Elliptical wing
An elliptical wing is a
Relatively few aircraft have adopted the elliptical wing, an even-smaller number of which attained
Properties
Theoretically, the most efficient way to create lift is to generate it in an elliptical spanwise distribution across the wing.[1] There is no inherent superiority to pure elliptical shapes, and wings with other planforms can be optimized to give elliptical spanwise lift distributions.
The basic elliptical wing shape also has disadvantages:
- The almost uniform washout, reducing the load on the tips so that the inner wing would stall first.[2][3] Such compromises depart from the theoretical elliptical lift distribution, increasing induced drag. An elliptical spanwise lift distribution cannot be achieved by an untwisted wing with an elliptical planform because there is a logarithmic term in the lift distribution that becomes important near the wing tips. [4]
- Elliptical wing planforms are more difficult to manufacture.[5] In it, either leading edge or trailing edge or both are curved, and the ribs change in a non uniform way along the wingspan. In practice, most elliptical wings are approximations, for example several sections of the Spitfire leading and trailing edges are arcs of circles.
The semi-elliptical wing
For a wing to have an elliptical area distribution, it is not necessary for both the leading and trailing edges to be curved. If one of these is straight, as in the semi-elliptical planform, the wing may still have an elliptical area distribution. Several aircraft of this type have been produced; one of the most successful being the American Seversky P-35.
During the
History
The British theoretical aerodynamicist Frederick Lanchester was perhaps the first person to write in detail about the elliptical wing, having done so during 1907.
The first aircraft to use the elliptical wing was the
Shortly thereafter, Heinkel developed the
Perhaps the aircraft company most commonly associated with the elliptical wing was the British manufacturer
The elliptical wing was decided upon quite early on. Aerodynamically it was the best for our purpose because the induced drag 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.
Beverly Shenstone[13]
Mitchell has sometimes been accused of copying the wing shape of Heinkel's He 70. Communications between Ernest Heinkel and Mitchell during the 1930s establishes Mitchell's awareness of the He 70 and its performance.[7] However, Beverley Shenstone, the aerodynamicist on Mitchell's team, observed that: "Our wing was much thinner and had quite a different section to that of the Heinkel. In any case, it would have been simply asking for trouble to have copied a wing shape from an aircraft designed for an entirely different purpose."[14]
Almost all
Since 2009, the British aircraft company
References
Citations
- ^ Clancy 1975, sections 5.17, 5.25 and 8.14.
- ^ "Spitfire"", Aeroplane icons No. 14, Kelsey, 2013, p. 33.
- ^ Smith, J. "The development of the Spitfire and Seafire." Journal of the Royal Aeronautical Society, 1947, p. 343.
- ^ Jordan, P.F. "On Lifting Wings with Parabolic Tips." ZAMM, 54, 1974. pp. 463-477.
- ISBN 978-1-62488-139-8.
- doi:10.2514/3.59236.
- ^ a b c d Garrison, Peter (February 2019). "The Perfect Airplane Wing". Air & Space Magazine.
- ^ a b Mackay 2003, p. 7.
- ^ Donald 1999, p. 494.
- ^ Mackay 2003, p. 9.
- ^ Regnat 2004 p. 31.
- ^ a b Ethel 1997, p. 12.
- ^ Price 2002, pp. 17–18.
- ^ Price 1977, pp. 33–34.
- ^ Francillon 1979, pp. 272–273.
- ^ Green and Swanborough 1982, p. 28.
- ^ Thomas and Shores 1988, p. 105.
- ^ Mason 1967, p. 3.
- ISBN 978-0-7106-2955-5.
Bibliography
- ISBN 0-273-01120-0.
- Donald, David, ed. (1999). The Encyclopedia of Civil Aircraft (illustrated, revised ed.). London: Aurum. ISBN 1-85410-642-2.
- Ethell, Jeffrey L. and Steve Pace. Spitfire. St. Paul, Minnesota: Motorbooks International, 1997. ISBN 0-7603-0300-2.
- Francillon, René J. Japanese Aircraft of the Pacific War. London: Putnam & Company Ltd., 1970 (2nd edition 1979). ISBN 0-370-30251-6.
- Glancey, Jonathan. Spitfire: The Illustrated Biography. London: Atlantic Books, 2006. ISBN 978-1-84354-528-6.
- Green, William; Swanborough, Gordon (August–November 1982). "The Zero Precursor...Mitsubishi's A5M". Air Enthusiast. No. 19. pp. 26–43.
- Mason, Francis K. The Hawker Tempest I–IV (Aircraft in Profile Number 197). Leatherhead, Surrey, UK: Profile Publications Ltd., 1967.
- McCormick, Barnes W. Aerodynamics, Aeronautics, and Flight Mechanics. John Wiley & Sons, New York, 1979. ISBN 0-471-03032-5. pp. 135–139.
- Milne-Thomson, L.M. Theoretical Aerodynamics, 4th Ed., Dover Publications Inc, New York, 1966/1973. ISBN 0-486-61980-X. pp. 208–209.
- Price, Alfred. The Spitfire Story: Revised second edition. Enderby, Leicester, UK: Siverdale Books, 2002. ISBN 978-1-84425-819-2.
- Regnat, Karl-Heinz (2004), Black Cross Volume 4: Heinkel He 111, Hersham, Surrey, UK: Midland Publishers, ISBN 978-1-85780-184-2
- Thomas, Chris and Christopher Shores. The Typhoon and Tempest Story. London: Arms and Armour Press, 1988. ISBN 978-0-85368-878-5.
External links
- The Spitfire Wing Planform: A Suggestion via aerosociety.com
- Induced Drag Coefficient via grc.nasa.gov