Cox .049 Thermal Hopper - a never ending story

GallopingGhostler Tue Apr 04, 2023 4:53 pm

Ayer en E-Bay, vi un motor pobre y desnudo que necesitó apoyo y amor. Sad

Lo fue un Cox .049 Thermal Hopper. ¿Qué iba a hacer? Huh...

La oferta inicial fue $24.95 US. Entonces ofrecí esa, después lo aumenté más. Hoy, lo he ganado por eso con $6.45 envió y $2.53 impuestos ($33.93 total). Very Happy

Just yesterday in E-Bay I saw a poor and nekkid engine that needed help and love. Sad

It was a Cox .049 Thermal Hopper. What was I to do? Huh...

Starting bid was $24.95 US. Then I offered that, after increased it. Today, I won it with that with $6.45 shipping and $2.53 taxes ($33.93 total). Very Happy

Cox .049 Thermal Hopper - a never ending story 2023-084

Cox .049 Thermal Hopper - a never ending story 2023-023

Cox .049 Thermal Hopper - a never ending story 2023-024

Cox .049 Thermal Hopper - a never ending story 2023-085

Después miré a las fotos, descubrí el motor es un modelo antes año 1956. After examining the photos, I discovered the motor is a pre-1956 model.

https://www.coxengineforum.com/t11650-a-thermal-hopper-story-thanks-levent-suberk#148519

Mark Boesen on Mar 06, 2018 wrote:

rdw777 Tue Apr 04, 2023 5:16 pm

Congratulations George… That is a neat engine!!!…. Excellent price too!!!….Nice to have a piece of early Cox history….. Closest thing I have to older is the tank/back end of a Space Bug Jr that came in a parts lot….I need to watch for the rest of the pieces!!

GallopingGhostler Tue Apr 04, 2023 6:30 pm

rdw777 wrote:Congratulations George… That is a neat engine!!!…. Excellent price too!!!….Nice to have a piece of early Cox history….. Closest thing I have to older is the tank/back end of a Space Bug Jr that came in a parts lot….I need to watch for the rest of the pieces!!

Thanks, Robert. Who knows, may be you'll luck out like I did and find the rest for a complete restoration. Smile

I have a feeling similar to the Tee Dee .051 I recently also won now sitting on my desk in front of me, this one is pure gold in disguise. Cool

Only speculating, but perhaps the masking tape was placed there with intentions of painting around some cowling. When it arrives, hopefully with a week, I'll be able to look at it more closely, plus clean it up. I thought it interesting how it has a 3 bolt mounting system for bulkhead use. Plus, it looks like that the slight extending of the 3-48? backplate screws have enough overhang for its special aluminum mount.

When here, I might be able to locate some plastic stand-offs from a hardware store, like I did for the Sure Start where it can be mounted without burying the venturi and needle behind a bulkhead through an access hole. It would make a really nice Cox Engine of the Month entry. Very Happy

balogh Tue Apr 04, 2023 10:10 pm

Nice haul George, congratulations, the lowest winning price I have ever seen for such a historical relic.

I think the masking tape was added by a careful owner to prevent any foreign material from entering and scratching the delicately fitted cylinder piston combo during an extended storage?

I guess the cylinder is the pre-57 design with the old style glow head sealing on its lowest fin shoulder unlike newer heads sealing on the combustion chamber rim?

GallopingGhostler Tue Apr 04, 2023 11:16 pm

Thanks, András, yes, I think your explanation may be closer to the truth as to the purpose of the masking tape, to keep the cylinder exhaust port sealed from dirt entering during storage. Thumbs Up

According to @Mark Boesen's illustration, the glow head has a raised ring around the head extension for the glow element pin. That is why I posted his photo on the 4th post above, from an earlier thread. According to Mark, this is a tipoff that it is the earlier pre-1956 (1955 and ealier) Thermal Hopper.

I don't know if someone makes a head adapter to use short standard glow plugs for this earlier version.

Oldenginerod Wed Apr 05, 2023 4:23 am

GallopingGhostler wrote:

I don't know if someone makes a head adapter to use short standard glow plugs for this earlier version.

Not sure about a commercial adaptor, but apparently the standard earlier OK Cub head, which takes a standard 1/4" short plug, will fit.

rdw777 Wed Apr 05, 2023 9:45 am

George, The small diameter Cox 302 head will fit my OK Cub .049 A so what Rod stated about alternative heads should be correct….. The head was in the group of parts I mentioned for the SB jr above…. It also fits a Cub .039 I have as well….

Cox .049 Thermal Hopper - a never ending story 517bf010

sosam117 Wed Apr 05, 2023 9:53 am

Here is my refurbished Thermal Hopper that I got from my Aussie friend for Christmas

The three engines Allan Lacock (Aussie friend) sent me for Christmas

Cox .049 Thermal Hopper - a never ending story Space_14

Cleaned, rebuilt, and mounted on home made stand

Cox .049 Thermal Hopper - a never ending story Therma15

Yes, find some nylon standoffs (you may have to screw two together to get the length) and then you'll be able to mount it.

