Spinning the Grob 103
Al Holst
I note with interest that of the replies to the question regarding the
spin characteristics of the Grob 103 only one respondent has actually
been the aircraft when spun, I presume as spectator.
Ergo The aircraft is VERY difficult to spin..
There is no future in spinning it..
It will spin if the CG is farther back than seems prudent..
Tim Daniel
Two members of our club were flying the club's 103 and happened to have a video
camera on board. These were both very experienced pilots. They decided to video a
spin from the cockpit. I have watched this video several times, and the spin
appears to be fairly slow, with recovery almost immediate. The aircraft spun
with a steep nose down angle, but there was no tendency to invert. They appeared to
have no trouble getting the aircraft to spin, and with these two pilots the C of G
would have been well forward.
Yes, I wasn't in the cockpit, but the video was the next best thing to being there.
Our club does extensive spin training on our Blaniks as a regular part of our
training and most pilots are comfortable with and enjoy spinning. We always wear
parachutes when spinning glass aircraft, and usually in the Blaniks as well.
Drop by for a spin sometime!
Tim Daniel
Vancouver Soaring Association
robert
the glider really does need to be held into the spin, which is very nose down (not inverted) but
not particulary fast. Recovery is straighforward, and I touched 98 knots before I got the nose
above the horizon. I've only done four spins in it. However, when solo in another, standard,
103 I was practising stalling and it did enter a spin. I weigh 140 lbs, no ballast weight but I
did have a chute, so thats just over the min limit. Recovery was standard (initiated straight
away).
I think the flight manual for the 103 says spinning is ok but only possible with the CoG at or
near the aft limit ?
Does anyone know what the official word from Grob is re the subject ? Its certainly possible,
but is it advisable ?
Robert Pepper
rob...@pdinsure.co.uk
Mark A. Matthews
OK, here's what the manual has to say about spinning a (non-acro) Grob:
> 3. Spin (possible in aft C.G. positions only)
>
> Preparation. Decrease speed slowly to 80 km/h (43 kts. 50 mph) pull stick
> back and apply full rudder. Glider spins slowly. Rotation rate is one
> turn every 3 seconds with a height loss of about 80m (262 ft.) per turn.
> The gilder has no tendency to turn into a spiral dive.
> Recovery: opposite rudder, neutralise stick and recover gently.
The above section was copied verbatim from the _Flight Manual Grob G103
>>Twin II<<_, published September 1981, LBA approved 17th March 1982
(English translation).
(I'm not responsible for the comment on the stability of dutch currency
included above, that's what it says in the manual. :-)
Personally, I've never been able to develop a real
pivot-about-a-central-axis,
my-there's-a-lot-of-ground-up-there-through-the-top-of-canopy kind of spin
in the Grob that I've done in a Blanik. My suspicion is that you have to
have the CG really aft, and determine the CG position by weight and
calcuation, not just going by the placards.
--
-Mark
Evan Ludeman
: I note with interest that of the replies to the question regarding the
:
Naw, it's not that difficult. The G-103, like the AS-K21 has a huge
polar moment of inertia. You can use this to trip off the spin. You
*do* need to be near aft limit, however. Begin deceleration with yaw
string to one side (let's say over your left shoulder), wings level,
speed 50 kts. Nose up about ten degrees, full right rudder about three
seconds before the break followed quickly by full aft stick and full left
aileron. The action of rudder and opposite aileron (adverse yaw)
*before* the break will give enough momentum about hte yaw axis to carry
you into a spin. Spin rate is *very* slow. Recovery for me was
immediate upon release of back pressure.
-Evan Ludeman
David Anderson
: I hope this doesn't add to the controversy...
I am training in a L-23. Recently I asked one of our instructors to do
a few spins for the experience. By the book we nosed high, a little bank, and
rudder. The Blanik began a spin. Now we applied opposite rudder and
as the spin stopped applied slight forward pressue to the stick. What happend
here was the glider NOSED DOWN increasing the angle of decent (and scaring
me out of my wits) instead of leveling out. I was told that is what a
Blanik does. Explanations? -DSA-
Krister Engvoll
>I am training in a L-23. Recently I asked one of our instructors to do
>a few spins for the experience. By the book we nosed high, a little >bank, and
>rudder. The Blanik began a spin. Now we applied opposite rudder and
>as the spin stopped applied slight forward pressue to the stick. What >happend
>here was the glider NOSED DOWN increasing the angle of decent (and >scaring
>me out of my wits) instead of leveling out. I was told that is what a
>Blanik does. Explanations? -DSA-
As you write this, I suppose the Blanik quit spinning ?
