NiBrAl propeller

The design and stress test of a 4 bladed NiBrAl propeller.
NiBrAl is a aluminium bronze material, it stands for Nickel, Bronze, Aluminum, not Nickel Broom and Aluminum as the ´Br´ would suggest.

The propeller has been designed and tested up till 5000 RPM centrifugal force for material strength purposes and 5000 RPM in a water basin to see the water pressure on the blade at such high rotational speeds. These stresses could give a indication where the propeller could be optimized for strength purposes. Also the lift and drag characteristics of the current design are determined.

Vibration in the propeller could be very dangerous. It is of importance to find the natural frequencies at which the propeller loses its structural integrity. 5 modal frequencies are found.