On 6/4/2013 10:42 PM, Bart wrote:
On Jun 4, 6:40 am, BobW wrote:
Personally, I find the mindsets I've encountered in fellow pilots (soaring and
power) regarding spins: often worrisome; always interesting; almost
universally lacking in fundamental understanding of the aerodynamic
uncertainties inherent to "departures from controlled flight" (typically
called "spin" for short).

To make a sweeping general statement which has long colored my own approach to
PIC-ing, if Joe Pilot doesn't truly believe "departure from controlled
flight/spinning" is "uncontrolled flight" Joe Pilot is doing him or herself a
serious disservice if living to fly another flight is personally important.
True whether margins are thin or not...

I have read this post several times and I am not sure if I fully
understand what you were trying to convey. ESL.

Are you saying that "unexpected departure is uncontrolled flight"? Of
course it is, almost by definition. If my glider is doing something I
did not want it to do then I obviously lost control, at least
temporarily.

But, you may also be saying that spins in general are "uncontrolled
flight." Is this the case?


Bart, who spins gliders for fun


Intentionally painting with a broad brush here, I'd wager polling professional
general aviation test pilots for their top two areas of professional concern
in flight test would yield (in no particular order): spin and flutter testing.
(Quite possibly true for military and passenger plane test pilots too, but
those planes differ sufficiently from "Joe Average Gliderpilot's sailplane
arena to warrant separate discussion...)

I doubt any general aviation test pilot approaches these tests with a
complacent mindset. That's not to suggest "real fear" is uppermost in their
minds, rather that "healthy respect" is. My view is a similar mindset is a
good thing for "Joe Average Gliderpilot" too...for the same reasons test
pilots have. Yes, for us sport sailplane pilots - in the case of certified
sailplanes - some of the uncertainties have been investigated (removed?), but...

We still have professional test pilots in this age of digital computational
fluid dynamics anyway because uncertainties still exist...manufacturing (e.g.
human factors), structural (arguably considerably more straightforward then
aerodynamics & including material variability, analytical uncertainties &
limitations, etc.), aerodynamic (interaction of the uncoordinated plane with
generally turbulent air in general, wing-profile dings/bugs, age-based
airframe changes, etc.), etc.

By their very nature, spins are a complex mixture of (rapidly) varying
aerodynamics (entry, rotation, convective turbulence), gravity, inertias
(longitudinal, rotational), balance (CG)...

In my view, spins are the closet Joe Average Gliderpilot is likely to
intentionally get to playing Joe Real Test Pilot. Mental complacency about
spins is - in my view - misguided, overly-hopeful thinking. I've flown only 13
or 14 different types of gliders, and intentionally spun only 3 of them (1-26,
2-32, Blanik L-13), though I've "pre-spin abused" all but 2 in which I've
minimal time and done nothing more than slow-flight airspeed "calibration" for
landing patterns. Never (yet) had an "unexpected departure from controlled
flight" experience...perhaps a result of "healthy paranoia"?

The type in which I've the most spin experience is (was) my 1-26 (S/N 105)
many years ago (it's still "in the flying fleet"). Over 2+ years of ownership
I spun it enough in both directions to learn it (then) would eventually
maintain a "stable spin" up to 17 consecutive turns (the most I ever did) in
one direction, while it wouldn't remain in a spin the other direction (at my
CG) for more than 6 turns...and each of those varied considerably in pitch,
bank angle and rotation rate throughout each 360. Spins in that direction
reminded me of what I then (minimally) knew of single-seat combat planes, most
specifically the A4 Skyhawk. In any event, it was a completely different
animal depending on the direction of spin, though - as with most (all?) 1-26s
- it took considerable abuse/inattention to depart controlled flight in the
ship, and considerable/intentional control inputs to keep it in the spin. I
doubt the example(s?) tested for certification exhibited the same behavior; no
1-26 driver I've queried over the years admits to similar experiences.

Likewise, a 2-32 formerly owned by my club "always" (and abruptly, if warnings
were ignored) departed left wing low for every intentional departure I/we
(instructor/co-pilot) experienced/messed with. And I don't recall it
"recovering on its own".

To the question, "Are spins uncontrolled flight?" the answer is something each
individual pilot gets to answer for themselves. Personally, I think they're
closer to "uncontrolled flight" than "controlled flight," or at the very
least, I think that having that mindset is better than complacently assuming
every certified sailplane will have "entirely predictable spin behavior if
flown within certified weight and balance conditions."

Am I fear mongering or arguing pilots should NOT spin or learn how to "safely
play around the edges of departing from controlled flight?" Heavens no! Once I
gut used to the sensations of "departing" and spinning, I too, found them
great fun. But the more I messed around with them and the more I educated
myself about "spinning," the more respect I gained for the uncertainties
inherent in "playing with a tiger."

Bob W.