Blackbird
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Maximum G-Capability / Different Eras

Thu Sep 11, 2008 7:22 pm

I have a question regarding typical and maximum-G capabilities of airplanes of different eras.


This normally would be a simple questions but I've heard various cases in which I've heard conflicting data.

- A book called "Wings" / "Cutting Edge" (it's two books that come together) which had a foreword by Chuck Yeager said that WWII capable aircraft could already pull 7.33 G's, and that they already used G-suits then, giving them an edge over German pilots who didn't, and lead-computing gunsights and all that... (I'm not sure if that's true -- suposedly Chuck Yeager is known for being full of it sometimes)

- I've also heard sources which said that 5.33 G's was a common G-force figure during the fifties and early sixties as well.

-There's also "fudge factor" as well -- deliberately underrating the figures to make the performance of the aircraft seem less. For example the F8U was listed as 6.5 G's max, but it could pull G's higher than that.


What was the typical G-figures for fighter-aircraft of WW2? Such as the F4U, and F6F, the P-40, P-47, F6U, P-51, and P-80?

What was the typical G-figures for fighter-aircraft of the Korean-War Era? Such as the FJ, F2H, F7U, F9F (Panther), and F-9 (Cougar), the F-84, the F-86, and F-84F?

What was the typical G-figures for fighter-aircraft designed between the Korean and Vietnam Era (and often served in Vietnam)? Such as the F4D/F-6, F3H/F-3, F11F, and F8U/F-8, the F-89, F-94, F-86D, F-100, F-101, F-102A, F-104, F-105, F-106A and F-4?


Blackbird
 
Blackbird
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RE: Maximum G-Capability / Different Eras

Wed Sep 17, 2008 3:08 am

Okay...

Let's keep this simpler. Did Chuck Yeager's statements about WW2 fighters being able to pull 7.33 G's, pilots already having G-suits, and lead-computing gunsights being brand new then?


Blackbird
 
TheSonntag
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RE: Maximum G-Capability / Different Eras

Wed Sep 17, 2008 9:21 pm



Quoting Blackbird (Thread starter):

- I've also heard sources which said that 5.33 G's was a common G-force figure during the fifties and early sixties as well.

The German F-4 Phantom is limited to 6.5 Gs, but can do more...
 
MissedApproach
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RE: Maximum G-Capability / Different Eras

Wed Sep 17, 2008 10:27 pm



Quoting TheSonntag (Reply 2):
The German F-4 Phantom is limited to 6.5 Gs

True, air forces commonly place a lower G limit on aircraft to reduce wear on their fleets, at least in peacetime.
Can you hear me now?
 
Blackbird
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RE: Maximum G-Capability / Different Eras

Thu Sep 18, 2008 1:44 am

How many G's could the F-4 take physically (like in quick bursts, or even prolonged high-g maneuvers) without coming apart or anything?


Blackbird
 
Jabs
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RE: Maximum G-Capability / Different Eras

Thu Oct 23, 2008 5:56 pm



Quote:
G-Suits

By autumn 1944, G-suits had been developed for pilots, and the 339th and 357th were amongst the groups which combat-tested them. They were filled with either water or air, and were designed to prevent black-outs during high speed manoeuvres, as ‘Bud’ Anderson recounts.

“The Mustangs, generally speaking, could take harder turns than the people who flew them. Long before the wings flew off, the pilots would simply lose consciousness. The blood drained from his head by centrifugal force, measured in Gs. Five Gs and you might ‘gray out’ but be able to function. Six or so and you could ‘black out’ and lose consciousness. The form-fitting suits simply inflated as the airplane pulled Gs, hugging you, and preventing your blood from running from your brain all at once.”

“They were strictly experimental, which was why we had two different kinds. The water suits were like overalls. The crew chief filled them up at the top with a funnel and pitcher (as I recall, it took several pitchers) and when the mission was done you would sit on the wing, open two little drains at your ankles and the water would simply empty in two silver streams. The problem with the water suits was that they were cold, and I only wore one a couple of times. We tried filling them with warm water, but at six miles up they cooled quickly. The air suits, attached to a G-sensitive valve, drew air through a line that ran from the pressure side of the engine’s vacuum pump. These suits wrapped around your abdomen, thighs and calves in three sections that looked like a cowboy’s chaps, and they inflated automatically. Those worked much better.”

“With the G suits, we could fly a little harder, turn a little bit tighter. We could pull maybe one extra G now, which gave us an edge. There was no resistence to wearing them as we understood what they meant right away: Wearing one was the same as making the airplane better.”


“Mustang Aces of the Eight Air Force” by Jerry Scoutts, Osprey Aircraft of the Aces Nº 1, ISBN 1-8553244-74, Osprey Publishing 1994

 
Blackbird
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RE: Maximum G-Capability / Different Eras

Thu Oct 23, 2008 6:09 pm

What was the max-G load of the F-86? Was it the same as the P-51?


Blackbird
 
ferrypilot
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RE: Maximum G-Capability / Different Eras

Thu Oct 23, 2008 10:52 pm



Quoting Blackbird (Thread starter):
What was the typical G-figures for fighter-aircraft of WW2? Such as the F4U, and F6F, the P-40, P-47, P-51,

It is reasonable to suppose that all of these types were good for at least 6g and probably 7g. Although that's a big generalisation it is based on the fact that I have not heard of any of them having a reputation for their wings clapping together which was a problem with early German Me109's and is usually what happens when you pull too much G. Since it is reasonable to suppose that almost all fighter pilots would instinctively pull to their blackout threshold in combat, especially whilst trying to escape an attacking fighter. ...And I think on average most guys blackout around 6g without g suits.
 
Blackbird
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RE: Maximum G-Capability / Different Eras

Fri Oct 24, 2008 4:31 am

Ferrypilot,

What do you mean "wings clapping together"?
 
ferrypilot
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RE: Maximum G-Capability / Different Eras

Fri Oct 24, 2008 11:27 am



Quoting Blackbird (Reply 8):
What do you mean "wings clapping together"?

If your main spar fails as a consequence of pulling too much G you can expect the wings to virtually slap together above your head.
 
Blackbird
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RE: Maximum G-Capability / Different Eras

Fri Oct 24, 2008 6:15 pm

You mean they flex so bad they it each other? Wouldn't that be a fatal problem?

Blackbird
 
ferrypilot
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RE: Maximum G-Capability / Different Eras

Fri Oct 24, 2008 10:04 pm



Quoting Blackbird (Reply 10):
You mean they flex so bad they it each other? Wouldn't that be a fatal problem?

A pilot pulling more g than an airframe can take is likely to break the wing main spar. When that happens he can expect the wings to break off the airframe almost instantaneously. As the fuselage immediately plunges down the broken off wings have a tendency to meet each other above. ...as if they are going to clap together.
 
Blackbird
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RE: Maximum G-Capability / Different Eras

Fri Oct 24, 2008 11:50 pm

Okay, I know what you're talking about.

Blackbird
 
Max Q
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RE: Maximum G-Capability / Different Eras

Fri Nov 14, 2008 5:42 am

'G limits are only applicable when you need to use the aircraft again'

I plagiarize from 'Palace Cobra' by Ed Rasimus, in any event, he mentions, in one chapter an F4 manoeuvering to avoid a SAM pulling 10g's overstressing the aircraft obviously but it held together until they made it back to base.
The best contribution to safety is a competent Pilot.

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