GallopingGhostler Wed Apr 05, 2023 10:06 pm

sosam117, I missed out on a cherry looking Space Bug like yours that closed at only $33.00. Shocked

Love the stunt tank on yours, plus the engine mount details in your Thermal Hopper photos. That machined mount is a work of art.

I have some ideas for mounting spacers that are long enough to support the engine without doubling nylon standoffs. Engine should be here in a couple days, when it is in my hands I can then start my research.

Problem solved glow head wise, today without hesitation, I snapped up two NOS 302-1 Heads for my earlier Thermal Hopper for $14.00 a piece shipping included plus tax.

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sosam117 Thu Apr 06, 2023 8:28 am

GallopingGhostler wrote:sosam117, I missed out on a cherry looking Space Bug like yours that closed at only $33.00. Love the stunt tank on yours, plus the engine mount details in your Thermal Hopper photos. That machined mount is a work of art.

I have some ideas for mounting spacers that are long enough to support the engine without doubling nylon standoffs. Engine should be here in a couple days, when it is in my hands I can then start my research.

I can't take the credit for the engine mount.
My friend Allan Lacock (Aussie) made the mount.
He does a very good job of machining. Just wished he lived a little closer?

GallopingGhostler Thu Apr 06, 2023 10:33 am

sosam117 wrote:I can't take the credit for the engine mount. My friend Allan Lacock (Aussie) made the mount. He does a very good job of machining. Just wished he lived a little closer?

Then, Allan did a stupendous job. Thumbs Up

But, isn't the mount he machined basically a duplicate of the one offered by Cox too, back then? It is a work of art, and I can understand why Cox engines evolved to simplify for better affordability, through the technology of the time. But because of its uniqueness indeed makes that version of engine a really prize for display.

Levent Suberk Thu Apr 06, 2023 11:11 am

There can be alternative stands for mounting multiple engines such as:

Cox .049 Thermal Hopper - a never ending story 20180111

Cox .049 Thermal Hopper - a never ending story 20180110

https://www.modelbouwforum.nl/threads/wankelmotor-4-98ccm.256862/

rsv1cox Thu Apr 06, 2023 12:01 pm

George be thankful that I am on an ebay/Cox sabbatical or I would have snatched that gem up in a New York minute. I love stuff like that! I would be tempted to leave it "as found." Congratulations on a really neat find.

Nice stands Levent, especially the Graupner Wankel.

GallopingGhostler Thu Apr 06, 2023 1:54 pm

rsv1cox wrote:George be thankful that I am on an ebay/Cox sabbatical or I would have snatched that gem up in a New York minute. I love stuff like that! I would be tempted to leave it "as found." Congratulations on a really neat find.

Just one further request, Bob. Please remain on your sabbatical while I finish my few other purchases. Then I'll let you know when you can return and carry on. Wink

pman1111 Thu Apr 06, 2023 6:14 pm

Nice buy G.G., you didn't even get sniped! I saw that engine on Fri. or Sat., passed on it because #1, not too familiar with the Thermal Hopper or the going prices, #2, I already have enough engines that are difficult to find parts for. Very Happy

BTW, that poor nekkid Medallion engine still hasn't been bid on yet either, the last time I checked! Will be looking for your feedback # on future purchases now that I know (about) what it is, so I won't be costing you more $.

sosam117 Thu Apr 06, 2023 10:46 pm

GallopingGhostler wrote:
sosam117 wrote:I can't take the credit for the engine mount. My friend Allan Lacock (Aussie) made the mount. He does a very good job of machining. Just wished he lived a little closer?
Then, Allan did a stupendous job. But, isn't the mount he machined basically a duplicate of the one offered by Cox too, back then? It is a work of art, and I can understand why Cox engines evolved to simplify for better affordability, through the technology of the time. But because of its uniqueness indeed makes that version of engine a really prize for display.

Allan copied the mount from a friend that had an original Cox mount.
Allan made it from thick-walled aluminum tubing, turned down the center section, then milled out the slots/holes.
Reason Allan did it was the cost (Aussie dollar to the US dollar).
He could make it cheaper as he has a lathe and mill and scrap metal at his house.

GallopingGhostler Fri Apr 07, 2023 6:06 am

sosam117 wrote:Allan copied the mount from a friend that had an original Cox mount. Allan made it from thick-walled aluminum tubing, turned down the center section, then milled out the slots/holes. Reason Allan did it was the cost (Aussie dollar to the US dollar). He could make it cheaper as he has a lathe and mill and scrap metal at his house.

sosam117, I could tell right away he did a superb job, having the right machines, tools and expertise. That is quite a bit of work for lathe turning, then milling. I can understand why it was only an interim solution under Leroy Cox's watchful eyes as his company developed.

To make the engines mass produceable and affordable resulted in what we have today with the extruded reed valves, Tee Dees, and poor man's Tee Dees (the Medallions).

Even the Cox postage stamp "donor" engines (post RTF crash salvage) were useable when Carl Goldberg came out with his EB-1 Engine Mount. The Testors pipe bomb engines were another story (considered disposable and more dificult to salvage).

