Hello new here.Will the old Fox engines .15 .19and .35 run on straight castor oil?Or does it need some nitro?

Not sure if I understand the question entirely.

To clarify:

These engines are two stroke engines which means that they have no oil sump and require a lubricating oil to be mixed with the fuel.

The fuel in these engines is a mixture of Methenol ( a form of alcohol) and nitromethane (gives the alcohol a real boost in energy).

The castor would be the lubricant added to the methanol/ nitromethane mixture for lubing purposes.

The castor does not burn so therfore adds no power to the mixture.

The purpose of the castor is to lubricate the engine while running and to remove heat from the engine thus providing a measure of cooling as well.
LT

Thanks LT for the info.

I think your question is will the Fox engines run on fuel with a mix of methanol and castor oil with no nitro?The answer is yes but with some reduced power. They all run with more power when nitro is in the mix.
Bob

jayseas,

If you are asking if these engines will run on no-nitro fuel, the answer is yes, but not as well as with nitro. Fox made some modified heads to use with FAI fuel. I do not know if they are still made nor which models were available.

If by "old" you mean with a lot of running time, all-castor (no synthetic) lube would maintain the castor varnish seal for best compression in those iron/steel engines.

The amount of nitro included is a personal preference for your situation thing. For the Fox .15, Duke Fox recommended his "Missile Mist" fuel which I think is 25% nitro. I like 15%-25% for my Fox .15's (any vintage). Thebaffle .19 likes 10%-25% nitro, I have not run my schnuerle ones enough to determine but they seem to like the same mix. The .35 stunt runs well on 5%-15%.

For lube, I like 20%-22% castor or castor/synthetic mix for the .15 and .19. The Fox .35 stunt is a "special" situation of maximum engine in a small case. It likes 25% 28% lube because much of the generated heat is carried off via the lube, especially when tightly coweled.

Remember that these are personal preferences, others may choose a different mix.

If one of these did not answer what you were asking...ask again.

George

George Aldrich flew Fox stunt 35's with 25% castor, no nitro.  I run 10% nitro. 

Thanks guy's, apreciate the information and your time.
Jim

I run my Fox 35's on 25% castor, 3% klotz and 15% nitro. This was suggested by Fox modification man Larry Foster and it produces the best Fox runs that i have ever had in over 40 plus years of operating them. Give it a try.
Chris...

Do you mix your own or where do you buy that miixture from?
Jim

jayseas,

Unless you have old worn-out engines, there is not a problem with the castor varnish. Synthetics or part synthetics keep the engine cleaner running. If you have problems with the varnish seal, switching to all-castor lube will get all or most of it back.

As far as the percentage of lube, many of us ruined engines back in the fifties and sixties by using popular fuels that had insufficient lube...they are no longer around.

One of the reasons we need to keep an eye on lube is that most "RC" fuels are blended for large BB engines, which require less lube. You can use the RC fuels...many do. By looking the contents up on the internet sites, you can figure what, if anything, you need to add. Castor can usually be purchased from hobby shops, or online from SIG. I'm sure there are other sourses, but I have used these.

BTW, methanol in the fuel is what keeps the glow plug working. It is a catalytic reaction between the methanol and the platinum in the glow element. Nitro makes it burn better.

George

George, thanks again for your input.I'm trying to get that varnish seal back and keep it.


stuntflyr,,I run my Fox 35's on 25% castor, 3% klotz and 15% nitro. This was suggested by Fox modification man Larry Foster and it produces the best Fox runs that i have ever had in over 40 plus years of operating them. Give it a try.
Chris...


Chris do you mix your own fuel. If not where do you get it from?

Hi Jim,
I was getting it from Excaliber Fuels in Phoenix AZ but I don't have a contact right now.
 Sig fuel is very good too. Their all castor fuel would be good, it comes in 15% nitro and just add the necessary catotr and klotz to make up the difference from their 20% oil content.
I ordered some online a while back and it took a little while but worth the wait.
Chris...

Just a thought...

Shipping and HAZMAT costs get cheaper (per gallon) when you purchase four or six gallon cases, I believe.

George

George, i'm on a budget that unfortuntly i can't spend that much at a time.
Take care.

I've never used nitro and some time ago someone asked me if a Fox 35 would run with zero nitro. I'd never run a Fox before although somehow I had an old one in my collection so I figured I might as well try it so I could answer him. Fuel was 25% all castor and after I figured the engine felt wet enough to start I gave it a flick and off it went. I stopped it when it was hot, gave another flick and it was running again. This was with an engine so worn it leaked like a seive when put up into compression.

So is that all castor and methanol?

All-Castor is referring to JUST THE LUBE. It means that whatever the percentage of lube (25% for downunder), all of it is castor...NOSYNTHETIC.

In this case, yes the other 75% is methanol.

If the fuel contained, say 10% nitro, the methanol would decrease to 65%.

George

Can person buy methannol?

I bought methonol at the dragstrip a couple weeks ago. It was $2.50 a gallon.

Of course will a FOX run with no nitro fuel ! The question is : how ?
To say the truth, the 35 will run fairly good, as we boys where doing back in the '70s here in Italy ( nitro scarce and expensive, wallets desperately empty..) so 25% castor 75% methanol was the norm.
When finally nitro was tried  (5 %) , boys what a discovery ! needle valve forgotten for months, the most consistent runs we ever had !
And when, because a faulty fuel tank, I switched to 29% oil ( with 25% oil I had to pull fuel from the tank in order to land within 7 minutes in F2b, but I was always forced to abort the four leaf clover due to the engine coughing, the only way was to completely fill the tank and increase the fuel consumption by adding oil..) then I understood I made the FOX superfuel replica.....and my best runs since !  Always follow grandpa's advice ! (DUKE's.....)

Renato</p>

Back around 1977, a discount house had Fox stunt 35's for $12.95. I bought four and took up flying stunt. I lapped the piston and cylinder with DuPont white rubbing compound. Gave each one several rich runs on a 9 x 4, and went flying. Could not get the Fox NVA to be consistant so put in ST NVA's. I was somewhat serious for several years and put a bunch of flights on them. They all ran the same, but I ended up using one as the workhorse. I don't recall what fuel I ran, 10% nitro and probably all castor.

About three years ago I built a Herns Demon for Old Time Stunt. Put the workhorse Fox in it. It has several hundred flights on Sig Champion 10% nitro, 20% oil-half castor, half synthetic. I am running a stuffer backplate and a stock head. I took the hemihead off because the engine was too powerful. One could not ask for better compression. Usually one flip starts and runs the same every time. I'm running a Taipan 11 x 5 propeller, turning about 7,800 on the ground but noticably faster in the air. The engine sounds terrible, but the airplane trucks right along. It's on 62 ft lines and is a hair faster than I really like.