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Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  RknRusty on Thu Jul 05, 2012 12:18 am

What a great engine. Is it ever going to fly?
I'm about to crack open my first larger than .049 engine, a much less exotic, TD .09. I wonder how they compare performance-wise.

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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  Jason_WI on Thu Jul 05, 2012 12:25 am

I am not going to fly this engine. I would not want to auger in a Cox prototype engine.

Not sure how it would compare to a TD 09.
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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  Cribbs74 on Thu Jul 05, 2012 12:33 am

Good for you Jason. Thanks for that.

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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  Jason_WI on Fri Jul 06, 2012 8:02 pm

I ran the Olympic 15 reed valve engine today. The RPM is a lot higher probably because I did not have the valve timing set right on the rear drum valve engine.

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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  RknRusty on Fri Jul 06, 2012 8:33 pm

Now you're cooking.

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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  coxaddicted on Mon Jul 23, 2012 5:36 pm

Nice working engine.

I have a question regarding the polished transfer ports of the cylinder. Does it really gives a better performance?
I have read (smattering) somewhere, that rough transfers would produce something like a lubricating film which increases the flow velocity Huh...

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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  RknRusty on Mon Jul 23, 2012 6:42 pm

coxaddicted wrote:Nice working engine.

I have a question regarding the polished transfer ports of the cylinder. Does it really gives a better performance?
I have read (smattering) somewhere, that rough transfers would produce something like a lubricating film which increases the flow velocity Huh...

I bet you'll have a hard time getting people to agree on that. If I had to trust an opinion, I would ask our performance expert, Paul Gibeault. He doesn't post in the forums a lot, but if you shoot him a PM, I bet he'll give you a good answer. I haven't re-read his mouse racing article lately but I don't think he addressed that. It's a sticky at the top of the Cox Discussions forum, and on Bernie's site too.

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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  Mudhen on Mon Jul 23, 2012 10:58 pm

coxaddicted wrote:I have a question regarding the polished transfer ports of the cylinder. Does it really gives a better performance? I have read (smattering) somewhere, that rough transfers would produce something like a lubricating film which increases the flow velocity
I've heard a similar report; that rough ports dramatically improve atomization. Although I have no comparisons, with my "Nosebleed .049" I purposely used 320 grit on the transfer ports.
Jason, that engine is, in the immortal words of Socrates, "Da Bomb!!!"
What an incredibly steady run!
Lates...Mud

BTW - Mine has rough ports.
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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  Jason_WI on Mon Jul 23, 2012 11:59 pm

Mudhen wrote:
Jason, that engine is, in the immortal words of Socrates, "Da Bomb!!!"
What an incredibly steady run!
Lates...Mud

BTW - Mine has rough ports.

Mud,

When are you going to run yours? Very Happy I think I need to get my port timing set right for it to pick up some more RPM but may never run it again for fear of breaking the crank.

I don't think the polished ports are hurting performance any. The venturi intake is polished also. The rotary valve is almost razor sharp on the edge.

Jason
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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  RknRusty on Tue Jul 24, 2012 2:06 am

Jason. why the concern about the crank, do you think the drive pin is a weak link? Is that historically what fails on that engine?

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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  Jason_WI on Tue Jul 24, 2012 9:20 am

Where are you going to find another one? All of the other parts with the exception of the rear drum valve and crank can be replaced with olympic reed valve parts.
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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  Kim on Tue Jul 24, 2012 11:22 am

Excellent !!! I kept forgetting to watch this video when I was out someplace that had a WiFi connection! Great Historic Stuff !!!!!!
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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  gcb on Tue Jul 24, 2012 2:12 pm

Just a guess, but back in this engine's time speed flyers polished things for "better transfer flow"...whether it worked was iffy.

Perhaps this engine was once in the hands of a speed flyer who "breathed" on it to make it all it could be. Now lets suppose the Tee Dee came out, or one of the other greats of the day like K&B, Supertigre, etc. took the flyer's interest and the Olympic was "retired".

In any case, you have an excellent piece of history.

For some reason I have not been able to see the video, but I've heard it. :-) I'll eventually figure out what I'm doing wrong.

George
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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  Jason_WI on Thu Aug 09, 2012 1:25 am

Here is the information I have on this engine from the ebay listing from the seller:

"I am selling off a very extensive model airplane collection for a friend. These are items from a life time of
collecting engines. This offering is a very rare, only one of twenty made, OLYMPIC ball bearing rear drum valve
glow speed engine. This engine was custom made by Bill Atwood, and given away at the 1960 Dallas Nats. This
engine is owned by "Doc" Richard Nichol, who was a young man flying speed at the 1960 Nats. He must have
made a good impression upon Bill Atwood, because he gave this engine to Doc to use and fly. Doc said he used
it briefly, but newer and faster engines soon surpassed it. He added it to his extensive model engine collection,
and it has been there collecting dust ever since. I will leave it to the new owner to clean. A very hard engine to
find, and a must have for the Cox engine collector."

Now if I could only confirm that "Doc" Richard Nichol actually participated in the 1960 Nats and if he placed.

Jason
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Have you tried using different plastics?

Post  zeissman on Tue Dec 05, 2017 12:33 pm

Jason_WI wrote:[color=black]
This material will soften up in methanol so not too practical to use

Hey Jason,

Do you still have the mold of the prototype Olympic carb body?

Have you tried making duplicate carb bodies using different plastics?

Also, is the mold you made heat sensitive? I'm asking because you could take a new cox carb body from a Medallion, melt it at around 300 degrees F, and pour it into your mold.
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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  Jason_WI on Tue Dec 05, 2017 4:18 pm

The mold I have is only for composites. Delrin needs to be injected molded under heat and pressure.

I might be able to 3D print one out of zytel which is a form of nylon. I just need to model it up in CAD.
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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  Cribbs74 on Thu Dec 07, 2017 12:55 am

Thanks again for running that up. Very cool! I tried to give you a greenie, but apparently I already did!
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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  roddie on Thu Dec 07, 2017 1:28 pm

This thread is SUCH a teaser now that the images/vids are gone... Crying or Very sad Sad Goodbye my inserted emoticons won't even show up.. Huh...
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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  Admin on Thu Dec 07, 2017 2:38 pm

roddie wrote:This thread is SUCH a teaser now that the images/vids are gone... Crying or Very sad Sad Goodbye my inserted emoticons won't even show up.. Huh...

No problem here, try clearing your cookies.

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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Post  Jason_WI on Thu Dec 07, 2017 3:32 pm

The vids are still linked but I will need to add the pics back because I wasn't going to pay the photobucket ransom.
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Re: Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

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