None of these big gliders are very good at diving. I don't believe there
is anything sinister about the N4DM. They're just not built for diving.
Any time the nose is well below the horizon, they will pick up speed
rapidly. Don't do that.

Large span gliders will fly slowly and that means that there is a large
airspeed difference across their span when circling - my "little" Nimbus 2C
can develop a 15 knot difference. This, plus a thermal gust, can make them
roll into a spiral dive.

Recognizing this and taking prompt action when it happens is actually easy
once you experience it a few times. Just allow the speed to increase a bit
to increase control authority, then stop the turn and then recover normal
airspeed.

If the glider is allowed to progress into a full spiral dive, the options
narrow considerably. Only very gentle and precise control inputs will save
the day. Try not to apply large aileron and elevator inputs
simultaneously - bending and twisting the wing at the same time can break
it.

Reading the Spanish report made it seem that the pilot did not have complete
control of his glider. That's a shame when it's a two seater and there are
a lot of experienced pilots who would have been willing to ride with him and
help him master it.

Bill Daniels


"HL Falbaum" wrote in message
...
Yes, indeed. If anything, the spiral dive recovery is more critical from a
structural standpoint. A modern glider is more likely to progress to
spiral
dive anyway. The pilot, by his own admission, did the wrong recovery for
either case.

However, since the Spanish report refers heavily to the Minden report,
with
many similarities, I wonder if there is something peculiar about the
Nimbus
4 DT. Both apparently departed into a stall and incipient spin in a strong
thermal. This pilot had sufficient recent flight experience, and total
time,
to have developed good "survival" reflexes, including the "stick forward"
manuver. He had little time in the Nimbus 4, but quite enough in the
Nimbus
3 to know how to fly it.

If it was purely the fault of very strong thermals, then the other gliders
in common use at places like Minden would also have similar accidents.
This
does not seem to be the case.

Obviously, I have never flown a Nimbus of any kind. I have a few hours in
the Duo-Discus, but nothing larger. The Duo is certainly not malignant in
any way.

So my question is to those with Nimbus D experience. Is there some
handling
characteristic that will bite a fairly experinced and competent, but
unsuspecting pilot?

I am thinking that the (biennial USA) Flight Review should include spiral
dive recovery routinely, in addition to the usual other "emergency"
maneuvers.
--
Hartley Falbaum
CFIG USA


"Stefan" wrote in message
...
W.J. (Bill) Dean (U.K.). wrote:

The Spanish report in English translation may be found at
http://www.gliding.co.uk/accidents/r...s4dtreport.pdf (3MB).

Thanks for the link. Very educational, indeed. I think this answers the
question whether spins and spiral dives should be demonstrated and
recovery should be regularly trained.

Stefan