Turning performance of SEA fighters

I have recently red that instantenious rate of turn of Vietnam vintage supersonic
fighters is less than 15 deg/sec. What are the excat figures for F-4, F-105 and
F-8? Please include speed and altitude.


Nemanja Vukicevic
student of aircreft engineering

"Wolfhenson" wrote in message
om...
I have recently red that instantenious rate of turn of Vietnam vintage
supersonic
fighters is less than 15 deg/sec. What are the excat figures for F-4,
F-105 and
F-8? Please include speed and altitude.


Well, I don't have any pubs or tacmans available, so we're going on memory,
but you number is maybe a bit low for a hard-wing F-4, real close for the
F-8, definitely too high for the 105.

Corner speed (6.5 G) for Phantom was about 425KIAS, 370 for F-8, 105 was
higher. Ed Rasimus should be able to give you some data there.

Ignoring momentary pitch rates (which can be phenomenally high) current
fighters can exceed 20 degrees/second.

R / John

On Fri, 13 Aug 2004 14:24:14 -0500, "John Carrier"
wrote:


"Wolfhenson" wrote in message
. com...
I have recently red that instantenious rate of turn of Vietnam vintage
supersonic
fighters is less than 15 deg/sec. What are the excat figures for F-4,
F-105 and
F-8? Please include speed and altitude.


Well, I don't have any pubs or tacmans available, so we're going on memory,
but you number is maybe a bit low for a hard-wing F-4, real close for the
F-8, definitely too high for the 105.

Corner speed (6.5 G) for Phantom was about 425KIAS, 370 for F-8, 105 was
higher. Ed Rasimus should be able to give you some data there.

Corner velocity, by definition, is the minimum speed at which you can
generate maximum allowable G-load. So, the corner for the F-4 relates
to 7.33+ G at most weights. We usually used 420 KIAS for the F-4
hard-wing. The max G, of course, could be considerably reduced based
on stores retained--even empty fuel tanks.

For the F-105, which had a max allowable G of 8.2, the speed was
higher--generally considered around 480 KIAS. But, the fact of the
matter was that drag rose so fast at high G that you couldn't sustain
for very long--airspeed bleed off put you below corner very rapidly.
(One reason why an F-105 driver only felt comfortable in the 540-600
KIAS region!).

Generally, the sustained turn rate was around 14-15 degrees/second for
the F-4 hard-wing and about 12.5-13.5 for the F-105.

The real issue with the 105 in air/air was that if an opponent could
come up to your speed, he couldn't turn with you. If you slowed to his
speed, you'd be the main course for lunch.

Ignoring momentary pitch rates (which can be phenomenally high) current
fighters can exceed 20 degrees/second.

That is SUSTAINED!!!! The idea of holding 9 Gs for a while still makes
my vision dim sitting at the computer.


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
"Phantom Flights, Bangkok Nights"
Both from Smithsonian Books
***www.thunderchief.org

Ed Rasimus wrote:

On Fri, 13 Aug 2004 14:24:14 -0500, "John Carrier"
wrote:


"Wolfhenson" wrote in message
. com...
I have recently red that instantenious rate of turn of Vietnam vintage
supersonic
fighters is less than 15 deg/sec. What are the excat figures for F-4,
F-105 and
F-8? Please include speed and altitude.


Well, I don't have any pubs or tacmans available, so we're going on memory,
but you number is maybe a bit low for a hard-wing F-4, real close for the
F-8, definitely too high for the 105.

Corner speed (6.5 G) for Phantom was about 425KIAS, 370 for F-8, 105 was
higher. Ed Rasimus should be able to give you some data there.

Corner velocity, by definition, is the minimum speed at which you can
generate maximum allowable G-load. So, the corner for the F-4 relates
to 7.33+ G at most weights. We usually used 420 KIAS for the F-4
hard-wing. The max G, of course, could be considerably reduced based
on stores retained--even empty fuel tanks.

For the F-105, which had a max allowable G of 8.2, the speed was
higher--generally considered around 480 KIAS. But, the fact of the
matter was that drag rose so fast at high G that you couldn't sustain
for very long--airspeed bleed off put you below corner very rapidly.
(One reason why an F-105 driver only felt comfortable in the 540-600
KIAS region!).

Generally, the sustained turn rate was around 14-15 degrees/second for
the F-4 hard-wing and about 12.5-13.5 for the F-105.

H'mm, those numbers seem kind of high for both, as far as sustained capability
goes.

