Re: An-124 and wing dihedral

Date:         18 May 98 16:02:59 
From:         Andrew Cruickshank <andrew@openkast.com>
Organization: OpenKast Limited
References:   1
Followups:    1 2
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Karl Swartz wrote:
>
>
> I can't see what "negative" dihedral (like the An-124) would accomplish,
> or why it would even be desireable.
>
> Would someone care to enlighten me on the aerodynamics of wing dihedral?

With a high wing position on a large 4 engine transport aircraft
like a C-5 or An124 the anhedral is used to introduce some
instability to counteract the high stability of the underslung
mass in the fuselage, the engines (spread further out along the
wing), and the aerodynamic effect of the high wing position.

In addition to engine failure considerations the 777 may also
require a greater dihedral than the 747 because the engine
layout of the 747 is more stable due to the outboard engine
masses.

---------------
Andrew.