(Mark James Boyd) wrote in message news:412b9c97

Not always true. An aircraft that has done a complete 180 during the
spin still has momentum, and is now to some degree flying backwards.
The excess forward momentum translates into excess reduction of airspeed.

Think about it for a minute. If you're going 50 knots in one direction,
and then one-half second later the nose of the glider is 180 degrees
pointed the other way, does this mean you are doing 50 knots in the other
direction? That's some G's, and I don't feel them in a spin.

Oh cmon, that's about the oddest explanation of what happens during a
spin entry I can imagine! Try this: a spin happens when both wings
are stalled, with one stalled more than the other. Stalled means a
lot less lift, so the flight path curves down (gravity is a wonderful
thing). If you do a snap roll, which is a spin in the horizontal
plane, you initially go pretty much level until speed is lost then
your flight path curves down. And what do you mean by doing "a
complete 180 during the spin ...and is now to some degree flying
backwards." That isn't a spin, it's a frisbee! As far as G's, if you
enter a spin at low speed (not accelerated), you can't pull any G's -
as the plane unloads and goes down there is actually a decrease in
G's!

This is why aircraft oscillate pitch up and down for a few turns before
stabilizing in a spin. For the first few turns, the aircraft momentum
is still slogging through the air.

I don't have a spin text handy, but I would think the oscillation is
more due to angular momentum and changing AOA as the glider rotates
around it's pitch and roll axes than from "flying backwards".

But some of what you point out is true. Aircraft without enough
elevator authority to stall, and with forward CG, won't have the
ability to stall in a steep bank. But if the CG is back a bit, the
elevator has a lot of authority because the glider is designed for a
wide range of speeds, and the pilot has in aileron to resist overbanking,
then whoa nellie!

Even with an aft CG, any glider is fully controllable up to the spin -
it's recovering that would be interesting. It's not going to make you
spin more. And I feel the whole aft CG is a bit of a bogyman to scare
people - It's pretty hard to get the CG that far aft (it can be done,
especially if you are light, but any sort of preflight should find it)
and if discovered the plane is still fully controllable - unlike a too
far forward CG that can lead to a heavy landing. Just my opinion, but
I bet there have been very few spin accidents caused by aft CGs (CG
out of the aft limit, not just at the aft limit). As far as
overbanking - It's not going to roll you over in a turn! You need to
hold off some aileron to compensate, but it's never so strong as to
cause control problems. It's a secondary result of use of the flight
controls (actually of the glider's attitude), like adverse yaw.
Coarse use of controls at or near stall speed IS a problem, that
reflects serious lack of knowledge by the pilot of how a plane works!

If we are not teaching pilots to do steep (60 degree) windup turns
until they recognize the approach of a stall/spin, then immediately
recover by releasing backpressure and continuing the turn, then we are
setting then up to be a statistic. Oh, BTW, try that in a 2-33!

A properly flown steep turn at higher speed isn't what I'm talking about.
I'm considering a 30-45 degree bank turn at low speed.

This thermal was very smooth and regular and wide. I was feeling it
out on the first turn, and was not eager to make any coarse inputs or
lose sight of my landing site or get vertigo during the circle.

Sounds like trying to turn via ground references down low - a big
no-no and probably the real reason for low altitude "stall-spin"
accidents. Airspeed, yaw string, bank angle, vario, altimeter, clear
the airspace - then check where you are. The ground isn't going
anywhere fast, so don't stare at it!!

The classic spin entry from a shallow bank is uninteresting.
I won't be jamming in the rudder for a skid at some obviously
low speed close to the ground. I think the focus on the classic case
is niave and dangerous. Yes, it's easy to teach and demonstrate,
but it ignores too much. The more complex, less discussed
spin entry is the one in the accident reports: tight pattern,
higher speed, steep bank, lots of inside rudder, pilot focussed on
keeping the yaw string straight, quite a bit of opposite aileron
in the steep bank, in vertigo, pulling stick back to tighten up the
turn, and then wham! I'll look back through the accident reports, but
the ones I recall, and the B-52 and the DG spin I saw on video, involved
stabilized, 30-45 deg bank turns before each of the spins. In each,
it looked like the craft was overbanking, and the pilot put in more
opposite aileron and more elevator and WHAM! Instant spin...

Again, you are describing a pilot who has no clue how to fly his
glider. A stabilized steep turn doesn't call for a lot of inside
rudder. When rolling the glider, you use as much as you need to
coordinate. An you ALWAYS make sure you have enough airspeed
(actually AOA, which is why I would love to have an audio AOA
intrument, set to replace the vario when the gear is down, that would
always indicate the optimum AOA regardless of bankangle and gross
weight - like a lot of military jets have). The solution is not to
take away a tool (steep turns) but to teach the proper use of all a
pilots tools. And I am a bit confused by your reference to vertigo -
again, this is avoidable (don't stare at the ground, no rapid head
movements, etc) and should be taught. If a pilot continually gets
vertigo in steep turns (and I have some really good friends who do,
unfortunately) they need to seriously consider the ramifications of it
and fly accordingly!

Too much rudder, maybe, but it wasn't because he moved it. It was
because the pilot put in more dragging aileron without RELEASING
inside rudder.

Practice, practice, practice...

This is usually the case for me on cloudless days (like that one).
High over the terrain, I usually just bump into a thermal. Of course,
at altitude, while thermalling, slow is good, and trim is your friend...

So true out here in AZ, too...

Shallow turns in power? Why? Just jam the throttle all the way in,
full flaps, and yo-yo base to final at 60 degrees. Gas is a good
substitute for brains ;PPPP

And burning JP-4 was so much more satisfying than AVGAS - especially
at the taxpayers expense! Noisier, too.

Power planes (except maybe the DA-20) often have lower
aspect ratios. Some even have frieze ailerons. And if the left turns
are flown with power off, there's even a little slip provided by the
P-factor of the prop. There's enough differences between the two
that the USA CFI practical tests require training and evaluation in each
category seperately (CFI transition from one to the other requires
spin training in the new class, except for Sport Pilots, but that's
another thread).

And some power planes are rolled primarily with rudder at low speeds,
including in the pattern! (F-4 comes to mind) In fact, the rudder is
also used to adjust pattern altitude during steep turns, such as the
90 degree break turn to downwind. It sure looks better and was easier
than trying to adjust altitude by changing bank angle.


Power flying can be boring. If an autopilot can do it, why do they
need me?

To feed the dog. His job is to keep you from touching the autopilot
controls.

Anyway Kirk, I welcome some more discussion. As you can see, there
are quite a few points where we agree, and a few nuanced ones where
we don't. I hope you have time to continue another response...

Fun discussion. Back to work, the dog looks hungry...

Kirk