400 KTAS, turn rate in Deg./sec. (rounded off) = 19 (7g); 22 (8g).

500KTAS, turn rate in Deg./sec. (rounded off) = 15 (7g); 17 (8g); 20 (9g).

600KTAS, turn rate in Deg./sec. (rounded off) = 13(7g); 14 (8g); 16 (9g).

One source (Richardson/Spick) gives steady state turn radii and time to make a
180 for the slat-wing and hard-wing, @ M0.6 and 0.9, 10kft. The slat-wing has
the advantage, making a 180 in 15.53 sec. @ M0.6 (11.59 deg./sec.), and 13.96
sec. @ M0.9 (12.89 deg./sec.). The hard wing appears to be perhaps 10-20 deg.
or so behind. Assuming ISA, @10kft, Mach 1.0 is 638 knots. M0.6 and M0.9 = 383
and 574 KTAS respectively, so M0.6 is well under F-4 (hard) corner, M0.9 a bit
over at that height -- assuming KIAS = KCAS, 420 KCAS = 490 KTAS @10kft. OTOH
the Thuds 480 KCAS corner is slightly under M0.9; ca. 558 KTAS.

FWIW, the same source has a graph comparing the hard and slat-winged F-4's Ps
capability @ M0.9 and10kft. The hard-wing has a Ps advantage at low g (4.5g),
with the slat-wing advantaged at higher g, although the slats apparently have a
lower max. g limit, +7 vs. +7.33g.

Guy

On Fri, 13 Aug 2004 23:08:33 GMT, Guy Alcala
wrote:

Ed Rasimus wrote:

Corner velocity, by definition, is the minimum speed at which you can
generate maximum allowable G-load. So, the corner for the F-4 relates
to 7.33+ G at most weights. We usually used 420 KIAS for the F-4
hard-wing. The max G, of course, could be considerably reduced based
on stores retained--even empty fuel tanks.

For the F-105, which had a max allowable G of 8.2, the speed was
higher--generally considered around 480 KIAS. But, the fact of the
matter was that drag rose so fast at high G that you couldn't sustain
for very long--airspeed bleed off put you below corner very rapidly.
(One reason why an F-105 driver only felt comfortable in the 540-600
KIAS region!).

Generally, the sustained turn rate was around 14-15 degrees/second for
the F-4 hard-wing and about 12.5-13.5 for the F-105.

H'mm, those numbers seem kind of high for both, as far as sustained capability
goes.

400 KTAS, turn rate in Deg./sec. (rounded off) = 19 (7g); 22 (8g).

500KTAS, turn rate in Deg./sec. (rounded off) = 15 (7g); 17 (8g); 20 (9g).

600KTAS, turn rate in Deg./sec. (rounded off) = 13(7g); 14 (8g); 16 (9g).

One source (Richardson/Spick) gives steady state turn radii and time to make a
180 for the slat-wing and hard-wing, @ M0.6 and 0.9, 10kft. The slat-wing has
the advantage, making a 180 in 15.53 sec. @ M0.6 (11.59 deg./sec.), and 13.96
sec. @ M0.9 (12.89 deg./sec.). The hard wing appears to be perhaps 10-20 deg.
or so behind. Assuming ISA, @10kft, Mach 1.0 is 638 knots. M0.6 and M0.9 = 383
and 574 KTAS respectively, so M0.6 is well under F-4 (hard) corner, M0.9 a bit
over at that height -- assuming KIAS = KCAS, 420 KCAS = 490 KTAS @10kft. OTOH
the Thuds 480 KCAS corner is slightly under M0.9; ca. 558 KTAS.

FWIW, the same source has a graph comparing the hard and slat-winged F-4's Ps
capability @ M0.9 and10kft. The hard-wing has a Ps advantage at low g (4.5g),
with the slat-wing advantaged at higher g, although the slats apparently have a
lower max. g limit, +7 vs. +7.33g.

Guy

Remember that fighter pilots generally don't have time (even in
today's computer laden techno-wonder aircraft) to go through that kind
of convolution of calculations.

For example, at 400 KIAS (not KTAS) you couldn't get 8G in an F-4.
Note that all of your start numbers are offered in "true" rather than
indicated airspeed. There are other issues, such as with the hard-wing
vs soft-wing question for the F-4--you'll get different performance
between the B, C, D, S, J, K, G, and E models depending upon things
like TISEO, slotted slabs, C/G etc.

Generally, you are correct that the hard-wing finishes the turn well
behind the LES bird, but in a lot of situations the hard-wing sustains
while the LES bird experiences rapid drag rise and airspeed bleed-off.
P-sub-s advantage, as you say, usually goes to the hard-wing. The LES
bird only wins in the knife fight.

