Are you talking autopilot for autonomus flight? Or are you talking about a training assist system like these:
The Futaba PA-2 PILOT ASSIST LINK AUTO PILOT SYSTEM - Approx $50
http://www.futaba-rc.com/radioaccys/futm0999.html
Manuals
http://www.futaba-rc.com/manuals/notes-pa1.html
Here is a newsletter review on the Futaba PA
http://farmclub.torqueroll.com/NewsL...Apr02-3rd.html
FMA Co-Pilot Flight stabilization system - $99
https://www.fmadirect.com/site/Detai...489§ion=20
Co-Pilot with receiver $180 - may have extra features - not sure
https://www.fmadirect.com/site/Detai...722§ion=29
Backyard Flyer Product review
http://www.backyardflyer.com/BY/articles/co_pilot.asp
Product Review
http://www.fmadirect.com/support_docs/item_1040.pdf
In-flight demonstration -e-glider
http://plawner.org/video/copilot_2axes.wmv
In flight demo - flying wing
http://plawner.org/video/copilot_delta.wmv
In flight demo - Helicopter
http://plawner.org/video/copilot_heli.wmv
As you can see from the video, they do not interfere with the flying of the
plane at all. They simply add a level of self stabilization that is already a
characteristic of a trainer. So if someone says this will interfere with your
flying, they are wrong. That is the value of the videos.