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Old 05-02-2008, 06:59 PM   #46 (permalink)
ptg0
EcoModding Lurker
 
Join Date: May 2008
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Kamm effect

Thanks for asking deisel. Dr. Kamm discovered that after wind tunnel testing different shapes, the shapes that were chopped off seemed to deliver lower Cd's. He determined that was occuring because the airflow over the body was allowed to take its most natural path of least resistance, which as we all know is what aerodynamics is all about. The path of least resistance. Shapes that had trunks for instance did not seem to be as efficient as those that were "chopped" off. That is why station wagon versions of sedans seem to have lower drag coefficients. (Cd) That is also why in Europe and occasionally here wagons are refered to as "Kamm Backs" (Vega of the 70's)
Now I am sure that we have all seen how short the lifespan of cloth tonnues
are. If you look at a truck with a soft tonnue, you will notice a large amount of vibration at the rear of the tonnue while at speed. That is because the
path of least resistance for airflow over the cab wants the air to hit the bed floor about 3'-0" before the tailgate. When you have a cloth tonnue, they
tend to have a steel rod in them that forces the tonnue up about 3'-0" before the rear of the vehicle in an attempt to prevent the vibration caused by the air taking its path of least resistance.

That is why I consider the tailgate to be a large contributor to the "frontal area" of the vehicle. Even though it is obviously not "IN FRONT" it IS in the
airflow over the vehicle. To design the aerodynamics around the "bubble of air" created by that disturbance is extremely short sighted. And only and IDIOT would call me a fool for making that statement. By the way, I figure the tailgate creates an additional 10 sq. ft. of DRAG.

My PATENTED "Aer-Lockers" take full advantage of the Kamm effect by smoothing out the airflow over the rear of the vehicle and allowing the airflow to take its "Path of least Resistance" That is why you do not see a substantial gain simply by lowereing the tailgate or removing it. The bed structure and wheelhouse design contribute a large amount of turbulence to the airflow over the rear of the vehicle. My boxes eliminate that. By the way, I have done extensive yarn studies to determine the airflow OVER the rear of the vehicle with EVERY design variance. MY BOXES WORK! And they work better that any tonnue cover. You see, tonnue manufacturers claim a 10% fuel economy increase. I contend that once again, they do not allow the air to take its path of least resistance, but my design does and that explains my substantially greater fuel economy gains.
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