I need to build a test stand for testing/rating props. It needs to run them at up to 7500 RPM and I will be measuring static thrust vs. power input. The current requirement is for testing 16x14 props, but I may need to do other sizes eventually. I'm thinking a large brushless airplane motor (2HP or so) might work. The stand will be stationary, so there will be only propwash for cooling and, to make things worse, there will be a 4 inch prop spinner and motor fairing to minimise turbulance. I can add cooling fins to the fairing if needed, and some vents for the motor, but it won't see anything like the airflow you'd have in flight.
Being a lab set-up, I don't have the usual power and weight limitations as on a plane. I just need to find an efficient motor setup that can spin the prop up to that RPM more or less continuously without smoke.
Is this even realistic, or should I be looking at another type of motor? I found some long-skinny DC servomotors that would fit behind the spinner, but they're big-$$ and it's hard to find one that will do that kind of RPM without gearing. Any advice?