Re: 737-400 Vortex generators

Date:         03 Oct 99 17:38:25 
From:         David Lednicer <dave@amiwest.com>
Organization: Analytical Methods, Inc.
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The vortex generators on transport wings are there for two purposes.
On some aircraft, such as the 767, there are just a few VGs, located at
roughly midspan.  They are there to improve the stick force
characteristics beyond intial buffet (this sentence is a quote form a
1985 Boeing "Airliner" magazine article).  They do this by shedding a
vortex that reenergizes the boundary, delaying local boundary layer
separation.

	On other transport wings, the VGs have been used to alleviate
shock-induced separation at cruise speeds.  While not a transport, the
Learjet 23 is an example of this.  The VGs on this aircraft eliminate
shock-induced separation on the aileron, getting rid of "aileron buzz".

	I do not know the rationale for the VGs on the wings of 737s.  I do
know that the VG patterns on the 737-100/200 wing is different from that
on the 737-300/400/500 wing.  My guess from viewing the patterns is that
they are there to improve low speed handling (reason #1 above).

-------------------------------------------------------------------
David Lednicer             | "Applied Computational Fluid Dynamics"
Analytical Methods, Inc.   |   email:   dave@amiwest.com
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Redmond, WA  98052  USA    |   fax:     (206) 746-1299