Quote:
Originally Posted by jimepting
I would have thought the rolling resistance data would be available from the folks who provide speed trials tires. There must be some source of this data at an event like the Bonneville Trials.
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I like to think that at some level,power absorption data would be available over the speed range of a particular tire at 'normal' load.
Nobody in N.Texas can tell me anything about Goodyear racing tires.
Cal Tech was provided with calibrated tires for coastdown tests at Edwards AFB,California.Those numbers are produced on a steel-drum roller though.During tests,the pressure and temperature had to be factored.
Walter Korff of Lockheed Aircraft Corp.,designer of the Summer's Bros.'Goldenrod',in a 1963 SAE Paper did include a power curve (probably for Firestone bias-ply speedway tires) up to 150 mph.It's the only thing I've seen like it.
I've been told about a curve which went to 250 mph but have never seen a copy.
If any 'spare time' comes along I'll root around some more.
By looking at drag-limited top speeds for cars in which their Cd and Af are provided,and test weight can be closely estimated,from the gearing and engine rpm at that speed,we can kind of reverse-engineer brake-horsepower available.Modern dual-clutch automatics are as efficient as manuals,so 92% mechanical efficiency for the powertrain can be used.
With the power known,and subtracting out the air drag horsepower,the R-R horsepower is left,and using the test weight,a R-R force coefficient falls out.