bcbigfoot wrote:
First thing this morning I went out with the TC and stuck the hose straight into the wind a foot ahead of the mirror and only got 2" WC at 55 mph. I will try some new tubing and a little alcohol, metal tube as suggested and see if I can get accurate data. If not I will look around for better test equip..
The 2-inches water column is pretty much what you should see. I am currently building a pitot tube to do some testing on my truck. I worked out the calculations this afternoon to see what kind of pressure range I would need and I found that at 60 mph, the pressure should be about 1.8 inches WC.
Also if measuring the air speed above the cab (assuming my musing about the Bernoulli effect are correct) having the low point static sensing side in the cab would give a misleading result. If the hypothesis is correct, the static air pressure will be reduced above the cab and therefore you need the static point there.
