At 20:18 13 July 2005, T O D D P A T T I S T wrote:
Don Johnstone
wrote:

If you have to open the brakes, do so before Vne is
reached

Absolutely correct, carve that in stone.

The implication here is that if you find yourself extremely
nose down, but at an initially low speed, opening the
brakes
is a desirable action. I disagree.

Opening the brakes might be advisable if brakes were
able to
produce large amounts of drag - sufficient to limit
you to
speeds below Vne - but that is generally not true.
So, your
only other option is to get the nose back up to stop
the
acceleration. The only way to do that is to apply
the
maximum force possible in a direction perpendicular
to the
downwardly angled path of the aircraft to curve it
back
towards level.

A force perpendicular to the path of the aircraft is
called
'lift' and by opening the brakes you prevent much of
the
wing from producing the lift you desperately need to
bring
you back to level flight. This delays the critical
recovery. Up until you reach Va, you can operate the
wings
at maximum lift coefficient and produce maximum lift
without
risk of structural damage, and that's exactly what
you want
to do to get the nose back up.

In addition, by opening the brakes, you seriously increase
the risk that the pilot will overstress the aircraft
at
higher speeds. With brakes open, the max G load for
many
gliders is so low that the pilot simply does not think
he's
about to break anything. His built in warning system
does
not begin to go off until much higher G loads are felt.

Finally, if you open the brakes, you increase the altitude
loss significantly, a potentially critical factor in
a low
altitude recovery.

The proposal to use a tail chute does not suffer from
these
problems, as a tail chute does not decrease lift or
max G
limits. It also has the advantage of allowing recovery
from
otherwise unrecoverable spin modes.

I accept what you say my original reponse was to the
whole paragraph 'My main original point was that the
first action in
any sort of loss of control situation in a flapped
glider must be to select neutral or negative flap.
If you have to open the brakes, do so before Vne is
reached'

I standby that. It is important to select a non positive
flap setting and if the brakes are going to be used
it should be before VNE is reached.