Re: Aircraft speed and weight at cruise.

Date:         24 Oct 97 04:33:14 
From: (Don Stokes)
Organization: Daedalus Consulting
References:   1
Followups:    1
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In article <airliners.1997.2480@ohare.Chicago.COM>,
jf mezei  <"[non-spam]jfmezei"> wrote:
>Sorry if this is very basic:
>Correct me if assumptions as wrong:
>-A wing generates a lift value which is proportional to the air speed.

This assumption is wrong, or at least incomplete.  It should contain the
qualification "at a given angle of attack".  This is important because...

>Assuming a LAX-SYD flight with no winds. Towards the end of the flights
>when the plane is much lighter, doesn't the lift provided by the wings
>exceed by quite a bit the lighter weight of the aircraft ?

... the angle of attack is adjusted as the plane lightens.  When heavy,
the plane flies a bit more nose-up than when light; by dropping the nose,
less lift is generated.  This is (part of) the "trim" of the aircraft.

Don Stokes, Networking Consultant  +64 25 739 724
Network Design, Cable Plans, LANs, WANs, Radio Networks, Internet Consulting