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Unrun .75 AX

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Old 04-13-2012, 09:11 PM
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CrocEnd
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Default Unrun .75 AX

Hi all

Just purchased today brand spanker OS .75 AX

Q time:

Have a 13x8 Apc and 13.5x8 Bolly for run in but would like a 3 BLADE

What size drop down to, this engine is not for speed but old clasic pattern plane

(Intruder or Dirty Birdi )

Thanks anyone.

CrocEnd.
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Old 04-16-2012, 05:57 AM
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Default RE: Unrun .75 AX

Try going down one inch in diameter with the same pitch. However, since 3-blade props don't come in a lot of sizes, you'll have to accept what is close. Usually, though, for scale models, you use a scale prop for display, and a 2-blade prop for flying. 2-blade props are more efficient, and can be found to fit the model better.
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Old 04-18-2012, 03:38 AM
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Default RE: Unrun .75 AX

Thanx Bax,

I ran it on the 13.5 x 8 Bolly seems to heavy how can I say does not pull started at9800 and two 10oz tanks later a bit leaner
10300 rpm this at a run IN setting. Next will try APC 13x 8 mutch less it weight as well next.

Hear you on 1" less dai., will go for what I can get I think.

Cheer's CrocEnd...
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Old 04-18-2012, 06:19 AM
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Default RE: Unrun .75 AX

Try to have the engine running in the high 11,000's for best power and operation, though high 10's could be OK. We tend to run the engine closer to 12,000 RPM at full throttle on the ground, and prop accordingly. O.S. recommends props more for noise reduction than anything else.
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Old 04-20-2012, 07:29 PM
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Default RE: Unrun .75 AX

Bax

Just picked up some Master Airsrew tripple bladers I know there not the best
but will try. ( I can get them to balance some what well )

11x7
12x6
12x8

Hope to get in the mid 11000 mark, I do have webra .60 to .90 long pipe and header
to try as well after.

Cheer,s Croc
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