Cox vs. Apc

JPvelo Thu Sep 06, 2012 2:40 pm

Starting to play around with an engine for the tach race using an apc 5x3. How much difference in performance can I expect with a cox 5x3? Just curious.

Thanks, Jim.

Ken Cook Thu Sep 06, 2012 3:13 pm

I personally don't use a tach. One thing for certain, the APC 5x3 has a thinner blade area which also tapers to the tip. Although the blade is thinner the design is more effective. I found this prop to generally provide more speed when using. The Cox black has a wide blade area all the way to the tip which absolutely provides more load on the engine. I would try the black over the grey. The grey isn't going to flex. The black under load probably provides less thrust than the grey due to the flexing therefore giving you more rpm's. Ken

Jason_WI Thu Sep 06, 2012 7:08 pm

If you are setting up an engine for the tach race then using a Cox grey 5x3 is probably the best to get a baseline of where you are at. The APC will wind up more.

**RknRusty** Thu Sep 06, 2012 8:43 pm

Yes, the APC props turn scary fast RPM compared to all of the others. I have an engine mounted in the shop I can use to compare them. I'll try each type tomorrow and post the results.

JPvelo Thu Sep 06, 2012 8:49 pm

Thanks Rusty, that would be awesome.

**RknRusty** Thu Sep 06, 2012 9:40 pm

The suspense was killing me. I just ran a Black Widow with a balanced Cox standard 5x3 and an APC 5.5x2. That's as close as I could come.
I burned a couple of tanks to warm it up and the Cox prop ran at 15.9k RPM and the APC ran at 19.2k RPM.

JPvelo Fri Sep 07, 2012 12:18 am

Not what I wanted to hear. I was pulling a solid 19.6 with an apc 5x3 and 25% nitro. Ordered some cox grey props today so we'll see what happens.

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Cox vs. Apc

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