"Flat spins"
Robert Steven Glickstein
about Geoff's spin/spiral article, the subject of "flat spins" arose.
My friend mentioned the flat spin depicted in the movie Top Gun; Tom
Cruise (in a F/A-18?) had inadvertently flown through the jetwash of
another fighter, lost an engine, and wound up in an unrecoverable flat
spin.
In the last several months I have read Kershner's "Student Pilot
Flight Manual," Langewiesche's "Stick and Rudder," and several
government handbooks, including a 1971 "Pilot's Handbook of
Aeronautical Knowledge." I've seen FAA, King, and Sporty's videos
about flying and flight safety. I've also closely followed the
discussions right here on rec.aviation.
I haven't seen anything about flat spins anywhere.
Are flat spins for real, or did Hollywood invent them? If real, what
is a flat spin? How is it entered and exited?
Thanks in advance.
______________ _____________________________
Bob Glickstein | Internet: bo...@andrew.cmu.edu
Information Technology Center | Bitnet: bobg%and...@cmuccvma.bitnet
Carnegie Mellon University | UUCP: ...!harvard!andrew.cmu.edu!bobg
Pittsburgh, PA 15213-3890 |
(412) 268-6743 | Sinners can repent, but stupid is forever
Ed Falk
>
>Are flat spins for real, or did Hollywood invent them? If real, what
>is a flat spin? How is it entered and exited?
Hell yes, the exist! Art Scholl, the pilot who shot the flat spin
scene in Top Gun, died doing it.
My aerobatics instructor told me the only time he'd ever bail out of
the plane I was training in, would be if a wing broke off or the plane
went into a flat spin. That should tell you something.
*Some* planes can recover from flat spins. I've seen planes at
Oshkosh do a 20-turn inverted flat spin and recover. Art Scholl
was flying a plane that's supposed to be able to recover from flat
spins, but something went wrong. One theory is that the weight
of the camera upset the plane's weight and balance enough to make
recovery impossible.
A flat spin is just what it sounds like, the plane is in a flat
attitude, spinning around its own center of gravity like one of
those "helicopter seeds" that come out of trees. I have no idea
how you enter one (anybody?), but I suppose it's something like
kicking rudder and elevator at just right time when coming out
of a hammer-head stall.
-ed falk, sun microsystems
sun!falk, fa...@sun.com
In the future, somebody will quote Andy Warhol every 15 minutes.
Matthew L. Ginsberg
Yes, flat spins are real. Roughly speaking, they are the result of
raising the nose during a normal spin; this can be done most
effectively simply by adding power while keeping the aircraft
spinning. (Out-spin aileron often helps as well, but that can be a/c
dependent.)
Flat spins are also pretty mellow; there is typically some side-to-side
buffetting but not too much else of interest. The problem with recovery
is that the tail has a much higher angle of attack than usual, and the
rudder may be stalled or partly stalled.
The recovery procedure is the following:
1. Cut power to idle.
2. Let go of the stick.
3. Push the rudder the way it doesn't want to go.
The above three steps, incidentally, will result in the quickest
possible recovery from *any* spin -- flat or normal, upright or
inverted. You should *not* push the nose forward during spin recovery
(I know, this is how people are typically taught) because the downward
position of the elevator will block a portion of the rudder from the
airstream, thereby making it less effective. Just *let go*. The
elevator will align with the airflow, which is what you need to make
the rudder as effective as possible. The stick will also probably
move slightly in-spin, which will help unstall the down wing.
A few other things:
1. Don't try this at home! (You'll wreck your living room.) And don't
try it in a plane that isn't checked out for flat spins -- the forces on
the tail are significant and can break it.
2. You *should* learn the above spin recovery procedure. It can save
your life if you find yourself in an unusual condition for some reason.
(Inadvertent spin with full power; it might even help if you've made
the -- very bad -- mistake of managing to spin a plane with the c/g
too far aft.)