Finally, my head hurts and I don't want to open the door to the
complexities of trying to calculate comparisons between KIAS, KTAS and
mach as related to turn rate.

Basic rule (kept simple for dumb fighter drivers) is that it takes
indicated airspeed to pull G. Mach don't make turn (and for that
generation super-sonic meant an incredible loss of G potential) and
true airspeed is only valuable for getting to the bar early. Indicated
(and it's close relative calibrated) is the only knots you need to
worry about when you want to max perform.



Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
"Phantom Flights, Bangkok Nights"
Both from Smithsonian Books
***www.thunderchief.org

Ed Rasimus wrote:

On Fri, 13 Aug 2004 23:08:33 GMT, Guy Alcala
wrote:

Ed Rasimus wrote:

Corner velocity, by definition, is the minimum speed at which you can
generate maximum allowable G-load. So, the corner for the F-4 relates
to 7.33+ G at most weights. We usually used 420 KIAS for the F-4
hard-wing. The max G, of course, could be considerably reduced based
on stores retained--even empty fuel tanks.

For the F-105, which had a max allowable G of 8.2, the speed was
higher--generally considered around 480 KIAS. But, the fact of the
matter was that drag rose so fast at high G that you couldn't sustain
for very long--airspeed bleed off put you below corner very rapidly.
(One reason why an F-105 driver only felt comfortable in the 540-600
KIAS region!).

Generally, the sustained turn rate was around 14-15 degrees/second for
the F-4 hard-wing and about 12.5-13.5 for the F-105.

H'mm, those numbers seem kind of high for both, as far as sustained capability
goes.

400 KTAS, turn rate in Deg./sec. (rounded off) = 19 (7g); 22 (8g).

500KTAS, turn rate in Deg./sec. (rounded off) = 15 (7g); 17 (8g); 20 (9g).

600KTAS, turn rate in Deg./sec. (rounded off) = 13(7g); 14 (8g); 16 (9g).

One source (Richardson/Spick) gives steady state turn radii and time to make a
180 for the slat-wing and hard-wing, @ M0.6 and 0.9, 10kft. The slat-wing has
the advantage, making a 180 in 15.53 sec. @ M0.6 (11.59 deg./sec.), and 13.96
sec. @ M0.9 (12.89 deg./sec.). The hard wing appears to be perhaps 10-20 deg.
or so behind. Assuming ISA, @10kft, Mach 1.0 is 638 knots. M0.6 and M0.9 = 383
and 574 KTAS respectively, so M0.6 is well under F-4 (hard) corner, M0.9 a bit
over at that height -- assuming KIAS = KCAS, 420 KCAS = 490 KTAS @10kft. OTOH
the Thuds 480 KCAS corner is slightly under M0.9; ca. 558 KTAS.

FWIW, the same source has a graph comparing the hard and slat-winged F-4's Ps
capability @ M0.9 and10kft. The hard-wing has a Ps advantage at low g (4.5g),
with the slat-wing advantaged at higher g, although the slats apparently have a
lower max. g limit, +7 vs. +7.33g.

Guy

Remember that fighter pilots generally don't have time (even in
today's computer laden techno-wonder aircraft) to go through that kind
of convolution of calculations.

For example, at 400 KIAS (not KTAS) you couldn't get 8G in an F-4.
Note that all of your start numbers are offered in "true" rather than
indicated airspeed.

Because TAS and g give turn radius and rate independent of altitude, while using
KIAS/KCAS doesn't. I converted them to KCAS to see what TAS/Mach the a/c would be at
a fairly 'typical' combat altitude for Vietnam.

There are other issues, such as with the hard-wing
vs soft-wing question for the F-4--you'll get different performance
between the B, C, D, S, J, K, G, and E models depending upon things
like TISEO, slotted slabs, C/G etc.

Sure, but lacking the graphs for all those, I can only provide what I have.

Generally, you are correct that the hard-wing finishes the turn well
behind the LES bird, but in a lot of situations the hard-wing sustains
while the LES bird experiences rapid drag rise and airspeed bleed-off.
P-sub-s advantage, as you say, usually goes to the hard-wing.

At low g, anyway. Once induced drag becomes the major component instead of form/wave
drag, the advantage appears to be the other way.

The LES
bird only wins in the knife fight.

Finally, my head hurts and I don't want to open the door to the
complexities of trying to calculate comparisons between KIAS, KTAS and
mach as related to turn rate.

