Phantom flight

Cockpit Colin wrote:

Newby question here - I've always been curious as to why any aircraft in the
1 to 1 thrust to weight ratio class (F/A-18? F4? F14? etc) would have
trouble being able to "simply" power out flat spins / falling leafs etc.

Can anyone give me a bit on an insight?

One way to think of it (not too scientific) is that adding power just
adds more "juice" to the spin. The power vector rotates around, just
making the plane do whatever it's doing with that much more vigor.

An airplane in a flat spin has very high angle of attack. Way above
any normal spin mode. Once stabilized flat you are sort of like a
frisbee, rotating with all the incoming air hitting just the bottom of
the plane. The break out of this spin or any for that matter, you must
lower your angle of attack somehow. In upright spins this means, stick
full forward. Flat spins, fwd stick doesn't help because the air flow
is under not over your vertical control surface, stabilator in the F-4
case. The rotation can't be altered for the same basic reason. Power
changes don't give you any significant nose up or down impulse. If you
deploy your drag chute it will just ride above you and not inflate,
like a streamer. You have lots of time to try lots of things on the
way down but like I said, we lost a lot of F-4s trying everything but
never found anything that worked. Answer was, be gentle when using
rudders when vertical and nose high. The F-4 gave you plenty of
warning when you did something it didn't like. Wing wobble, some
buffet, very loose nose in yaw, and often some "Oh ****s" from the rear
seat. My theory, and I never tried it, was if all else failed in a
flat spin, have the back seater eject and maybe the reaction to the
seat firing would lower the nose a hair. You just never told the RIO
what your plan was. In Navy planes, he could eject me but I couldn't
eject him. A serious design fault IMHO. Actually there was a way to
eject the rear seat from the front but it wasn't widely advertised.

One way to think of it (not too scientific) is that adding power just
adds more "juice" to the spin. The power vector rotates around, just
making the plane do whatever it's doing with that much more vigor.

I understand what you're trying to say, but I just can't get a handle on the
physics of it ...

Sure, I can understand how (without power) the aircraft would want to
continue rotating about it's centre of gravity (like a spinning top) - but
with power applied it would seem to me to want to accelerate the aircraft in
a given direction - which I would of thought would have initially increased
the distance from the centre of the spin to the centre of gravity (one and
the same with no power) to something bigger and bigger until control was
regained. In the case of a little power I could see how the aircraft might
continue to spin (perhaps to a point where the nose or some point further
forward becomes the spin center) - but with a LOT of power I would have
thought that eventually the aircraft would just start traveling in the
direction of the thrust (with less inclination to turn).

Obviously I'm wrong, but I just can't understand why adding say, 16,000 to
32,000 pounds thrust along a given line won't accelerate the aircraft away
from the centre of the spin.

I can only visualise it increasing the spin rate if the thrust was somehow
vectored 90 deg.

Where am I going wrong?

Cheers,

CC

PS: Thanks to the 2 other posters - I hadn't thought of decreased engine
power in the equasion, and I can appreciate how adding power in a
conventional spin maked things worse - it's just the flat spins / falling
leafs etc that have me baffled.

