Date: 08 Jun 98 02:57:53 From: JF Mezei <email@example.com> References: 1 2 Followups: 1
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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 ?