McCauley CM 74/39 Propeller Question

Props, Spinners and McDowell Starter issues.
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akchamp
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McCauley CM 74/39 Propeller Question

Post by akchamp » Wed Apr 24, 2013 21:33

I just found a very nice McCauley 1B90 CM 74/39 propeller (original configuration). I've never heard of one pitched this flat for a Continental A-65 and am not sure what airplane it came off of. I plan to use this on my 7AC, but figured I need it twisted to a 43 pitch for the best climb performance. Am I on the right track? Thanks.

Paul Agaliotis
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Re: McCauley CM 74/39 Propeller Question

Post by Paul Agaliotis » Wed Apr 24, 2013 22:30

It sounds like a seaplane prop. I'd bolt that dude on and see what it performs like. I had a 70/38 on the L16 and it worked pretty good. I changed to a 71/44 and the climb was similar but the cruise was a little slower.
Props are a little strange, nobody really knows how they work.
Paul
Mailing Adress : Paul Agaliotis 2060 E. San Martin, San Martin,Calif. 95046

MikeB
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Re: McCauley CM 74/39 Propeller Question

Post by MikeB » Wed Apr 24, 2013 22:32

74/43 seems to be the standard prop for a 65 horse 7AC. At least the three Champs on our field have that pitch. They static at around 2150 RPM. I suppose 42 might give a bit better climb and more RPM. I never felt I needed more to fly out of our 2100 foot strip but then I'm a light guy and usually only fly alone. My .02 cents.

Mike

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