X-Mozilla-Keys:                                                                                 
Al Gietzen wrote:

Paul;

tape. The fiberglass should have
some ribs or other stiffening techniques as it will be
subjected up to about 100 pound per square foot pressure
at 200 MPH and above. It must be bolted to the sides of the
rads as under this much pressure it will try to separate.

I think that even if you got 100% pressure recovery the pressure at 200mph
at the rad face would be only about 50 lb/ft^2 (.36 psi); and it decreases rapidly
moving toward the inlet.  Of course maybe you have a diffuser generates more
pressure than the dynamic head in :>).

Al

You are right Al. I should have said 275 MPH because as Fred just
pointed out external diffusion will take it down to 50 pounds
per square foot at 100 MPH. 

But the the dynamic pressure is indeed 104 pounds per square foot at 
100 mph and not the 50 pounds per square foot you mentioned..

The formula is MPH^2 X 0.0026 for pounds per square foot.

So at 275 MPH the dynamic pressure is about 200 PSF. Half of that
is about 100 pounds.

I was just guessing on the conservative side for duct stiffness. 
Just in case we come up with a duct that will recover more than 50% :-).
 
Paul Lamar
 
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