They are bizarre, but actually quite user friendly - get it about right and off they go. The Russians held the helicopter duration record for ages with one - in the '50's, 60's Russians and Brits and who else would build these things with built up wings and small diesel engines with central tanks.. and fly forever. Too much fun not to build one. It's a 1-1/2 - 2 hour build plus finishing touches. Run a Sure Start on pressure, solves the centrifugal fuel delivery nightmares. Depending what engine/tank arrangement you use, I've had examples where the engine had to be almost choking on fuel before I could let it go. Others needed only a minor offset. Helps when you take a couple of minutes to plan ahead on the fuel system..

Needs an LED strip and small LiPO at the hub.