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From http://en.wikipedia.org/wiki/Stall_%28flight%29
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There she blows!
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2, Lower induced drag on the Spit doesn't have anything to do with wing shape, its simple that its a huge wing, and needs less angle of attack to provide the same lift. Less angle of attack - less drag. |
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BTW if the elliptical shape didn't bring advantages, why would the Brits bother to manufacture them? |
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If wing shape would have been such a factor, planes like the Curtiss Hawk, Zero or Hawker Hurricane wouldn't run circles around the Spitfire, but they did. Quote:
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Spit has a negatively twisted wing that means that angle of attack will be always lower on the wingtip + wingtip probably uses different airfoil than root with different lift characteristic so that it will never stall first. That means spit can have eliptical wing without dangerous stall characteristics.
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In 1934, Mitchell and the design staff decided to use a semi-elliptical wing shape to solve two conflicting requirements; the wing needed to be thin, to avoid creating too much drag, while still able to house a retractable undercarriage, plus armament and ammunition. Beverly Shenstone, the aerodynamicist on Mitchell's team, explained why that form was chosen: The elliptical wing was decided upon quite early on. Aerodynamically it was the best for our purpose because the induced drag, that caused in producing lift, was lowest when this shape was used: the ellipse was ... theoretically a perfection ... To reduce drag we wanted the lowest possible thickness-to-chord, consistent with the necessary strength. But near the root the wing had to be thick enough to accommodate the retracted undercarriages and the guns ... Mitchell was an intensely practical man... The ellipse was simply the shape that allowed us the thinnest possible wing with room inside to carry the necessary structure and the things we wanted to cram in. And it looked nice. So again, you are doing a simplification here. |
My 2 cents...
Lift is related to the wing foil used and the surface area of the wing. An elliptical wing is not needed to increase the surface area or change the wing foil. However.... One of the big culprits of drag in a wing are the wing tips. The elliptical wing is very good at not creating a vortex in the wing tips thus reducing drag. See http://en.wikipedia.org/wiki/Wing_tip |
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Elliptic planform theoretically means even lift distribution. Even lift distribution means the whole wing stalls all at once. With a twisted wing you no longer have an even lift distribution, no reduced induced drag, and no dangerous stall charateristics. Simply to put from the aerodynamic POV, it's not an elliptic wing. |
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What I have pointed out that you have made a very specific claim about the relative lift distribution on the 109 and Spitfire, based on generalisations. I wonder if even Supermarine or Messerschmitt were aware of how it looked like back in the 1940s... Quote:
Whatever increased efficiency they may or may not have gained by using the shape they lost it as they sacrificed the aspect ratio in return. Elliptical wings seemed to be a nice idea in 1930s, and the theory was that they would offer some advantage, but as it turned out it simply did not, and everybody dropped them quickly, including Supermarine when it first got a chance (Mark 2x series Spitfires). |
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