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Guy Alcala wrote in message .. .
Peter Stickney wrote: As for the Stirling, well, actually, fir all its bulk, it doesn't seem that heavy.They really should have taken the fuselage out of hte box before they bolted the wings on, though. The empty weight (46,000 lb. IIRR) has always seemed far higher than was the case with the Lanc or Halifax, and the MTOW (70klb. IIRR) not that much more. It is possible that this is a mistake and isactually the OWE rather than the empty weight losted for the others. Still, its range with a comparable bombload is significantly less than either, and while the wing design undoubtedly plays some part I expect the main factor is the restricted useful load. Shorts' structural methods seem to stem from the flying boats, and appear a bit out of date. From the Stirling file by Michael Bowyer Early Stirling I, Hercules II engines, the first production aircraft N3635 came in at 41,160 pounds tare when under trials, max take off weight 64,000 pounds initially. Stirling III, Hercules VI/XVI tare weight 44,856 pounds, max flying weight 70,000 pounds. The tare weights appear 2 to 3 tons more than the Lancaster and Halifax. The books notes the advantages of the "strongly built" airframe as well as the penalties. Apparently the outboard sections of the wing were watertight. Interestingly the Stirling's wing area was 1,460 square feet, Lancaster 1,297, later Halifaxes 1,275, B-17 1,420, B-24 1,048 and B-29 1,736. The Stirling wingspan was 99 feet 1 inch versus the B-17 103 feet 9 inches, it was also the thickest wing, able to carry bombs in cells within the inner wing. three cells on each side capable of carrying 500 pound bombs at least. Geoffrey Sinclair Remove the nb for email. |
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In article , Geoffrey Sinclair
writes Apparently the outboard sections of the wing were watertight. Interestingly the Stirling's wing area was 1,460 square feet, Lancaster 1,297, later Halifaxes 1,275, B-17 1,420, B-24 1,048 and B-29 1,736. I'm not disputing the figures above, but I thought the B-24 had a larger wing area than most contemporary bombers allowing it to fly higher? -- John |
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In article , John Halliwell
writes In article , Geoffrey Sinclair writes Apparently the outboard sections of the wing were watertight. Interestingly the Stirling's wing area was 1,460 square feet, Lancaster 1,297, later Halifaxes 1,275, B-17 1,420, B-24 1,048 and B-29 1,736. I'm not disputing the figures above, but I thought the B-24 had a larger wing area than most contemporary bombers allowing it to fly higher? Was it not the thick section Davis wing that gave it the improved lift? Cheers, Dave -- Dave Eadsforth |
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On Tue, 9 Sep 2003 15:13:14 +0100, Dave Eadsforth
wrote: In article , John Halliwell writes In article , Geoffrey Sinclair writes Apparently the outboard sections of the wing were watertight. Interestingly the Stirling's wing area was 1,460 square feet, Lancaster 1,297, later Halifaxes 1,275, B-17 1,420, B-24 1,048 and B-29 1,736. I'm not disputing the figures above, but I thought the B-24 had a larger wing area than most contemporary bombers allowing it to fly higher? Was it not the thick section Davis wing that gave it the improved lift? Cheers, Dave The Davis wing was a high aspect ratio wing with a low angle of attack. Al Minyard |
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Alan Minyard wrote:
The Davis wing was a high aspect ratio wing with a low angle of attack. Al Minyard Is there something that I'm missing here?...how can a wing's design decide that?...I'd think that only the elevators could control the AOA?. -- -Gord. |
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"Gord Beaman" ) wrote:
Alan Minyard wrote: The Davis wing was a high aspect ratio wing with a low angle of attack. Is there something that I'm missing here?... Probably, but then, that's nothing out of the ordinary for you. how can a wing's design decide that?...I'd think that only the elevators could control the AOA?. He obviously meant low angle-of-incidence (e.g: the acute angle which the wing chord makes with the longitudinal axis of the A/C). Angle-of-incidence can vary depending on the wing design. -Mike Marron |
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"Gord Beaman" ) wrote:
how can a wing's design decide that?...I'd think that only the elevators could control the AOA?. Also see: F-8 Crusader -Mike Marron |
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Mike Marron wrote:
"Gord Beaman" ) wrote: Alan Minyard wrote: The Davis wing was a high aspect ratio wing with a low angle of attack. Is there something that I'm missing here?... Probably, but then, that's nothing out of the ordinary for you. how can a wing's design decide that?...I'd think that only the elevators could control the AOA?. He obviously meant low angle-of-incidence (e.g: the acute angle which the wing chord makes with the longitudinal axis of the A/C). Angle-of-incidence can vary depending on the wing design. -Mike Marron Really?...seems to me that the angle of incidence would be decided by the way that the wing was mounted to the fuselage...how could the DESIGN of the WING itself control the angle of incidence?. Some advice, Lay off the personal insults, they aren't helping your image much. -- -Gord. |
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Alan Minyard wrote:
