B-52 design
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"The INTRODUCER"
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From: London
Joined: Jul 2007
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From: 51.50N 1W (ish)
Not being part of the design team, I can merely hazard a guess.
The low-drag high aspect ratio wing was part of the performance envelope optimisation, but gave substantial wing flexing from the no-lift full fuel state to the max all-up weight flight condition. This needed wing-tip auxiliary undercarriage wheels to keep the tips from dragging on the ground; these would have needed to be much stronger for wings that were intially 20ft closer to the ground. They would also of course have relieved wing-root bending to some extent; so optimisation is an interesting exercise.
The low-drag high aspect ratio wing was part of the performance envelope optimisation, but gave substantial wing flexing from the no-lift full fuel state to the max all-up weight flight condition. This needed wing-tip auxiliary undercarriage wheels to keep the tips from dragging on the ground; these would have needed to be much stronger for wings that were intially 20ft closer to the ground. They would also of course have relieved wing-root bending to some extent; so optimisation is an interesting exercise.
Joined: Sep 2003
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From: away from home
They say the mother of the last B-52 pilot is not born yet.
I have a question, according to Flight International, USAF is still operating 77 B-52. Are engines for them still being built, or are they overhauling old engines to keep the fleet running?
What happened to the programme to re-engine them (CFM56 as I recall)?
The youngest B-52 will turn 50 in 2012...
I have a question, according to Flight International, USAF is still operating 77 B-52. Are engines for them still being built, or are they overhauling old engines to keep the fleet running?
What happened to the programme to re-engine them (CFM56 as I recall)?
The youngest B-52 will turn 50 in 2012...
Joined: Apr 2004
Aviation Qualifications: LAME
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From: Dorset UK
I read an article a few years ago that stated that there are enough spare engines to see the B52 through to about 2045 and a re-engine program would not be cost effective.
So 80+ year old bombers.
Also there are many engine types in service that have been out of production for years. You just keep overhauling them. The spare parts will still be made as long as there is a demand for them.
Mind you some of these engines could be like "Trigger's broom". Apart from 3 new heads and two new handles...........................
So 80+ year old bombers.
Also there are many engine types in service that have been out of production for years. You just keep overhauling them. The spare parts will still be made as long as there is a demand for them.
Mind you some of these engines could be like "Trigger's broom". Apart from 3 new heads and two new handles...........................
Joined: Apr 2004
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From: Dorset UK
Why high wing?
Because the B47 had a high wing and the B52 was scaled up.
So I suppose the question is why the B47?
As others have said, to get the biggest bomb bay.
Because the B47 had a high wing and the B52 was scaled up.
So I suppose the question is why the B47?
As others have said, to get the biggest bomb bay.
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From: Ex-pat Aussie in the UK
Setting the wing high, and keeping the body low also means that the aircraft can be serviced from the ground without extra equipment - stairs for the crew, and high loading scissor lifts for the load.
That's an important consideration for a battlefield aircraft which may have to operate from a remote base.
That's an important consideration for a battlefield aircraft which may have to operate from a remote base.
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From: South
Just to add another one-
The wings are very long and droop somewhat, hence the outriggers.
A low wing would not be able to droop as much, meaning more strength = more weight = less payload etc etc
Also, due to the wing length, even applying outriggers on a low wing would make the a/c very ungainly and difficult to land in crosswinds without losing engines etc.
These are secondary considerations, although all things would have been considered to end up with the best compromise of a design.
4015
The wings are very long and droop somewhat, hence the outriggers.
A low wing would not be able to droop as much, meaning more strength = more weight = less payload etc etc
Also, due to the wing length, even applying outriggers on a low wing would make the a/c very ungainly and difficult to land in crosswinds without losing engines etc.
These are secondary considerations, although all things would have been considered to end up with the best compromise of a design.
4015
Joined: Mar 2006
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From: Ormond Beach
The remark about the mother of the last B-52 pilot not being born yet reminded me of a rumor I recently heard. It's been reported that there are guys at Delta who are not only flying their fathers' ex-Northwest DC-9s, but also doing their fathers' ex-Northwest flight attendants.
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From: Sheffield
Wing tip undercarriage because main undercarriage is bicycle type?
N'est ce pas? Aircraft too difficult to handle at high speed on ground with narrow track main undercarriage - as with the Harrier?
Actually reason given also seems good, but even if tip droop (I sometimes suffer from this
) is a factor, controllability seems likely to be another.
Actually reason given also seems good, but even if tip droop (I sometimes suffer from this
) is a factor, controllability seems likely to be another.
Last edited by 911slf; 22nd December 2011 at 12:15. Reason: after thought
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From: South
911slf-
Yes, you're quite right. The outriggers are also for ground stability, if they had utilised a wing based main undercarriage then the outriggers would probably not be needed, but again the wings would need to be stiffer in order to hold the weight when on the ground without the fuselage scraping the ground, thicker in order to house the stowed u/c, etc etc.
As with most things in engineering, a solution is very very rarely the result of a single factor, it will always be the best compromise between all of the variables as you have elegantly pointed out
Yes, you're quite right. The outriggers are also for ground stability, if they had utilised a wing based main undercarriage then the outriggers would probably not be needed, but again the wings would need to be stiffer in order to hold the weight when on the ground without the fuselage scraping the ground, thicker in order to house the stowed u/c, etc etc.
As with most things in engineering, a solution is very very rarely the result of a single factor, it will always be the best compromise between all of the variables as you have elegantly pointed out
Joined: Apr 2008
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From: nowhere
Found an interesting quote about a B52 which I didn't want to disappear in time so I thought that I would post it here,
"This also reminds me of the issue with the B-52G. When going around and applying maximum thrust, fuel moved in the tanks displacing the CG aft of the aerodynamic center, making the aircraft statically unstable. Two B-52s and crews were lost. The solution adopted was a simple detent in the throttle quadrant which discouraged rapid thrust build-ups."
"This also reminds me of the issue with the B-52G. When going around and applying maximum thrust, fuel moved in the tanks displacing the CG aft of the aerodynamic center, making the aircraft statically unstable. Two B-52s and crews were lost. The solution adopted was a simple detent in the throttle quadrant which discouraged rapid thrust build-ups."
