There is already a fair amount of activity in this subject and there are some models already available.

Although a UAV can be made more or less from a conventional R/C Airplane,
http://www3.towerhobbies.com/cgi-bin...=LXNVC0**&P=ML

these UAV somewhat scale jobs also exist

http://www.nitroplanes.com/4eluavrqprra.html

Here's a lessor one

http://www.nitroplanes.com/uav3arfbrelr.html