Blackbird
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World War II Fighter Question

Wed Sep 17, 2008 8:00 pm

Does anybody have any idea (guesstimates, actual figures etc) as to the maximum G-capability of fighters during the Second World-War were?


Blackbird
 
Bengan
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RE: World War II Fighter Question

Wed Sep 17, 2008 8:27 pm

I have a book on the FFVS J22 that quotes an unnamed P51 instructor saying
"I was never told the maximum allowable G-load on the J22 ... but I suspect that is was low. In the Mustang the limit was 10g and we routinely pulled 8,5-9g with it during combat"

The J22s G-limit was 6G

/Bengt
 
Blackbird
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RE: World War II Fighter Question

Wed Sep 17, 2008 8:33 pm

How the hell did they withstand that kind of G-load (8.5g - 9.0g routinely, and up to 10g) without blacking out? Did G-suits exist yet?


Blackbird
 
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RE: World War II Fighter Question

Wed Sep 17, 2008 9:13 pm



Quoting Blackbird (Reply 2):
How the hell did they withstand that kind of G-load (8.5g - 9.0g routinely, and up to 10g) without blacking out? Did G-suits exist yet?

In the last couple years of the war British and American pilots were using them. I remeber Chuck Yeager talking about them in his book.
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vzlet
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RE: World War II Fighter Question

Wed Sep 17, 2008 11:03 pm



Quoting Blackbird (Reply 2):
How the hell did they withstand that kind of G-load (8.5g - 9.0g routinely, and up to 10g) without blacking out?

It's not just the intensity that matters, but the duration as well.
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Blackbird
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RE: World War II Fighter Question

Thu Sep 18, 2008 1:51 am

Vzlet,

So it was just quick bursts where they got to 8.5 or 9.0, and mostly they were doing less?


Blackbird
BTW: I remember hearing that machine guns often had problems jamming when fired at high-g's, at least in some cases due to the belt-links breaking (at least it happened on the F-8 Crusader in the 1960's) -- How come I've never heard of anything like this happening in the WW2 era (or even Korean war actually)? I have only heard mention of this happening in the early to mid-fifties...yet it must have happened before right?
 
Kukkudrill
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RE: World War II Fighter Question

Fri Sep 19, 2008 8:18 pm

I recall reading that the Spitfire was stressed for 10g too. The earliest Spits to have cannon installed also had problems with stoppages because wing flex in tight turns would constrict the ammo feed channels, which were already a tight fit for 20mm shells. The problem was fixed later on.
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GST
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RE: World War II Fighter Question

Fri Sep 19, 2008 10:24 pm



Quoting Blackbird (Reply 5):

So it was just quick bursts where they got to 8.5 or 9.0, and mostly they were doing less?

Essentially yes, when you put an aircraft though that type of G for long periods of time without descending you will loose airspeed and stall pretty quickly.
 
Blackbird
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RE: World War II Fighter Question

Sat Sep 20, 2008 2:07 am

Kukkudrill,

So the caliber of the bullet also plays a role in jamming problems related to G-forces? Is that the reason why post Korean-War fighters had a lot of problem with the jamming as they had larger guns (20 mm, vs the 12.7 mm of WW2 and Korea) -- or is it just because G's could be sustained longer post-Korea with more powerful fighter engines and guns were fired more at these higher G-forces?


Blackbird
 
Kukkudrill
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RE: World War II Fighter Question

Sat Sep 20, 2008 3:16 pm



Quoting Blackbird (Reply 8):
So the caliber of the bullet also plays a role in jamming problems related to G-forces? Is that the reason why post Korean-War fighters had a lot of problem with the jamming as they had larger guns (20 mm, vs the 12.7 mm of WW2 and Korea) -- or is it just because G's could be sustained longer post-Korea with more powerful fighter engines and guns were fired more at these higher G-forces?

Wish I had the knowledge to answer this, but I don't. All I know is that in the Spitfire's case the ammo feed channels were originally designed for .303 inch bullets and were a tight fit for 20mm, so wing flex in tight turns would literally trap the shells. Like I said the redesign of the wing solved the problem.

As to the rest, all I can say by way of speculation is that the bigger the calibre, the greater the weight that has to be pulled in towards the gun and high g conditions accentuate the weight difference. This means failures would be more likely with bigger calibres unless the belt feed mechanism and links are specially designed to cope with it (which may not have been the case in the 60s). The rate of fire could also be a contributing factor.
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Blackbird
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RE: World War II Fighter Question

Sun Sep 21, 2008 10:29 pm

Was the rate of fire for guns different in WW2, Korea, and Post Korea?

Blackbird
 
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RE: World War II Fighter Question

Mon Sep 22, 2008 4:27 am



Quoting Blackbird (Reply 2):
How the hell did they withstand that kind of G-load (8.5g - 9.0g routinely, and up to 10g) without blacking out?

