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Cox Engine of The Month
June-2018
Davenz13's

".049 Bee"



PAST WINNERS
Speed Contest 2018
CEF Traveling Engine

Win This Engine!
The Traveling Prop
Gallery


World of Aviation

Recent engine acquisitions

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Re: Recent engine acquisitions

Post  roddie on Sat Jun 16, 2018 5:02 pm

Loddie likes your latest engine acquisitions.. Leally tellific.. Smile
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Re: Recent engine acquisitions

Post  MauricioB on Sat Jun 16, 2018 10:04 pm

Congratulations Kari !!, well deserved you have those engines, they are very well taken care of in your hands! Thumbs Up
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Re: Recent engine acquisitions

Post  GallopingGhostler on Sun Jun 17, 2018 10:39 pm

My recent engine acquisitions, A Norvel .40 Big Mig R/C and a Cox .049 Medallion.



I wanted a reasonably powerful yet light engine for my Goldberg Falcon III (Falcon 56 Mark III). It is a tad heavier because of the light ply fuselage sides and slightly beefier construction over the original one, so my Enya .35-V TV would be slightly underpowered at my 4,300 ft (1,311 m) location. My MDS Pro .46 is heavy, although it would work.

I picked up the Norvel at half the cost of new, it still has plenty of compression. The Medallion was for under $30 shipping included. It is stiff from congealed Castor, so I'll have to gently heat it, disassemble and clean. I was wondering how it might perform with a new Sure Start cylinder and Cox OEM exhaust throttle muffler. I have an extra Norvel extended clunk tank that would make a compact package to use on one of my .049 RC planes.

Just just won tonight a near NOS K&B .35 Stallion:


It has casting imperfections, which seemed to be the norm 60 - 70 years ago, cost $30 shipping included.

Also just won a Cox .049 Dragonfly with white fuel tank:


It was also $30 shipping included. A departure from traditional black, I don't know if these were used on a Cox RTF R/C plane or not. I liked the fuel capacity of the R/C Bee. This one has a touch more, which makes it nice for longer R/C flights.
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Re: Recent engine acquisitions

Post  ticomareado on Mon Jun 18, 2018 8:20 am

If the Medallion cleans up good and the original piston cylinder still has good compression, you're rolling a set of loaded dice on switching to a Sure Start top end. Otherwise, it would only be worth it from your perspective if you've got good two port non SPI sure start top end if you have to have muffler. IMHO.

Your carb body looks a little chalky and will probably benefit from a careful coating of West System epoxy. I know zero about the big engine.
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Re: Recent engine acquisitions

Post  GallopingGhostler on Mon Jun 18, 2018 10:00 am

ticomareado wrote:If the Medallion cleans up good and the original piston cylinder still has good compression, you're rolling a set of loaded dice on switching to a Sure Start top end. Otherwise, it would only be worth it from your perspective if you've got good two port non SPI sure start top end if you have to have muffler. IMHO.

Are you sure about the Sure Start cylinder? I just pulled the head off of mine, one I purchased from the Estes surplus engine sales outlet back in 2004. It has dual ports with dual boost ports. It appears to be the same as the one sold by Cox International, new parts salvaged from unsold engines:

Cox Engines CA, Cox .049 Cylinder and Piston

Cox International wrote:This item is derived from disassembling brand new, never-run, engines and may show minor traces of having been mounted and/or minor tool marks.

Cox part # 1472

Features:
Non sub-induction
Dual bypass ports
Dual boost ports - extra power
Slit exhaust to lessen burn risk
Brand new Original Cox item

It is a development from the QZ days, where the designers were attempting to come up with a solution to muffling without significant power loss. Power loss was due to SPI inducing exhaust gases back into the cylinder since muffler cut off the fresh air stream. My late 1970's R/C Bee muffled with such a cylinder had more power than the Babe Bee with single bypass unmuffled.

Peter Chinn's 1967 test of the Cox .049 QZ showed 0.065 HP at 15,000 RPM.

Sceptre Flight Model Engine Tests, Cox 049 QZ

According to Peter Chinn's 1966 engine test of the .049 Medallion with R/C throttle, peak HP of 0.064 occurred at 12,500 RPM. According to H.R. Warring's 1961 engine test, the Cox Golden Bee's peak HP was 0.0625 at 14,000 RPM. Looking in the exhaust port, my Medallion has a single bypass port like the Golden Bee.

