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Originally Posted by OKXXFE
So according to some info I found 'round here that I think may have originally been posted by Aerohead (?), the cooling system or just the engine bay in general is responsible for about 30% total aero. drag. By blocking off just my upper grill I achieved (conservative first estimate) 10-15% increase in FE. It will be interesting to see if fully isolating the airflow from around the engine will actually increase my overall FE to anywhere near the theoretical 30%. I know I have a whole lotta work to do in fabricating what I want and also the testing testing testing.
Does anyone know if the SGII or UG can compile select data for a spreadsheet? The easiest way I know to determine if variables are effective is to show it on a graph and plotting by hand is super tedious.
As it's Sunday, I think today is a good day for cardboard mockups and a trip to the hardware store! don't tell my wife...
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The experts would tell us to treat each vehicle on a case-specific basis as far as numbers go.
In the past,messengers suggested that a production cooling system would be responsible for about 12% of the overall aerodynamic drag.Hucho,in the mid-1980s suggested that the drag of a carefully designed cooling system drag could be reduced to 2% of the overall drag.
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Fiat published an SAE paper in the 1980s,based on wind tunnel studies of a 1/2-scale model with very detailed underbody.
Their tests showed that completely blocking off the cooling system didn't necessarily eliminate the cooling system drag.It might reduce under-body drag,while increasing upper-body drag.They did mention that this phenomena warranted further study.So this is the exception to the rule.************
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We do know that positive thrust was achieved in the North American P-51 Mustang cooling system do to heat flux air expansion.
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Walter Korff,aerodynamicist for Lockheed, tested the system diagrammed ,and demonstrated low drag.(so something as close to it should pay dividends).All NASCAR race cars use Korff's inlet geometry and airtight ducting.
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A look at the 1978 Pininfarina CNR 'banana' car illustrates the pains Dr. Alberto Morelli went to to design a low drag cooling system.(he could easily have spent a $100,000 in wind tunnel time just to develop the extractor vents,which blend the cooling system air at matched-velocity to the surrounding flow as it emerges).
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The 1987 Oldsmobile AEROTECH,closed-course LSR racer demonstrates careful attention to heat-exchanger airflow.
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We might want to think of mpg increases on the order of 6% for a perfect system.