I designed my Buster Hell on Rails, BustaHOR a couple years ago and used it for training and balloon bust. It's loosely a Buster shaped wing and tail, I was going to put a 2 mil fuse profile on it, may still do it, but it works as is and uses fp 20 or 25 for a motor.
It's an aluminum fuse like the regular SPAD HOR and a flat bottom RNAF wing. That means it's a 4 mil bottom with 2 mil wrapping on the top. I figured it would be just an upright machine anyways so didn't worry about the flat bottom and the RNAF wing takes hitting the Balloon sticks well. I rubberband the wing on as well for easy transport and shock absorption on hard landings.
Here's a picture of me going after a balloon
Build thread on Spadworld.net