As far as I can tell, aviation piston engine power output is typically measured in HP (horsepower).

Automotive engine power output is typically measured by running the host vehicle on a rolling road, or dyno or dynamometer. This directly produces a torque curve, which may be integrated with respect to RPM to provide a power curve.

Obviously it wouldn't make much sense to put a piston-engined aircraft on such a device. Instead, how is horsepower measured for aviation piston engines?

  • 3
    $\begingroup$ You can put engines on a dyno hooked up to the shaft directly. $\endgroup$ – ratchet freak Oct 26 '15 at 23:38

Like anything else a Dynamometer is used except the engine is bolted directly to it (most likely on a test bench). In a car a rolling road is simply a way to couple the tires to the dyno without having to have any custom fittings. For what its worth cars lose a bit of horse power in the transmission/drive shaft/differential so shaft horse power and wheel horsepower are not always the same. However in a plane the prop is bolted more or less to the end of the crank (with the exception of some planes with stepper gear boxes). In any case shaft horsepower on a plane engine is more or less whats available at the prop.

Here is a lycoming engine on a dyno

enter image description here


|improve this answer|||||
  • 1
    $\begingroup$ Also, long before the first engine is installed in a car on the assembly line, various pre-production examples are run on a dyno in exactly the same fashion. $\endgroup$ – FreeMan Oct 27 '15 at 14:38

How is horsepower measured for aviation piston engines?

One idea is to use a "shaft power meter".

|improve this answer|||||
  • $\begingroup$ Measuring it is one thing, but you actually have to absorb the power output somehow. And spinning a big propeller in a small room is not the best way of doing this. $\endgroup$ – Peter Kämpf Oct 27 '15 at 22:34

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.