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Old January 19th 04, 09:14 AM
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Uzytkownik "Alan Dicey"
napisal w wiadomosci ...
As far as I can recall, forward sweep confers the advantage that
spanwise flow is now inwards, and the wingtips (with associated control
surfaces) stall last instead of first, so control authority is retained
at higher angles of attack or "deeper into the stall". In the X-29 they
were combined with canards, a supercritical wing and aerodynamic
instabilty in a search for enhanced maneuverability. See here

for the NASA Dryden infosheet. I seem to remember that the advantages
gained did not warrant the construction costs/difficulties (aeroelastic
tailoring with composites in the wing structure, as I recall) and so the
technique was not carried forward into new fighter design. Perhaps Mary
Shafer may know more of the projects findings?

I dug through my old notices on X-29A and X-31X and found these references:
[1] Bandyopadhyay G. - "Low-Speed Aerodynamic Characteristics of
Close-Coupled Canard Configuration at Incidence and Sideslip", Journal of
Aircraft, Vol. 28, No. 10, October 1991
[2] Er-El J. - "Effect of Wing/Canard Interference on the Loading of a Delta
Wing", Journal of Aircraft, Vol. 25, No. 1, January 1988
[3] Manoeuvring Aerodynamics, AGARD CP 497, Toulouse, France, May 1991
(especially papers)
[3.a] Ross Hannes - "X-31 Enhancement of Aerodynamics for Maneuvering beyond
Stall", Paper 2
[3.b] Kraus W. - "X-31, Discussion of Steady State and Rotary Derivatives",
Paper 13
[3.c] Ferretti A., Bartoli A., Salvatore A. - "Prediction of Aerodynamic
Phenomena Limiting Aircraft Manoeuvrability", Paper 5
[3.d] Visintini L., Pertile R., Mentasti A. - "Parametric Effects of some
Aircraft Components on High-Alpha Aerodynamic Characteristics", Paper 6

Close-Coupled Canard was my main area of interest these days so sweep
(-forward or -back) can be treated mariginally in these papers, but I hope
they can help you.

Warsaw, Poland