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Can.i.say?

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- Thread starter Can.i.say?
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Can.i.say?

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A.T.

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http://en.wikipedia.org/wiki/Drag_equationI just want a general formula to figure it out.

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russ_watters

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Can.i.say?

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What do you mean cross sectional area?

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Can.i.say?

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I know I have been clocked at 210 mph fastest and 90 mph approx. slowest. I am not sure of average area of someone skydiving on with their stomach to the wind. But I was more thinking about the lift I get from my hands. Approx. 25 square inches

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Can.i.say?

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Is there something more simple? Area, wind speed=lbs?

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A.T.

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Area & wind speed is all you need there. You can look up the drag coefficient in some tables:Is there something more simple? Area, wind speed=lbs?

http://en.wikipedia.org/wiki/Drag_coefficient

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PhanthomJay

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zoki85

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And which one of these profiles is his body in a horizontal position?Area & wind speed is all you need there. You can look up the drag coefficient in some tables:

http://en.wikipedia.org/wiki/Drag_coefficient

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A.T.

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He didn't ask about his body, but something that is flat and has a surface area of 25 square inches.And which one of these profiles is his body in a horizontal position?

- #11

zoki85

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He wants to know how slow he can fall. In the wiki page you linked to, there's actually listed drag coefficient range for a "man in upright position"He didn't ask about his body, but something that is flat and has a surface area of 25 square inches.

(= 1-1.3). If it is measured, numerically calculated or somehow aproximated I don't know, but maybe could be of use.

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A.T.

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No, he already knows it's 90 mph.He wants to know how slow he can fall.

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PhanthomJay

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At 90 mph, the drag force on each outstretched flat- to -the- wind 25 square inch hand is 0.00256(k)(90)^2(25/144), where k is the shape factor (I'll use k= 1.3), which works out to about a mere 5 pounds of air drag force on each hand. So when falling straight down belly down with hands closed tight to your body versus hands open and extended away from your body, you increase your exposed area from the assumed 10 square feet to perhaps let's say 11 square feet including extended arms , and now your speed instead of being 90 mph is more like 85 mph, or that order of magnitude. As you know, the more surface area of your body you can expose to the wind, the slower will you fall. And you want a large drag factor...'flat out' versus 'curled up' yields a greater drag...I know I have been clocked at 210 mph fastest and 90 mph approx. slowest. I am not sure of average area of someone skydiving on with their stomach to the wind. But I was more thinking about the lift I get from my hands. Approx. 25 square inches

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