Re: Stalls

From:         etate@mcl.bdm.com (C. Emory Tate)
Organization: BDM Federal, Inc.
Date:         24 Apr 94 22:23:42 
References:   1 2 3
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In article <airliners.1994.1164@ohare.Chicago.COM>, ap183@freenet.carleton.ca (Kyle D. Jackson) says:
>In a previous article, drinkard@bcstec.ca.boeing.com (Terrell D. Drinkard) says:
>
>>devices (a la the MD-11 that had to land at Shemya).  The airplane can also
>>stall because it is moving so fast that the shockwave along the upper
>>surface of the wing becomes so strong that the flow separates behind it.
>>This is a Mach buffet.  Contributing factors are weight (which falls out as
>>an angle of attack) and ambient air conditions.
>
>I had the understanding that the commercial transport aircraft were designed
>with supercritical airfoils to completely avoid the chance of a sonic shock
>forming on the upper wing surface...

hehehe... you obviously never had a down-sun, over-wing window seat on
a 747 or DC-10... transoceanic in midafternoon's usually a good time.

You can see the Mach front quite clearly as a (Schlieren?) refraction
line, extending straight up for a foot or two, and then aft... about
mid-chord, but jumping back and forth slightly according to small
variations in airflow (it looks like the edge of a bubble, or a 
wake wavelet in clear water).

Maybe more modern aircraft have supercrit wings, but the old hosses
are still flying.

___________________________________________________________
C. E. Tate	etate@mcl.bdm.com
snailmail:	BDM Federal, Inc.
		1501 BDM Way
		McLean, VA  22102
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Stick forward and opposite rudder to stop the spin...
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