I've often thought a turbine U-2 would be a really cool project. Just have some functional spoilers and a low residual thrust turbine...it'll float a LOONG way. I had an 8' span PSS U-2 glider a few years back, looked very cool way up high on those days when I could 'sky out' with it, but it did not have spoilers and it was a BE-AATCH to land, especially when ballasted up in heavy winds.

The SR-71's drone was the "D-2", a hypersonic scramjet powered UAV that was never very succesfull. An M-21 (a specially modified A-12/SR-71 "mothership" ) was lost during launch tests so it was later launched off modified B-52's with very limited success. Mostly used over China in the mid-60's where almost all of them were lost, a few made succesful missions but were lost during the recovery process. Lots of interesting info on the D-2/M-21 "Tagboard" program in Jay Miller's history of the Skunk Works. A very cool read, highly recommended!

Barry