The Spitfire pilot I knew told me that he would be aware of his vision becoming impaired. I think he described it as 'greying out'. I guess that when your vision started going you eased off the G.
 
Kukkudrill
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RE: World War II Fighter Question

Mon Sep 22, 2008 1:33 pm



Quoting Blackbird (Reply 10):
Was the rate of fire for guns different in WW2, Korea, and Post Korea?

Don't think you can compare machine-guns with cannon due to the different calibres involved. But taking cannon you can certainly see an increase over time:

Hispano 20mm cannon as used in WW2: c. 750 rounds per minute
Colt-Browning Mk 12 20mm as used in the F-8: 1,000 rpm
Mauser BK-27 27mm as used in the Tornado and Typhoon: 1,700 rpm

I've deliberately listed single-barrel weapons only to compare like with like. Multi-barrel Gatling-type weapons are capable of much higher rates of fire: the M61A1 20mm as used in F-15s and F-16s can do 6,000 rpm (all info from Wikipedia).
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Blackbird
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RE: World War II Fighter Question

Mon Sep 22, 2008 5:38 pm

Kukkudrill,

Okay, so refire rate along with caliber both went up. And I guess this combination would make jams more likely at high-G's?

I made an observation looking at footage taken from WW2 and Korea... while there were some tight turns pulled, it seemed as if the pilots were firing the guns while during lower G's than they do now... for all I know it was probably because they couldn't sustain the high-G's like they can now, though I could be wrong...


Blackbird
 
Kukkudrill
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RE: World War II Fighter Question

Mon Sep 22, 2008 8:13 pm



Quoting Blackbird (Reply 13):
Okay, so refire rate along with caliber both went up. And I guess this combination would make jams more likely at high-G's?

I expect yes, if all other things are equal. Of course other things are never equal: some guns are simply more reliable than others. The gun used by the F-8 seems to have been especially prone to problems.
Make the most of the available light ... a lesson of photography that applies to life
 
Blackbird
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RE: World War II Fighter Question

Mon Sep 22, 2008 11:12 pm

Kukkudrill,

Oh, the F-8's guns were prone to problems?


Blackbird
 
epten
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RE: World War II Fighter Question

Tue Sep 23, 2008 8:18 am



Quoting Blackbird (Reply 2):
How the hell did they withstand that kind of G-load (8.5g - 9.0g routinely, and up to 10g) without blacking out?

Not only they did black out, but sometimes deliberately blacking out was the only mean of surviving a superior aircraft on your tail. I remember reading from an P-40 fighter pilot. He says that when engaged with a more powerful and faster Zero, he would dive to gain speed and then pull so much Gs that anyone trying to follow him will black out as well. This tactics, he says, saved his life more than once.
 
Blackbird
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RE: World War II Fighter Question

Tue Sep 23, 2008 12:33 pm

Epten,

Yikes...


Blackbird
 
rwessel
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RE: World War II Fighter Question

Tue Sep 23, 2008 8:18 pm



Quoting Epten (Reply 16):
Not only they did black out, but sometimes deliberately blacking out was the only mean of surviving a superior aircraft on your tail. I remember reading from an P-40 fighter pilot. He says that when engaged with a more powerful and faster Zero, he would dive to gain speed and then pull so much Gs that anyone trying to follow him will black out as well. This tactics, he says, saved his life more than once.

I have to express some doubts about this. Coming out of G-LOC is not quick. You are quite disoriented and foggy for a while (several tens of seconds to several minutes), and will have minimal situational awareness. If you did this, and the other pilot didn't G-LOC, you'd be dead meat. All that would have to happen is that the pursuer not fly that tight a turn, and he has you. Or if there was another opposing fighter around, you'd be in real trouble.

Doing something like that would have to be absolutely last ditch, and even then it’s unlikely to work.

Perhaps somewhat more realistically I could see deliberate trying to get the pursuer to G-LOC, which might be possible if you had a G-Suit and they didn't (AFAIK, G-Suits were not widely used by US aircrews in WWII), you had a better seating position (more reclined), or you had a few seconds to prepare (the "straining" maneuver) to increase your tolerance. Then you're relying on the other guy to put himself in that position.
 
Blackbird
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RE: World War II Fighter Question

Tue Sep 23, 2008 10:46 pm

Epten,

Rwessel makes a good point, I'm guessing the idea was that the P-40 pilot would get himself almost blacked-out... like his vision would be almost completely tunnelled or just black, but he'd be conscious. The other guy behind him if he had no G-suit, or might just over do it and black-out completely...


Rwessel,

When did pilots start performing that "straining" maneuver to improve G-resistance?


