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Cox .09 Medallion engine tests, or rpm readings.

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Cox .09 Medallion engine tests, or rpm readings.

Post  smooth_bill on Wed Apr 06, 2016 1:04 am

Hi Folks,

Looking for information on the Medallion 09 engines.

There were two Aeromodeller engine reviews of the Medallion .09, and I would love to have a copy, if anyone has the following old magazines.

May 1963 Aeromodeller - Medallion .09 review

Sep 1967 Aeromodeller - Medallion .09 review

Mine came with a plug adapter head that looks like Mecoa, and ran poorly. Replacing it with a new Cox Medallion glow head upped the rpm a minimum of 600, but I have no idea what to expect?

Any information appreciated!

Bill
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Re: Cox .09 Medallion engine tests, or rpm readings.

Post  KariFS on Wed Apr 06, 2016 1:13 am

Bill, the Sep 1967 review is here (lots of other reviews too):

http://sceptreflight.net/Model%20Engine%20Tests/Cox%20Medallion%2009.html

That's the RC version though, not sure if there is notable difference between RC and standard versions.

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Re: Cox .09 Medallion engine tests, or rpm readings.

Post  smooth_bill on Wed Apr 06, 2016 6:10 pm

Kari,

Thanks for the link.

I read that review some time ago, and the only rpm figures given are at idle speeds, with several different props. I'm not sure why they did not test at WOT with different props?

I have found that R/C engines typically have higher WOT rpm than C/L versions of the same engine, probably because idle and WOT mixtures can be adjusted separately for optimum performance.

Sorry, I didn't make note of that publication date and realize that I'd already read that review, but the list I got that pub date from didn't state the engine was exhaust throttle equipped.

I hope the earlier review is for the C/L version.

Bill
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Re: Cox .09 Medallion engine tests, or rpm readings.

Post  Cribbs74 on Wed Apr 06, 2016 10:30 pm

Bill,

Take a look at the graph if you want to see performance. Usually CL engines outperform RC engines due to less restriction, albeit with a narrow margin. Everyones hands on experience varies though.

Ron
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Re: Cox .09 Medallion engine tests, or rpm readings.

Post  getback on Thu Apr 07, 2016 8:15 am

Bill , there are reading of RPM test in the Instruction Sheets to the left under latest topics , have you looked at them? Eric Small Cox Logo
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Re: Cox .09 Medallion engine tests, or rpm readings.

Post  KariFS on Thu Apr 07, 2016 9:20 am

Eric, that was a good idea Smile

Looks like the 09 Medallion is not exactly an rpm monster, the manual states as follows:

6D x 4P - 15000rpm (smallest prop)
8D X 4P - 10800rpm (biggest prop)

What kind of rpms did you get Bill and with what kind of propellers?
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Re: Cox .09 Medallion engine tests, or rpm readings.

Post  smooth_bill on Thu Apr 07, 2016 5:52 pm

Kari, Eric,

The prop I used was a Master Airscrew 7X6 composite, but my fuel was 25% Castor oil! As I recall the readings were 10,000 with the glow plug adapter, and 10,600 with the OEM Cox glow head.

My local hobby shop has no wood props under 9" diameter, so I'm waiting for the new Master Airscrew wood props due out in Sept. They are supposed to include props down to 8" diameter.

Unfortunately, the Cox instruction sheet gives no indication of prop style, or fuel used for their readings.

Oddly enough, this used engine was leaking compression (bubbles) when flipped slowly, but after re-seating the ball socket, and running a couple times on the bench - it no longer leaks!

Thanks everyone for your comments. I have a copy of the instruction sheets, but had indeed missed the rpm readings!

Bill
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