Unintentional fully-developed spins...

Trouble is we don't know how many general spin accidents there would have
been if no instruction were given in full spin recovery.

There are many (many) more private/club single seat gliders that we
might assume are not used for spin TRAINING.

Is there any data to provide an idea of the ratio of training vs
single seat spin incidents relative to the number of flights?

Even this isn't the answer, since the training mission is spinning,
vs the unintended end of a flight with a spin.

Yes, solid spin avoidance training is critical, but if that habit fails
to prevent one,
where's the experience to get out of it quickly?

Overall, I think a good measure would be training related spin-ins
per 1,000 training flights vs spin accidents per 1,000 solo flights.

(You could argue ~ x10 factor for the training since maybe 1 in 10
training flight involve spinning.)


Andrew Nairn wrote:
I too am astounded that more is not done by the worthy's in our sport.
Between 1987 and 1997 there were 34 fatal accidents in the UK. 4 in Puch's
and 3 in Pirats. That's one in five! There are many ways to dismiss the
figures but like it or not, these airplanes are killing people and out of
all proportion.

I too am astounded that more is not done by the worthy's in our sport.
Between 1987 and 1997 there were 34 fatal accidents in the UK. 4 in Puch's
and 3 in Pirats. That's one in five! There are many ways to dismiss the
figures but like it or not, these airplanes are killing people and out of
all proportion.

"Caracole" wrote in message
om...
(JJ Sinclair) wrote in message
...
SNIPPED A BIT

The brits, on the other hand, went out looking for a 2-seater that was
easy to
spin and they found a GOOD one in the Puch. Mike believes that 15 have
spun-
in, world wide and the Brits are investigating their 4th Puch-in.

Hate to tell you this boys and girls,
my list,
confirmed by direct contacts, of spinning Puch impacts is now up to
23 whacks worldwide.
And I am now chasing down a story about a 24th ... which is an 'old'
one, not the January English tragedy. The unveiling of #24 came about
through these threads....

On a production run of about 200 gliders, we only have a few more low
spinning fatalities to go, to remove the fleet from service.
Macabre enough yet?

Many of these wretched losses could have been avoided, had there been
a requirement for a hard deck for recovery that would allow egress and
use of parachutes. I know I won't get the Puchacz retired from
service, but possibly, maybe, by the grace of a higher power,

I might get people to STOP spin training in the Puchacz (at the least)
at low altitudes.

With a prayer,

Cindy B
Caracole Soaring

I have over 2000 hours in gliders including many types of glass. I also
have extensive experience in powered and glider aerobatics. Not long after
the purchase of my first fiberglass glider (Pegasus) I was thermaling around
400' over a mountain (US east coast variety) and attempted the hang glider
maneuver (which I had also been flying a lot of lately) of horsing the
aircraft into the center of a turbulent rotor type thermal. Retrospectively
the fact that it meant cross controlling while in a 60 degree bank made it a
no brainer re what resulted.....in a heartbeat I was looking at the mountain
through the top of the canopy. My first thought was "Hmmm....I've been here
before" and made immediate corrections with little more than a couple
hundred feet and an increased heart rate to show for it. Luckily the only
other pilots were above me. Take home message.....what they teach you re
spin entry is real and aerobatic training is a definite help if you get in
that situation, or at least spin training is.

As a sidebar to this discussion I noticed one person posted that he is
constantly on the edge of stalling his glider during thermaling. I would
argue that he is flying very inefficiently if that is in fact the case. To
convince yourself try thermaling (when alone) at the buffet speed vs adding
5-10 kts at differing angles of bank and focus on the VSI and see what the
results are. Look at any polar as well. Also if you try this out here in
the turbulent wild west let me know when you go flying 'cause I don't want
to be below you!

Casey Lenox
KC
Phoenix

As a sidebar to this discussion I noticed one person posted that he is
constantly on the edge of stalling his glider during thermaling. I would
argue that he is flying very inefficiently if that is in fact the case. To
convince yourself try thermaling (when alone) at the buffet speed vs adding
5-10 kts at differing angles of bank and focus on the VSI and see what the
results are. Look at any polar as well.

