Fuel?
 

What is the best fuel to run in the cox 049? Will the Sig champion 25 work?

RE: Fuel?
 

Which Cox .049? There were/are a number of varities. Way back before dirt, I ran a high nitro fuel with about 22% castor oil and that worked fine. At that time I was using the TD .049s for 1/2A Proto Speed and 1/2A FF, plus the .051 for A FF. The TD had to be set ultra lean for the CL reliability needed for speed runs. I found that out after being frustrated and dedicated to burning the S*/%)X up. That was totally against some 15 years of previous CL activity especially in stunt. Never to old to learn when willing to do so!!! :)

Starting a few years ago, I began using the Cox Black Widow .049 for sport CL because I had moved to where I can fly up to 52' lines in my back yard. I did this because of grandkids and grand nephews, etc.
My regular RC fuel didn't seem to work very well. I was trying to locate something higher that 15% nitro in my barn. I had some YS 20% synthetic, 20% nitro, but that did not improve reliability.

I found a gallon of Ducted Fan fuel, 10% nitro and 20% castor oil. Having read an article about small engines needing more oil, I set out to try it, thinking not enough nitro. WRONG! Those Cox .049s loved it. They still do as now I use any 10-15% nitro and add castor to assure some 22% oil with at least 1/2 of that being castor. NO PROB-LEEMS, Senior! They run anytime I take them out and I haven't blown a plug in 5 years. :D

So that doesn't answer, "What is best..." but maybe you can use that info. to find something suitable. Good Luck.

RE: Fuel?
 

As Hossfly said, most fuels will work. Check the oil content because some RC fuels are formulated for large BB engines that don't need as much lube, and lube can be as low as ~14% by volume.

I THINK the Cox formulas contained ~18% castor for lube. Later tests conclude that ~20%-22% is better. Most recommend that at least half be castor for the ball socket. Some synthetic keeps it cleaner and lessens varnish buildup that many experienced in all-castor fuels. Cox regular fuel contained 15% nitro, and their "Racing" formula was 25% nitro, if I remember correctly.

I find that with less than 10% it is harder to set the needle correctly, but perhaps that's just me. I fly sport/stunt so 25% nitro is as high as I go. Most of the time I use 15% nitro and ~22% (mostly castor) oil.

BTW, SIG sells 1/2A fuel.

George

RE: Fuel?
 

I have had excellent results using RC Car Fuel. I buy the 30% Nitro, 14% Oil version, then add "10% by Volume" Castor Oil. Remove 12.8 OZ. of fuel, then add back 12.8 OZ of Benoil or other Castor Oil. Mix well and you will have about 27% Nitro and 24% oil of which 10% is Castor. My TD 0.10, 0.20, and 0.49's run very well on this fuel.

Ralph

RE: Fuel?
 

I have been mixing my own 10% nitro / 20% castor and 15% nitro / 20% castor fuels, which run great in my Coxes and the Norvel 061. I can't detect any advantage in performance, starting, reliability or needle sensitivity from the 15% nitro, so will probably just do 10% from now on.