I didn't measure it, but from the look of it the blade pitch at the tip of
the main rotor of my jetranger when its at 90 degrees to the right (the
most negative pitch point) and the collective full down is roughly 0
degrees, it might even be a shade negative.

Bart


"The OTHER Kevin in San Diego" skiddz "AT" adelphia "DOT" net wrote in
message ...
On Sat, 24 Feb 2007 15:06:40 -0800, Steve L. wrote:


I know of only one big helicopter that ever had negative pitch (-3°). It
is a military American one; can't recall the type.
The reason for that is that it should be able to do a very quick
vertical descent while hovering just over tree tops.

A&P buddy of mine who was in the Marines told me the CH-53 can do
about -3 degrees collective. Not sure of the reasoning behind it..

For all other helicopters it were pretty useless but would cost a lot
because the control rigging would need far more travel.

There is no civilian helo with negative pitch, not even 0°. The minimum
pitch might be as high as +4°.

The negative twist in the blades might get parts of the blade into
negative pitch in an auto (or even a rapid power descent) but I don't
know if the AoA ever goes negative...