Originally Posted by Halcyon66

Actually as per the first rule you cannot get more out than actually went in initially. Yes the fan maybe be more efficient and the turbine use less fuel yet it would be difficult to get more thrust than you got in the first place. RC turbines are very inefficient due to the size, turbines do get more efficient as they get bigger. As per your comment you will have more thrust with less rpm, so your turbine output (KW) would be even lower than it was initially as igt is running a lower rpm.

So you for instance you have a shaft turbine that produces 10kw, then you have a generator connected to that. You could get 8~9KW or 80~90% efficiency back out, there are your losses. more parts, gears etc the losses increase.

So as above you would need at least 10+kw from the turbine in the first place to run a 200mm fan to get 150N, also you would have little residual thrust from the turbine as again it is all a closed loop.

It is also getting to the point whereas EDF's are getting to the point of mass power in a very efficient setup. Brushless motors at 90% running straight fans are putting out massive thrust, Vasyfan have a 570mm that is in the 150kg range which is amazing, 250mm fans running 55kg pretty awesome.

Regards,