Checked tracking, my Thermal Hopper should be delivered today. Very Happy

sosam117 Fri Apr 07, 2023 7:57 am

GallopingGhostler wrote:
sosam117 wrote:Allan copied the mount from a friend that had an original Cox mount. Allan made it from thick-walled aluminum tubing, turned down the center section, then milled out the slots/holes. Reason Allan did it was the cost (Aussie dollar to the US dollar). He could make it cheaper as he has a lathe and mill and scrap metal at his house.

sosam117, I could tell right away he did a superb job, having the right machines, tools and expertise. That is quite a bit of work for lathe turning, then milling. I can understand why it was only an interim solution under Leroy Cox's watchful eyes as his company developed.

To make the engines mass produceable and affordable resulted in what we have today with the extruded reed valves, Tee Dees, and poor man's Tee Dees (the Medallions).

Even the Cox postage stamp "donor" engines (post RTF crash salvage) were useable when Carl Goldberg came out with his EB-1 Engine Mount. The Testors pipe bomb engines were another story (considered disposable and more dificult to salvage).

Checked tracking, my Thermal Hopper should be delivered today.

Yes, Allan has been sending me his Cox engines as I'm able to get replacement parts cheaper than he can.
So, I've been sending to Allan some of my rebuilt Enya .049/.06/.08 and .10 engines as a trade.

The Enya .049-II Series #4

Cox .049 Thermal Hopper - a never ending story Enya_211

The Enya .06-II Series #4

Cox .049 Thermal Hopper - a never ending story Enya_212

The Enya .08 Series #4

Cox .049 Thermal Hopper - a never ending story Enya_213

The Enya .10 Series #4

Cox .049 Thermal Hopper - a never ending story Enya_214

pman1111 Fri Apr 07, 2023 12:05 pm

Just curious, have you come across this yet? https://www.ebay.com/itm/266200212477

GallopingGhostler Fri Apr 07, 2023 12:20 pm

pman1111 wrote:Just curious, have you come across this yet? https://www.ebay.com/itm/266200212477

Just bidded! eBay

pman1111 Fri Apr 07, 2023 12:36 pm

You're welcome! I've seen this sellers items quite a few years now, he's located 90 or so miles north of me, usually has good stuff. Good luck on your bid! Cool

GallopingGhostler Fri Apr 07, 2023 10:04 pm

Now I have this little jewel of an engine in my possession. The mummified paper masking tape covering the cylinder exhaust ports came off with very little prying. The adhesive glue had long since dried out. I removed the snap spring starter to remove the remaining masking tape. Now King Tut is exposed in all its glory. The four 2-56 screws holding the backplate in place show no signs of wrenching. The 3 bulkhead mount plate screw holes in the aluminum backplate show no sign of ever being mounted.

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Just twisting the prop thrust plate, it feels it has the same compression as my .051 Tee Dee. Moving it quickly through compression in a snap like manner makes a chirping sound from the reed valve. Interesting, the piston does not have SPI. The glow head still had on each notch for the wrench tangs, a small chunk of swarf that had not been knocked loose yet from the broaching to cut the notches.

Cox .049 Thermal Hopper - a never ending story 2023-089

The rear venturi screen is intact and clean. This engine apparently has very little use if any. The 5-40 prop shaft is missing the prop nut, but I can use a Cox spinner nut to secure a prop in place, then cover it with a spinner.

I basically have not a worn out battle hardened relic, but an NOS 1955 or earlier Thermal Hopper. It looks like I really scored big! Very Happy

balogh Sat Apr 08, 2023 12:21 am

Yes George, a big score. I see on one of the pics the piston has the shine of a new one, and bet it has a tapered fit in the thin wall cylinder. If you happen to disassemble it please check, just to verify the fact that, even if not frequently mentioned, all old stock thin wall COX cylinders had taper bore, no matter if SPI or not, 1 or 2 transfer ports...at least my thin wall reedies all have taper bore.

Congratulations.

GallopingGhostler Sat Apr 08, 2023 7:20 am

balogh wrote:Yes George, a big score. I see on one of the pics the piston has the shine of a new one, and bet it has a tapered fit in the thin wall cylinder. If you happen to disassemble it please check, just to verify the fact that, even if not frequently mentioned, all old stock thin wall COX cylinders had taper bore, no matter if SPI or not, 1 or 2 transfer ports...at least my thin wall reedies all have taper bore. Congratulations.

Thanks, András. When I get a chance, will shine a light into the chamber and see how many bypass ports it has. For now, because it is so clean, I'd rather delay any full disassembly. Thin wall cylinders are easy to damage when attempting to remove, and cylinder / piston sets now are almost non-existant.

You are probably right though, even though this is an earlier unit, it is possible that it has cylinder bore taper. Perhaps @Mark Boesen can chime in with his knowledge of whether the pre-1956 Thermal Hopper has this feature, or is simply straight bore.

sosam117 Sat Apr 08, 2023 8:25 am

GallopingGhostler wrote:
pman1111 wrote:Just curious, have you come across this yet? https://www.ebay.com/itm/266200212477
Just bidded!

[b]I hope you get it.
It would be a fine addition to your Thermal Hopper![/b]

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