Lee Schaumberg
Well-Known Member
Hello
500 ft lbs of torque at 4000 RPM = 380.8 hp. 500 ft lbs at 2000 = 190.4 hp. Torque times speed divided by 5252 = horsepower. These numbers are then corrected to 29.92 inches of mercury and 59.5 deg far at 0% humidity.
This is why some automobile engines have PSRU's . Building a good PSRU that is light and long lived is hard. Aircraft engines produce thier horsepower at a much lower RPM than automobiles. To turn the output shaft ( prop shaft ) requires horse power. Again that is speed times TORQUE divided by 5252 . This number then has to be corrected to the temp and pressure.
The reason aircraft engines run slower is turning the prop fast makes them run near mach 1 (inefficient ) and noisy.
500 ft lbs of torque at 4000 RPM = 380.8 hp. 500 ft lbs at 2000 = 190.4 hp. Torque times speed divided by 5252 = horsepower. These numbers are then corrected to 29.92 inches of mercury and 59.5 deg far at 0% humidity.
This is why some automobile engines have PSRU's . Building a good PSRU that is light and long lived is hard. Aircraft engines produce thier horsepower at a much lower RPM than automobiles. To turn the output shaft ( prop shaft ) requires horse power. Again that is speed times TORQUE divided by 5252 . This number then has to be corrected to the temp and pressure.
The reason aircraft engines run slower is turning the prop fast makes them run near mach 1 (inefficient ) and noisy.
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