Well, okay, I rise to the challenge. I have a little over 700 hours in
the 104A (including some time in the Dash 19 version) and just over
2000 in the F4D/E/E-LES. I was fortunate in that the IP who checked me
out in the F4 respected my 3000 hours fighter time and together we
explored the envelope. I found the F4 to be an honest airplane (as was
the 104) and once you learned what it was trying to tell you you could
fly it to its real envelope, not the Dash One or NATOPS figures, but
what it was really capable of. The one aerodynamic thing I didn't like
was the G-dig decelerating through M 1.0 while loaded up - it came on
really sudden and if you happened to be looking outside (as is usual
while chasing someone) you were looking at a probable over-G. As for
fighting the birds, once in knife-range the old engined 104 vs F4 it
was the pilots - with the Dash 19 it could run the F4 out of fuel,
keeping the speed up and the G on, working the vertical a lot better,
and then assassinate it. With a missile fight - if the Sparrows worked
the 104 was going to be in trouble. Muscles per G? I guess I'm a bad
example because at 6-2 and 225 I never had any problem getting the
stick wa-a-a-y back. Landing - on a wet slippery runway at DaNang my
routine was on-speed plus a slow chevron, aim for the numbers at the
end of the runway and about eight feet up (eyeball guess) have the back
seater pull the throttles back while I popped the chute. PS I did not
like the loss of speed in the LES version for a dubious gain in turn
rate for a measly 180 degrees. I'd been through that in the F102 - turn
like hell and then dive for airspeed after having lost 250 knots in 180
degrees. Never got out of control when I was flying it but had a stud
try to pick up a wing with aileron down around first nose-rise in an
approach to a stall. This guy had been previously current in F4s and
had tons of Hun time so I was complacent. (Bad Walter! Bad boy! No
donut!) Anyway my lightning reactions responded and my white knuckles
now firmly gripping the rear stick hit the radar scope and the bird
unloaded to zero alpha in a microsecond and we were back flying again.
(Said reactions honed by 104's propensity to pitch up when working it
slow and hard) Used to spiral up in the F4 turning toward the sun just
out of a being-tracked position and at the appropriate time and 200
KIAs or slower go zero alpha, full rudder, inboard engine idle and
outboard full AB and sort of do a lateral pivot on a dime and blast
past the other guy going straight down accelerating in both ABs while
he was still going up and getting even slower. This also worked in the
Dash 19 104 with the advantage of much faster accel due to 1+:1 T/W.
Damn. I miss that kind of flying! Walt BJ

Before I read that post I was confused about getting out of flat spins using
power - but now I'm envious, and confused about getting out of flat spins
using power!

wrote in message
oups.com...
Well, okay, I rise to the challenge. I have a little over 700 hours in
the 104A (including some time in the Dash 19 version) and just over
2000 in the F4D/E/E-LES. I was fortunate in that the IP who checked me
out in the F4 respected my 3000 hours fighter time and together we
explored the envelope. I found the F4 to be an honest airplane (as was
the 104) and once you learned what it was trying to tell you you could
fly it to its real envelope, not the Dash One or NATOPS figures, but
what it was really capable of. The one aerodynamic thing I didn't like
was the G-dig decelerating through M 1.0 while loaded up - it came on
really sudden and if you happened to be looking outside (as is usual
while chasing someone) you were looking at a probable over-G. As for
fighting the birds, once in knife-range the old engined 104 vs F4 it
was the pilots - with the Dash 19 it could run the F4 out of fuel,
keeping the speed up and the G on, working the vertical a lot better,
and then assassinate it. With a missile fight - if the Sparrows worked
the 104 was going to be in trouble. Muscles per G? I guess I'm a bad
example because at 6-2 and 225 I never had any problem getting the
stick wa-a-a-y back. Landing - on a wet slippery runway at DaNang my
routine was on-speed plus a slow chevron, aim for the numbers at the
end of the runway and about eight feet up (eyeball guess) have the back
seater pull the throttles back while I popped the chute. PS I did not
like the loss of speed in the LES version for a dubious gain in turn
rate for a measly 180 degrees. I'd been through that in the F102 - turn
like hell and then dive for airspeed after having lost 250 knots in 180
degrees. Never got out of control when I was flying it but had a stud
try to pick up a wing with aileron down around first nose-rise in an
approach to a stall. This guy had been previously current in F4s and
had tons of Hun time so I was complacent. (Bad Walter! Bad boy! No
donut!) Anyway my lightning reactions responded and my white knuckles
now firmly gripping the rear stick hit the radar scope and the bird
unloaded to zero alpha in a microsecond and we were back flying again.
(Said reactions honed by 104's propensity to pitch up when working it
slow and hard) Used to spiral up in the F4 turning toward the sun just
out of a being-tracked position and at the appropriate time and 200
KIAs or slower go zero alpha, full rudder, inboard engine idle and
outboard full AB and sort of do a lateral pivot on a dime and blast
past the other guy going straight down accelerating in both ABs while
he was still going up and getting even slower. This also worked in the
Dash 19 104 with the advantage of much faster accel due to 1+:1 T/W.
Damn. I miss that kind of flying! Walt BJ

The one aerodynamic thing I didn't like
was the G-dig decelerating through M 1.0 while loaded up - it came on
really sudden and if you happened to be looking outside (as is usual
while chasing someone) you were looking at a probable over-G.

