GallopingGhostler

Hi, Tower Hobbies web page on fuels shows a quart bottle of 25% nitro Cox fuel for 1/2A engines. The oil make up is not specified.

I gather that by the manufacturer's address given, it is probably a Hobbico product.

Does this fuel contain Castor oil? If so, what is it's percentage? (For example, O'Donnell, now a Hobbico brand lists the percent quantity of synthetic oil and Castor oil for its model airplane fuel.)

I heard from another that it does not, but would like to know the facts. If it does not, then I'll fore go purchasing it for my stash of Cox engines.

Dave Harmon

George.....get some castor from SIG and mix it yourself....25/25....never any synthetic because of the ball socket on the rod top end.
Works great in the Cox engines.

GallopingGhostler

Dave, I hear you and already that is my methodology. Reason for my posting is for hopefully someone intimate with the fuel, to post what they know. If the fuel lubrication is totally synthetic oil content, then it is not a good fuel for Cox and other plain bearing small displacement engines with aluminum crankcase journals and/or ball and socket piston rod end.

My question is more for the benefit of others than it is for me.

JPMacG

My Feedback: (2)

Tower Hobbies might give you the answer if you call. Or they may not know but they might tell you who the manufacturer is. I don't think Tower or Hobbico are in the business of blending fuel.

FYI, S&W and others sell fuel for Cox engines. I think it's 25/25 as Dave mentioned.

GallopingGhostler

I PM'd a Hobbico representative, and they have updated their web page:

[link]http://www.coxmodels.com/fuel/index.html[/link]

Their fuel does contain Castor oil.

Dave Harmon

I still would not use this fuel in a Cox engine with that ball socket.
This fuel has too much synthetic and not enough castor oil.
These engines run great with straight castor and will last much, much longer.

dennis

My Feedback: (90)

While castor is the preferred oil for 1/2A especially Cox a little synthetic is not a bad thing to have in the fuel. It is really helpful in preventing the formation of varnish on the cylinders which they are all subject to getting. Also keep a Davis de varnishing brush to keep the bore clean.It's amazing how bad these engines run with varnish and how difficult they are to start until the varnish has heated and liquefied

Dennis

GallopingGhostler

According to recommendations from Bernie: [link=http://coxengines.ca/files/FG.pdf]Fuel Guide[/link] (PDF), Cox International, Canada

Recommends at least 20% oil content with at least 1/2 Castor and 1/2 Synthetic. Sig 25% Champion meets this criteria. Hobbico's Cox Fuel with its 18% oil content made of 10% Castor and 90% Synthetic does not meet this criteria.

I think your advice on the older lapped engines, earlier Schnerles and plain bearings of aluminum including K&B Sportsters of a slightly higher 24% oil content with both Castor and Synth provides an extra margin of prophylaxis (i.e., safety) in these smaller engines as well.

dennis

My Feedback: (90)

The original Cox fuel was 25% oil all castor 25% nitro for the sport and 30% nitro for racing. The nitro percentages dropped over the years as Cox cheapened their whole product line after Ray Cox sold the company it was a slow downhill till Estes flat out murdered it.

GallopingGhostler

I remember that fuel. One didn't have to worry about whether it had the correct oil or not back then, whether it was Duke Fox's Missile Mist, K&B 500, K&B 1000, or Cox. They were all safe and good for the motors. Only caveat was the periodic devarnishing the smaller Cox engines, which was not hard to do with a piece of fine steel wool.

Toward the end I wondered what happened to Cox. They came out with the RC Bee engine, which I bought. It seemed decent, albeit with a more costly die cast crankcase. Don't know why they didn't stick with a successful formula. The silicon muffler cover over the chambered exhaust throttle was a novelty and effective. Then they cheapened things up with the Dragon Fly engine.

Then they came out with the monstrosity called the .074 Queen Bee, heavy to the get go. Had a real RC carburetor, but they would have been further ahead to have stuck with the lighter exhaust throttle muffler and screw machine crankcase with a standard venturi back retaining the .049 tank back bolt pattern. I had a tough time starting it with the stock glow plug.

You're right, things went further south when Estes took over. I've heard that Bernie at Cox International and a few others are now turning out predictable results, by carefully matching cylinders, pistons and other parts for better quality engines.

Back to the original issue, one is left to add Castor oil back to correct these malnourished fuels.

aspeed

18% oil does seem a bit low, unless the synthetic is a new magic type, which could be.  The motors never really lasted 100's of hours anyway.  The crankcases wore out and they ran uneven after that.  The Queen Bee .074 is kind of heavy, but does run fairly well, as reedies go, if the muffler is removed.  The .049's are pretty much useless with any of the mufflers installed too.

GallopingGhostler

Yeah, I wore out that RC Bee's cylinder, it was more like about 100 plus flights at about 6 or 7 minutes per flight with the larger fuel tank. It definitely showed loss of compression. 6x100 = 600 minutes or 10 hours. That was back in the early 1980's, when the better standard fuels were readily available. Bought a new cylinder and piston set, which added a new lease of life. Since parts were fairly cheap and readily available then at any hobby store, one just bought and was back in business.

There was another gentleman who posted of his experiments with fuels, found that the Castor oil didn't benefit until running the engines at hotter temperatures. Wear was about the same whether synthetic or Castor. Wear was reduced by a chemical additive, I think it was used for paints. I haven't seen any official tests done under controlled laboratory conditions to substantiate that.

What I gathered is that it was very important to under sport flying use, not run engines lean. One cuts down on the available oil in the fuel spelling for premature wear or engine damage. With todays fuels, even with the modern ABC/ABN ball bearing engines they were "designed" to operate in, with the lower oil content, running lean could spell for trouble. The CL fliers add additional prophylaxis with additional oil content and running the engines richer more or less, 4 cycle burble or wet 2 cycle. Discussions, I gather that they get almost wear forever performance.

Regarding mufflers, the only effective muffler seemed to be the RC Bee's one with the silicon sleeve. It had some give to it with the engine's pulses. It was the only muffler that I used. You are correct thought about the others. Overall I never flew .020's and .049's muffled due to loss of power.

dennis

My Feedback: (90)

The queen bee's performance can be improved by getting rid of the head and substituting a Cox TD09 head. If you have the high compression head even better. You can also use the head from the Fox 09,Fox 10qmd the Gilbert 11. The guys who made that engine were asleep it seems as Cox killed most of the old original 049 engine simply by making a glow head for all of their engines, except the Queen Bee. Presto a short lived dog.

As to life of the engine the cox baby bee had a lifespan of about 6 hours or so. But remember that you were getting that time at a rate od 1.5 minutes a flight so it really took time to wear out a P/L set. also you would be surprised at how slowly a connecting rod really traveled at 14/15K. I remember it being about 6 miles an hour. Remember the stroke is about 1/4 inch or so for the rod. You needed the high oil simply because of the non bushed anodized case at the shaft and the lead alloyed cylinder
Dennis