On Tue, 9 Sep 2003 15:13:14 +0100, Dave Eadsforth wrote: In article , John Halliwell writes In article , Geoffrey Sinclair writes Apparently the outboard sections of the wing were watertight. Interestingly the Stirling's wing area was 1,460 square feet, Lancaster 1,297, later Halifaxes 1,275, B-17 1,420, B-24 1,048 and B-29 1,736. I'm not disputing the figures above, but I thought the B-24 had a larger wing area than most contemporary bombers allowing it to fly higher? Was it not the thick section Davis wing that gave it the improved lift? Cheers, Dave The Davis wing was a high aspect ratio wing with a low angle of attack. I'll step with some trepidation into Pete's territory here as he explains this stuff far better than I do, but we've been keeping him busy doing calcs. The high aspect ratio wing provides good L/D ratios, increasing range performance as well as lift at low angles of attack. Here's how the a/c's aspect ratios stack up, from low to high: Stirling 6.72:1;. B-17, 7.58:1; Halifax (early) 7.81:1; Lancaster 8.02:1; Halifax (late) 8.51:1; B-24, 11.55:1; B-29, 11.48:1. As you can see, the B-24, designed a couple of years later than the British heavies and five years or so after the B-17, has a much higher aspect ratio wing, and the B-29 follows this practice. The wing area of the B-24 was considerably lower than the others, for low drag. Good altitude performance requires some combination of low wing-loading (high wing area for weight), engine thrust, and aspect ratio. While the B-24 had good engine power at altitude and a high aspect ratio, it also had high wing-loading compared to its contemporaries (not the B-29). It had better altitude performance than the British a/c because of its engine supercharging, not its wings. The B-17, with similar supercharging as the B-24 had a higher combat and service ceiling, because although it had a moderate aspect ratio wing it also had far lower wing-loading, and was able to fly slower. The B-24 cruised between 10-20 mph IAS faster than the B-17, but then it had to to be comfortable. The crews hated having to fly in company with B-17s. It's also easier to make lower aspect ratio wings of the same area stronger for the same weight, because the stresses can be spread over a longer (and thicker) root, which is one reason why a/c like the Stirling and B-17 have reputations for being able to take lots of wing damage and survive, and why a/c like the B-24 had opposite reps. However, the lower aspect ratio wing requires more area to get the same lift at the same AoA, increasing drag. Guy |
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In article , Guy Alcala
writes Alan Minyard wrote: On Tue, 9 Sep 2003 15:13:14 +0100, Dave Eadsforth wrote: In article , John Halliwell writes In article , Geoffrey Sinclair writes Apparently the outboard sections of the wing were watertight. Interestingly the Stirling's wing area was 1,460 square feet, Lancaster 1,297, later Halifaxes 1,275, B-17 1,420, B-24 1,048 and B-29 1,736. I'm not disputing the figures above, but I thought the B-24 had a larger wing area than most contemporary bombers allowing it to fly higher? Was it not the thick section Davis wing that gave it the improved lift? Cheers, Dave The Davis wing was a high aspect ratio wing with a low angle of attack. I'll step with some trepidation into Pete's territory here as he explains this stuff far better than I do, but we've been keeping him busy doing calcs. The high aspect ratio wing provides good L/D ratios, increasing range performance as well as lift at low angles of attack. Here's how the a/c's aspect ratios stack up, from low to high: Stirling 6.72:1;. B-17, 7.58:1; Halifax (early) 7.81:1; Lancaster 8.02:1; Halifax (late) 8.51:1; B-24, 11.55:1; B-29, 11.48:1. As you can see, the B-24, designed a couple of years later than the British heavies and five years or so after the B-17, has a much higher aspect ratio wing, and the B-29 follows this practice. The wing area of the B-24 was considerably lower than the others, for low drag. Good altitude performance requires some combination of low wing-loading (high wing area for weight), engine thrust, and aspect ratio. While the B-24 had good engine power at altitude and a high aspect ratio, it also had high wing-loading compared to its contemporaries (not the B-29). It had better altitude performance than the British a/c because of its engine supercharging, not its wings. The B-17, with similar supercharging as the B-24 had a higher combat and service ceiling, because although it had a moderate aspect ratio wing it also had far lower wing-loading, and was able to fly slower. The B-24 cruised between 10-20 mph IAS faster than the B-17, but then it had to to be comfortable. The crews hated having to fly in company with B-17s. It's also easier to make lower aspect ratio wings of the same area stronger for the same weight, because the stresses can be spread over a longer (and thicker) root, which is one reason why a/c like the Stirling and B-17 have reputations for being able to take lots of wing damage and survive, and why a/c like the B-24 had opposite reps. However, the lower aspect ratio wing requires more area to get the same lift at the same AoA, increasing drag. Guy Agree with all of the above analysis - and thanks for the useful summary of aspect ratios; both the B-24 and the B-29 must have glided well... To enlarge on my 'thick wing section' description, and working from memory of a book read long ago (which can be fatal), I recall that Davis conceived of a wing section that was based on a mathematically deformed circle, which he believed would give a more laminar flow. The thicker, 'teardrop-shaped' aerofoil section that resulted was also very useful structurally, given that he wanted to combine it with a high aspect ratio wing. Of course, any wing section inboard of the engines was going to have its airflow messed up considerably by a few minor essentials; like engine nacelles and de-icing boots etc etc, but the wing outboard of the engines may have performed as Davis believed it should during cruise. True that the high aspect ratio conferred most of the advantages of L/D ratio, but perhaps Davis's ideas on the wing section itself should not be forgotten. Cheers, Dave -- Dave Eadsforth |
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