C-85 Props

flybuoy · Post by **flybuoy** » Wed Mar 04, 2026 7:05 pm

Is anyone using a 1B90 CM pitched at 44 inches for a land based airplane?

Post by **6643** » Wed Mar 04, 2026 7:59 pm

Not I, but, I would be surprised if it met the static RPM requirements.

6597 · Post by **6597** » Wed Mar 04, 2026 8:26 pm

I have a 1B90 CM 71"x42" pitch on my 0-200, static maximum 2400 static minimum 2100, from an approval from Witchita. Climbs like crazy but have to watch redline when I level out. I call it the seaplane pitched prop. I think a previous owner, when coverting to the 0-200, didn't want to spend the $$ to get a 69x-- prop as per the Lucas STC so he somehow got an approval back in 1987. Yeah, I know, kinda different but I've learned to work with it for over 30 years...

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hotrodmac · Post by **hotrodmac** » Wed Mar 04, 2026 9:37 pm

According to my logbooks, I am. Static is around 2250. I’ve never had the prop measured though, so can’t confirm it personally. I’m guessing @flybuoy already knows that about my airplane though.

Post by **6643** » Thu Mar 05, 2026 12:44 pm

Diameter
- not over 71 inches
- not under 71 inches

I want to see the prop that meets those limits! (And the person who measured it!)

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