The thing that causes a wing to stall (and subsequently perhaps to
spin) is that it meets the air at greater than the stalling angle.
All subsonic thin wings, flown at speeds where compressibility is not
an issue(below about 200 knots) stall at around 15 degrees angle of
attack (the angle at which the wing meets the air) for large aspect
ratios (glider wings).
The pilot controls this angle with the position of the elevator. The
elevator is pretty rigidly connected to the control column so what
you do with that controls whether the wing is stalled or not.
Nothing to do with speed or attitude at all.
However if you fly below a certain speed the maximum lift force
generated by the wing is less than the force on the glider due to
gravity and you cannot sustain level flight. This speed is the level
flight 1 g stall speed.
At angles of attack close to the stalling angle, coarse use of the
ailerons and/or rudder can cause one wing to exceed its stalling
angle and it only takes one wing to stall to initiate an incipient spin.
So the lesson really is quite simple: If the glider stalls (usually
recognisable by the pitch down or the nose slowing its progress
around the horizon in a thermal) just STOP PULLING THE STICK BACK.
Most gliders have heavy wings and won't actually snap roll as the
wing has a high moment of inertia in roll. As Gel Cuming (long time
RAAF chief test pilot) told me once about stalls and departures from
controlled flight (a better term possibly): if the aircraft wants to
go in the opposite direction to your control inputs, move the stick
in the direction the aircraft wants to go. By the time you get to the
middle things will usually be under control.
Rules of thumb about speeds are no substitute for proper
understanding. There's really no need to ever enter a full spin accidently.
Mike
_______________________________________________
Aus-soaring mailing list
[email protected]
To check or change subscription details, visit:
http://lists.internode.on.net/mailman/listinfo/aus-soaring
