Cox Engines Forum
You are not logged in! Please login or register.

Logged in members see NO ADVERTISEMENTS!


What Medallion is this? Cox_ba12




What Medallion is this? Pixel

Log in

I forgot my password

Search
 
 

Display results as :
 


Rechercher Advanced Search

Latest topics
» OCD TV-a pictorial of modeling madness
by roddie Yesterday at 11:31 pm

» Feed Station Zebra.. Spring 2024
by roddie Yesterday at 10:42 pm

» Does this book interest anyone?
by GallopingGhostler Yesterday at 9:54 pm

» tap.. tap.. tap.. tap.. tap.. tap.. (reset)
by roddie Yesterday at 9:23 pm

» Willy Nillie's Shoestring micro racer powered by COX TeeDee010
by roddie Yesterday at 9:06 pm

» Top Dawg is Going to S.M.A.L.L.
by Kim Yesterday at 8:47 pm

» Scientific Gulfhawk
by 944_Jim Yesterday at 8:39 pm

» Jim Walkers FireBee - This is going to be fun
by 944_Jim Yesterday at 8:05 pm

» music vids.. some of your favorites
by HalfaDave Yesterday at 7:41 pm

» S1 Ringmaster
by GallopingGhostler Yesterday at 7:13 pm

» Sold out Cox .049 silencers for sale
by 1/2A Nut Yesterday at 1:14 pm

» Pool music.. on a beautiful afternoon..
by roddie Yesterday at 9:08 am

Cox Engine of The Month
May-2024
1/2A Nut's

"Cox Tee Dee .051 RC Marine"



PAST WINNERS
CEF Traveling Engine

Win This Engine!
Gallery


What Medallion is this? Empty
Live on Patrol


What Medallion is this?

Go down

What Medallion is this? Empty What Medallion is this?

Post  kaplangmk Thu Apr 11, 2024 3:14 pm

Please tell me what Medallion engine this is and is it .09 or .15? What’s the ring around the cylinder for? It spins but doesn’t seem to have any function
Thanks .
kaplangmk
kaplangmk
Beginner Poster
Beginner Poster

Posts : 7
Join date : 2024-04-11

Back to top Go down

What Medallion is this? Empty Re: What Medallion is this?

Post  kaplangmk Thu Apr 11, 2024 3:18 pm

What Medallion is this? 0c293410
What Medallion is this? 1a81f010
What Medallion is this? 24c25810
kaplangmk
kaplangmk
Beginner Poster
Beginner Poster

Posts : 7
Join date : 2024-04-11

Back to top Go down

What Medallion is this? Empty Re: What Medallion is this?

Post  Ken Cook Thu Apr 11, 2024 3:23 pm

It appears to me to be the .09, the .15 utilized a different needle valve whereas the .09 uses the same one from the .049. The ring around the cylinder is a throttle ring for r/c use.
Ken Cook
Ken Cook
Top Poster
Top Poster

Posts : 5495
Join date : 2012-03-27
Location : pennsylvania

Back to top Go down

What Medallion is this? Empty Re: What Medallion is this?

Post  GallopingGhostler Thu Apr 11, 2024 4:00 pm

According to https://sceptreflight.com/Model%20Engine%20Tests/Cox%20Medallion%2009.html Sept. 1967 Aero Modeller Engine Test -  Cox .09 Medallion with Cox throttle control engine test by Peter Chinn
The cylinder bore measures to 0.497 inches. Your measurement, @kaplangmk is 31/64th inch or 0.484 inches. Considering the relative accuracy of a vernier caliper and its round off error versus a more accurate micrometer, your Medallion is a .09 one.

The .15 Medallion has a bore of 0.591 inch or 38/64th inch, so it definitely isn't a .15.
https://sceptreflight.com/Model%20Engine%20Tests/Cox%20Medallion%2015%20RC.html Dec. 1964 Model Airplane News Engine Review - Cox Medallion .15 R/C by Peter Chinn

If noise isn't a problem, you are blessed to have the unmuffled exhaust throttle ring. This allows air subport injection (SPI) to increase engine power. (SPI is the air gap at the piston skirt and exhaust port when the piston at top dead center.)

