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Old 09-28-2019, 10:33 AM   #51
DickR
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Quote:
Originally Posted by thinkxingu View Post
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Though isn't there a formula that says a major increase in speed requires a doubling of horsepower or something?
IIRC, the drag force on a plane surface goes up with speed to the 1.8 power. That would make horsepower go up with speed to the 2.8 power (almost speed cubed). Offsetting that would be factors like hull shape, reduction in wetted surface with speed, etc. But otherwise, yes, going just a modest amount faster usually requires a huge increase in power.
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