3. The most common method of entering a flat spin in *practice* is to
screw up the bottom of a loop when you're just beginning aerobatic
training. The most common way to enter an inverted spin is to screw
up the top of the loop.
Matt Ginsberg
David W Levy
In article <1991Apr29....@ism.isc.com>, m...@arte.sos.ivy.isc.com
(Marc Goroff) writes:
|>
|> |> 3. The most common method of entering a flat spin in *practice* is to
|> |> screw up the bottom of a loop when you're just beginning aerobatic
|> |> training. The most common way to enter an inverted spin is to screw
|> |> up the top of the loop.
|>
|> airspeed is typically quite high and the corresponding g loading for a stall
|> would be very high!
I have been in a Citabria that spun out of the bottom of a loop, so believe
me, it can be done. I don't recall the g load to be too high, probably
less than 3 or 4 g's. There were two of us, so we were probably close to
max gross weight.
I don't know if this is a common way to enter flat spins, however. My
understanding about this subject is that it is not a matter of the type
of spin entry used, but rather the characteristics of that particular
airplane (whether through its design or c.g. location) and the control
positions during the spin. Then if the spin is prolonged, it will eventually
become flat. Certain airplanes are, of course, worse than others.
The Grumman Yankee comes to mind. I would welcome supporting or contradictory
testimony.
------------------------------------------------------------------------------
David W. Levy Internet: dl...@caen.engin.umich.edu
University of Michigan
Department of Aerospace Engineering Tel: (313) 936-0102
This is great! They actually pay me to do this!
------------------------------------------------------------------------------
Margaret Puckette
> raising the nose during a normal spin; this can be done most
> effectively simply by adding power while keeping the aircraft
> spinning. (Out-spin aileron often helps as well, but that can be a/c
> dependent.)
I've been waiting for someone to clarify this flat spin discussion, but
since no one with more expert knowledge has yet done so, please bear with
my more limited understanding. An upright flat spin is fatal and un-
recoverable unless one has sufficient excess thrust to provide some kind
of directional control with the rudder, or can move the CG forward or aft
enough to cause the aircraft to find a recoverable spin mode.
In a flat, upright spin, the aircraft is spinning around its CG, the wings
are completely stalled, and the rudder is blanked from airflow by the
stabilizer. The only known surviver of a Grumman Yankee flat upright
spin saved himself by opening the canopy and standing up in his seat and
rocking himself back and forth to get the aircraft to pitch down enough
into a "normal" spin. He barely had time to recover, however, and crashed
during the pullout.
Some aircraft like to go flat, not shallow, but flat, and the shape of
the *fuselage* is a contributing factor! A fuselage with a flat bottom
and rounded top is the worst for wanting to "go flat", the reverse shape
of a rounded bottom and flat top is the best...this according to a NASA
sponsored lectured at Oshkosh in '89. In fact, their spin test GA aircraft
(including the deadly Grumman Yankee) had stall strips on the fuselage
to test where airstream breaks would be most effective in preventing flat
spin modes from developing.
Remember, each airframe will find its own spin mode whether it be a shallow
nose down spin like the J-3 Cub or a steep screaming nose down spin like
the C-152 Aerobat. A good normal spin is recoverable when the rudder is
effective--when it has airflow going past it. And this is why an inverted
flat spin is more easily recoverable!!! The rudder can still be effective
as it is not shielded by the horizontal stabilizer.
I spoke with one of the only two surviving pilots of an inverted Grumman
Yankee flat spin (he is now a controller at the Boston - Logan TRACON
which he says is less stressful :-) ). He was a student pilot at the
time, he said his instructor was an idiot who was trying to teach him
spin recovery in this airplane. They ended up inverted, and the instructor
began to apply power in surges, full then idle then full... He said
the nose began to pitch slightly up and down, and on the down sequence
they could get some rudder effectiveness. But it took time! They recovered
at 500' AGL.
