15-20 mph headwind...a touch of up elevator....and BAM, yer flyin backwards...

I can fly my Senior Tele backwards in a 10mph wind.

The boys and I crank the wind up on Realflight to 20-25 and you can practice a lot of flying and aerobatics (and backwards) 3 feet off the ground, about 10 feet out from ya, and the plane never goes anywhere...