Casey Lenox
KC
Phoenix

I haven't seen polars that take into effect bank angle, but
from doing the calculations of turn radius and angles of
bank, I'm convinced that in very long wing gliders at
high angles of bank and slow speeds (and ergo light weights too),
the inner wing is significantly slower than the
outer wing, and tacking on some knots is most
efficient (to keep the length of the inner wing nicely above stall)...

Mark Boyd

(Mark James Boyd) wrote in message news:401ec4d0$1@darkstar...
As a sidebar to this discussion I noticed one person posted that he is
constantly on the edge of stalling his glider during thermaling. I would
argue that he is flying very inefficiently if that is in fact the case. To
convince yourself try thermaling (when alone) at the buffet speed vs adding
5-10 kts at differing angles of bank and focus on the VSI and see what the
results are. Look at any polar as well.

Casey Lenox
KC
Phoenix

I haven't seen polars that take into effect bank angle, but
from doing the calculations of turn radius and angles of
bank, I'm convinced that in very long wing gliders at
high angles of bank and slow speeds (and ergo light weights too),
the inner wing is significantly slower than the
outer wing, and tacking on some knots is most
efficient (to keep the length of the inner wing nicely above stall)...

Mark Boyd

I don't believe your argument is correct. What determines the lift and
drag coefficients is angle of attact, NOT airspeed. The inner wing is
flying at the same angle of attack as the outer wing, think about it.
Speeding up won't make you climb better.

F1y1n wrote:
high angles of bank and slow speeds (and ergo light weights too),
the inner wing is significantly slower than the
outer wing, and tacking on some knots is most
efficient (to keep the length of the inner wing nicely above stall)...

Mark Boyd


I don't believe your argument is correct. What determines the lift and
drag coefficients is angle of attact, NOT airspeed.

This is true, and if the glider is at a certain pitch angle straight,
level, and coordinated in still air, both wings are at the
same AOA. If the two wings are at different airspeeds,
like in a turn or skid, the two wings are at different angles of attack.

The inner wing is
flying at the same angle of attack as the outer wing, think about it.

Not if the wings are at different airspeeds. This is how we
do a spin. One wing is "more" stalled than the other wing
(i.e. has a higher AOA because it is the inside wing, and has less
airspeed). A turn is similar in the sense the wings are at
different airspeeds (but the same pitch angle), but in a turn,
it isn't true that both wings are stalled (that is the difference
between a turn and a spin).

Speeding up won't make you climb better.

Err...well, we are trying to sink less. If the wingspan is very
short, the point on the polar is the same for every part of
the wing. If the wingspan is long and in a turn, different
parts along the wings are flying at different airspeeds, and
are at different "efficiencies" and points along the polar.

The goal is to minimize the average sink rate along the
wing. The best way to do this is to strongly avoid the
back side of the polar (which drops off steeply), which
is the inner wing in the turn. If we fly a little faster
than recommended IAS (from the "G" table for bank) then
a larger portion of the long inner wing is near the
min-sink point, and the outer wing, although not optimally
efficient, is just displaced a little way along the front side of
the min-sink curve (which is a little flatter).

The amount of extra speed that is optimal should be based on
wingspan, the polar, and the bank angle. The
magnitude of this speed "correction" is something I have yet
to calculate, but thank you to the folks who have corrected
some of the previous attempts to calculate it...

(Mark James Boyd) wrote in message news:40252a00$1@darkstar...
F1y1n wrote:
high angles of bank and slow speeds (and ergo light weights too),
the inner wing is significantly slower than the
outer wing, and tacking on some knots is most
efficient (to keep the length of the inner wing nicely above stall)...

Mark Boyd


I don't believe your argument is correct. What determines the lift and
drag coefficients is angle of attact, NOT airspeed.

This is true, and if the glider is at a certain pitch angle straight,
level, and coordinated in still air, both wings are at the
same AOA. If the two wings are at different airspeeds,
like in a turn or skid, the two wings are at different angles of attack.

In a coordinated turn both wings are at the same AOA (please see my
reply to the other post in this thread). In an uncoordinated turn this
is not the case. Think of the direction of the airflow over the wing -
in a coordinated turn the airflow is always from the same direction
regardless of position on the wings; in an uncoordinated turn this is
not so, hence the AOA will be different. I was talking about
coordinated turns only (and I presume you were too in your original
post).