Bill Kershner has lots to say about spins. In his words, the easier it is
to get an airplane into a spin, the easier it is to recover...and vice
versa, a plane that doesn't like to spin in the first place will also not
like to recover. He also says the *incipient* spin stage is easier to
recover, this means within the first 2 to 4 rotations, before the aircraft
has spooled up and the pilot must overcome rotational inertia.
This guy is a test pilot, he's spun over 35 different kinds of aircraft,
and he says they're all different. If you try to get him to give you a
universal spin recovery technique, he'll Hum-n-Haw and give you one with
lots of exceptions and qualifications.
*The rule is: there is no hard and fast rule* This is why you only
want to spin aircraft that some test pilot has already worked out a
recovery technique for, and in many test situations and with a spin
recovery chute attached.
When I won the Archer, I was told that the airplane spins nicely but please
do not try. A few months later, some test pilot at Piper discovered that
the Warrior (same airframe, smaller engine) will go into an unrecoverable
flat spin mode with a certain amount of the CG in the aft part of the
envelope. I was sent a Service Bulletin that required the installation
of new stall strips on all Archers and Warriors, designed to cause a stall
before a situation when autorotation would initiate this flat spin mode.
I believe every pilot should practice spin recovery, but before that
happens, we need to have every potential spinning aircraft flight
tested for spins, and recovery techniques developed FOR EACH ONE. That's
going to be expensive. I'm not holding my breath.
************************************************************************
Margaret "round, and round (and on) she goes" Puckette
AOPA Archer N1939G
Matt Bartley
>In article <Ec64ikO00...@andrew.cmu.edu> bo...@andrew.cmu.edu (Robert Steven Glickstein) writes:
>>
>>Are flat spins for real, or did Hollywood invent them? If real, what
>>is a flat spin? How is it entered and exited?
>
>Hell yes, the exist! Art Scholl, the pilot who shot the flat spin
>scene in Top Gun, died doing it.
>
>My aerobatics instructor told me the only time he'd ever bail out of
>the plane I was training in, would be if a wing broke off or the plane
>went into a flat spin. That should tell you something.
A person I know got into one in a Cessna 152.
He was flying a cross country flight with a friend. They were at high
altitude, around 9000' AGL, and he decided to demonstrate spins. He
entered one in the usual way, except he couldn't get out of it. He
had no idea what was going wrong. He tried moving controls around all
over the place, cycling the throttle, etc for a couple minutes
(panic). Somehow, the plane broke out eventually, after they'd
dropped in altitude many thousand feet.
They went on to their destinations. Once there, he asked to talk to
an instructor and to ask him what had happened. After he described to
an instructor what happened, the first thing the instructor said was,
"you're lucky to be alive."
This is a 2nd hand story, so some details might be wrong.
--
Internet: mdbo...@leland.stanford.edu Matt Bartley
Bitnet: mdbomber%lel...@stanford.bitnet 73 de N6YWI
ICBM: 37 25' 34'' N Cost of this message has been
122 10' 40'' W billed to US government.
Joakim Karlsson
>will get you into different modes. The best way to get your F-15 into a
>flat spin is to cross the controls in a bunt. However, you may still drop
^^^^
>Into an oscillatory spin using this technique.
Excuse my ignorance, but what's a "bunt"?
>was spinning. This is also true in the F-18. In fact, the F18 spin
>recovery system tells the pilot which direction he should put the stick,
>because his perceptions are so unreliable.
>
>Mary Shafer sha...@skipper.dfrf.nasa.gov ames!skipper.dfrf.nasa.gov!shafer
So, what I've heard about the F-18's spin recovery procedure being "let go
of all controls" is a myth?
