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Old December 14th 03, 08:18 PM
BllFs6
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Default Wing in Ground Effect?

Hi all...

I know this is somewhat off topic perhaps...but maybe somebody here has the
tidbit of info I need....

As Im sure you all know....the Lift to drag ratio of a wing goes way up once it
gets close to ground.....and roughly speaking the effect becomes pronounced
when the wing has an altitude on the same order as the span of the wing or
less.....

What I was looking for was:

1..... a graph that shows the L/D ratio as the wing gets closer and closer to
the ground......anything rough will do...I found such a rough graph once a year
or 2 ago on the internet....but I cant find it again......

2.....question.....as you approach the ground VERY closely (lets assume your
landing gear are up AND you somehow maintain a constant forward speed AND you
maintain the same angle of attack) does the drag GO down or does the lift go
up?

3.....lets assume a wingspan on the order of 6 feet and a chord of 2 to 3
feet.....flying say 6 inches to a foot about the ground at 40-60mph....(yeah,
Im gonna be building the worlds fastest flying lawnmower .....what kind of
lifting force could I reasonably expect? .....if you dont have the values for
the ground effect itself......I could still use the numbers for "high" altitude
values and fudge them from there to get back of the envelope ground effect
numbers....

take care all

Blll