How Low to Spin??

Knowing your glider is the key. Open class ships are built to the
limits of acceptable flying characteristics, as is the case with
aerobatic aircraft (one reason they are typically certified
"experimental"). You must read and understand the flight manual,
noting the divergence from the norm, which is what I cited in this and
previous threads.

I suspect that many pilots are simply not used to the difference in
force required to displace the rudder equally with the aileron. A
tendency to underrudder at flying speed is common. Applying the same
"balance" near the stall would produce much less rudder force, which
means that the greatly increased and unbalanced aileron drag will
produce a skid, and the angular momentum required to start
autorotation.

Flying your glider at MCA and experimenting with various displacements
of the controls is a good exercise. Gentle turning stalls while using
coordinated aileron and rudder (not solely determined by the yaw
string but also by percentage of travel applied) to pick up the lower
wing will help you understand what your glider can and cannot do in
the stall.

In previous threads, we discussed intentionally spinning at pattern
altitudes to acclimate pilots to this "view." Such practices are
patently absurd. However, regular practice flying on the edge of the
stall while applying coordinated aileron and rudder should have real
(and much more valuable) benefits. Does your yaw string act differntly
at low speed? Are you able to accurately judge onset of the stall?
During a stall, are you applying sufficient rudder? We all make
assumptions that we will react correctly, but I'd guess that without
regular practice of the type I descibed above, we're probably not
flying as efficiently near the stall as we think. So if we get there
by accident, is it possible that we might not be aggrevating the
situation through improper control inputs?

BTW, recall that during my test flights, I was able to avoid a spin
while holding full back stick throughout the stall and ensuing spiral.
Simultaneous release of back pressure and coordinated use of aileron
and rudder is the key. Flying MCA and reacting this way to any sign of
an impending stall is the best training you can give yourself. Then
add 15 knots in the pattern to be sure you won't have to exercise
those skills.

Honestly, how many of you really practice stall recognition and
recovery as a regular flight proficiency routine? I typically only fly
on the cusp of a stall for several seconds each flight: as I take off
(I get impatient) and just before I touch down. That's not a whole lot
of opportunity to experience a critically important flight regime.

Over my quota for the week. I'll check in next week.

OC



Robert Ehrlich wrote in message ...
Chris OCallaghan wrote:

BTW, as I noted in another thread, spins are not caused by lack of
airspeed, but uncoordinated use of the controls -- at least in modern
sailplanes. Two things must happen to enter a spin: 1) you must
stall, and 2) you must fail to apply sufficient rudder during your
attempt to pick up the low wing with aileron. That is, the sailplane
is designed with enough rudder to stop autorotation, even with full
deflection of the aileron throughout the stall break.


Well, you have to precise what you are calling "uncoordinated use". I
remember an incipient spin in an ASH25 (can be considered as a modern
sailplane, although it existed well before I started gliding 9 years ago).
My mistake was only a to high nose up attitude while circling, which was
not obvious to me as it was my first flight in the aircraft (with an
instructor of course). Due to its high inertia, the sailplane was slowing
down very slowly to the speed corresponding to its attitude, and needed
while slowing down more and more action on controls to counter induced
roll and induced bank up to the point where I had almost full out stick
and a lot of inner rudder when the inner wing dropped. Of course the controls
were badly crossed, but some amount of cross control is normal in order
to counter induced roll and induced yaw, this is not an uncoordinated
flight, the yaw string is is the middle. The excess in cross control
was due to the fact that both induced effects increase when speed decrease,
not to a lack of coordination.

Another experience I had, which is also in contradiction with this opinion
(i.e. spin can only occur by lack of coordination) was when I was
preparing my instructor rating. As there was no other spinable glider
available, we had to demonstrate spin entry and recovery in a Fox, an
aerobatic glider. My instructor was Katona, a well known aerobatic
pilot, and he explained that in order to spin this glider I should
slow it down just very close to the stall and then have stick and rudder
to the same side. I objected that I had always be taught to push the
rudder to the side I want to spin ans the stick to the opposite side.
He said that in this case the Fox would do a flat spin, which is difficult
to exit and was not the objective of the present exercise.