Re: An-124 and wing dihedral

Date:         08 Jun 98 02:57:53 
From:         JF Mezei <jfmezei.spamnot@videotron.ca>
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MechB747 wrote:
> The wings on a 747 flex  A LOT on take-off...
> I think the 747 wings may be less stiff because of the additional  weight of
> the engines  help to "pull" the wing down against the lifting force.
> Aircraft that have engines mounted on the fuselage and not on the wings, like
> 727s and DC-9s, actually have to have stronger wings because of this.

During take off, with tanks filled to the brim, are there any general
guidelines as to the percentages of weight each of the following
represents ?
			-fuel
			-engines
			-aircraft itself.
			-passengers/cargo

Would these vary significantly between different aircraft types from the
bae-146 up to an AN-124 or B747 ?

If engines are a lot lighther than the fuel, then once at cruise, the
wings would have a lot of available strength to support the engines once
much of the fuel has been burned since the wings would have to be
designed to lift a whole lot more at take off.  Correct ?

Also, am I right in assuming that lift is not evenly produced along the
length of the wing ? (eg: less lift generated near wing-tip ?). Would
that also not contribute to the placement of engines ? You'd want the
heavier stuff nearest to the area where the greatest lift is being
produced, right ? Or aerodynamic considerations much more important in
selecting placement of engines ?