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 | | From: | Ed Ruf | | Subject: | Forward swept wings | | Date: | Fri, 21 Jan 2005 10:00:11 -0800 |
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>I recently read that a forward swept wing is aerodynamically better than a
>rear swept wing, provided that aerodynamic divergence can be prevented
>through the use of stiffer materials. However, I found another aero book
>which stated that analytically there is no difference between a forward and
>rear swept wing. From what I understand, the sweep angle reduces the free
>stream Mach number seen by the wing, because the normal component is
>Moo/cos(sweep angle).
>
>My question is, why use a forward swept wing, and how is this
>aerodynamically better assuming the divergence is controlled?
Found this on the NASA report server, you might look at the other cites:
http://ntrs.nasa.gov/index.cgi?method=search&limit=25&offset=0&mode=simple&order=DESC&keywords=forward+swept+wing%0D%0A
You might take a look at:
In-flight lift-drag characteristics for a forward-swept wing aircraft and
comparisons with contemporary aircraft)
Saltzman, Edwin J.; Hicks, John W.; Luke, Sue
NASA Center for AeroSpace Information (CASI)
NASA-TP-3414; H-1913; NAS 1.60:3414 , 19941201; Dec 1, 1994
Lift (L) and drag (D) characteristics have been obtained in flight for the
X-29A airplane (a forward swept-wing demonstrator) for Mach numbers (M)
from 0.4 to 1.3. Most of the data were obtained near an altitude of 30,000
ft. A representative Reynolds number for M = 0.9, and a pressure altitude
of 30,000 ft, is 18.6 x 10(exp 6) based on the mean aerodynamic chord. The
X-29A data (forward-swept wing) are compared with three high-performance
fighter aircraft: the F-15C, F-16C, and F/A18. The lifting efficiency of
the X-29A, as defined by the Oswald lifting efficiency factor, e, is about
average for a cantilevered monoplane for M = 0.6 and angles of attack up to
those required for maximum L/D. At M = 0.6 the level of L/D and e, as a
function of load factor, for the X-29A was about the same as for the
contemporary aircraft. The X-29A and its contemporaries have high transonic
wave drag and equivalent parasite area compared with aircraft of the 1940's
through 1960's.
Accession ID: 95N18565
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19950012150_1995112150.pdf
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Ed Ruf Lifetime AMA# 344007 (Usenet@EdwardG.Ruf.com)
http://EdwardGRuf.com
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