Research/theory on propeller shapes and airfoils?

spicmart said:

The blades on the foto has clipped tips similiar
to a German VS-9 prop with such as well.

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Sisu said:

Propeller design is a complicated and frustrating process involving black magic, voodoo, and invocations of the forces of the dark side. I've been around racing for many years and seen numerous attempts at prop design, modification and construction, and I've seen many very fine minds humbled. Having said that -- sometimes these things do work.

This guy spent months researching, cutting, grinding and reworking, and made his airplane almost 50 mph faster. You just never know...


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Engineman said:

RR Griffon with, I expect, the De Haviland contra-prop from a Shackleton. Difficult to judge, but it looks like maybe 20% reduction in dia, no doubt also running higher rpm.
Interesting if those swept-back tipped blades were re-cut from the originals or, redesigned and made new?
Excellent gif of De Havilland contra-prop operation by Sergio Pasquali.

Eng


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Sisu said:

Good calls. This aircraft formerly had Shacleton props just cut off with the tips cleaned up. Not an optimal solution, but cutting a low altitude cruise prop right through the meat, and living with the thickness and inappropriate profile were the only solution in the 1970s and 1980s -- there was no other choice for a Griffon Mustang prop. Thom Richard, the owner, got a sponsorhsip deal with a shop with one of those million dollar CNC computer milling machines. He had to work out the program and the company gave him a weekend day with the machine and personnel.and he cut a prop down according to the data he had worked out in the Caltech library.

He said it was a very scary process with an awful lot of points where it could have gone wrong. It all ended up working fabulously well.

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