Thanks...Joakim
--
Joakim Karlsson | avi...@athena.mit.edu
Flying Fanatic in Training |
"Oh, I have slipped the surly bonds of earth
And danced the skies on laughter-silvered wings"
Rob Farlee
mdbo...@leland.Stanford.EDU (Matt Bartley) writes, regarding spins:
>A person I know got into one in a Cessna 152.
this is very difficult to understand. i took spin training in a 152
Aerobat, which is aerodynamically identical to any other 152. (the
vertical stabilizer is internally strengthened, and the door hinges are
replaced with quick-release pins).
spin recovery is rapid, once you figure out which rudder to stomp on. (spin
attitude in a 150/152 is very nose down, so you can't see the horizon, and
the windscreen is filled with a blur. i found it disorienting! but the
needle of the electric turn&bank is always a reliable guide to which way
the world turns.)
just HOLD rudder all the way down until the blur stops.
i found spin entry harder than recovery; falling out of the stall, any
inadvertant (yikes!) relaxation of full "pro-spin" controls at all, even
for a second, and all i got was a spiral dive. older 150s without the
dorsal fin feel less resistant to a true spin entry.
a local TV station shot a 5-minute clip on aerobatic training, including
several spins in the Aerobat. the TV camera, mounted in the aft baggage
area for an "over the shoulder" view, did shift the CG aft enough to retard
the spin recovery. (on the TV tape, you can hear our languid cropduster/
instructor pause and say "humm!" at this point; the reporter was busy
squealing with delight and didn't notice. she demanded six spins before
she'd let him land!) a shot of forward pressure is needed to break the
stall if the CG is aft. all this is covered in the Aerobat POH.
spins in 150/152s are fast, compared to Champs anyway, and are a fun, low-G
maneuver, and recovery is easy and rapid.
(p.s. most 152s are placarded against intentional spin entry; most 150s
are not; but neither are placarded against intentional spin recovery!)
--
The UUCP Mailer
Marc Goroff
Refering to flat spins ...
|> The recovery procedure is the following:
|>
|> 1. Cut power to idle.
|> 2. Let go of the stick.
|> 3. Push the rudder the way it doesn't want to go.
|>
|> The above three steps, incidentally, will result in the quickest
|> possible recovery from *any* spin -- flat or normal, upright or
|> inverted. You should *not* push the nose forward during spin recovery
|> (I know, this is how people are typically taught) because the downward
|> position of the elevator will block a portion of the rudder from the
|> airstream, thereby making it less effective. Just *let go*. The
|> elevator will align with the airflow, which is what you need to make
|> the rudder as effective as possible. The stick will also probably
|> move slightly in-spin, which will help unstall the down wing.
The procedure I was taught for recovering from any spin is PARE:
1) Power off
2) Alierons neutral
3) Rudder - opposite
4) Elevator - neutral
After rotation stops, neutralize rudder and recover from the resulting dive.
This is very similar to Matt's procedure, with at least one potentially
important difference. The application of opposite rudder before elevator
neutral can be important. Moving elevator neutral before opposite rudder
can result in a more nose down attitude with a faster rotation rate.
Opposite rudder then slows the rotation rate, but it can then
crossover into an inverted spin to the opposite direction.
|> 3. The most common method of entering a flat spin in *practice* is to
|> screw up the bottom of a loop when you're just beginning aerobatic
|> training. The most common way to enter an inverted spin is to screw
|> up the top of the loop.
I can't imagine entering a spin of any sort at the bottom of a loop. Your
airspeed is typically quite high and the corresponding g loading for a stall
would be very high! A much more common upright spin entry would be at the
top of a poorly executed immelmann, where the front part of the loop was
executed without enough pull on the stick (typically my first immelman of
the day :-)). I think it would also be difficult to enter an inverted spin
at the top of a loop. Even though your airspeed is too slow at the top, the
amount of forward stick required to stall the airplane inverted is
very substantial. The typical beginner will tend to keep pulling on the
stick at the top and turn the loop into an oval. What typically happens
is the airplane just drops like an arrow straight down. It's not really
a stall/spin.
