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Building Tips and technical articles. => 1/2 A building. => Topic started by: nathan Metzner on June 16, 2012, 06:09:33 PM
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So, I bartered a Cox Medallion out of my dad in order to build a beam 1/2 A with a little more umph. I ran it today with a few experiments. First I ran it with a standard head and a Cox 5X3 she ran a fairly stable 18,500. I then switched to a grish 5.5X3 She ran 17,100. Next I used a APC 5.7X3 17,200. Then I switched to a Merlin adapter head with the hot plug. I stayed with the APC prop as I liked it the best. I started with one head gasket and it ran 17,900 - 18,200 Then went to two head gaskets and it ran a very stable 17,800-18,00. I then used three head gaskets and it went 17,700 but was unstable. So I am sticking with the APC prop the Merlin Head and two head gaskets. I need a better fitting needle valve as this one was a little loose fitting. I am tickled pink I was not expecting it to perform this well. Now I got to get building.
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Hi Nathan,
I have been told (and not as a joke) that the Medallion will do a nice 4-2 stunt run, if desired.
BIG Bear
RNMM/AMM
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You know bill as I was running it it seemed to be pretty stable in a four stroke. I never tried to investigate it further but you may just be right.
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I am seriously considering building a 24" baby ringmaster for it.
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Hello Nathan, you can go to www.texastimers.com and scroll to the bottom of the page for needle valves. Be sure to read all the info available on the page prior to ordering. I believe Hank now has direct fit replacements for the Medallion. If not he had a tutorial on how to use what spraybars he had. These are fine like the Kirn Kraft needles. Keeping in mind that the Medallion is a single ported cylinder, which is essentially a Babe Bee with better adjustment. For a very few dollars, a Sure Start cylinder could be purchased and give you some more power if it's needed. Ken
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A little Teflon tape will seal up the threads on the needle valve. I run my Medallions with 6-3 or 6-4 props for stunt flights. Never checked RPM as the plane flies good for me. H^^
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Doug Galbreath has a VERY nice needle setup for the Medallion. Doug Galbreath (F1CDoug@aol.com) Here is his contact information. I have all my Medallions equipped with his needles. :)
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A little Teflon tape will seal up the threads on the needle valve.
I'm going to have to try this on my reedies. I was the "King of Cox" at an RC club when I was in my twenties, but somehow in my long hiatus from modeling I lost the recipe and haven't gotten it back.
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Kenneth, Thanks on the link for the NVA, As far as the cylinder I have a dual port on another motor; however, The single port on the medallion is subport and I have never had a babe bee run 18,000 on a 5.7X3 lol. She runs real good except needing a NVA. John, I am apprehensive about the teflon tape due to it geting in the motor or the extra diameter of the nv cracking the spray bar. There are a couple of people offering stock NVA's for her and a couple making aftermarket set-ups. I'll try the stock one first because this one is using a NV out of a sure start rather than the medallion specific one. I am hoping to be able to flip the thing over but other than that I am super tickled. John, I was thinking of switching to a 6X2 if the plane is too fast but I didn't consider a 6X3 or 6X4.
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The APC 6x2 makes a great stunt prop, lotsa power but speed is controlled. I use 'em on my .061s too. Wish someone made a 6x1.5, or 6.5x2, etc., or even a 7" with low pitch I could cut down. I know, I know, no market for it.