"John Hairell" wrote in message
...
On Wed, 10 Mar 2004 06:06:46 GMT, "John?]
"
wrote:

In article , Bill
McClain wrote:

And this got me wondering: Does anybody test to see how high up
you
can successfully autorotate from? Is there an actual record for
this?

Sounds like a self correcting problem. If you are too high to
autorotate,
you will very soon be much lower.

Ummm, yeah, I guess so, but...seriously, is it even possible to try
and keep the RPMs up by diving and turning...I guess WITH the
direction of rotor spin...trying to maintain as much inertia in the
mast and blades before they lose so much torque as to be unable to
provide any lift to pull out of the dive and try to flare close to the
ground? I'm pretty much talking through my hat speculating like this;
I don't really know all that much about helicopters (other than that
I'm not all that keen on riding in one).

Believe it or not, the problem is just the opposite.

In a high altitude autorotation the rotor tends to overspeed if you
don't keep an eye on it and a small application of collective pitch is
necessary from time to time to keep it within limits. Turning and
diving are unnecessary.

When I was instructing at Fort Rucker many moons ago we would take
students to 10,000 MSL in a UH-1H and let them play with the
autorotative characteristics. The airspeed for minimum rate of descent
in the UH-1 is 63 knots indicated while the maximum glide distance is
attained at 98 knots. From 10,000 feet the student has lots of time to
vary the airspeed and get a feel for different rates of descent before
a power recovery is required.

We did touchdown autorations every day in the training cycle, but were
limited to six per student per day because they are so intense to a
student that any training benefit beyond that is negligible. On days
when I had three students, I would do eighteen touchdown autorotations
from 1000' to a concrete runway and not think a thing about it.

I used to watch students at Rucker flare and sometimes hit their tail
stingers on the ground after autorotations at tac fields, and one day
I saw an instructor gesticulating wildly at a WOC and grabbing the
controls as the Huey went skidding down a paved strip in a
semi-controlled run-on landing. Another day I saw a near mid-air
between a WOC-flown UH-1 and a Flatiron bird - if they would have hit
they would have landed right on top of the old hospital.

The last autoration I was involved with was due to a fuel-pump fire in
a Huey in Korea, with the end result that we landed on a sandbar in a
river up near the DMZ, nearly hitting some high-tension lines in fog
and drizzle, and spent a long cold winter night waiting for rescue.

John Hairell

John, you might be able to answer a question I have regarding autorotations.
My late brother experienced exactly one serious mishap in a helo (outside
getting shot down once in Vietnam and having various small arms rounds zing
through the cabin on other occasions). It involved an autorotation in a
Schweizer 300C (read as Hughes 300/TH-55). He was checking out a cop from
the (unnamed big city) police department, which had recently purchased a
couple of 300C's for law enforcement work. Apparently the cop, who was also
a part-time ARNG Cobra pilot, had come through flight school during the
post-TH-55 days. During the autorotation, the guy apparently treated the
300C like it was a Cobra, which I gather is a bad thing to do, and when my
brother tried to take back over the guy froze up and fought the
controls--resulting in a hard landing and rolling the aircraft onto its side
(he compounded that by stomping all over my brother, who was left on the
lower side, in his haste to depart the now-stationary aircraft). Any idea
what the guy could have done that led to my brother trying to take control?
And FYI--the accident investigation cleared my brother in the incident, so I
gather that his side of the story was the way it happened.

Thanks.

Brooks