-------------------------
Marc Goroff
Interactive Systems Corp
Calabasas, CA
m...@ism.isc.com
Mary Shafer
In article <Ec64ikO00...@andrew.cmu.edu> bo...@andrew.cmu.edu (Robert Steven Glickstein) asks about flat spins.
Yes, flat spins are real. Roughly speaking, they are the result of
raising the nose during a normal spin; this can be done most
effectively simply by adding power while keeping the aircraft
spinning. (Out-spin aileron often helps as well, but that can be a/c
dependent.)
Not really. The airplane has a number of spin modes and different entries
will get you into different modes. The best way to get your F-15 into a
flat spin is to cross the controls in a bunt. However, you may still drop
Into an oscillatory spin using this technique.
We at Dryden hold the unofficial record for number of turns in a flat
spin. 84 turns from 45,000 ft to 18,000 ft in the SRV (spin research
vehicle, a 3/8-scale model of the F-15, unpowered, remotely piloted).
He then recovered and spun it another 15 or so turns in the opposite
direction before recovering and landing.
Flat spins are also pretty mellow; there is typically some side-to-side
buffetting but not too much else of interest. The problem with recovery
is that the tail has a much higher angle of attack than usual, and the
rudder may be stalled or partly stalled.
I don't consider 6-1/2 gs eyeballs out to be really mellow. There are
substantial side forces too. We added handles to the F-14 so that the
pilot could keep himself in the neighborhood of the controls. Hanging
on to the stick to keep your head from bashing the canopy interfers with
making precise recovery inputs. Watch the over-the-shoulder films some
time--the pilot's really rattling around in the cockpit.
The recovery procedure is the following:
1. Cut power to idle.
2. Let go of the stick.
3. Push the rudder the way it doesn't want to go.
The above three steps, incidentally, will result in the quickest
possible recovery from *any* spin -- flat or normal, upright or
inverted. You should *not* push the nose forward during spin recovery
(I know, this is how people are typically taught) because the downward
position of the elevator will block a portion of the rudder from the
airstream, thereby making it less effective. Just *let go*. The
elevator will align with the airflow, which is what you need to make
the rudder as effective as possible. The stick will also probably
move slightly in-spin, which will help unstall the down wing.
Another generalization that's not quite true. It's almost always full
stick against in fighters. Yes, I know, you're not flying fighters,
but if you are flying any airplane with small or swept wings and a
pointy nose, you might want to use full stick against.
Another point is that spins can be very disorienting. In our F-14
experiments the pilot could not always tell in which direction that he
was spinning. This is also true in the F-18. In fact, the F18 spin
recovery system tells the pilot which direction he should put the stick,
because his perceptions are so unreliable.
--
Mary Shafer sha...@skipper.dfrf.nasa.gov ames!skipper.dfrf.nasa.gov!shafer
NASA Ames Dryden Flight Research Facility, Edwards, CA
Of course I don't speak for NASA
"Turn to kill, not to engage." CDR Willie Driscoll
Randy Gobbel
> As a case in point, the 2-32 has a reputation (questionably
> deserved) for being able to enter an unrecoverable flat spin at aft CG's.
> It also loves to attempt a spin entry at low thermaling speeds.
*Un*questionably, it is very to easy get a 2-32 to spin. I've done it, at
least once when that wasn't what I really had in mind (it was supposed to be
just a stall). A mechanic at Sky Sailing back when it was in Fremont,
California, once took one of their 2-32s for a test flight from the back
seat, with no front seat passenger. Somehow he got into a flat spin, and I'm
told was only able to recover by climbing into the front seat.
-Randy
--
Internet: gob...@ucsd.edu
My hovercraft is full of eels.
Paul Raveling
>
> 1. Cut power to idle.
> 2. Let go of the stick.
> 3. Push the rudder the way it doesn't want to go.
Whether flat or otherwise, spins sometimes need different
recovery techniques in different aircraft. Here's an example
that I posted maybe 3 years ago, as told to me by Gus Briegleb.
