HP required for speed?
HP required for speed?
(OP)
I realize theres a few varibles. Cd being one, and rolling resistance of the road surface, even gear set friction in drive train etc. Is there a place that has a listing of various drag coefficients for various vehicle types as well as aircraft?
After watching some bonneville speed record videos, got curious about a few things.
After watching some bonneville speed record videos, got curious about a few things.





RE: HP required for speed?
This might help:-
http://www.mayfco.com/tbls.htm
RE: HP required for speed?
I also found this.
RE: HP required for speed?
Acceleration simulator
To understand what affects drag, this should help:
Vehicle aerodynamics
RE: HP required for speed?
RE: HP required for speed?
RE: HP required for speed?
Weight is more to do with acceleration, although it does impact on rolling resistance, but the faster you go the less important that becomes as part of the overall equation as aero goes up exponentially and rolling resistance probably goes down due to lift unless you have big wings.
Regards
Pat
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RE: HP required for speed?
- Steve
RE: HP required for speed?
If you're writing your own acceleration simulation and defining top speed as that where a = 0, be prepared to continually rewrite the whole thing as you decide that something else is important enough to consider.
Steve's right, and a halfway decent acceleration sim will show how long it takes to add the last couple of mph.
Norm
RE: HP required for speed?
Cheers
Greg Locock
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RE: HP required for speed?
I have done this recently, started out as a perfectly simple gear ratio calculator and somehow ended up as a comparison tool to compare different setups taking into account weight, tyre profiles gear ratios and a full two step power curve 'I am a Honda fan and wanted something that could represent a VTEC power curve' to give distance and time measurements for half, quarter and full mile drags, 0-60, 0-100, 40-80 and top speed runs.
Unfortunately it is of limited accuracy as it ended up with Excel telling me I could not add any more variables as there was no more space in the cells!
Monster task though, the spreadsheet weight in 6MB!
RE: HP required for speed?
It'll always be an approximation. At 6MB, it sounds like some things are being polished a bit more than necessary.
Norm
RE: HP required for speed?
I also wonder about driveline drag which is significant, about 10-15% of horsepower, and being proportional to HP, if represented as a drag factor, should be proportional to the CUBE of velocity. I think it is accounted for as merely an excess power needed to reach a particular speed.
Anyway, related to aero lift is a tire slip factor that often foils speed projections at Bonneville.