Split elevon & clamshell airbrakes with differential airbrake rudder...
March 16, 2015
I've been working with Openaero2 and a KK2.1 HC board on a fin less flying wing that's (intentionally) un-stable in pitch and yaw just to get to grips with PID control and the different stabilisation modes. I am however running into a minor hiccup that I can't seem to get past.
I'm using split clamshell elevons as air-brakes with differential air-brake for yaw stabilisation, but I can’t stop the yaw gyro from pinching the two surfaces together, it's not a biggie but it could be solved by a set of +ve and -ve travel limits on the output of the OpenAero2 Channel Mixing stage to limit -ve travel on the left and right air-brake demands prior to mixing the surfaces.
I'm basically using a 30% output mix of aileron elevator and left/right airbrake for each servo with signs and handing as appropriate.
L/R airbrake demand is separately mixed on my Tx via Throttle and Rudder channels, 70% airbrake and 30% rudder on each, with 0% negative travel. The 0% negative travel is the only reason I think I need to do this on my Tx.
The OpenAero2 channel mixers pick up the pitch and yaw gyros (yaw on L/R airbrake = throttle and rudder inputs) but because of this when the rudder gyro demands is -ve it pinches the surfaces if the airbrake is closed.
Think it's time to look at a software patch...
I'm busy working on my blog posts. Watch this space!