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Hi all,

I've crunched some numbers using the formulas here.

Originally, I was optimistic about these numbers, until I double-checked them against another calculator here.

I'm confused. Is there a reason the wiki's calculation for power uses 1/2 the density of air, instead of the full density? I'm not claiming to be an expert or anything, but because of the substantial number difference I was getting I wanted to confirm. The second calculator also has a hard-coded slope, which will definitely affect the numbers as well.

Going to go back and run my numbers again making sure I didn't make a mistake.
 

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I'm confused. Is there a reason the wiki's calculation for power uses 1/2 the density of air, instead of the full density?
Drag losses are due to the energy required to move the mass of air around, and so it is governed by the equation for kinetic energy which is 1/2mv^2.

And before you ask, the reason why the wiki equation has v^3 instead of v^2 is because it is power which has an additional velocity factor. Think about it this way: if you double your speed, the power you need to overcome drag goes up 8 times (2^3) but it only takes you half as long to get to your destination so the energy you use only goes up 4 times (2^2)
 
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