Quote:
Originally Posted by drmiller100
Hey Aero,
if we take the car in the picture above, and start right above the back window.
then we angle down at 20 degrees. Will we end up with almost the same aero, but have a much shorter car?
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I'd hoped to have Walter Lay's work posted by now.Hucho touches on it but kind of butchers what he did.
Lay did not follow the 'Template' per se,but he did pull the roofline down gently for the 1st 15% of the 'Template' to a 18-degree angle,and then held that constant slope out to 88% of the 'Template.'
He bent the sides in gently,starting at 10% of 'Template',into a 12-degree inward slope and held that constant 12-degrees all the way to 88%'Template',where the body ended in a point.
Lay published Cd 0.12 for the model.
Four of his models were reported at Cd 0.12.They all had 100% tails.All the tails were identical.The models only varied at the front.
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His models end at 88% of 'Template' with Cd 0.12 for a simple model with wheels.
I'm representing Cd 0.13 at the same length and I mean to be conservative in light of the wheel fairings.
Lay's tail would 'tin-can' and would require internal bracing across all spans,like Lindbergh's Ryan Flyer or Beech Bonanza.
The 'Template',being ovoid,is among the strongest structures known,would require no bracing and can be made the lightest of all,which is a non-aerodynamic driver for its choice.Of course,it's also the most complicated to fabricate as there isn't a straight line on it anywhere.
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20-degrees might work.It did okay on the VW and I think NASA stayed around 20-degrees with their Ford van.
Lay's design would be a no-brainer,it's a little more conservative,but he got pretty tasty numbers.With cooling system mods,skirts,MOONs,and wheel fairings,I don't see any reason why the gas pumps wouldn't be suicidal towards it.