It will work. I know because I have had one on my Tango 2 for
about a year. I didn't want to build the mechanism to move the trim
tab on the already moving aileron, and then have to rebalance the whole
works. Since the aileron moves a tiny amount for roll control, I
figured a large trim tab on the wing tip might work. I sawed off the
trailing edge of one wingtip with the same chord as the aileron and put
on a simple hinge. Not pretty, but its a prototype. I used a $78 R/C
servo, about 2 1/2 inch square, plenty of force, rigged it to give
about 20 degrees up and down. I picked that servo because that's what
Craig Sellars, PCFlight Systems, had laying around for free. He
initially gave me just a knob to manually control the trim tab to test
the concept. I could start a slow roll either direction and reverse it
at will. At full deflection I could easily overpower the trim tab with
the aileron. Runaway trim, not an issue.
Craig then hooked up one of his solid state AHRS units to the
servo to try wing leveling. First flight, worked great. The AHRS
senses turn rate, so it will attempt to correct for bank and yaw. When
I trim the ball to the center, the wings stay level and the heading
remains steady. If I want to turn a little, I just turn, roll out and
let the AHRS figure out what happened. Heading hold and course
tracking will be simple, requiring only a signal from a GPS, VOR or
magnetometer.
For a low budget system it seems like any system that can control
an R/C helicopter should be able to handle a simple wing leveler.
wrote:
With the summer thermals upon us, and not being able to scratch my nose
without having my small homebuilt tossed off course got me to thinking
about how to build a low cost wing leveller.

A small servo tab mounted out on the aileron, controlled by a jumbo
sized R/C servo would probably work fine. If the tab was sized fairly
small, even if the servo went nuts, the pilot could easily overpower
it.

The servo would be controlled by a rate gyro that is also used in model
airplanes and helicopters to provide the stabilizing function.

The overall system would be controlled by a simple pulse-width
modulator using a 555 chip. A small amount of trim adjustment would be
provided.

Operation would be simple: turn on the system and adjust the pulse
width trim knob to get the wings level. Sit back and scratch your
nose, take a pee, eat a sandwich.

This simple system could be put together for under $300. Any thoughts
on how it might work?

tom