BobHH

My Feedback: (18)

Tim, Dickeybird, I just picked up a box of old vintage engines and found this in it. I think it is a Spacebug but am confused a bit about the rear end. I would love to restore it to running condition to put in one of my vintage RC models. Is it complete in this stage or has someone modified? Can it be broght back to original condition? I have lots of Cox engines but not this old.

Thanks,

Bob Harris
Early RC Models
www.earlyrcmodels.com

DesignMan

That is a Thermal Hopper. If you hunt around, there is a nice extruded mount made for it. An alternative is long bolts and aluminum tubes to make a stand-off. Or, as it was intended, there is a hole in the firewall and the venturi goes inside the fuselage.

That was THE hot engine until the Holland Hornets showed up. C*x then made the Space Hopper for a year as a stopgap, and followed up with the Tee Dee series that blew everyone away for the next 30 years.

Tim Wiltse-RCU

The only thing "wrong" with it is that it looks like the NVA is off a TD as it looks like it anodized gold other than that nice looking!


Later,
Tim

DesignMan

Got to disagree with you on this one Tim. I think that is just cruddy old Castor on the outside of the NVA. Do the photo blow-up and take another look.

gcb

I think you are correct, Larry. The knob on the Thermal Hopper is much larger than the one on the TeeDee. Don't know if they are interchangeable, never tried it. The TH/Space Bug needle has a much thinner point if I remember correctly. I believe the entire needle assembly IS interchangeable, however.

Hmmm! Wonder if an entire needle assembly from a TD would work with pressure on a TeeDee?

George

BobHH

My Feedback: (18)

Thermal Hopper hum, At least I know what it is. Yep the needle assembly is aluminum and not inodized but does look real close to a tee Dee. I will compare. Is there a place to get this cast mount somewhere or do I just need to improvise?

Bob Harris
Early RC Models
www.earlyrcmodels.com

flyinrog

My Feedback: (1)

Bob, of the very few of those engines I've seen only 1 in ten had the funky aluminum mount on them, if you see one, you'd think (at least I would) no way that mount could survive a crash, you can mount with tubes, but if you go through the fuse you need a cutout for the needle..Rog

gcb

The "cage" mount was an extra that you could get from Cox, I don't remember them selling with the TH's (at least not mine). They also had a needle assembly with two needle valves for two-speed flying (throttles not available).

Update on the needle valve:
The taper on the Thermal Hopper needle is much finer than the TeeDee. It is EXACTLY like the current reed needles (BW, Texaco) except the knurled knob is smaller on the current models. I noticed that the needle on one of my Space Bugs has a replacement needle with the smaller knob. I then noticed that some of my Gloden Bees had the large and some the small knob so I ASSUME they were changed during the Golden Bee period. Also, one of the Black Widows has the large knob. Larry could tell us more there.

George

DesignMan

Sorry, a connoiseur of needle valves I ain't.

gcb

BobHH,
The engine is complete as-is. You can mount it without the cage. I used them in control line models in the 50's. You have to drill a hole for the intake to go through and provide means to choke, unless you want to start it completely with exhaust primes. I preferred to remove the needle assembly when mounting to allow for a smaller hole. You can also use long screws and aluminum tubing to mount the engine in front of the firewall (as someone mentioned previously).
Check the cylinder and glow plug to see if they match the current Cox sizes. The early issues of Cox engines had a smaller plug. The current cylinder will fit if necessary.
Good luck with it. I have some happy memories of a Thermal Hopper in a plane called the Bluetail Fly. Built several.

George

BobHH

My Feedback: (18)

Yep, I hope to put it in the first Live Wire Kitten prototype in the near future. Still got a few to finish up before then though. Thanks for all the help.

Bob Harris
Early RC Models
www.earlyrcmodels.com

Ragwing

My Feedback: (2)

What is the purpose of a two speed carb on a Thermal Hopper? Did that allow the user to equip a throttle sleeve? Where two speed carbs something that Cox came up with or was it an aftermarket modification? Would a Thermal Hopper with a two speed carb be more valuable/desirable to a collecter than a "regular" one?


Whew.


Derek

ajcoholic

My Feedback: (10)

The two speed nv was to be used with some kind of escapement driven gizmo to close off one or the other fuel line, ie, one needle was set to run leaned out and fast, one set rich and slower. Kind of a 2 stage throttle.

They are not that rare, I have passed a number in my travels at swap meets and also the birdcage mounts for the thermal hopper, but they do add a bit of collector value to the engine.

I machine the birdcage mounts from 6061-T6 barstock aluminum, its a lot of machining but they look sweet.

If you look around they are there to be had.

AJC

jessiej

Two speeds via two needle valves predates Cox, BTW. I have a Forster 99 two speed in my collection.

jess

ajcoholic

My Feedback: (10)

I thought the Forster 99 had a two speed timer (two sets of points for more advanced, and more retarded settings giving two speeds)?

There were many other dual NV engines, I had a K&B Torpedo .09 or .15, and last year in Toledo I bought a NIB Holland Hornet two speed. I am sure there were more..

AJC