Quote:
Originally Posted by AeroMcAeroFace
How much do you think (although of course there is no way of knowing without testing) of the benefit of your air curtains come from the increased surface pressures pulling back less, on the tapered sides of the car and how much do you think is thanks to better flow attachment causing better wake patterns?
I suppose my question is, all other things equal, on a non-tapered car would the resultant drag decrease be the same?
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Now
that's interesting!
I measured pressures down the side of the car and in the wake with air curtain ducts (front and rear, but a different design from Julian's, made of sheet metal). I found no change on the doors and wake (both directions showed exactly the same pressure with and without ducts), but a +10 Pa difference on the (tapered) bumper cover behind the rear wheels. Fuel economy testing suggests that overall the ducts are reducing drag slightly; I wonder if this is how?