"Peter Dohm" wrote in
:

wrote in message
news:5d0da5e0-2006-442e-8e74-
.
..
On Apr 25, 10:55 am, "Robert M. Gary" wrote:
On Apr 25, 5:23 am, es330td wrote:

Fortune magazine online has a photo essay about their new 787. On
one

page,http://money.cnn.com/galleries/2008/.../gallery.boein
g_dream..., they make this statement:

The Dreamliner's wingspan is 197 feet, or about 25% longer than a
similar-sized plane, which increases lift and reduces drag.

I thought that lift, in addition to causing a net upward force on
the wing, also contributes to the drag force on the wing as well.
If this is the case then increasing lift should also increase
drag. Did I misunderstand?

It could be more efficient. The Mooney wing produces more lift for
the amount of drag than a Cessna wing.

-Robert

From the original statement, it seems clear that they're
referring to the increase in efficiency that come from aspect ratio.
I wonder, now, if that increased span was made possible with the use
of composites instead of aluminum? Longer wings flex more, and
aluminum fatigues faster, I think, than composite construction. And
carbon or aramid fibers are stronger per unit weight than aluminum.

Dan

There are a lot of trade offs, and the gate spacing might also be
larger at the airports that the Dreamliner is expected to serve.
Also, IIRC, a few years ago, Boeing talking about future aircraft with
folding wing tips to overcome some of the spacing problems at the
gates. I also agree with you, that advances in materials also play a
major role.


It's not going to be that big. The widebody Busses ( A 330 and 340) are
already massive with a much larger span than the 747 so it shouldn't be
an issue.

Bertie