1/2 A Stunt Tank Mods

1/2 A Stunt Tank mods: Using a conventional built-in tank, like you would see on a Cox Golden Bee, OK Cub, Fox, etc, what are some of the mods you perform to ensure a good stunt-type run; i.e., runs the same rpm when inverted, doesn't cause surges, etc?

This subject was briefly covered in the current Model Aviation, but I would like to hear some other ideas. I have had fairly decent luck with a dead stock Golden Bee over/under ported tank, but I am not quite satisfied with run consistency. Thanks. Currell

Cox, I turn the vents sideways. If you cap off the outboard facing tube ,you have a uniflow. Some of the bigger venturied Cox run poorly with the vent capped tho. I tried the vents up and down, found uneven run maybe due to the fuel uncovering the vent partway thru the run.( Just after half)
OK cub ran fine with the vents inboard(no tube on vent).
.03, MM

Currell, not sure this is what you want but we used to drill a hole in the tank and connect a fuel line to the backplate nipple and then connect to a regulat tank or balloon tank or pacifier. one of the advantages of this is it was really easy to prime the engine and of course the runs were consistant.
What with the insane price of c*x motors today I'd do it to a Baby Bee tank and save those expensive Black Widow and Golden Bee tanks
Another thing is that we always used the red can c*x fuel and even now I still like 30% in them. No motor likes nitro more then a 1/2A. Dennis

I got a new Black Widow for my Grandson for Christmas and the current model has the spun aluminum tank similar to the Texaco model. The fill and vent are on the plastic backplate.
Another "trick" I've heard about but never used is on the old Babe Bee engines you can run fuel tubing from one fuel nipple under the engine to the other fuel nipple, then cut a hole in the tubing on the bottom. This is supposed to prevent siphoning.
Also heard that the single nipple and vent hole models don't siphon when inverted. Have not tried it yet.

Currell, is this for one of the "logs?"

You can drill the solid tanks and put in vents. Plug the little holes in the backplate. Use a 1/8 in bit and force fuel tubing in . works, You only need one vent from the inboard side, tip the outer wing up to fuel. A SLICE INTO T HE AIRSTREAM WILL PREVENT IT FROM DUMPING FUEL . MM

Mogren is correct as far as he goes. The real key, though is to have the cylinder oriented to the inside or outside of the circle. Don't know why it helps, but it makes a big difference.

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We are just getting ready to power my Son's/Dad's P-38 with two Cox Black Widows on a bladder. two extra inches of line to the inboard engine, with a "T" fitting from the bladder. This is the most reliable fuel system for the little critters that I have seen. The BW with the larger venturi only runs about 2:00. a real strong one, less than 2. ( w/ 4.8x3prop@ 16-17k).
I would think that you Leprechaun guys would have gone to bladders by now.
Larry, awsume mini-stunt in the mag. I am not easily impressed, but your wing structure is very nice. The article wasnot that clear , to me, but the essence was there. I like the swept foreward wing,( For tip stall resistance). I will sneek a little foreward sweep into the next retro combat ship, Greased Lightning. I can use the same fixtures as for the Half Fast. Can I call it a Renger/Lightning??? Have you used newspaper/epoxy over foam? Have fun, MM

> Currell, is this for one
>of the "logs?"
>
> George : Yes. A Stunt one. Currell

Jan/Feb Stunt News has tip on getting Cox engines fitted with the integral tank to run inverted. It's in Doug Dahlke's column, looks weird. But if Doug says it works, I'd try it.

Does anybody else remember when Cox engines were cheap to run? I've got a big stash of 1702 hi-comp heads, will be putting them up for bid when retail price goes past the 10-dollar mark. Which might be next week...

>Jan/Feb Stunt News has tip on
>getting Cox engines fitted with
>the integral tank to run
>inverted. It's in Doug Dahlke's
>column, looks weird. But if
>Doug says it works, I'd
>try it.

Still no SN...Currell

Dan, I'd dump the c*x heads and get a Nelson adaptor and their plugs. In my opinion the Estes plugs,, are inferior. The Nelson is almost impossible to wear out. It will get frosty looking after a lot of runs, and I mean a lot of runs, even though it glows well if you replace it then all your problems disappear.Add to that they are really significantly cheaper to buy and only a one time cost for the adaptor.
Really is tragic to watch the demise of an american modelling icon. C*x was a great company once.

Interesting point. I have seen plugs still work but not well when they get frosty looking. Surely that is just a surface coating, and could be removed somehow to restore performance?

Anyone out there got an idea? What happens in the crockpot/antifreeze routine. Will that do it?

The hi comprestion heads are very good for mouse racing.

As Dana Wall points out, there are indeed certain applications where the Cox 1702 is the very best available glowhead.

denlip, where you been, my man? I used to bring in the VA 049, all the original ABC sets for Fox 35s and as sold by GMA, a bunch of other stuff, most of it high-perf two-stroke related but not for the model industry.

Even back then, pricing of 1702 heads was hurting us. The Commies were asked to develop any kind of head, glowhead, whatever that would at the very least equal a 1702. Months went by; they couldn't do it. So I took over a big bag of Nelson plugs, they were assigned the task of designing the very best conversion kit. Months went by; their best was not the equal of Mr. Doug Galbreath's Nelson-plug conversion set. Most of the sample heads were not near as good as a 1702.

I gave up, especially as much of this early screwing around was a way to test them and their abilities, the response time to new challenges. You judge the results.

I gave up. Called Galbreath, bought some heads, told him what had happened so far, that I was fixin' to simply copy his design, if it worked out well I could probably bring his design in at less than his cost to produce, would make him one sweet deal, we'd both come out okay.

To this day I use the Galbreath Nelson-plug adaptors, although I will admit to not being 100% current with what's hot in 1/2A Combat and FF.

Dan, I bought a few of those origional VA's from you , mostly roll your own. And I believe it was you who turned me on to the Nelson set up at that time. I checked my post and remembered that pharenthesis don't transfer but I had said that C*x plugs were inferior,except pre Estes. At any rate i loved those motors and was relly disappointed when they disappeared. Never got one of the Va mk2 versions so I don't know what they are capable of. At the time we were using then for 1/2A pylon racing and had very good luck with them. Dennis

You can't use the high compression heads in the Musciano Meet. Stock only. And only one port cylinders, too.

denlip,

Oooh, my apoligies; you continue to know your stuff.

My only defense is that at least I was consistent is suggesting Galbreath's head as the hot tip then and now.

Some of the most interesting people by far are those who have tried modeling disciplines along the way. Some may be real surprised that a guy who raced (still does?) any sort of RC Pylon is at all interested in CL Stunt. I'm not one of them.

Dan I guess the Cyclone is still the hot set up for FF the Stils was out for awhile.I haven't been keeping current on those as there is no use for them in slow C/l. 30,000 rpm stunt has not been invented yet.
Shame really that all the hot 15's and 049's are made in Russia,the economics of motor making pretty much precluded more then one or two people trying to make a living selling combat, and formula motors. And thats about how many are in it here