Spinning the SZD 50-3

On Wed, 28 Jan 2004 00:56:12 UTC, (Tim Shea)
wrote:

: After 4 or so rotations, the nose seemed to float up and the rotation
: *seemed* to slow considerably. I remember thinking that this is cool!
: Kind of like floating. When it was time for the recovery I applied the
: control inputs I'd been taught (as specified above) and much to my
: surprise, nothing different happened.....for a long time. I estimate
: that we completed another 5+ rotations nose high before it broke,
: rolled over and recovered.

I am told that a Junior oscillates nose up and down while spinning,
and that recovery is much much snappier nose down.

Ian

On 28 Jan 2004 11:17:41 GMT, "Ian Johnston"
wrote:

On Wed, 28 Jan 2004 00:56:12 UTC, (Tim Shea)
wrote:

: After 4 or so rotations, the nose seemed to float up and the rotation
: *seemed* to slow considerably. I remember thinking that this is cool!
: Kind of like floating. When it was time for the recovery I applied the
: control inputs I'd been taught (as specified above) and much to my
: surprise, nothing different happened.....for a long time. I estimate
: that we completed another 5+ rotations nose high before it broke,
: rolled over and recovered.

I am told that a Junior oscillates nose up and down while spinning,
and that recovery is much much snappier nose down.


That's all in the POH. A Junior has three different spin behaviours
depending on cockpit load. IIRC the oscillation occurs with a light
pilot.

I'm in the middle group (180 with a chute) and it recovers
automatically after just over 2 rotations, even with the controls
still fully crossed. The last half rotation gets really slow. I was a
bit annoyed. Having just done Silver height and wanting down in a
hurry, I was after 3 turns and was intending to come most of the way
down in a 3-turn - recover - spin the other way sequence. Still, I
repeated the experiment in the other direction and with recovery by
merely centreing the controls and got consistent recovery after just
over 2 rotations.

Be sure to read the POH before attempting more than one rotation.


--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :

Depending on the cockpit load, the spin is not possible, or it stops =
rotating itself. Maybe this third, slow turn was because it wanted to =
get out, and You were forcing it to stay in the spin?

Regards,


--=20
Janusz Kesik

visit www.leszno.pl - home of the www.css-leszno.it.pl

I'm in the middle group (180 with a chute) and it recovers
automatically after just over 2 rotations, even with
the controls
still fully crossed. The last half rotation gets really
slow. I was a
bit annoyed. Having just done Silver height and wanting
down in a
hurry, I was after 3 turns and was intending to come
most of the way
down in a 3-turn - recover - spin the other way sequence.
Still, I
repeated the experiment in the other direction and
with recovery by
merely centreing the controls and got consistent recovery
after just
over 2 rotations.


I quite frankly find this a quite scary post! I do
hope you allowed suficient height above the start of
your 1000m gain. I take it you are also one of the
'glider pilot hero' types? Still, i'm sure you impressed
everyone at the bar afterwards..........

So, what was wrong with a more conventional 'rapid
decent', you know, the one that uses full airbrake
circling in sink, or sideslipping with full airbrake.

On 28 Jan 2004 13:42:00 GMT, Pete Zeugma
wrote:

I'm in the middle group (180 with a chute) and it recovers
automatically after just over 2 rotations, even with
the controls
still fully crossed. The last half rotation gets really
slow. I was a
bit annoyed. Having just done Silver height and wanting
down in a
hurry, I was after 3 turns and was intending to come
most of the way
down in a 3-turn - recover - spin the other way sequence.
Still, I
repeated the experiment in the other direction and
with recovery by
merely centreing the controls and got consistent recovery
after just
over 2 rotations.


I quite frankly find this a quite scary post! I do
hope you allowed suficient height above the start of
your 1000m gain.

I was at 5300 ft when I decided to come down and to practise spinning
on the way, ending the last spin at about 2500 ft. That's quite low
enough for me: I won't deliberately initiate a spin under 3000 ft.

So, what was wrong with a more conventional 'rapid
decent', you know, the one that uses full airbrake
circling in sink, or sideslipping with full airbrake.

Not as much fun. Besides I hadn't spun the Junior for a while and
thought I needed the practise.

--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :

On Wed, 28 Jan 2004 15:51:28 UTC, Martin Gregorie
wrote:

: On 28 Jan 2004 13:42:00 GMT, Pete Zeugma
: wrote:

: So, what was wrong with a more conventional 'rapid
: decent', you know, the one that uses full airbrake
: circling in sink, or sideslipping with full airbrake.
:
: Not as much fun.

Coo. You've been and gone and said it now. "Fun", eh?

Ian

Also it seems strange for me, especially considering that Junior has the =
most effective airbrake I have ever seen.
If one adds a deep sideslip to this, it's sink rate can be compared with =
a stone only.

Regards,


--=20
Janusz Kesik

visit www.leszno.pl - home of the www.css-leszno.it.pl

So, what was wrong with a more conventional 'rapid
decent', you know, the one that uses full airbrake
circling in sink, or sideslipping with full airbrake.

Shawn Curry wrote "So I'm a test pilot every time I fly from my home
field at 7,500 ft MSL?"

I suspect you may be, if you go in for multi-turns spins at much above
that sort of altitude. That's the point I was asking about. What do
you think?

