Quote:
Originally Posted by mistareno
G'day.
Your photoshopping is far better than mine.
I was going to have the rear wheels completely enclosed and have the side panels hinged.
95% of the time it will be empty so I'm going to concentrate on the aero in the down position.
When it's up the tarp side idea is what I had planned, but to make it fit neatly, It would have to be designed for just one position - ie - fully up.
On a side note, the Schl'o'rwagen has a much steeper tail section than the template, yet still has a very low cd? Does it suffer flow separation?
The Schl'o'rwagen has a side profile that fits my wheelbase much better.
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At Cd 0.186,the pillbug is pretty sweet.The hash marks I've drawn in behind it designate the area compromising the boundary layer.A down-slope of 22-degrees is the maximum the boundary layer can tolerate.Buchheim found that at 23-degrees,the wake becomes that of a squareback.
If you stay on 'Template' you can get to Cd 0.13-0.12.With wheel fairings you can approach Cd 0.08.Here is the 2013 Cambridge University Eco Racer (CUER),with Cd 0.10.
For the lowest drag per length it's better to just truncate the 'Template' than pull the roof curvature into a steeper slope.The boundary layer cannot tolerate the increased pressure rise from the steeper slope,and will trigger flow separation and induce lift, exactly the thing we're trying to avoid.
Here is W.A.Mair's final boat tail schematic.Mair did special boat tail research and found the 22-degree angle to be superior.And you can see how much length he took before he got to 22-degrees.If you can follow my scribbling,you can assess the body drag at differing amounts of boat-tailing