Sceptre Flight Model Engine Tests, Cox Medallion 049 RC
Sceptre Flight Model Engine Tests, Cox Babe Bee & Golden Bee

As you may see, there is much room for improvement for the muffled Medallion. Here is where I see the bottleneck is, the single port SPI cylinder in muffled condition:

Peter Chinn wrote:Since the Medallion features sub-piston supplementary air induction (i.e. the piston skirt clears the bottom edge of the exhaust port as TDC is approached and thereby opens the crankcase to atmospheric pressure) there is a rather bigger drop in maximum power output in the throttle equipped version than would normally be the case. This is because when the collector housing is fitted, residual exhaust gas, rather than fresh air, finds its way into the crankcase. One would expect this to be particuarly noticeable at high speeds and, in fact, this was exactly borne out by our tests on all the Medallion models when comparisons were made with and without the Throttle Control fitted.

If it were unmuffled, I'd go instead with a Tee Dee cylinder with SPI and a throttle ring. My Medallion has a single bypass cylinder with SPI like the Babe Bee or Golden Bee. There is a lot of room for improvement, and AFAIK, no one has yet to do a test with the dual bypass non-SPI cylinder, so I think it is worth giving a shot.

Would you not agree?  Very Happy

Your carb body looks a little chalky and will probably benefit from a careful coating of West System epoxy. I know zero about the big engine.

The photos don't really do it justice. It is actually better than it appears, with a coating of dust, like it laid exposed on a tool bench or basement shelf for a long time. I was able to wipe portions off with my finger. The plastic is bright red underneath, which tells me it has not seen much daylight after being stored from running. Very Happy

So, regarding the non-SPI dual port cylinder, I think it worthwhile to at least try. After all, if trials using the non-SPI cylinder proves promising, may set a precedence and new direction for using the Cox .049 Medallion for muffled flights. Huh... Are there any others out there who might want to give it a shot? Surprised
Would you not agree? lol!
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RE: Recent engine acquisitions

Post  66 Malibu on Mon Jun 18, 2018 11:24 am

Kari
Great score !!!! You're quite the treasure finder !!!
Regarding the muffler you pictured, it is a Tatone "MUFF-L-IT" #300 muffler for Cox 1/2A Engines.
I'm guessing late 1960's to maybe late 1980's ? vintage . No date on the instructions on back of the package.
The small aluminum ring is the spacer sealer ring to seal the muffler to the cylinder. Unfortunately it takes two spacer rings to mount the muffler properly.
The rings are kind of unique but I stumbled ( as usual) on a suitable substitute after the first muffler I found only had one ring also.
While looking thru a box of spare small car parts, I found a small blue steel spring O-ring that fit perfectly. You might go to your local auto or hardware outlet and look thru their O-ring assortment.
FWIW, Steve...……….
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Re: Recent engine acquisitions

Post  Jason_WI on Mon Jun 18, 2018 5:46 pm

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Re: Recent engine acquisitions

Post  Jason_WI on Mon Jun 18, 2018 5:48 pm

GallopingGhostler wrote:

Also just won a Cox .049 Dragonfly with white fuel tank:


It was also $30 shipping included. A departure from traditional black, I don't know if these were used on a Cox RTF R/C plane or not. I liked the fuel capacity of the R/C Bee. This one has a touch more, which makes it nice for longer R/C flights.

With the white tank its a Ranger V engine used in the RTF planes. Harder to find than the Dragonfly. Nice find.
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Re: Recent engine acquisitions

Post  GallopingGhostler on Mon Jun 18, 2018 8:42 pm

Jason_WI wrote:This is on its way to me now.

RCGroups: 1959 Cox Olympic 15 In Original Box NIB $165.00 Free Shipped!!



Never seen one with the cardboard sleeve intact.

Nice, you don't see those often, first I've seen of a ball bearing crank on an earlier Cox, plus in the spirit of Red, White (silver aluminum) and Blue. Eyebrows (OT) May be this is what some were thinking of color wise for the next Cox International special engine? Huh...
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Re: Recent engine acquisitions

Post  GallopingGhostler on Mon Jun 18, 2018 8:46 pm

Jason_WI wrote:
GallopingGhostler wrote:Also just won a Cox .049 Dragonfly with white fuel tank. It was also $30 shipping included. A departure from traditional black, I don't know if these were used on a Cox RTF R/C plane or not. I liked the fuel capacity of the R/C Bee. This one has a touch more, which makes it nice for longer R/C flights.

With the white tank its a Ranger V engine used in the RTF planes. Harder to find than the Dragonfly. Nice find.

Thanks for clarifying, Jason. I didn't know that the Ranger version was a rarer find. In the RTF's, was the cylinder mounted vertical as shown, or was it to the side pancake style like the Dragonfly?
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Re: Recent engine acquisitions

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