PPRuNe Forums - View Single Post - Very basic EPR question.
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Old 24th October 2007 | 08:37
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Capt Pit Bull
 
Joined: Aug 1999
Posts: 1,050
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From: England
seems a little low
Try quantifying it, you'll feel better. Back of an envelope approximation:

Say we have an engine with a fan diameter of 5 feet. Thats a radius of 30 inches.

pi R squared for the fan area gives about 2,800 square inches.

Atmospheric pressure at sea level 14.7 psi. EPR of 1.85 means the prssure differential is 14.7 *.85 = 12.5 psi.

Pressure x Area = Force = 12.5 * 2,800 = 35,000 lbs of thrust.

Pretty fair?
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