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Old 09-19-2015, 03:09 PM   #2 (permalink)
aerohead
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think

Quote:
Originally Posted by skyking View Post
I tried some of that when doing my first cardboard stuff on the beetle.
I had two hills, both of which i rolled on at a specific speed so as to avoid conflicts with traffic.
One yielded 59 MPH or so before it flattened, the other 61 MPH.
I think it needs to be slower to really see a CD change, more like high 40's or 50 tops.
What do you think?
My reasoning is, the drag is getting so high up in those speeds that a subtle change will be hard to quantify.
The only official tests done in the past are top speed testing under full power on a level track.
At top speed,we'd have a chance to discern a minor drag change,as there are formulas to do that.So my gut feeling is that 'faster',not 'slower' testing would be the order of the day.
Rolling resistance and powertrain losses would also have to be a constant during the test,so the test car would have be fully pre-warmed before starting.
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Last edited by aerohead; 09-19-2015 at 04:56 PM.. Reason: spelling
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