He insists this actually happened, and he'd be the one to know
as "father" of the old El Mirage soaring operation. I've left
intact my original added remarks about CG dependence and
subtle use of ailerons in recovery.
A fellow flying a Schweizer 2-32 solo at El Mirage returned
to the field at more than 6000 feet AGL one day. Instead of
opening the dive breaks to get down, he decided to spin off
a little altitude first.
When he got down to about 3000 AGL he initiated a recovery,
stopping the rotation and neutralizing the stick. The
2-32 stopped spinning briefly, then dropped off into a
spin in the opposite direction.
He repeated the recovery, again achieving no more than swapping
which direction he'd rotate in the spin. And he repeated,
and repeated, and ...
Finally, with impact imminent, the pilot shoved the stick
to its forward stop in sheer desperation. This finally
brought it out of the spin to stay, at 300 feet AGL.
Miraculously, his unintentional recovery was at a location
just off the end of a runway and he was pointed toward it.
He landed safely, thanks to more luck than any 9 pilots
deserve in a day.
This suggests an important point: Many aircraft, and particularly
the 2-32, behave differently when flown solo than when flown dual.
Dual spin instruction is an excellent idea, but be sure to to
discuss the aircraft's behavior at other loading conditions.
As a case in point, the 2-32 has a reputation (questionably
deserved)
for being able to enter an unrecoverable flat spin at aft CG's.
It also loves to attempt a spin entry at low thermaling speeds.
This is due to its limited washout at the wingtips, a wing shape
that encourages a stall to begin at the tips, and large ailerons
(for a sailplane), which can significantly affect AOA at the tips.
When practicing incipient spins with an instructor I also found
a slight bit of aileron, to raise the aileron on the stalled wing,
helped recovery. This is a bit unnatural -- full rudder against
the spin, aileron applied as if to roll into it -- but it worked
well on this particular aircraft.
Finally, if you fly a 2-32 solo, don't be afraid to take some
extra ballast and some extra knots in the thermals and the
landing pattern. Preventing an unintentional spin beats even
a skillful recovery every time.
---------------------
Paul Raveling
Rave...@vaxa.isi.edu
------------------
Paul Raveling
Rave...@Unify.com
Geoff Peck
writes:
> (p.s. most 152s are placarded against intentional spin entry; most 150s
> are not; but neither are placarded against intentional spin recovery!)
Nope. 152's are not placarded against intentional spins. As with many
spinnable airplanes, you must pay attention to the loading so that the
aircraft is loaded within the utility envelope.
Geoff
Tom R. Myers
> experiments the pilot could not always tell in which direction that he
> was spinning. This is also true in the F-18. In fact, the F18 spin
The percept I find most interesting is the first 3 or 4 seconds after a
15+ turn spin. My ears and head are telling me I'm still spooled up in
the spin, when I can plainly see that I'm not. Definitely one of the
better acro head-rushes.
TRM N1005E
Tom R. Myers
> is a flat spin? How is it entered and exited?
Yes, they are quite real. There are upright flat spins (stick back)
and inverted flat spins (stick forward). Flat spins are entered just
like normal spins (stall with stick forward or back, kick in pro-spin
rudder), and are flattened out with power and inside aileron to raise
the nose. Recovery is chop power, neutral stick, opposite rudder.
It takes longer to recover from flat spins, so kids, have lots of
altitude, and an airplane whose nose will drop back down when you
want to recover. The gyroscopic precession forces on the prop attach
flange will build up, so try this in a plane built for it.
The theory on Art Scholl is that the camera way back on the tail
had enough lever arm/moment to keep the nose of his plane from
dropping back to a normal spin, and he hit the Pacific flat.
