[DeTomaso] Airflow test #2

[Matt]

Well I had a chance to make another test run Sunday morning. I used plastic laminate instead of yarn.Thanks for the suggestion Tomas.
I think it provided a more reliable test due to it would only show flow either in or out,not all over the place like the yarn.
Yarn works better for aerodynamic tests on the body but not in this case. The flow behind the Pantera is somewhat chaotic as most are aware.
The question is which direction does air naturally like to flow at varying speeds for optimum cooling for the rear mounted condensor.

"It sucks air from the outside in, which is problematic at high speeds.   
At low speeds it works fine, but as the speeds elevate, airflow is 
compromised as a stagnant region forms at the back of the car.   This means that the 
condensor (which is just a fancy word for 'radiator') no longer has any 
meaningful airflow, so the high-temperature gas in the system isn't cooled.   
Temperatures go up and pressures skyrocket, and BOOM you blow a hose, usually 
right near the compressor in the engine bay." Mike Drew

"The whole scheme seems to depend on the Pantera's 
aerodynamics: at speeds up to maybe 90 mph, air passing over the roof & out 
the rear window area join over the decklid   about 3-4 feet up and forms a 
big swirl behind the car that bends   back toward the rear bumper. This swirl 
feeds the condenser fan with a very slight positive pressure at lower speeds. 
But as speed increases, the swirl moves back further and further, so around 
the rear bumper, there's now a partial vacuum... and the condenser fan 
cannot suck enough air in to exchange heat from the condenser. So the AC 
head-pressure goes up until a hose blows off. Panteras didn't have a stock pressure 
safety switch. Its well known that stock Pantera AC didn't work very well, 
and didn't work at all above about 100 mph & we think this is the reason. 
Around town, the rear mount works fine but it may need the luggage tub in 
place to work best. Good luck- J DeRyke"

I would say this is more likely due to no safety relief valve or other weak link in the stock system, not lack of positive airflow at high speeds.
In fact to me, just the opposite of the believed theory seems to be true at higher speeds.
Myth busted?

Looking at the video I see 3 things.
1. Between 0-70mph flow is slightly negative.
2. At speeds above 80-90mph flow is more positive providing MORE air for cooling.
3.The general flow is always swirly and chaotic and not very strong either way, except at maybe speeds few would ever maintain for extended periods.

Next weekend I'll try it without the tub in just for grins. And then I'll be looking at the rest of the body aerodynamics in general.
If any conclusion can be made, I'll let you be the judge. 

http://www.youtube.com/nwpantera#p/u/0/Q83Im4mpdUE

The Ghost
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