The inner wing is
flying at the same angle of attack as the outer wing, think about it.

Not if the wings are at different airspeeds. This is how we
do a spin. One wing is "more" stalled than the other wing
(i.e. has a higher AOA because it is the inside wing, and has less
airspeed).

Yes, in a spin the inner wing is flying at a higher AOA. But spin is
not a coordinated maneuver - see above. This analogy is moot.

Speeding up won't make you climb better.

Err...well, we are trying to sink less.

Well, it's half-full for me.

I don't believe your argument is correct. What determines the lift and
drag coefficients is angle of attact, NOT airspeed. The inner wing is
flying at the same angle of attack as the outer wing, think about it.
Speeding up won't make you climb better.

In fact, the inner wing is not flying at the same airspeed. It has the
same angular speed, but it is transribing a smaller circle than the
outer wing and thus going a shorter distance in the same amount of
time. Both wings are sinking at the same rate, therefore, since the
tangential (straight line) speed of the inner wing is lower, its angle
of attack is higher. Same thing happens at the wheels of your car,
which is why you need a differential gear, to accomodate the
difference in speed between the inside and outside wheels during a
turn. The outside wheel travels a greater distance, though both have
the same angular speed.

(Chris OCallaghan) wrote in message . com...
I don't believe your argument is correct. What determines the lift and
drag coefficients is angle of attact, NOT airspeed. The inner wing is
flying at the same angle of attack as the outer wing, think about it.
Speeding up won't make you climb better.

In fact, the inner wing is not flying at the same airspeed.

Agreed. I didn't say it did.


It has the
same angular speed, but it is transribing a smaller circle than the
outer wing and thus going a shorter distance in the same amount of
time. Both wings are sinking at the same rate, therefore, since the
tangential (straight line) speed of the inner wing is lower, its angle
of attack is higher.

This I do not agree with. The angle of attack of both wings is the
same. The air is impacting both wings from exactly the same angle -
the wings are connected by the fuselage. The inner wing is flying
slower, and thus producing less lift, while the outer wing is flying
faster, and thus producing more lift. The angle of attack and hence
the position on the polar is the same for both wings. You are correct
that both wings are sinking at the same rate, but this does imply that
the both create the same amount of lift.

Incidentally, the reason why you need some contra-aileron in a steep
turn is precisely for this reason - to correct for the net torque
trying to lift the outer, faster, wing!

On Thu, 29 Jan 2004 18:28:59 GMT, 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 was going to say once but on thinking about it I doubt that it got
to even one turn.
Late 1968 on my first flight in a Schneider ES57 Kingfisher(look it up
in a Directory of World's Crummy Old Gliders) .
I was thermalling at 4000 feet and kept pulling in tighter and all of
a sudden it snapped in to a spin. I took full recovery action and it
recovered instantly. Did it twice more that flight while exploring the
boundary. I had about 50 hours at the time and only one spin training
session 18 months before.

The ES57 is a very small lightweight glider of about Grunau Baby
performance but without struts. Very low inertia about all axes hence
the quick entry once it let go and there weren't any great
oscillations on spin entry.

Since then the only times a glider has gone even a quarter turn on me
is during deliberate spinning.

I used to spin my Salto a bit at first(fairly exciting oscillating
entry), I spun my Mini Nimbus a couple of times at first to find out
what would happen(rolls upside down on entry), I never bothered to
spin my ASW20B and incipient spins is all I've done in the Ventus C.

I once had the Nimbus 3DM we owned roll wings level and pitch down
maybe 20 degrees in a turbulent narrow thermal at 5000 feet over
Kingaroy airfield. No problem to reduce AOA and continue in the
thermal.

I think it is fair to say that full spin recovery training is of
little to no use for the failed winch launch/base/final turn/low
thermalling cases. In all these cases departures from controlled
flight are to be avoided at all times. Likewise I would hope that
nobody ever gets into a full spin accidently while thermalling. There
may be gliders below you.

Maybe I'm a little hard on the Kingfisher. I did get my Silver C in
it.

Mike Borgelt