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View Full Version : How many Gs can B-17 pull ?



majnos64
11-19-2006, 01:56 AM
I was tempted to ask this question for some time. And not only B-17 but another B's. Or generally bombers of all nations.<div class="ev_tpc_signature">

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OMK_Hand
11-19-2006, 02:32 AM
Maximum Load:

When loaded to 64,500 pounds, maximum maneuver permissable:

230 mph
2.056 positive
1.22 negative<div class="ev_tpc_signature">

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DuxCorvan
11-19-2006, 02:44 AM
I doubt their surface controls and powerplants to be able to induce very agressive manoeuvers on them, anyway.

For example, I guess you can't make very tight turns even if you try, or recover too fast from a steep dive, even if you employ all your muscle, so it's not Gs, but unresponsive controls and structural failure you are fighting against.

But I don't think you can push beyond envelope in a slow and sluggish WW2 heavy bomber. Their speed and slow response prevent it to have high Gs at all.

Lighter bombers are another matter, but even so, unless in a dive, you are more likely to stall it than to break it if you pull too hard; and in a dive, controls may stiffen.

DmdSeeker
11-19-2006, 06:06 AM
I've read more than one account of young RAF pilots trying to bounce Lancasters and getting nasty surprises on how manouverable the Lanc was.

I've no idea what G's it could pull; but two things should be rememebered: The established tactic of the corkscreww escape; and (the surprising) fact that like the He-177; the Lanc was designed to be able to dive bomb.

R988z
11-19-2006, 08:20 AM
I remember reading something about B-24 and B-17 pilots in the pacific having an argument about which could turn tighter and then going up and trying it! I think the B-24 won that one.

jarink
11-19-2006, 09:17 AM
No, they couldn't handle a lot of Gs like a fighter or dive-bomber, but then they weren't designed to do so! OTOH, I've read many personal accounts of pilots that pulled B-17s out of steep dives where they obviously exceeded the max Gs and survived.

Most Allied heavy bombers were fairly maneuverable when they had a light load.<div class="ev_tpc_signature">

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Taylortony
11-19-2006, 10:03 AM
I do remember reading about one of the Lancs that had modified for the dams raid........ these things had been stripped to the gunnels of any excess weight and had yet to be fitted with the bomb gear so were the Gt version of the Lanc.

The Lancs in general were renowned as being slower than the B17, but not this baby..... one of them was up on a test flight, unarmed and with not a lot of go juice on board when one of the observers reported a B17 on their six... the captain eased the throttles slowly back and allowed the B17 to catch up and pass.

When passing the American crew obviously taking delight in the situation made several gestures at which point the Lanc pilot told everyone to hang on, nailed the half closed throttles fully fwd and barrel rolled the Lancaster AROUND the B17 then dissappeared off into the distance leaving a stunned a B17 crew wondering what the feck was that!

vocatx
11-19-2006, 04:05 PM
One of my cousin's grandfathers flew as a co-pilot in a B-17 during the War. His pilot was a Boeing test pilot at one time. During a training flight over New Mexico one day the crew got into a discussion about whether a Fortress could do a loop. After securing all the loose equipment, the pilot proved that it could indeed do a very lop-sided loop. He said it barely made it over the top. Unfortunately they got caught and the pilot very nearly got courtmarshalled for it. As far as they knew, they were the only people to ever intentionally loop a B-17.<div class="ev_tpc_signature">

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Sergio_101
11-19-2006, 04:12 PM
Originally posted by vocatx:
One of my cousin's grandfathers flew as a co-pilot in a B-17 during the War. His pilot was a Boeing test pilot at one time. During a training flight over New Mexico one day the crew got into a discussion about whether a Fortress could do a loop. After securing all the loose equipment, the pilot proved that it could indeed do a very lop-sided loop. He said it barely made it over the top. Unfortunately they got caught and the pilot very nearly got courtmarshalled for it. As far as they knew, they were the only people to ever intentionally loop a B-17.

A lightly loaded B-17 has ample power to do a loop.
Wing loading is low and the G rating is very
good when you don't have a crew or war load.

There is no reason why it should not be able to loop
if there is enough altitude.

Sergio<div class="ev_tpc_signature">

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Aaron_GT
11-19-2006, 05:04 PM
I've read more than one account of young RAF pilots trying to bounce Lancasters and getting nasty surprises on how manouverable the Lanc was.