Basic rule (kept simple for dumb fighter drivers) is that it takes
indicated airspeed to pull G. Mach don't make turn (and for that
generation super-sonic meant an incredible loss of G potential) and
true airspeed is only valuable for getting to the bar early. Indicated
(and it's close relative calibrated) is the only knots you need to
worry about when you want to max perform.

I agree, but since the question was asked (and answered) relative to dps at various
altitudes and speeds, you need to look at that using TAS vs. g, because radius/rate
at constant TAS and g don't vary with altitude. Once you do, you can convert it to
KIAS/KCAS, to see how fast the a/c thinks it's going (and if it's even capable of
that combination). As you say, for corner velocity the pilot's only concerned with
KIAS or KCAS, whichever the instruments display.

Guy

Easy question but no easy answers.

Turn performance is going to depend on gross weight, configuration, and
density altitude. It all boils down to drag and engine performance...so
clean configurations, low fuel weights, and low density altitudes are
required to get max performance.

Unfortunately, we seldom had these when turn performance counted...we were
usually heavy and relatively high...so much of this is just an academic
discussion.

As Ed pointed out, corner is the most g for the min speed. I might add that
there is no "one" corner speed. Corner varies with the three variables I
mentioned above. Most of our energy maneuverability (EM) diagrams were
based on optimistic conditions (relatively clean and 1/2 internal fuel).
From these, here are some generalizations.

1. Corner velocities varied from the high 300s to the high 400s (indicated
airspeed...we didn't think in terms of TAS or mach, again as Ed said)...and
this varied with aircraft type, weight, and altitude.

2. Max g in the F-4 was 8.5...but you had to be running practically on fumes
to be able to get there without over-g'ing the jet.

3. A slatted F-4 at about 420KIAS could hit a little over 20 degrees per
second in instantaneous turn rate...but could not sustain this. A relatively
clean F-4E(S) at 39000+ lbs and 5000' MSL could sustain about 7.5 g's...but
had to be at about 525KIAS to do this. Sustained g in the lower 400s dropped
off to around 6g for these conditions.

4. I haven't flown the F-8 but I would imagine its numbers would be similar
but attained a slightly slower speeds.

5. An interesting comparison is the F-104G. Under similar conditions, the
Zipper had a lesser instantaneous g capability...about 15 dps (lower placard
g limit) but a higher sustained capability (around 10-12dps, depending on
which EM diagram you want to believe). Corner for the 104 was about 420KIAS
under 10,000'MSL and best 0 Ps was at about 500KIAS or so.

These numbers and observations come from personal experience in the jets and
moldy old EM diagrams!

Andy Bush


"Wolfhenson" wrote in message
om...
I have recently red that instantenious rate of turn of Vietnam vintage
supersonic
fighters is less than 15 deg/sec. What are the excat figures for F-4,
F-105 and
F-8? Please include speed and altitude.


Nemanja Vukicevic
student of aircreft engineering

Seriously snipped.

Corner velocity, by definition, is the minimum speed at which you can
generate maximum allowable G-load. So, the corner for the F-4 relates
to 7.33+ G at most weights. We usually used 420 KIAS for the F-4
hard-wing. The max G, of course, could be considerably reduced based
on stores retained--even empty fuel tanks.

The F-4's I flew (non-slatted J) had a 6.5 limit in the fighter
configuration. There was a flight regime and gross weight where up to 8.5
G was permissible (around .7 mach ... which meant you had to be pretty low
otherwise the KIAS wasn't there ... and 37.5K). IIRC, the Vn diagram
tapered off from that peak of 8.5 at .7 IMN to 6.5 at approx 1.0 IMN. (I
suspect a function of fuselage bending loads as the center of lift moved
aft).

Any time we'd exceed 6.5, the maintenance types would get your G, mach and
weight and enter the performance charts to compute whether the over-G was
truly in or out of the envelope. Typical culprit was an unexpected
transonic pitch up at low altitudes.

Generally, the sustained turn rate was around 14-15 degrees/second for
the F-4 hard-wing and about 12.5-13.5 for the F-105.

Don't know where you got these numbers, but sustained for the F-4 was under
10 degrees/sec at combat altitudes and weights (we typically used 15K, 4+4,
no tanks, and 60% fuel) and was found at around 450 KIAS. The F-8 could do
just under 11 degrees/sec @ 400 in similar conditions (better wing, less
wing loading, not much less T/W). ... roughly a 1 degree/sec advantage. Of
course the Mig-21 (the adversary we trained for) was a couple better than
that. Still looking at under 15 degree/sec sustained.

