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Experimental Aircraft

Posted by Michael Adams on September 15, 2010 at 3:03pm
I have an experimental aircraft that I have flown for many years. I know that the autopilots discussed here are for model aircraft but.... The idea is to have the auto pilot drive small trim tabs on alerons to gently level the wings in flight. It would be a system that woud be easy to overide even if the servos failed, due to the small size of the trim tabs. This is a project that anyone could comment on and all (good and bad) I'm not taking this as joke! My butt will be in the seat.
Lets discuss this
Mike Adams
N767EE

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Replies

  • John Dal September 28, 2010 at 6:53am
    What type of plane is it?
  • Michael Adams September 27, 2010 at 10:43am
    Hi Guys
    The trim I'm looking for is a wings leveling trim system. I have a manually controlled pitch, elevator/rudder trim on the stick to reduce stick pressure.
    The wing leveler would be a plus for longer flights. If I have my pitch/yaw trimmed leveling the wings would be even less work, and give me more time to scan for traffic and monitor systems.All of the thoughts will be addressed. The fludder issue is very important. My existing trim for pitch and yaw are controled by servos that are used by a large experimentialuser base.
    They are lenear servos that lock in position if a failure occurs pressure on the stick but, not a in flight failure emergency due to the size of the trim tab size Fire is also addressed by fused link like all my electrical equipment.
    Test period will also be required when any change to the flight control systems that were signed off by my FAA inspector.
    My hope is someone can give a lesson on the auto pilot capabilities related to a fullsized aircraft (or giant scale) Also the avability of code for this purpose.
    Thanks for your expertice
    Mike
    Thanks for the input
    Mike
  • Jonathan Lussier September 16, 2010 at 11:14am
    Hi Michael,
    If your aircraft does not yet have trim tabs, an easier method may be to just have two small actuators on the stick (ELEV & AIL), automatically trying to level the aircraft. This would greatly reduce your pilot workload. Also, if something screws up with the servos, you can just rip them right off as they're right in front of you.

    PS
    SLOWLY turn the gain up ;)
  • Greg Fletcher September 15, 2010 at 6:52pm
    Hello Micheal, I think this could be done. I would use the best(reliable) servos I could get and they would have to be big enough, how big? I would use a full 6dof imu and gps. The gps just keeps the heading correct. If you have an aircraft gps or vor you could use the +/- 50 mV output into the Ardupilot and now you could navigate as well. It could be done, but your on your own with the FAA. Any help would be "for educational use only" .
  • Mike Bakula September 15, 2010 at 5:44pm
    This is certainly within the purview of an Amateur-built Experimental aircraft. You would need to do the engineering to size the servos and tabs, and ensure that there isn't any mechanical failure mode (like say, a broken servo gear) that could permit a tab to flutter, driving the surface and wing into oscillation. Same for the software; you would need to work out a slimmed-down version for which you could confidently verify the functions.

    A lot of time would go into failure scenarios -- you know what to expect when it works, but what happens when it quits? How about hard-over in multiple axes? What if a board shorts and catches fire? You may never get them all, but forethought in your design will minimize the chance of a nasty surprise in the air.

    Once you understand the changes you want to make, you would then need to put together a test series, something like the original test series the aircraft went through when it was built, but focusing on how the new system behaves and interacts with the rest of the airplane. And of course, don't be doing test flights with any more than required crew in the aircraft.

    If you enjoy the engineering process, this would be a fun project! Done with the same care as the design and construction of the original airplane, there's no reason it couldn't be done safely.
  • Michael Adams September 15, 2010 at 3:06pm
    I moved this to the hardware section
This reply was deleted.

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