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Question about the dynamic pressure in the lifting/drag coefficients

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Old   May 16, 2011, 23:26
Default Question about the dynamic pressure in the lifting/drag coefficients
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Hi all,
The Lifting coefficient is defined by (Lifting force )/(0.5*density*Velocity^2*Area)

Should I replace the denominator with (dynamic pressure * area)
which dynamic pressure = Total pressure - static pressure = (Ps)*[(1+0.2*M^2)^3.5-1]
(note: Ps= static pressure, M= mach number)

but when in compressible flow, we can find that the 0.5*density*Velocity^2 is different from the dynamic pressure(which is Total pressure - static pressure = (Ps)*[(1+0.2*M^2)^3.5)-1]

I am confused about which denominator should I use in Lifting/Drag coefficients. The 0.5*density*Velocity^2*Area or (Pt-Ps)*Area ?

Thanks

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Old   May 17, 2011, 12:23
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The first one.
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