Can someone tell me more about "G-dig" (using low-time piston guy type
language!)

Thanks!

Cheers,

CC

IIRC the F-4 experienced an increase of the actual G-loading when
manouevering through the Mach 1. If you were pulling close to the structural
limit you could have an overstress problem. Aerodinamics thing, displacement
of the center of pressure, that kind of thing. Maybe a Phantom driver could
explain it better.

"Cockpit Colin" escribió en el mensaje
...
The one aerodynamic thing I didn't like
was the G-dig decelerating through M 1.0 while loaded up - it came on
really sudden and if you happened to be looking outside (as is usual
while chasing someone) you were looking at a probable over-G.

Can someone tell me more about "G-dig" (using low-time piston guy type
language!)

Thanks!

Cheers,

CC

Dang, Walt! I love the stuff you post here. Have you ever thought
about writing a book? You and a few others here (Ed R. comes
immediately to mind) have the gift to write in detail and help those of
us who were not there get sense of what it was like.

Thanks for the post.

Blue skies to you all.

"J.A.M." wrote in message
...
IIRC the F-4 experienced an increase of the actual G-loading when
manouevering through the Mach 1. If you were pulling close to the
structural
limit you could have an overstress problem. Aerodinamics thing,
displacement
of the center of pressure, that kind of thing. Maybe a Phantom driver
could
explain it better.

The aerodynamic center shifted forward abruptly as you were decelerating
through about .95 IMN. As the aero center shifts forward, the stabs
downward trim force becomes greater and a pitch up occurs. (This is rather
typical transonic behavior, although it varies from jet to jet.)

In the F-4's case, if you were pulling 6 G or so, you'd suddenly find
yourself around 9 G during this transient. At medium/high altitudes, the
airframe would give a hint that this was about to happen with a subtle
buffet cue. You could reduce your back stick just as the aircraft dug in
and maintain your G without exceeding it. If you were low (say 5,000',
higher IAS for .95) the buffet cue wasn't there and it could sneak up on
you.

I experienced the low altitude manifestation once and use the incident as an
illustration of the effects (big time overstress) of transonic pitch up for
my aero lecture.

R / John

On Tue, 29 Mar 2005 06:17:42 -0600, "John Carrier"
wrote:

of the center of pressure, that kind of thing. Maybe a Phantom driver
could
explain it better.

The aerodynamic center shifted forward abruptly as you were decelerating
through about .95 IMN. As the aero center shifts forward, the stabs
downward trim force becomes greater and a pitch up occurs. (This is rather
typical transonic behavior, although it varies from jet to jet.)

In the F-4's case, if you were pulling 6 G or so, you'd suddenly find
yourself around 9 G during this transient. At medium/high altitudes, the
airframe would give a hint that this was about to happen with a subtle
buffet cue. You could reduce your back stick just as the aircraft dug in
and maintain your G without exceeding it. If you were low (say 5,000',
higher IAS for .95) the buffet cue wasn't there and it could sneak up on
you.

I experienced the low altitude manifestation once and use the incident as an
illustration of the effects (big time overstress) of transonic pitch up for
my aero lecture.

R / John


Walt used the term "G-dig", but I always heard it called "Mach
tuck"--(coincidentally we had a guy in the squadron with last name
Tuck, so his call sign became Mach -- rather than the more
conventional "Friar".)

Most jets of the period really couldn't command a lot of G when
supersonic--the slab simply didn't have enough authority. So, if a
fight was engaged in the supersonic speed range, guys trying to get as
much turn rate as possible would have a yard of stick pulled into
their gut. When the airplane decelerated through the Mach, that slab
prepositioning when it went sub-sonic would then command a whole lot
more AOA and G. Overshoot of the allowable G limit was damn near
inevitable.

One solution was to ask the back-seater to keep on eye on the mach for
you and call when it looked like you were going to transition. Good
situational awareness also helped--you knew your altitude, your entry
airspeed, your attitude and your tactical position relative to the
adversary. Predicting when you were going to go sub-sonic was then a
function of art rather than science for the experienced guys.


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
www.thunderchief.org
www.thundertales.blogspot.com