Blackbird
 
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RE: World War II Fighter Question

Wed Sep 24, 2008 2:26 pm



Quoting Epten (Reply 16):
I remember reading from an P-40 fighter pilot. He says that when engaged with a more powerful and faster Zero, he would dive to gain speed and then pull so much Gs that anyone trying to follow him will black out as well. This tactics, he says, saved his life more than once.

Blackbird, like you, I'm working from 'theory.' If I'd actually had the job of flying the (distinctly 'below-average'') P40 against Zeroes, I reckon that I'd probably have bailed out (even over the trackless Pacific) rather than take the sods on.

Though on the other hand - a personal memory - I still recall being trained to take on the (AK47-armed) Russian infantry with virtually the self-same bolt-action Lee-Enfield ('No. 4 Rifle') that my old man (a veteran of a rifle regiment) got issued with in late 1917. He was a 'good old guy' - he laughed like a drain when I showed it to him, said, "You poor bugger - at least the one that they gave to me was brand-new, not all scratched and worn like like this one. Bet the bore's halfway worn out already. Did they tell you that it isn't the gun that counts, it's the bloke behind it? That's what the bastards told US.....It's crap....."

Same applies to my late father-in-law. Like me, he finished up in the artillery. Got two days 'confined to barracks' for even suggesting, during a lecture, that the 1940 British two-pounder anti-tank gun might not bother the German panzers much - except at what they all called - the British odd-ball sense of humour being the same then as it still is, up to the present day - "VCR'...........

"Victoria Cross Range'...........
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PhilSquares
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RE: World War II Fighter Question

Wed Sep 24, 2008 4:30 pm



Quoting Blackbird (Thread starter):
Does anybody have any idea (guesstimates, actual figures etc) as to the maximum G-capability of fighters during the Second World-War were?

Again, you amaze me with the questions you ask and further amaze me with a complete lack of searching on your part. A simple search of google would give you this result in 0.49 seconds.

http://mustanghighflight.com/planespecs.html

Remember, Google is your friend!!!!
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ferrypilot
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RE: World War II Fighter Question

Thu Sep 25, 2008 9:32 am



Quoting Bengan (Reply 1):
In the Mustang the limit was 10g and we routinely pulled 8,5-9g with it during combat"

Sounds like B... S... to me. ...I'd be very surprised if many guys were deliberately trying to pull more than 6g in combat manoeuvres. More than that and I think it would have been accidental.
...Personally I start to black out at 6g and I believe that is about average without a G suit, unless you deliberately train yourself as competition aerobatic pilots do to take more.
 
deskflier
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RE: World War II Fighter Question

Sun Oct 05, 2008 7:52 pm



Quoting Epten (Reply 16):
He says that when engaged with a more powerful and faster Zero, he would dive to gain speed and then pull so much Gs that anyone trying to follow him will black out as well. This tactics, he says, saved his life more than once.

The Zero would more likely tear its wings off. Japanese fighters (Zero, Hayabusa) from the early part of WW2 was very lightly built, often without armour, and frequently equipped with a main wing-bearer that was under-dimensioned. Nakajima had to re-engineer the wing of the Ki-43 Hayabusa to cure it from the wing-falling-off-during-combat-disease, which transformed the Ki-43, not only to a plane that could maneuver hard without losing its wings, but to a fighter-bomber capable of carrying two 250kg (550lb) bombs. The problem with wings falling off became very visible after the introduction of the Fowler-type combat flap, introduced in response to Imperial Army pilots complaints of poor maneuverablilty, especially compared with their previous mount, the Ki-27.
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keesje
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RE: World War II Fighter Question

Mon Oct 06, 2008 12:47 pm



Quoting Rwessel (Reply 18):
I have to express some doubts about this. Coming out of G-LOC is not quick. You are quite disoriented and foggy for a while (several tens of seconds to several minutes), and will have minimal situational awareness. If you did this, and the other pilot didn't G-LOC, you'd be dead meat. All that would have to happen is that the pursuer not fly that tight a turn, and he has you. Or if there was another opposing fighter around, you'd be in real trouble.

Not always that long..

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ferrypilot
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RE: World War II Fighter Question

Mon Oct 13, 2008 3:27 am

Just out of curiosity I put a protractor on the screen during the two turns in that video above. ...Looks like 75-80degrees of bank and so assuming they are level turns that fellow is blacking out from experiencing between 4 and 6g.
 
soon7x7
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RE: World War II Fighter Question

Thu Oct 23, 2008 3:39 am



Quoting Ferrypilot (Reply 22):

A buddy of mine has a P51 and P-40. He took me in P-51 for an hour. We consistently pulled 6 as I could see the accelerometer...in other aircraft 6 starts shutting me down but the Mustang went through the six G maneuver faster, I suppose thats why I never blacked out.

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