Ken's right - tip jet designs seem like a great idea - no transmission,
minimal antitorque (you still have a small amount of friction torque and you
have to have some form of yaw control) - but tip jet drive is incredibly
inefficient. I researched these a number of years ago, as a young engineer.
I remember a quote about the YH-32, to the effect that its major success was
it's ability to turn fuel into noise.

Dan Hollenbaugh

Ken Sandyeggo wrote in message
. ..

I think that the general concensus is that they all proved extremely
noisy and consumed an inordinate quantity of fuel, 2 factors that have
limited their success and further development.

Ken J. - Sandie A. Geaux