# How much "Thrust" could WWII aircraft such as the P-51 P-47 generate?



## csteimel47591 (Oct 18, 2011)

Greetings,
I've always wondered if there has been any research or conversions showing the amount of "thrust" some of these old warbirds could produce? After the engine dumped it's power in the prop and the prop transfered it to the air, how much was the reaction force (in lbs) which propelled the aircraft forward? 

I thought it would be interesting to compare it to those figures of the turbo-jets.

Thanks,
CS


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## Ivan1GFP (Nov 10, 2011)

An Aero Propeller is surprisingly efficient. Under ideal conditions, it can convert about 70-80% of the power supplied into thrust. If I were just trying to estimate, I would use a low forward speed such as 15-20 mph and 70% efficiency to do the calculations and see what results. The formula for static thrust is different if there is no forward motion.

- Ivan.


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## krieghund (Nov 18, 2011)

Here is a primer on jet engines from the 40's which touches on this subject

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## thunderbird (Apr 19, 2019)

props generate about two and a half pounds of thrust static as a very rough, starting point guestimate. At high speeds, props get around 80-85 percent efficiency, but at climbing speeds, takeoff speeds, the efficiency is much lower, (and being defined as zero percent at zero velocity ). How much power the prop can absorb and turn into thrust is complicated, but is affected by among others, the number, width, shape, pitch angle and twist of the blades and diameter of the prop.


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## pbehn (Apr 19, 2019)

Thrust does not only come from the prop but also from the exhaust


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## Shortround6 (Apr 19, 2019)

"Thrust does not only come from the prop but _can_ also _come_ from the exhaust."

This rather depends on the exhaust pipe/stacks configuration and turning thrust into power was very speed dependent as unlike a variable pitch propeller, there was no way to adjust the exhaust gas exit speed to the speed of the airplane.


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## Zipper730 (May 27, 2019)

Whoops! Deleted


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