My experience is that many spinning aircraft will nose down on recovery, indeed you had the the stick forward.
The Jantar, and certainly the LS4s nose down very severely when recovering from a spin. It looks/is very scary when the earth is ABO=
VE your head and speed is building...
BTW our L-13 stops spinning when the controls are left alone.Not tucking under though, but it is quite different from the L-23.
Krister
Bruce Hoult
> I am training in a L-23. Recently I asked one of our instructors to do
> a few spins for the experience. By the book we nosed high, a little bank, and
> rudder. The Blanik began a spin. Now we applied opposite rudder and
> as the spin stopped applied slight forward pressue to the stick. What happend
> here was the glider NOSED DOWN increasing the angle of decent (and scaring
> me out of my wits) instead of leveling out. I was told that is what a
> Blanik does. Explanations? -DSA-
Um, yes, your instructor should have pointed out to you in the briefing
before doing spins that spin recovery involves you finishing up in a very
steep or even vertical dive afterwards.
The flight path during a spin is -- ignoring the rotation -- straight
downwards, so you'll appreciate that in order to get the wings unstalled
you have to get the nose pointing to within 15 degrees or so of the flight
path, and that means within 15 degrees of vertical.
When the wings do become unstalled, there is a sudden decrease in drag, and
since drag is all that is slowing your descent, the glider will accelerate
rapidly into the dive. You suddenly feel that you're falling, although you
didn't feel that way in the spin itself. This aceleration is the main
indication that you're no longer spinning -- the ground won't necessarily
stop rotating, as many gliders will accelerate into a spiral dive after one
or two turns of a spin, even if you hold full back elevator.
-- Bruce
Nick Leaton
do
> a few spins for the experience. By the book we nosed high, a little
bank, and
> rudder. The Blanik began a spin. Now we applied opposite rudder and
> as the spin stopped applied slight forward pressue to the stick. What
happend
> here was the glider NOSED DOWN increasing the angle of decent (and
scaring
> me out of my wits) instead of leveling out. I was told that is what a
> Blanik does. Explanations? -DSA-
It will do. When you are spinning you are stalled. To recover from any
stall (appart from inverted) you relax the back preasure on the stick
by easying it forward. In a spin part of the recovery is the same.
However, the spin recovery says slowly move the stick forward. When you
recover from the stall you don't want to carry on moving the stick
forward lowering the nose further. If you do it will bunt. There are
also gyroscopic effects that will also lower the nose. Puchaz and
Juniors do this as well so it may also be associated with Polish
designs.
Nick
Software department
In article <424fmr$f...@longwood.cs.ucf.edu>, David Anderson (ada...@longwood.cs.ucf.edu) writes:
Snip ...
>I am training in a L-23. Recently I asked one of our instructors to do
>a few spins for the experience. By the book we nosed high, a little bank, and
>rudder. The Blanik began a spin. Now we applied opposite rudder and
>as the spin stopped applied slight forward pressue to the stick. What happend
>here was the glider NOSED DOWN increasing the angle of decent (and scaring
>me out of my wits) instead of leveling out. I was told that is what a
>Blanik does. Explanations? -DSA-
>
The spin stopped when the rotation stopped after the opposite
rudder was applied and BEFORE the stick was moved forwards. Moving
the stick forwards then had the usual effect - the nose went down.
There will be a nose down pitch in any case when the spin stops
because the wing becomes unstalled.
Once the rotation stops the glider is not spinning so doesn't need
any more spin recovery, you just need to pull out of the dive. If
you pull too hard there is a risk of stalling and - if there is yaw
present - it could spin again so you should centralise the rudder
during the recovery.
Some gliders will recover from a spin with just opposite rudder,
some need the stick to be moved forwards before the spin - and the
rotation - will stop. The amount of each needed will depend on the
glider type and the CofG position.
best wishes
Chris Rowland.
-----------------------------------------------------------------
Please reply to this e-mail with the name of the person you
wish to receive it on the subject line
(e.g. "FAO Janet Smythe/..subject.."),
as this is a shared e-mail address.