Phantom flight

"Bob" wrote in message
oups.com...
Hi John,
I had the pleasure of flying most all the F4 models made for the Navy
[snip]
Nasty and unrecoverable flat spin mode, not as bad
as the F-14 but usually resulted in either a punch out or a mort. So
you didn't spin it, simple enough.


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?

Many thanks,

CC

On 3/27/05 6:21 PM, in article ,
"Cockpit Colin" wrote:


"Bob" wrote in message
oups.com...
Hi John,
I had the pleasure of flying most all the F4 models made for the Navy
[snip]
Nasty and unrecoverable flat spin mode, not as bad
as the F-14 but usually resulted in either a punch out or a mort. So
you didn't spin it, simple enough.


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?


That 1:1 thing is a sort of fallacy in many cases. It assumes a combat
loaded aircraft (air-to-air load) at half fuel with the motor being run at
sea level--large amount of static sea-level rated thrust on a relatively
light aircraft... Hence the 1:1 ratio. Most spins and departures occur at
much higher altitudes where the thrust of the motor is quite a bit lower.
At higher altitudes, the T:W may be less than 1:1.

Also keep in mind that if you're spinning, the thrust is spinning with you.
Adding full power (providing your jet isn't susceptible to compressor stalls
at slow speed and high alpha) simply adds a thrust vector that rotates with
the jet. It's not effective in "powering the jet out" of a spin.

A falling leaf is essentially a spin with no established rotation. The
aircraft establishes itself in a coupled departure mode. Thrust MAY help
power you out depending on aircraft configuration and altitude... I think
there were some Marines that claimed to have powered out of the falling leaf
in the Hornet, but most folks don't have a lot of success with it. IIRC,
adding power in the falling leaf INCREASES time to recover.

This is all without reviewing the NATOPS notes on falling leaf recoveries.
Any TPS dudes want to sing out here?

--Woody

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.

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