TRM N1005E
Charles K. Scott
My father told me that while he was in flight school for the Navy in
1942, his flight instructor told him they would now demonstrate an
inverted spin. The instructor rolled the aircraft over then pushed the
nose up until a stall occured, then kicked the rudder. My father was
following him on the controls. He said what happened next was
disturbing. The plane snapped into a spin and he said that it was not
only very disorienting because not only were they upside down and
nothing looked right, he had great difficulty reaching the controls
because he was hanging by the belts, the stick was almost out of reach
and his feet were above the rudder pedals. The instructor then
recovered from the spin and rolled back rightside up and gruffly
commented that he (my father) would not be required to do this himself.
They never did, and my father never attempted to do this himself.
Once was quite enough.
Corky Scott
Jordan Brown
>This is actually a story about an inverted spin, but still interesting.
I found inverted spins to be rather anticlimactic. Spins are already
wierd enough; the difference between 70 and 110 degrees of nose down
wasn't a big deal.
>he had great difficulty reaching the controls because he was hanging
>by the belts, the stick was almost out of reach and his feet were
>above the rudder pedals.
This was his problem. You should be VERY tightly strapped in if you're
going to be doing any acro work, and this very definitely includes any
kind of spins. (No loose objects in the cockpit, either!)
Claude Goldsmith
(In a flat, upright spin, the aircraft is spinning around its CG, the wings
(are completely stalled, and the rudder is blanked from airflow by the
(stabilizer. The only known surviver of a Grumman Yankee flat upright
(spin saved himself by opening the canopy and standing up in his seat and
(rocking himself back and forth to get the aircraft to pitch down enough
(into a "normal" spin. He barely had time to recover, however, and crashed
(during the pullout.
About 15 years ago I saw the remains of an American Yankee behind a
hangar at the Salinas, CA (SNS) airport. That aircraft had
reportedly flat spun (spinned?) to the ground with **three** people on
board. Who knows where the CG was! There was one survivor,
I was told, who ended up severly disabled due to spinal
injuries.
Claude Goldsmith, CFI-IA <cla...@leadsv.UUCP>
twisted-pair (408) 742-7514 | Opinions expressed are not
on the air - WB6UOO | necessarily those of my
through the air - Mooney N6416U | employer.
Mary Shafer
It's almost always full stick against in fighters. Yes, I know,
you're not flying fighters, but if you are flying any airplane with
small or swept wings and a pointy nose, you might want to use full
stick against.
In a fit of global searching and replacing, I managed to change "full
stick with, rudder against" to "full stick against" because I wanted
to leave out the part about the rudder. It should be full stick with,
optional rudder against.
Mary Shafer
>In article <SHAFER.91A...@skipper.dfrf.nasa.gov> sha...@skipper.dfrf.nasa.gov (Mary Shafer) writes:
>>will get you into different modes. The best way to get your F-15 into a
>>flat spin is to cross the controls in a bunt. However, you may still drop
> ^^^^
>>Into an oscillatory spin using this technique.
>Excuse my ignorance, but what's a "bunt"?
Push the stick forward, holding the wings level. When you're inverted
and pointing back the way you came, put the stick back to neutral and
roll wings level. That's a bunt. The place you should cross the
controls is at about 135 deg through the vertical 180 deg maneuver.
You'll be upside down and flying toward the ground. Throttle back to
flight idle. You're trying to kill your airspeed and fool the
anti-spin logic in the flight control system.
Just to add another interesting note, the way to get an F-16 out of a
deep stall is to pull all the way back on the stick and count "one
hippopotamus, two hippopomatus, ..., five hippopotamus" and then push
the stick all the way forward to rock out of the deep stall. Bet you
weren't expecting "full aft stick" to get out of a stall, were you?
>>was spinning. This is also true in the F-18. In fact, the F18 spin
>>recovery system tells the pilot which direction he should put the stick,
>>because his perceptions are so unreliable.
>So, what I've heard about the F-18's spin recovery procedure being "let go
>of all controls" is a myth?
Yes. If you are in a fully developed spin fast enough for the spin
recovery system to come on, you must put the stick in the direction of
the SRS arrow (in the direction of the spin) or you will not recover.