And reputedly the Lancaster was a comparative sluggard compared to the Stirling, which is impressive given that Short's was a bigger plane. The problem was that the Stirling was just too slow and had too low a ceiling to be as survivable as the Lancaster, and its maximum bombload was only a shade bigger but with less flexible bombload options.

Philipscdrw
11-19-2006, 05:49 PM
The Stirling had a shorter wingspan - it was constrained to have a wingspan less than 100ft, to fit inside existing RAF hangars. The Lancaster and Halifax didn't have this limitation.<div class="ev_tpc_signature">

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darkhorizon11
11-19-2006, 08:14 PM
Not as many as it does in the game thats for sure

BfHeFwMe
11-19-2006, 08:20 PM
There's plenty of tricks up the heavies sleeves. Four engine heavies have no problem increasing roll rates by chopping power on one side a bit, of course with modern boosted controls not much of a need too. They still practice it once in a while for ailerons out situations.

Another thing is the heavies have and had electric trim motors on the elevator along with oversized tabs. They were designed with overcomming heavy loads in mind, and if that isn't enough there is a heavy duty yoke with foot rests to push against above the rudder petals for both pilot and co in most. Next time you get in an old heavy take a look for these foot braces.

Remember the guy who landed the DC-10 in Sioux City, no ailerons, no rudder, and no elevator. He made a nice lineup with only power, and trim.

Skycat_2
11-19-2006, 08:30 PM
Over the summer I found a book from the 60s that was entirely dedicated to the B-17. It even included a reproduction of most of the pilot's manual, printed at a ratio of four of the manual's pages per book page. Anyhow, there were pilot recollections within the main text, and one of the stories centered around the question of whether the B-17 could do a loop.

In this brief recollection, as I remember it, the pilot said that during a mission one of the B-17s dropped out of the formation without explanation, dived, and suddenly did three loops before disapearing in the clouds below. The plane and crew were never seen again.

I don't have a citation so I can't prove this book even exists; even so, I may have the details of the incident slightly wrong. I think the publisher was ARCO or ABCO ... something like that.<div class="ev_tpc_signature">

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jolly_magpie
11-19-2006, 08:43 PM
When the Stirling was designed, a half-scale flying testbed was built. One day it was bounced by a pair of p-47s and actually got on their tails in a mock dogfight...<div class="ev_tpc_signature">

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WWMaxGunz
11-19-2006, 08:44 PM
Just over 2 G's with over 32 tons was allowed. Probably go another -- loaded.
Figure it out empty plus 1/4 fuel in the wings.

I knew a B-29 crewman who had signalled bombs drop right at the edge of a firestorm in Japan.
The thermal threw the plane high and turned it. When they regained control, they were headed
straight down well beyond the Vne (Velocity Not Exceed) and still got the B-29 clear back to
Iwo Jima (they based at Tinian) and landed it. It was twisted and buckled from heat and G's.
That got Joe Worsley a Silver Star to go with the rest of his decorations.

How does anyone think they built bombers to go up against flak? Heavy. They had to be able
to take damage and still complete the mission and get back home. Think of a 4 engine P-47
and in the case of the B-17 that was designed with the idea of not needing escorts, add some.

JamesBlonde888
11-19-2006, 09:34 PM
Less than a Lancaster.<div class="ev_tpc_signature">

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IL2-chuter
11-20-2006, 09:01 AM
Remember the guy who landed the DC-10 in Sioux City, no ailerons, no rudder, and no elevator. He made a nice lineup with only power, and trim.


They had no trim as that was hydraulic also. Flaps/slats were non-functioning as well. Damage on right stab/elevator kept pulling nose right and differential power could ALMOST keep it straight. Without the trim slowing down for landing increased sink rate so speed (without flaps/slats remember) was rather high.


(former DC10 mech who worked on aircraft in question)

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joeap
11-20-2006, 01:23 PM
Originally posted by IL2-chuter:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Remember the guy who landed the DC-10 in Sioux City, no ailerons, no rudder, and no elevator. He made a nice lineup with only power, and trim.


They had no trim as that was hydraulic also. Flaps/slats were non-functioning as well. Damage on right stab/elevator kept pulling nose right and differential power could ALMOST keep it straight. Without the trim slowing down for landing increased sink rate so speed (without flaps/slats remember) was rather high.


(former DC10 mech who worked on aircraft in question)

http://forums.ubi.com/images/smilies/16x16_smiley-indifferent.gif </div></BLOCKQUOTE>

Wow.



Just wow. http://forums.ubi.com/groupee_common/emoticons/icon_eek.gif