Quote:
Originally Posted by Phase
I would extend the sides. I’m saying the angle would be very minimal. Most of the low Cd cars out there just have a long roofline and the width in the rear isn’t as narrow as how most ecomodders do their after market boat tails. I understand it’s not as optimal, but in theory a proper boat tail would give me an average of 10 extra mpg, but I’m willing to add some styling personality and say, get only 8 mpg
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I would respectfully submit that, all low drag cars use as much plan-taper boat-tailing as length will permit. And the taper continually increases along a continuous, non-uniform, streamline path.
The 'angling' of the sides is pressure recovery, along with injecting the higher pressure flow 'towards' the wake, 'multiplying' the effect. Ask a tuna.
Also, since we're talking about a 'fastback', their drag is the most sensitive to tumblehome.
As the sides extend rearwards, their 'tops' should also simultaneously 'fall' inwards, along with incrementally increasing in radii.
It's a very 'complex' build if you're going to get it right.
Any benefit accrued to the tail will be dependent upon the care you take in it's design and dimensions.