eroc144

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Go Andy, go! Let me know if you need a field tester!

EG

AndyW

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Eroc144,

I'm making up a thread about how to convert old Cox heads using the tools that anyone can get and a drill press. Once done, I may have a few to give away for testing. Send me a PM with your address and I'll make sure you get one.

Again, the beauty of turbo conversions is that a variety of manufacturers make them in a good variety of heat ranges and you can get them from a number of sources.

classicalgas

Has anyone tried to make a turbo plug head for a COX TD 0.020 and if so would you care to share some dimensions and performance numbers. I have made heads for the TD 0.020 with the Nelson plug and in my experience they must be made of steel as there is not enough material between the OD of the Nelson plug and the ID of the Cox cylinder to allow the use of aluminum. My primary interest is for free flight applications where the TD 0.020 is used in numerous events.

Thanks

PlaneKrazee

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Andy,

Very cool!

Do the turbo plugs have as small a element hole as the Nelson plugs? Are you getting about the same or more rpms as the stock freedom plugs?

I am looking for a replacement head for the 7L in my .074. The plug that came with my .074 leaks around the stem

AndyW

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Classicalgas,

At the moment I'm downloading pics that describes the process of creating turbo buttons for the .049/06. At the same time I had a look at the TD .020 plug but there's very little meat to play with. The only way to do it would be to get the right size die and make a button from scratch. In other words, you can't use old .020 plugs and adapt them.

I'm looking into the price and availability of the proper die. If it could be done, it would be very tight. Can you give us pics as to how you adapted Nelson plugs?

AndyW

My Feedback: (1)

Skypilot,

Yes, the turbo buttons have a small hole for the element and performance is equal to stock Norvel plugs AND the Nelsons. I managed to find a way to allow one to make these buttons without the need of a lathe. You just need to get the proper tap and have access to a drill press. All other bits you likely have or are very cheap to buy.

Working on this now, have a bug or two to work out and will post a new thread to cover how to do it.

classicalgas

Andy,

Attached are 3 photos of the Nelson adapter for the TD 0.020. It is made on a lathe, no way around that. There is very little material between the ID and OD of the adapter requiring that it be made from steel. I made one from aluminum a while back and it broke after a few uses. I was hoping that someone worked out the best combustion chamber geometry for the TD preferably running on about 65% nitro with lots of proplyene oxide for the turbo plug

With a turbo plug one could make the adapter from aluminum and have sufficient wall thickness.Given a lathe and a bottoming tap the part is relatively easy to make with only the external thread being a bit of a pain to cut on the lathe. Even with a quick change gearbox I am not a fan of cutting fine threads especially in steel.

Cutting the female thread for the turbo plug can easily be done using a tap available from Enco or MSC for about $4.00. They only have plug taps in the required size but they can be easily ground to serve as a bottoming tap.

By the way I make lots of heads for nostalgia and modern engines for the Neslon plug for fellow free flighters. In general the Nelson plug properly setup on an old nostalgia engine will add about 400 rpm and on a modern engine one can often get another 1000+ rpm.

Bob

injunnut1

>I'm looking into the price and availability of the proper die.<

Andy W.,
This round split die is close (see link below), perhaps it could be 'expanded' (or adjusted?) to the correct diameter, I believe the thread pitch (or '40' threads per inch) is correct ..... what do you think? The price is right too maybe?
http://www1.mscdirect.com/CGI/NNSRIT...PMT4NO=9925649

AndyW

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Thanks Injunnut and the same source which classicalgas has also referred me to has the tap real, super cheap. Under 6 bucks,, I paid nearly 30 dollars CA for mine. This one isn't a bottoming but a little grinding would take care of that. Neat.

http://www1.mscdirect.com/CGI/NNSRIT...2459&PMCTLG=00

And for the die, I'm going to check with my contact at "Cox" tomorrow and get the exact thread size.

D Bronk

Well Andy and I, made a bit of a trade,Here`s his offerings .Thank you Andy..I asked him ,if I could add some tests, to My Chart I had made a Week, or 2 ago ,and, he liked the Idea,I got his permisson.My goal, is ,not to sell his idea to anyone,just to inform my RCU pals, of what I`m finding for myself..I`m not sure, when, I`ll start doing,this testing, but ,most likely early next week..Unfortunately I don`t have a temp. reading apparatus.But I do have a Hobbico tach,and ,that is a common device amongst us.Reasonablely priced, for those considering, a Hand held optic Tach..My first round of testing, will be, with my near new, Norvel BigMig 0.061" R/C engine..I already have data Charted started ,so, I`ll just add to it..I`m going to use Sig Champ fuel @ 25% Nitro, with 20% oil content,of that ,50% is Castor oil,& the other 50%,is Klotz synthetic oil.I have a new Bottle here,never opened..I won`t re-test what`s on the chart now, because that info ,is all obtained, on a New, Factory Glow plug insert..To keep things a bit simpler,I`m going to use the Engines Spec. sheet Propellor.It claims That the Average performance is 4,500-18,500 RPMs, on ,a TORNADO 6"X3" propellor..I have Several other Props that were not Tested(just got`em)..I have no test data on The APC stuff,so a 6"X3" of there`s ,will get tested too..Anyone have a prop, that they would like, to suggest to see the results too?As far as the Glow heads go, I`ll be useing a Cox Factory(NEW) glow head,Andys modified Cox Glow head, ,and the modified Norvel insert (0.061") ,.For the O.S. ,Turbo glow plugs.I wanted to try all 4 of O.S.s` offerings, but at their prices ,[X(]I only purchased the P-6 med.,&,P-7 Hot plug.Those 2 turbo Plugs, will be Exchanged ,between The Cox Head ,and,the Norvel insert..So is their anything, I`m missing, that folks want to see me do.I`m going to put my Test Chart here,and a few other pics..see if something grabs Ya..A Couple Cox 0.049" engines, and, a fairly new BigMig 0.074" ,will get their turns Bolted to the Table, after this is taken care of.. In around about way,I know Injunnut will be intrested ,with the Cox testing..thats`s later though

Tim Wiltse-RCU

Andy,

If you need thread sizes or stuff like that I can help

LAter,
Tim

Japanman

Classicalgas,
I converted a couple of heads for someone a year or so ago. The stock TD020 glow head has enough meat to simply cut the taper and threads in it and you are away. I never heard how they ran but I imagine it would be very similar to the nelson, perhaps a little better due to more flexibilty in the combustion chamber shapes you can make.
What advantage is there in running extra proplyene oxide in the fuel?

Stefan

PlaneKrazee

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What ever became of the test?

Yuu

August '06 was about the time Bronk left RCU for some reason.... I've read he did make a comment on ONE thread since. I hope he comes back.

Tim Wiltse-RCU

Dave's been around alot in the last month or so.

Later,
Tim