Quote:
Originally Posted by jimepting
Though we much admire his work, the Aero Civic is a much different animal than the Insight 1. Larger, more powerful engine for one thing. Do you see a problem with my math? Lets stick to substance on the Insight. Cross car comparisons are of limited value.  |
Jim,I think the premise of the math is okay.
The power absorption of the tires isn't going to very much so the rolling force will remain a constant,however at the higher speed,the power necessary to overcome R-R will increase.
If we knew the original R-R power at lean-burn,and working with ft/sec velocity,then :
Power(RR)=[ initial lean-burn velocity/550( lb-ft/hp)x ( R-R drag force [weight X coefficient RR] )]
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New Power(RR)=[ new velocity/550 X ( R-R drag force )]
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Once you're cruising at the new lean-burn velocity,the only variable you changed was the Cd.
Acceleration affects(Polar moment of inertia) have disappeared.
If the BSFC characteristics of the engine are 'flat',as the power curve suggests,then projecting the required Cd seems reasonable.