I have a muffled .09 R/C with an exhaust ring muffler, which reduces power by reintroducing exhaust gases into the air-fuel mixture essentially diluting the charge with inert spent exhaust gas. However, its weight is 3.38 oz. with muffler, which being light enough makes it a good upgrade for a larger half-A plane, for those wanting throttle control and where its modest power being muffled isn't a drawback.
GallopingGhostler
GallopingGhostler
Top Poster
Top Poster

2023 Supporter

Posts : 5362
Join date : 2013-07-13
Age : 70
Location : Clovis NM or NFL KC Chiefs

Back to top Go down

What Medallion is this? Empty Re: What Medallion is this?

Post  kaplangmk Thu Apr 11, 2024 7:18 pm

I’m still unclear what the ring is for. It spins in the groove but doesn’t change anything in the grove it rides in. Can someonevplease explain it in simple terms. The way it looks now if I completely remove it it will have no effect on the engines performance
kaplangmk
kaplangmk
Beginner Poster
Beginner Poster

Posts : 7
Join date : 2024-04-11

Back to top Go down

What Medallion is this? Empty Re: What Medallion is this?

Post  kaplangmk Thu Apr 11, 2024 7:19 pm

I’m  still unclear what the ring is for. It spins in the groove but doesn’t change anything in the grove it rides in. Can someone please explain it in simple terms. The way it looks now if I completely remove it it will have no effect on the engines performance
Thanks
kaplangmk
kaplangmk
Beginner Poster
Beginner Poster

Posts : 7
Join date : 2024-04-11

Back to top Go down

What Medallion is this? Empty Re: What Medallion is this?

Post  JPvelo Thu Apr 11, 2024 8:28 pm

kaplangmk wrote:I’m  still unclear what the ring is for. It spins in the groove but doesn’t change anything in the grove it rides in. Can someone please explain it in simple terms. The way it looks now if I completely remove it it will have no effect on the engines performance
Thanks

The ring is a throttle. It changes rpm by blocking the exhaust. Block the exhaust, engine slows down. Open exhaust and engine speeds up.
JPvelo
JPvelo
Diamond Member
Diamond Member

Posts : 1972
Join date : 2011-12-02
Age : 56
Location : Colorado

Back to top Go down

What Medallion is this? Empty Re: What Medallion is this?

Post  roddie Thu Apr 11, 2024 8:34 pm

Check out this YouTube video by our member Kim Stricker. He explains its function in the text at the beginning.. and then shows its function while the engine is running.


roddie
roddie
Top Poster
Top Poster

Posts : 8353
Join date : 2013-07-17
Age : 64
Location : N. Smithfield, Rhode Island

http://www.stilburnin.com

Back to top Go down

What Medallion is this? Empty Re: What Medallion is this?

Post  GallopingGhostler Thu Apr 11, 2024 9:19 pm

For these small engines, throttling or choking the exhaust gas release has the same effect as air intake carburation. However, one thing to note is that this action is not linear.

The ring's half open exhaust is not half throttle, it is more like 2/3rd to 3/4th throttle. Open about 1/3rd is roughly half throttle.

It works very effectively well for its simplicity. It is one of the most trouble free throttling systems around.

I was able to make my venerable Cox .049 R/C Bee, an exhaust throttle reed valve engine to function "linearly" with my quick blip sequential KRD throttle servo on my old Ace R/C Pulse Commander rudder only system. It had a single push button that one would tap with their finger.

For a normal R/C carburetor, it would command RPM's of High, then Medium, then Idle, then back to High. It's servo wheel went in one direction. When I used the servo with my "1965" OS Max .10R/C, it worked perfectly.

For the R/C Bee, through trigonometry, I figured out how to make the KRD throttle servo work with its exhaust throttle ring. I fenegaled it by:

1. Pushrod in servo wheel all the way forward, (0° for reference) exposed the exhaust notch in the ring against the forward edge of the cylinder's exhaust slot for idle. (It had this notch cut in the ring's exhaust window, not all rings have this.)
2. Then all the way back (180° rotation) pulled the ring back until 1/3rd of the exhaust port was exposed against the cylinder's rearward exhaust slot edge.
3. Next blip to mid servo wheel postion (90° rotation forward) held the ring in fully exposed exhaust for full throttle.
4. Back to Position #1 with a 90° rotation for again idle. Wash, rinse, repeat.  Arrow Cool

Back to the math, I was able to figure out where to drill a new hole in the servo wheel from the center for the engine pushrod, so that the range of motion would do exactly all of the above. My scheme reversed the servo's action so now it was Idle - Middle - Full throttle back to Idle, but I still had a blast with Minnie Mambo.

