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Subject: Re: [LML] Re: Apologies to the farmer's daughter
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Mike,
 
I never studied parachutes, but I think round parachutes work primarily from 
velocity pressure. The formula is pressure = 1/2 * density * v^2. Pressure 
must be constant at equilibrium, so velocity would vary more or less with the 
inverse of the square root of density. This ignores viscous and aerodynamic 
effects, which I would expect to be small.
 
Thus, for standard atmosphere, the speed at sea level would be about the 
square root of 2.048/2.377, or 92.8% of the velocity at 5000'. Based on the 
assumed 1500 fpm decent rate at 5000', this would yield a sea level decent of 1392 
fpm or 23.2 fps. This is equivalent to stepping of a 8.36 ft ladder.
 
Rob



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<DIV>Mike,</DIV>
<DIV>&nbsp;</DIV>
<DIV>I never studied parachutes, but I think round parachutes work primarily=
 from velocity pressure. The formula is pressure =3D 1/2 *&nbsp;density * v^=
2. Pressure must be constant at equilibrium, so velocity would vary more or=20=
less with the inverse of the square root of density. This ignores viscous an=
d aerodynamic effects, which I would expect to be small.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Thus, for standard atmosphere, the&nbsp;speed&nbsp;at sea level would b=
e about the square root of 2.048/2.377, or 92.8% of the velocity at 5000'. B=
ased on the assumed 1500 fpm decent rate at 5000', this would yield a sea le=
vel decent of 1392 fpm or 23.2 fps. This is equivalent to stepping of a 8.36=
 ft ladder.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Rob</DIV><BR><BR><BR><DIV><FONT style=3D"color: black; font: normal 10p=
t ARIAL, SAN-SERIF;"><HR style=3D"MARGIN-TOP: 10px">Get a sneak peek of the=20=
all-new <A title=3D"http://discover.aol.com/memed/aolcom30tour/?ncid=3DAOLAO=
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=3DAOLAOF00020000000982" target=3D"_blank">AOL.com</A>.</FONT></DIV></BODY><=
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