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Pattern props for the big block .61?

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Old 09-08-2014, 01:10 PM
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Jim Oliver
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Default Pattern props for the big block .61?

Hi Bob,

Educate me on props/rpms for the big block 61 for pattern use. I will be using the Jett 61/90 size muffler with a ~ 1/4" extension to get the muff below the wing just a bit, probably 10-15% fuel. I am at about 400 msl.

I expect to use an APC 11x7 or 11x8 for actual flying, unsure of what rpm to expect.

Thanks,
Jim

Last edited by Jim Oliver; 09-08-2014 at 07:16 PM. Reason: added details
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Old 09-21-2014, 12:35 PM
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Hi Jim .. sorry for delayed reply.

.61 big block engine is rare. Were custom built. But it uses the same jettstream muffler as the .90L.

Rpm range and target is the same as .76 big block. Expext peak rpm around 14000 with 11x7. Launch rpm.. find peak rpm and back off 500-800. Needs the fuel to unload in flight.

The extension will drop the tune rpm 200-300. But it will do better with 11x8 like that
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Old 09-21-2014, 06:17 PM
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Jim Oliver
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Bob,
Thanks for the comment about the extension vs. the 11x8; thought that might be the case.

Jim
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