How Low to Spin??

Chris - always thoughtful and articulate - even when
pedantic. ;-)

Seriously, I agree with your point about avoidance
AND early, reflexive recovery to avoid a full-on spin.
I used to work on wing-drop recovery in an early S/N
Ventus A/16.6 - which had the most pronounced stall
break of any glider I can recall. The control input
was stick forward and into the turn plus top rudder.
It takes some practice to make it reflexive.

I recall the main reasons for teaching stabilized approach
are to provide a consistent visual reference for the
pilot and to keep from changing too many flight variables
at the same time. Honestly, I don't know how they
come up with recommended 'correct' pattern speeds -
nor how scientific or precise the algorithm. My assumption
is that the speed is picked as a tradeoff between stall
margin and approach energy - but that there is an acceptable
range. We regularly add 1/2 the wind speed - how exact
is that?

My personal experience is that it's quite easy to bleed
off 5-10 knots by accident in a moment of distraction,
but 15-20 knots takes longer and is more apparent.


9B


At 15:36 30 August 2004, Chris Ocallaghan wrote:
With the big spoilers on modern gliders, there's not
much risk in
adding 10 extra knots, and while your argument that
it adds an
increased cushion before stall is unarguable, I guess
the measure of
value comes in whether that reduced risk is a justified
departure from
the 'correct' pattern airspeed. I'm with Mark... it
deserves some more
discussion.

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.

As demonstrated by my thread last fall, a Ventus 2
won't spin if the
controls remain coordinated (half stick/half rudder...
full
stick/rudder). It enters a controlable spiral, instead.
However, half
rudder and full stick (or half stick and no rudder)
would induce a
spin if the stick is held full back throughout the
stall break.

Avoiding the stall is the first most important step,
but thorough
training of the appropriate response during an inadvertent
stall is a
close, close second. And I could even argue that it's
more important,
since once you've stalled by accident, the outcome
is determined by
how well you've been trained to recover (that is, it
becomes the
failsafe for your stall avoidance error).

Though I'm not a fan of axiomatic training, there's
some value in
remembering that you can stall at any attitude and
any speed. If you
wear that axiom on your sleeve, then you'd be best
served by
understanding and practicing superlative stall recovery
technique in
addition to practicing stall avoidance.

That so many capable pilots have stall/spun in relatively
docile
aircraft indicates to me that there is a training gap.
We are clearly
handling the controls diffently at low altitudes. Why?
If we can agree
that this is the case, then adding speed is good insurance.
But it
doesn't address the cause.

Andy, apologies for being the pedant. I'm spitting
this stuff out at
60 words per minute, so I'm not giving much thought
to 'balance.'