Subject: SV: Re: SV: [harryproa] some more Elementarry data points
From: Kenneth Hernemalm
Date: 3/13/2006, 10:36 AM

Biplanes and eagles enjoy different benefits here. By
staggering wings, biplanes achieve higher coefficient
of lift (Cl)- more lifting force per area. The
fingerlike feathers of an eagle reduce tipvortices -
less drag.

High Cl is good to help a heavy aircraft takeoff at
slow speed When speed increases, high
drag of that structure becomes a liability only as
more lift thant to counter gravity is not necessary.
It can takeoff heavy loaded from short airstrips, but
it can't fly fast.

High Cl is also good for boats as more lift gives more
speed. Downwind sailing in a moderatly fast boat is
all about high Cl.

Pointing ability is however all about lift vs. drag. A
really fast boat (iceyacht etc.) always sails "upwind"
as it sails on apparent wind. So low drag becomes
equally important as high lift.

Low drag is a good thing on a boat like Elementarry,
because, even thought it has higher drag than an
iceyacht, drag is still low, more drag in the rig
increases leeway force, which has to be countered by
rudder, which in turn causes more drag and ultimately
less speed.


--- Robert <> skrev:

> I suppose this is why the old biplanes and triplanes
> had the wings
> staggered and eagles wings have those finger like
> feathers on their
> ends.

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Bästa hälsningar

Kenneth Hernemalm

om du vill ringa finns jag på 0701-593302 eller 031-552121

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