More conventional high flying is probably within the range of Reynolds
numbers that correspond with tests, provided you don't push the envelope
at the edges. Also the difference in density and RN is not great from
7,000 to 7500 feet.

If you know all this, of course, you can educate me by telling me the
answers.

If you don't - . . . back to your own question, I think, or perhaps an
aerodynamicist could tell us both (and any others who may be
interested).

The higher you go, of course, the more difference it makes. As pointed
out in other threads, if you go high enough, you stall at the same speed
as flutter onset, which leaves no usable envelope at all.

In my earlier post about true velocities/IAS/density/AoA/rotational
speed etc., as I don't know if everyone realises their tie up with
Reynolds numbers, I deliberately didn't refer to RN. Few (certainly not
me) would know off by heart the formulae, even if they have heard of the
things, or how the other factors and RN change with height. I did,
however, presume that all post bronze or equivalent people will have
done some reading on true vs IAS, flight envelopes, etc.. and might
therefore appreciate that the geometry of a spin, effectiveness of
control surfaces, and rotational aspects, high up could be different
from lower down.

Chris N.

Chris Nicholas wrote:
Shawn Curry wrote "So I'm a test pilot every time I fly from my home
field at 7,500 ft MSL?"

I suspect you may be, if you go in for multi-turns spins at much above
that sort of altitude. That's the point I was asking about. What do
you think?

More conventional high flying is probably within the range of Reynolds
numbers that correspond with tests, provided you don't push the envelope
at the edges. Also the difference in density and RN is not great from
7,000 to 7500 feet.

If you know all this, of course, you can educate me by telling me the
answers.

If you don't - . . . back to your own question, I think, or perhaps an
aerodynamicist could tell us both (and any others who may be
interested).

The higher you go, of course, the more difference it makes. As pointed
out in other threads, if you go high enough, you stall at the same speed
as flutter onset, which leaves no usable envelope at all.

In my earlier post about true velocities/IAS/density/AoA/rotational
speed etc., as I don't know if everyone realises their tie up with
Reynolds numbers, I deliberately didn't refer to RN. Few (certainly not
me) would know off by heart the formulae, even if they have heard of the
things, or how the other factors and RN change with height. I did,
however, presume that all post bronze or equivalent people will have
done some reading on true vs IAS, flight envelopes, etc.. and might
therefore appreciate that the geometry of a spin, effectiveness of
control surfaces, and rotational aspects, high up could be different
from lower down.

My education on the subject has been to the extent that TAS increases
for a given altitude vs IAS and the need to decrease Vne to avoid
flutter at altitude. The notion that RN changes significantly from sea
level to 17,999 feet (where I often fly over Colorado) and that this
changes how the aircraft performes WRT spins, or any other performance
factor is news to me. From reading about the PERLAN project in Soaring
a couple years ago, I new this was significant at 100,000 ft MSL. Maybe
someone else can give more insight into real changes up to the bottom of
Class A.

Shawn

Tim,

I've experienced exactly the same scenario (spin flattening) in the
G103. It began with a penulum motion of the logitudinal axis, quickly
progessing to a point where the apex was above the horizon and the
nadir nearly vertical. Then it simply parked the nose a few degrees
below the horizon and continued to spin. It was very slow to recover.
So much so that I started pumping the stick and cycling the spoilers.

Since then I recover at first sign of these oscillations, though I
typically wait for the nose to rise before releasing the stick (a much
more graceful, less nose down recovery that way).

It is very possible that you have found a mode that makes the Puch
unreliable for spin training. At least the Grob gives some warning.
But it only spins to the left with the trim handle full forward and
the cg well aft.

(Tim Shea) wrote in message om...
I love to spin. It's exciting. I took aerobatic training with Wayne
Handley and was taught spin recoveries by him.

I have direct experience spinning the Puchacz at Minden. This is what
I remember from my experience. Your mileage may vary.
With friends (usually lighter than me) in the front, I spun it while
sitting in the back seat more than a dozen times. The CG was within
the published range and I didn't have any trouble with simple
recovery- stick centered and forward and rudder away from the
direction of rotation. Worked great.
I should mention that I used to be 50 lbs heavier than I am now, but
still in the published range for the plane.
During the training towards my instructors rating, I spun the Puch
twice with my instructor. The first 2 or so rotation spin I was able
to recover normally, no sweat. The second manuver was quite different.
I was asked to let the spin develop a little deeper for the second.
After 4 or so rotations, the nose seemed to float up and the rotation
*seemed* to slow considerably. I remember thinking that this is cool!
Kind of like floating. When it was time for the recovery I applied the
control inputs I'd been taught (as specified above) and much to my
surprise, nothing different happened.....for a long time. I estimate
that we completed another 5+ rotations nose high before it broke,
rolled over and recovered. I had the stick centered and against the
front stop with the rudder also pegged away from the rotation. We
recovered with several (4 or 5) thousand feet under us (we'd been
playing at cloudbase at about 15K).
Once on the ground, we discussed this incident in the grumpy bar for
at least an hour. I (and he) decided to never spin the Puch again. I
didn't. I doubt he did either.
I had heard of this happening before. I assumed that it was from
operation outside of the design envelope. Apparently I was wrong.
John Shelton probably said it best: "On my own as a test pilot, I will
certainly get killed". I felt like a dumb-ass for quite a while (more
than usual) after that.