Igor,
I just came back from my noon walk, and spent the time thinking about what you are saying.
You are right that the accelerometer does not measure directly the acceleration since it is also sensitive to the gravitational field (in the direction of that axis). I think the net result I would measure from the accelerometer along the longitudinal axis (vertical climb) would be the actual kinematic acceleration-9.8m/s
2 (1g). So I think this is what you are saying and I have been missing
from your comments.
However I wasn't thinking about trying to adjust power to keep the longitudinal acceleration=0 (constant airspeed) , but actually instead use the inputs from all three axes to provide some type of a power "burst" (hopefully not explosive!) in the lower altitudes (below 45 degrees). So I am not trying to hit constant airspeed--I am not sure how important that is. Just improving the airspeed above 45 degrees may be enough. I don't really know.
But at first I'd just like to record what the accelerometer is seeing in a typical pattern. Also I will probably be experimenting with more propellers next year, just to try and see how I can improve things "passively". If I can really get my head around the setup I just ordered (logomatic and 3 axis
+ 16g accelerometer), maybe then I might consider actually feeding in a throttle input to the ESC. That issue is basically reprogramming the device.
And moving off topic now and onto the setup Kim D. was talking about, I wonder if decoupling the line tension from the control effort (Netzeband wall) might be just as effective in improving control near the top as trying to get the airspeed up---as long as the tension is >0 on the lines and the bellcrank/pot moves.