Ignoring momentary pitch rates (which can be phenomenally high) current
fighters can exceed 20 degrees/second.

That is SUSTAINED!!!! The idea of holding 9 Gs for a while still makes
my vision dim sitting at the computer.

Many jets have a lower G limit (typically 7.5). I've timed the F-14 and
F-18 at airshows (do the T-bird solos do a max perf 360?). Of course,
whether or not the pilot is truly at max performance or not in the wind-up
turn is unknown, but a 360 (roll in to roll out) takes around 20-24 seconds,
somewhat less than 20/sec. I got a single seat A-4 (stripped adversary) to
20 degrees/sec (not quite sustained, I lost a couple knots) in a 360 @ 1,000
feet and 180 KIAS 1/2 flaps.

R / John

Generally, the sustained turn rate was around 14-15 degrees/second for
the F-4 hard-wing and about 12.5-13.5 for the F-105.

H'mm, those numbers seem kind of high for both, as far as sustained
capability
goes.

400 KTAS, turn rate in Deg./sec. (rounded off) = 19 (7g); 22 (8g).

500KTAS, turn rate in Deg./sec. (rounded off) = 15 (7g); 17 (8g); 20 (9g).

600KTAS, turn rate in Deg./sec. (rounded off) = 13(7g); 14 (8g); 16 (9g).

I'm missing something here. You say the numbers are high and then offer
higher numbers. Or are these just basic computations of turn rates w/o
regard to airframe factors?

Our thread has digressed slightly as we shifted the discussion from
instantaneous turn to sustained turn. The former is reached at the upper
left corner of the Vn diagram (curiously referred to as corner speed). The
latter is achieved at zero PsubS, typically at higher KIAS and influenced by
induced drag and (usually) transonic drag. To my knowledge no aircraft can
sustain a turn at corner speed at typical combat altitudes (but get a clean
F-16 low enough, hmm).

One source (Richardson/Spick) gives steady state turn radii and time to
make a
180 for the slat-wing and hard-wing, @ M0.6 and 0.9, 10kft. The slat-wing
has
the advantage, making a 180 in 15.53 sec. @ M0.6 (11.59 deg./sec.), and
13.96
sec. @ M0.9 (12.89 deg./sec.). The hard wing appears to be perhaps 10-20
deg.
or so behind. Assuming ISA, @10kft, Mach 1.0 is 638 knots. M0.6 and M0.9
= 383
and 574 KTAS respectively, so M0.6 is well under F-4 (hard) corner, M0.9 a
bit
over at that height -- assuming KIAS = KCAS, 420 KCAS = 490 KTAS @10kft.
OTOH
the Thuds 480 KCAS corner is slightly under M0.9; ca. 558 KTAS.

FWIW, the same source has a graph comparing the hard and slat-winged F-4's
Ps
capability @ M0.9 and10kft. The hard-wing has a Ps advantage at low g
(4.5g),
with the slat-wing advantaged at higher g, although the slats apparently
have a
lower max. g limit, +7 vs. +7.33g.

I had the opportunity to fly against both hard and soft wing F-4's as an
adversary on many occasions. The dynamics of ACM don't allow such fine
measurements. Subjectively, the slat generated significantly better turn
rates at the expense of energy addition rate and vertical performance.
IIRC, the VX-4 brief advertised around the order of 2 degrees/sec advantage
for the slat sustained and a 50 knot reduction in corner speed. One thing
stood out, it's buffet-free performance didn't give the pilot many cues as
to where his airspeed was headed ... easy to decell to a point where the
energy package was zip-point.

R / John

John Carrier wrote:

Generally, the sustained turn rate was around 14-15 degrees/second for
the F-4 hard-wing and about 12.5-13.5 for the F-105.

H'mm, those numbers seem kind of high for both, as far as sustained
capability
goes.

400 KTAS, turn rate in Deg./sec. (rounded off) = 19 (7g); 22 (8g).

500KTAS, turn rate in Deg./sec. (rounded off) = 15 (7g); 17 (8g); 20 (9g).

600KTAS, turn rate in Deg./sec. (rounded off) = 13(7g); 14 (8g); 16 (9g).

I'm missing something here. You say the numbers are high and then offer
higher numbers. Or are these just basic computations of turn rates w/o
regard to airframe factors?

snip

Yes. I wanted to show what the maximum turn rate was for the various KTAS/g
combinations; sustained would be less.

Guy