Unintentional fully-developed spins...

On 29 Jan 2004 21:46:51 GMT, Bob Kuykendall
wrote:

I've watched an ASW-20, flown by a well-respected pilot,
flick into a spin while thermalling. Including the
recovery, it went about a turn and a half. The thing
that impressed me about it was the dynamic and asymmetric
flexing of the wings in the entry. I seem to recall
that it was an over-the-top entry, but I could be wrong
on that. I have no idea what precipitated the entry,
but I can say that it made more of an impression on
my opinion of the ship than on my opinion of the pilot.

Typical for an ASW-20 in flap setting 4.

My only unintentional spin also happened in a 20. At flap setting 4
the 20's departure can be aprupt and if the CG is halfways backwards
it immediately enters a spin with an over-the-top entry if not
immediate corrective measures (anti-spinwise rudder, flaps to neutral
or even negative) are applied. Time from stall to spin less than two
seconds. Really impressive.

My spin happened when I was hit by strong lift while flying along a
cloud street at very low speed (below 75 kp/h) and flap setting 4.
I consciously delayed my correction with the rudder when the 20 began
to turn towards one wing because I wanted to see what would happen,
and was amazed how quickly I was going trough inverted into a
fully-developed spin.

Immediate application of rudder had prevented that, and at neutral or
even flaps the 20 has very docile stall manners.

Bye
Andreas

Bob Kuykendall wrote in message ...
Earlier, Marc Ramsey wrote:

OK, I'm curious. How many of you have
had to recover from a fully developed
(greater than one turn), unintentional
spin that occurred during normal non-
aerobatic flight?

I've watched an ASW-20, flown by a well-respected pilot,
flick into a spin while thermalling. Including the
recovery, it went about a turn and a half. The thing
that impressed me about it was the dynamic and asymmetric
flexing of the wings in the entry. I seem to recall
that it was an over-the-top entry, but I could be wrong
on that. I have no idea what precipitated the entry,
but I can say that it made more of an impression on
my opinion of the ship than on my opinion of the pilot.

I came away from that incident wondering to what degree
the limber structures of second-generation composite
wings might interact with hard-to-predict post-stall
aerodynamic behaviors to incite spin entries and perhaps
inhibit recovery.

Thanks, and best regards to all

Bob K.

Do you also mean high aspect ratio wings with poorly glued spar caps?

Earlier, (Slingsby) wrote:

Do you also mean high aspect ratio
wings with poorly glued spar caps?

Geez, there you go again.

No, I don't.

Bob Kuykendall wrote:

I've watched an ASW-20, flown by a well-respected pilot,
flick into a spin while thermalling. Including the
recovery, it went about a turn and a half.

I haven't spun gliders, but I have hundreds of hours spinning Navy jets.
In the larger planes, there was a period of post stall gyration (PSG)
before entering a spin proper, with a spin defined as steady state yaw
rate, pitch attitude, and AOA (or not too big oscillations about a
state). PSG could last a fair number of turns.

So was the ASW-20 really in a spin? Steady state?

Earlier, nafod40 wrote:

...So was the ASW-20 really in a
spin? Steady state?

I saw it go thundering down out of the thermal, a-whirling and
a-waggling. I don't think it ever arrived at a steady state, but I
wasn't in a situation that allowed much attention to it.

Bob K.

Marc:

I had an unintentional spin from a thermalling turn in a Baby Lark.
There was no warning (at least that I noticed), the entry was over the
top and the glider ended up spinning oposite the direction I had been
thermalling. Once I realized that it was spinning, it recovered
normally but I lost a lot of altitude before I figured it out. At
12,000 feet where it happened, it was a non-event. At 1,000 feet it
most likely would have killed me.

In turning stalls, this particular Baby Lark ALWAYS dropped a wing,
but this was quite different. In a turning stall, my own ship just
mushes until the nose drops. It will spin, but it has to be put there.

The Lark was, BTW, a rental ship and I don't remember any special
emphasis on its spin characteristics during my checkout. I continued
to fly it afterwards until it was destroyed by someone who tried to
land it perpendicular to a road. I never let it get slow near the
ground or unintentionally again, though.

Ray Warshaw

Marc Ramsey wrote in message om...

IS 28 and IS 29 both have relatively large cordwise ailerons. Using too
much aileron for incipient recovery may result in a full spin, but
especially in where the aileron is a large percentage of the chord.. Our
club chairman test flew an IS 29 that our club (1979?) was considering at
one point and rejected it for this very reason. I personally found the IS
28 a nice platform but know that others were cautious or critical. I recall
comments, a la Puchaz, from around 1980, after a few spin-ins, including two
UK instructors in one instance.

You are invited to google this thread from 1995, http://tinyurl.com/2gg7r

Frank Whiteley


"Raphael Warshaw" wrote in message
m...
Marc:

I had an unintentional spin from a thermalling turn in a Baby Lark.
There was no warning (at least that I noticed), the entry was over the
top and the glider ended up spinning oposite the direction I had been
thermalling. Once I realized that it was spinning, it recovered
normally but I lost a lot of altitude before I figured it out. At
12,000 feet where it happened, it was a non-event. At 1,000 feet it
most likely would have killed me.

In turning stalls, this particular Baby Lark ALWAYS dropped a wing,
but this was quite different. In a turning stall, my own ship just
mushes until the nose drops. It will spin, but it has to be put there.

The Lark was, BTW, a rental ship and I don't remember any special
emphasis on its spin characteristics during my checkout. I continued
to fly it afterwards until it was destroyed by someone who tried to
land it perpendicular to a road. I never let it get slow near the
ground or unintentionally again, though.

Ray Warshaw

Marc Ramsey wrote in message
om...

Raphael Warshaw wrote:

The Lark was, BTW, a rental ship and I don't remember any special
emphasis on its spin characteristics during my checkout.

Hmm, it's strange. This glider is "famous" for it's stall
characteristics. Lot of pilot died in small IS...

/Janos

Mark,
I have owned over 40 sailplanes and flown over 50 types while logging 4110 hrs
in sailplanes. I have never entered an unintentional spin and "get this" I have
never even had a full unintentional stall in any sailplane. Once turning final
for a rocky, up hill, landing, I got pre-stall buffet in my H-301 libelle,
eased off a bit on the back stick and landed OK. On another occasion I was
stretching the glide to a duster strip in the Sierras (Sunrise) and arrived
there with 500 feet, flew an abbreviated down wind, lowered the flaps, lowered
the gear, cracked the spoilers and turned left, all from about 45 knots. The
LS-6 just shook its head and said, "I don't think so". Shoved the stick forward
and landed OK. I think its all about feeling the ship. Most pilots have the
feel of what's going on, a few don't and they never will.
I believe we should be doing spin entry followed by emmediate recovery, just in
case, but a well flown sailplane won't be in need of any spin recovery.
JJ Sinclair

(JJ Sinclair) wrote in message ...
Mark,

I have owned snip...
I think its all about feeling the ship. Most pilots have the
feel of what's going on, a few don't and they never will.

JJ Sinclair

JJ, that says it all.

(except you got the "most" and the "a few" mixed up.)

-Dan