"Dan & Jan Hollenbaugh" wrote in message
...
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.

The reason the British Rotordyne was finally scraped was because of the
noise problem.
Unfortunately government committees work so slowly that the problem was
almost solved before they finally scrapped it!
So it is possible to quieten tip jets down. I believe they did it by
changing the original round exits into long trailing edge slots.
http://www.asra.org.au/rotordyn.htm

Slatts