Digital flight control research from the '80s

Jared Reabow March 3, 2015 at 4:00pm

can you imagine flying an x8 past them no flight controller hehe

Stephen Gloor March 3, 2015 at 3:58am

You might need two and use the speed difference between them to estimate it. Mind you I could just take the Penquin out this week and move the battery back a bit and see how it goes. I also have a wing that is eventually getting an APM so it could be a good test.

Andrew Rabbitt March 3, 2015 at 3:51am

I think if you have an accurate airspeed signal you should be able to infer angle of attack from that and the acceleration vector

Stephen Gloor March 3, 2015 at 3:42am

And if this is the same Steve Morris then he at least has done a fair bit since

https://www.youtube.com/user/smorrismlbco

http://mlbuav.com/

smorrismlbco

Flying things and other stuff I do for fun.

Stephen Gloor March 3, 2015 at 2:19am

Yep - they had an angle of attack sensor as well as this would be pretty critical. An accelerometer or magnetometer can only give you a pitch angle not one referenced to the on-coming airstream.

Andrew Rabbitt March 3, 2015 at 2:07am

It would be fun to explore this Stephen, but I think there are two issues that might arise. Firstly the extra servo work might cost you flight time in mAh rather than L/D and secondly, (I think) you'd need a pretty reliable airspeed sensor to add in your stabilizing function which needs to operate all the time, not just in FBW and Auto modes.

Actually, I wonder if just by having an open-loop airspeed-vs-pitch trim function whether this would be enough to add synthetic stability without needing any high-speed feedback loops running. After all, this is all static margin is going you, isn't it?

Stephen Gloor March 3, 2015 at 1:00am

Makes you wonder how unstable our UAVs could be and still fly. Relaxed stability gives more efficient flight sometimes and a greater maneuver envelope potentially.

I have a couple of times been guilty of launching a plane in stabilise or FBWA mode that has been completely out of trim and flown around easily and then switched to manual and have it nearly crash before I can cut the autopilot in again. It is amazing (when you are dumb enough to do it :-)) what the APM will compensate for.