi Mike,
ArduPlane flys very well without an airspeed sensor. In fact, tuning ArduPlane with an airspeed sensor enabled is often more difficult than without one.
One common misconception is that some people assume that ArduPlane uses the GPS ground speed as an input to throttle control. It doesn't do that. The throttle control is based on the nav_pitch. The code adds more throttle when the plane is pitched up, and less throttle when pitched down. The nav_pitch is in turn based on the altitude error.
The key parameter is to set TRIM_THROTTLE correctly for your airframe, setting it to a level that gives you a comfortable cruise speed in level flight. Work out what that level is while flying in FBWA mode, then set it in TRIM_THROTTLE and the plane should fly very well without an airspeed sensor.
The only time when an airspeed sensor is really important is for automatic landing, when the plane will be flying close to the stall speed.
Cheers, Tridge
Hi Tridge,
I was wondering how does APM plane show me an airspeed (not groundspeed) if I don't have an airspeed sensor?
I posted this in a new thread: http://diydrones.com/forum/topics/how-does-arduplane-calculate-airs...
My glider tends to stall around 25kph when loaded, or 30kph plus depending on the angle of bank (which is expected of course).
I read your post at https://groups.google.com/forum/#!topic/drones-discuss/zdaEfa_EfBY and basically I would also love a mode where I can plug in my stall speed (I know what it is from test flights), APM Plane would calculate a predicted stall speed depending on the bank angle (that's known math) and then add a generous fudge factor to allow for airspeed errors which are as you point out more of an issue at lower speeds (percentage wise).
I started a new thread for that:
http://diydrones.com/forum/topics/suggestions-for-stall-avoidance-m...
Best,
Marc