Will this hanging shape produce lift?

[Joel Price]

Dear Group,

Dear Group,

I am developing a light weight product that will be hanging outside
and wanted to ask your collective wisdom about wind effects on it's
shape. It is approximately 30 (28 on shorter surface) x 40 x 2
inches. It has a symmetrical shape (with respect to leading and
trailing edges), basically a trapezoid (kind of like a stackable bin).
It will look something like this character picture if it comes out
correctly on your browser and font.

_________________________ / ^
/ \ /______wind |
/___________________________\ \ | lift?
\

I am trying to anticipate or design how this thing will move in the
wind. The wind would be coming perpendicular to the 2 inch width,
that is, parallel to the flat top and bottom of the trapezoid. I want
it to not flap around so I am trying to create a shape that will force
it to flap backward (in the direction of the shorter surface) in a
wind and more or less stay there.

Any opinions?

Thanks in advance.

[Wright1902Glider]

Well, the redneck school of engineering recomends that you make a quick
prototype out of poster board/foam board/sheet metal/whatever. Then mount the
sucker in the back of a pickup truck, as it would hang normally, making sure
that its in the free-air stream.

To test, start driving and watch the rear-view mirror. That should answer most
of your questions real quick.

Just a thought,
Harry "10 tie-downs ain't enough" Frey
Wright Brothers Enterprises
Wright 1902 glider, 1899 kite, 1878 Bat

[Corrie]

You'd have to mount it up above the cab - the wind in the back of the
truck won't be parallel to the top and bottom surfaces. It blows off
the back and curves down around the back and blow around and eddy and
turbulate and all that. 'Course, so will real wind.

Mount the contraption firmly, though, and it won't flop around.

(Wright1902Glider) wrote in message >...
> Well, the redneck school of engineering recomends that you make a quick
> prototype out of poster board/foam board/sheet metal/whatever. Then mount the
> sucker in the back of a pickup truck, as it would hang normally, making sure
> that its in the free-air stream.
>
> To test, start driving and watch the rear-view mirror. That should answer most
> of your questions real quick.
>
> Just a thought,
> Harry "10 tie-downs ain't enough" Frey
> Wright Brothers Enterprises
> Wright 1902 glider, 1899 kite, 1878 Bat

[Kevin Horton]

Actually, I think it is hard to predict exactly what direction the air
over the cab is going too. You need to mount this thing on a framework
way out in front of the truck if you want to be able to get credible
results.

I think it would be easier to hang the prototype from a framework out in
the middle of a field, with no obstructions near it. Then wait for a day
with some wind and see what happens.

Kevin Horton

On Mon, 29 Mar 2004 20:46:31 -0800, Corrie wrote:

> You'd have to mount it up above the cab - the wind in the back of the
> truck won't be parallel to the top and bottom surfaces. It blows off the
> back and curves down around the back and blow around and eddy and
> turbulate and all that. 'Course, so will real wind.
>
> Mount the contraption firmly, though, and it won't flop around.
>
> (Wright1902Glider) wrote in message
> >...
>> Well, the redneck school of engineering recomends that you make a quick
>> prototype out of poster board/foam board/sheet metal/whatever. Then
>> mount the sucker in the back of a pickup truck, as it would hang
>> normally, making sure that its in the free-air stream.
>>
>> To test, start driving and watch the rear-view mirror. That should
>> answer most of your questions real quick.
>>
>> Just a thought,
>> Harry "10 tie-downs ain't enough" Frey Wright Brothers Enterprises
>> Wright 1902 glider, 1899 kite, 1878 Bat

[Richard Lamb]

Joel Price wrote:
>
> Dear Group,
>
> Dear Group,
>
> I am developing a light weight product that will be hanging outside
> and wanted to ask your collective wisdom about wind effects on it's
> shape. It is approximately 30 (28 on shorter surface) x 40 x 2
> inches. It has a symmetrical shape (with respect to leading and
> trailing edges), basically a trapezoid (kind of like a stackable bin).
> It will look something like this character picture if it comes out
> correctly on your browser and font.
>
> _________________________ / ^
> / \ /______wind |
> /___________________________\ \ | lift?
> \
>
> I am trying to anticipate or design how this thing will move in the
> wind. The wind would be coming perpendicular to the 2 inch width,
> that is, parallel to the flat top and bottom of the trapezoid. I want
> it to not flap around so I am trying to create a shape that will force
> it to flap backward (in the direction of the shorter surface) in a
> wind and more or less stay there.
>
> Any opinions?
>
> Thanks in advance.

Well, dog gone it. No, it probably will just blow around in the breeze.

When the wind hits the sloping side, the thingie will probably pitch
some. All bets off then.

There is nothing there to hold the thingie in pitch...

Just my opinion, could be wrong.

Richard