"Guy Alcala" wrote in message
. ..
Stan Gosnell wrote:

"Phillip" wrote in
:

Also, I've seen some photos of early kit helicopters that
appear to have just a tilting head (no way to auto-rotate
?). Isn't this a bit of a death wish? Does a helicopter
need to have collective pitch for anything other than
auto-rotaion?

Helicopters depend on collective pitch for control of power -
they have no other way to fly. Without collective pitch, you
can't get off the ground, or change power, or get back on the
ground in one piece.

IIRC, at least the first Piasecki helo and maybe the first Hiller
lacked collective pitch. Lift was controlled by the throttle
(which controlled the engine and thus rotor rpm), and they seemed
to have flown just fine. There are clearly advantages to the
collective system as later models all included it, but it's not
as if a helo has to have one to fly.

Guy


I guess what I wondered was , other than a need to auto-rotate, a tilt
system would work on a helicopter the same as a gyro? Yes I know
auto-rotation is needed...I'm just wounding if the concept is the same.

That's what these kits mentioned (it's been a long time), you added power
to go up, remove power to come down...seems simple enough. Don't think I'd
like the idea of no collective control for auto-rotation.