[sci.space] X-29

TSHARP@BROWNVM.BITNET (H. Thomas Sharp) (11/10/86)

>From: weltyc%cieunix@rpics.arpa (Christopher A. Welty)
>
>   The new technology represented in the advanced forward swept
>wing aircraft (X-29) seems very interesting.  Does anyone know exactly
>what the advantages of the forward swept wing are and how the
>technology may be applied to the next generation space plane?
>
>                   -Chris


There are several advantages of a forward swept wing (FSW) over an aft
swept wing (ASW).  Among these are

   o Improved performance at high angles of attack.  For the ASW flow
     separation occurs at the wing tip and degrades the responsiveness
     of the control surfaces.  Flow separation on a FSW occurs inboard
     and generally never reaches the tip.  This allows for higher roll
     rates than would be possible with an ASW.

   o While wing sweep, either fore or aft, postpones the drag rise near
     Mach 1, a FSW has a lower wing profile drag than a ASW.  Therefore,
     one can obtain higher lift coefficients under transonic conditions.
     This translates into a greater payload capacity for a given aspect
     ratio.

Of course the major disadvantage of a FSW is it's desire to bend.  The
major contribution of the X-29 is the knowledge which has been gained on
the manufacturing and use of composites which can be tailored to the
aeroelastic bending.

 H. Thomas Sharp  (TSHARP@BROWNVM.ARPA)
 Division of Applied Mathematics
 Brown University

weltyc%cieunix@CSV.RPI.EDU (Christopher A. Welty) (11/13/86)

	I appreciate the comments H Thomas Sharp has on the X-29, but
I have one question about something he said:

>   o While wing sweep, either fore or aft, postpones the drag rise near
>     Mach 1, a FSW has a lower wing profile drag than a ASW.  Therefore,
>     one can obtain higher lift coefficients under transonic conditions.
>     This translates into a greater payload capacity for a given aspect
>     ratio.

	I'm by no means an expert, but isn't profile drag simply the
sum of the skin friction and form drag of an object?  How could the
wing being forward or backward swept have anything to do with it, do
you mean the FSWs are generally of a different shape?  

			-Chris