Slowrotor, steam is a non-starter. You have to carry all the water you are going to boil, in addition to the fuel. Also steam is not efficient because you have to add extra energy to overcome latent heat of vapourisation. Been a while since i looked at that stuff, but Sir George Cayley did some calcs for his rotorwing ideas and realised power-to-weight was way below that required. I've seen a museum for some steam powered fixed wing model's in south UK - but that's about it.
My interest is to take a proven system, Jet A1 powered turbines, and see if there is a better way to design the powertrain. Tip jets have flown, in both compressor bleed form and tip burner form. The system is flight proven, if not comercially competetive. It is really to establish whether, for a tailrotorless design, the best concept is son-of-notar coanda effect tail system or rotor tipjet. Both in principle are similar concepts, but will have to struggle hard to stay competetive with tail rotor efficiency.
Dave, retreating jet may well be limiting factor for fuel burn (speed ratios are badly matched). Tip jets need to be at tips for maximum torque, but autorotation with additional propulsion at speed is a possibility. However, tip jet looses it's appeal once the system gets too complex. Maybe a cyclic valve to the jet gives it one last chance at surviving the engineering evolution process.
Thanks for feedback all.
Mart