If you've just departed and are slopping around the sky, let go of the
stick and the airplane will eventually return to "point end forward,
shiny side up".
Lars-Henrik Eriksson
>*Un*questionably, it is very to easy get a 2-32 to spin. I've done it, at
>least once when that wasn't what I really had in mind (it was supposed to be
>just a stall). A mechanic at Sky Sailing back when it was in Fremont,
>California, once took one of their 2-32s for a test flight from the back
>seat, with no front seat passenger. Somehow he got into a flat spin, and I'm
>told was only able to recover by climbing into the front seat.
You can hardly blame the aircraft for this! A tandem two-seat glider
with the front seat empty is almost certainly outside CG limits.
--
Lars-Henrik Eriksson Internet: l...@sics.se
Swedish Institute of Computer Science Phone (intn'l): +46 8 752 15 09
Box 1263 Telefon (nat'l): 08 - 752 15 09
S-164 28 KISTA, SWEDEN
Bob Spidell
>I don't know if this is a common way to enter flat spins, however. My
>understanding about this subject is that it is not a matter of the type
>of spin entry used, but rather the characteristics of that particular
>airplane (whether through its design or c.g. location) and the control
>positions during the spin. Then if the spin is prolonged, it will eventually
>become flat. Certain airplanes are, of course, worse than others.
>The Grumman Yankee comes to mind. I would welcome supporting or contradictory
>testimony.
The Piper Cherokee line is known for "going flat." I once saw a photo in
one of the aviation mags (_Aviation Safety_?) of a Cherokee that had
impacted from a flat spin. The airframe appeared eerily intact, except
it was sitting flat on the ground with portions of the main gear
structure protruding from the upper surface of the wings. Both occupants
perished from "compression" type injuries. Didn't mean to be morbid;
maybe there are Cherokee drivers on the net who aren't aware of this
trait of the airplane.
Spin Cherokees? Just Say No!
Regards,
Bob Spidell PA28-180 N7094W (1963 Cherokee)
Tom R. Myers
> equipped to do so?
Only speculation. Theory #1 is that he was too low to bail when he
realized the tail was too heavy. Theory #2 is that the gyrations
of the plane and the resulting orientations of the g loads prevented
him from bailing. His last transmission was only to the effect of,
"hang on a sec, I've got a problem," so it is unclear that the
theories will ever be verified.
TRM N1005E
Steven Philipson
> Flat spins are also pretty mellow; there is typically some side-to-side
There are aircraft for which a flat spin is a decidedly un-mellow
experience. An F-14 pilot will experience 6-g's eyeball out, yaw rate
approaching 720 degrees per second, and a descent rate of 14,000 feet
per minute (numbers from memory). The recommended recovery procedure is
to eject immediately upon recognition of a flat spin. Most GA aircraft
aren't quite this nasty, but they can still present a disorienting and
very confusing ride.
> 1. Cut power to idle.
> 2. Let go of the stick.
> 3. Push the rudder the way it doesn't want to go.
> The above three steps, incidentally, will result in the quickest
^^^^^^^^
> possible recovery from *any* spin -- flat or normal, upright or
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> inverted.
This is just plain WRONG. The "let go" method is useful as it will
work in most airplanes, and usually will work whether upright or inverted.
It will NOT yield the "quickest possible recovery" in the vast majority
(if not all) aircraft. (The FAA publishes an advisory circular which
states that explicitly. Other sources corroborate. I can dig out a
few references if someone feels it to be necessary.) It will also
NOT work for some aircraft. In those cases, positive and maximal
deflection of the elevator in the correct direction is required.
Generic recovery procedures are good to know for those times when
you either don't know the procedure recommended for your aircraft, or
when there aren't any. They are not a favored substitute for the
procedures worked out to be optimal for your airplane. Once again,
RTFM -- Read the Manual.
Steve
(the certified flying fanatic)
ste...@decwrl.dec.com