Re: DC-10 Engine pod fins

From:         drinkard@bcstec.ca.boeing.com (Terrell D. Drinkard)
Organization: Boeing Commercial Airplane Group
Date:         22 Mar 94 09:52:48 PST
References:   1
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In article <airliners.1994.1025@orchard.chicago.com>,
Clemens Emmanuel Tillier <ctillier@flagstaff.princeton.edu> wrote:
>I've noticed on several DC-10's that the wing engines have two small
>fins (one on each side of the engine pod, sort of at the 10 o'clock
>and 2 o'clock positions). I noticed that these often produce a stream
>of condensation on takeoff- a great way to see the airflow over the
>wing.
>
>What function do these fins serve?

They are called 'chines.'  They provide a strong vortex at high angles of
attack to keep the flow more or less attached to the wing behind the
engine.  What we find is that the high bypass ratio turbofans tend to
blanket the wing at high angles of attack, particularly when tucked up 
close to the wing, causing flow separation and loss of lift.  This is
generally frowned upon by the aerodynamics community.

You will also find chines on the 737-3/4/500 airplanes.  Probably on the
737-6/7/800s as well, but I haven't seen any drawings yet.

-- 
Terry
drinkard@bcstec.ca.boeing.com
"Anyone who thinks they can hold the company responsible for what I say has
more lawyers than sense."