Cox postage stamp backplates.

Postage stamp backplates and production backplates are different. If the postage stamp backplates with the fine threaded needle valve assemblies are currently offered I'd be very interested. I can only assume the reasoning for the use of the postage stamp backplate is the use of the 128 TPI needle valve . Andrew, are these speed planes using bladders? Why the use of the postage stamp vs the production horseshoe style? Is the mounting on your planes integrated for the postage stamp backplate only? Ken

Hello Ken,
The speed model I am talking about was an attempt at a standard design using the Cox postage stamp engine. My memory is a little befuddled, but I seem to remember they were termed E 320, or a similar name. One of the kits was boxed and had this name on it. I will try to unearth the box, which I think I still have somewhere. The mounting arrangement in the kits was unique to the Cox postage stamp backplate and I would like to keep things as original as possible, hence my query.
Certainly the NVA assembly is 128 tpi on the only backplate that I have. The tank arrangement is certainly not a pressure feed, but a simple Perfect 1/2A tank. I could use any of the Cox backplates, but I would then lose originality. If I cannot find any more of the backplates, then I am sure I could modify the mount for any of the Cox products. I have seen quite a few of the required backplates over the years and I may even have a second one somewhere in the depths of some storage draw! They are not exactly super rare and I am sure that given a little time and patience, I can find some more. They are red in colour and are around 5/8" square with the 128 tpi NVA thread, they are definitely not the backplates now offered by Cox International or Ex Model Engines!

Regards,

Andrew.

round  you sure its not a .020 pee wee size ? http://www.mh-aerotools.de/airfoils/cox_frameset.htm they show a round one on this site

Hello Ken,
I have just found the kit box. It is obviously some rather good cottage industry offering, Highly prefabricated and that done to a very high standard. The legend written on the box is 290+E / Special.
I have a feeling that the design is on the Tom Wilkes CD of US speed planes. So now I will search for my copy and that may throw some more light on the subject!

Regards,

Andrew.

Is this the one you are talking about?

http://www.outerzone.co.uk/plan_details.asp?ID=6104

Yes indeed that is the design I am talking about.

Andrew.

getback wrote:round  you sure its not a .020 pee wee size ? http://www.mh-aerotools.de/airfoils/cox_frameset.htm they show a round one on this site  

I think he said "around", not a - round.

Yes,
I did not follow the round / around bit either! Back to the 270 design by Dale Kirn. My kits have some nifty prefabbed metal mounts to fix the postage stamp coxes onto the model. I am a touch confused as the postage stamp backplate that I have is somewhat different to the one some kind person showed in one of the above replies. I will try and upload a photo of the one I have.

Thanks everyone,

Andrew.

Well Stupid Me that's what happens when you try and muti-task and cant anymore well I am interested in seeing this back plate I do like the looks of the 290 plane , Eric

Andrew, did you notice that the "290 Special" plan instructs to cut off two portions of the already small backplate? It's shown in the lower left corner of the plan sheet. I think an unmodified one would fit too, but not sure.

Anyway, if your backplate is already modified it would seem different compared to the pic getback posted above.

One more "Edit"... In the following thread there's an article about the 290 Special posted by GWILLIEFOX:

https://www.coxengineforum.com/t7914-dale-kirn-s-290-special

It shows the before and after pictures of the backplate.

I was just going through my collection of old 1/2 A stuff and found Carl Goldberg mount kits with fuel tubing and a balloon for these postage stamp backs,
I did not know they had the finer NV threads. I would be willing to sell 1 or 2 of the CG kits I have if there is interest, I'm going to take some picks of them just so everyone can see what they look like .
What I could not find that I know I have is Kavan tank extensions and normal glow heads for the bees.
The older I get the more I can't find !

Jayd

We have a few red ones here (new and used) that we have not had time to list.

jayd3 wrote:I was just going through my collection of old 1/2 A stuff and found Carl Goldberg mount kits with fuel tubing and a balloon for these postage stamp backs,
I did not know they had the finer NV threads. I would be willing to sell 1 or 2 of the CG kits I have if there is interest, I'm going to take some picks of them just so everyone can see what they look like .
What I could not find that I know I have is Kavan tank extensions and normal glow heads for the bees.
The older I get the more I can't find !

Jayd

I'd bee interested in one or two....post the pictures and a price, thanks!!

It may be a while until we get to that project but, essentially, they are the one in red in the top row here:

https://www.coxengineforum.com/t6641-cox-049-delrin-back-plate-collection

$9.95 including copper reed and retainer. Less for used ones but simply no time to go through them all at the moment, sorry.