Has anyone done/know of any testing comparing different props and their noise levels at different speeds?

I would be interested in know how the noise of different prop lengths and designs varies by the prop speed.

Sorry if this is a newbie question.

Thanks,
James

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No this is not a Newbie question.

in most cases a longer fatter slower turning club makes less noise.

The noise from the prop can come from multipule things but the two that I notice most are just from the turblance caused by the blade. So a slower turning(may need a gearbox) larger diameter prop normaly makes less noise.

On our AT-301 air tractors we went from a plane that could be heard over 7 miles away at takeoff to one that can only be heard at 3, and we could now hear the engine over the prop.
We did this by incresing the prop length by ~10% going to 3 blades and dropping the RPM by 50%
Thanks for your reply.

I was assuming that slower speeds are less noisy but just wondering if anyone had done any actual tests of how speed, length, width, etc. relate to noise.

That would be helpful because it seems like most of the UAVs are noisy and reducing that noise would be a benefit in a lot of applications.

Your information on going to a 3 blade prop and reducing the RPMs is interesting. I guess that the knock against more blades is that the prop then has more mass and requires greater torque to turn. There must be resources comparing the number of blades, prop design, etc. at different speeds and the resulting thrust. Those would also be interesting.

Thanks,
James
MT prop out of Germany would be a good place to start looking for some data, I know that they helped us to play with the props. They do full sized planes but the theory does cary to the models as well.
Also MT does have a tool to check performace of the props using FEA, I don't know what the tool is but they might be willing to to give you the name of it.

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