(Tony Williams) wrote in message om...
"killfile" wrote in message ...
"James Cho" wrote in message
om...
Why aren't they more common? It seems like the advantages of them
compared to single main rotor + tailrotor helos are pretty
significant, not great enough to replace traditional designs entirely
but at least sufficient to be more popular than they are now.

It's the classic trade off. Co-Ax helicopters are more stable and don't have
a vunerable tail rotor, but they aren't as manouverable, and require a
vunerable and complex rotor linkage. Manouverability was what saved a lot of
helicopters in Vietnam, so I doubt we're going to be seeing a glut of co-ax
machines.

I haven't heard that the Ka-50 series of combat helos suffers from
poor manoeuvrability. I suspect that its more that manufacturers find
it easier to carry on making what they've always made, because they
understand it very well.

I'd suspect it may also have to do with the fact that the transmission
of a helo is already a rather complex, and sensitive in some respects,
piece of equipment--a coax system would likely increase the level of
both.

Brooks


Tony Williams