Flying my one and two channel half-A and A planes in college in the late 1970's / early 1980's helped me to maintain my sanity.

Ditto flying my planes while working in aerospace, too. lol!
GallopingGhostler
GallopingGhostler
Top Poster
Top Poster

2023 Supporter

Posts : 5362
Join date : 2013-07-13
Age : 70
Location : Clovis NM or NFL KC Chiefs

Back to top Go down

What Medallion is this? Empty Re: What Medallion is this?

Post  kaplangmk Fri Apr 12, 2024 11:53 am

I hate to be a burden here but I’m not getting any answers that help. The video also isn’t any help because it’s hard to see the throttle.
Let me try again.
The ring on my Medallion when turned does not cover any part of the exhaust port. It looks like it’s there for no reason at all. I could remove it and it will have no impact on the engines performance. Cox must have put it on the engine for some reason but why is a mystery to me.
Thanks
kaplangmk
kaplangmk
Beginner Poster
Beginner Poster

Posts : 7
Join date : 2024-04-11

Back to top Go down

What Medallion is this? Empty Re: What Medallion is this?

Post  kaplangmk Fri Apr 12, 2024 12:05 pm

Found this Medallion throttle picture on EBay.
Sort of looks like mine. I’m thinking the throttle sleeve is frozen on the cylinder and isn’t turning with the ring. When I get home I’ll have to check
What Medallion is this? 3a134310
kaplangmk
kaplangmk
Beginner Poster
Beginner Poster

Posts : 7
Join date : 2024-04-11

Back to top Go down

What Medallion is this? Empty Circlip

Post  Coxfledgling Fri Apr 12, 2024 12:42 pm

That ring, the thin circular bit with "ears" that have holes in, is called a "circlip" in the UK. This one is an "external" type. The holes in the eyes are for the ends, the "pegs" of a special pair of pliers, external circles pliers, that when the pliars handles are squeezed together, the pegs go further apart.

A lever type that I cannot remember the type of, a lazy fart probably 😁

To remove the circlip, use suitable external circlip pliers to expand the spring steel circlip enough to slip off

Be warned, recessed internal combustion engine clips need carefull treatment, respect, technique and internal circlip pliers.

Break an ear off one of them and have great fun !!!!!!!!!!!!!!!!!!!!

Yes u have been warned.

Yes have a hydraulic disc brake bike ????
Coxfledgling
Coxfledgling
Gold Member
Gold Member

Posts : 375
Join date : 2021-01-10
Location : Near Caernarfon, Snowdonia, Wales, UK

Back to top Go down

What Medallion is this? Empty Re: What Medallion is this?

Post  kaplangmk Fri Apr 12, 2024 1:04 pm

What Medallion is this? Ebe89010What Medallion is this? Ebe89010
Problem solved!
The sleeve was frozen. Took cylinder off, removed the glow head and soaked the cylinder in some lacquer thinner. It easily then came off. Put it all back together and now it moves as it should..
Thank you all for your input
Much appreciated!

My circlip removal tool. Did use it to remove the clip
kaplangmk
kaplangmk
Beginner Poster
Beginner Poster

Posts : 7
Join date : 2024-04-11

Back to top Go down

What Medallion is this? Empty Re: What Medallion is this?

Post  GallopingGhostler Fri Apr 12, 2024 1:19 pm

Glad you solved your problem, @kaplangmk . Now that it is freed up, hence forth it should be reasonably easy to re-orient the servo "C" clip by hand so the throttle ring can be aligned to your servo action.

You'll find that this type of throttle is very foolproof, works effectively, and is basically troublefree.

You probably already know this, also a good help is the engine manual section of this forum available for download as PDF's at the bottom of the Latest Topics list if you are using a desktop browser.
GallopingGhostler
GallopingGhostler
Top Poster
Top Poster

2023 Supporter

Posts : 5362
Join date : 2013-07-13
Age : 70
Location : Clovis NM or NFL KC Chiefs

Back to top Go down

What Medallion is this? Empty Re: What Medallion is this?

Post  Sponsored content


Sponsored content


Back to top Go down

Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum