Andrew

I ran across this article and thought you guys might find it interesting reading.

[link=http://www.georgiacombat.com/CASTOR_OIL.htm]Castor Oil[/link]

SGC

that article with further explanantion can be found here :- http://modelenginenews.org/faq/index.html#qa5
Stewart

Sneasle

while we are on the nature of this topic, can anyone suggest a good fuel for 1/2a use in general. from .15 and down in size?

combatpigg

My Feedback: (3)

FOX MISSLE MIST

flyinrog

My Feedback: (1)

http://www.flitelinesolutions.com/fuelprops.html

in this article it says in the 1970 Missile Mist was 25% nitro and 22% castor but that now it is 24% nitro and 17% castor...actually I thought CP was kidding so I looked this up Missile Mist does sound pretty 70ish...Rog

gcb

Missile Mist was designed mostly for .15 and below (although sometimes used for the Combat .35, etc.). At that time all Fox small engines were iron/steel plain bearing. The only small engine made by Fox now is the .15BB. Although it is iron/steel, it is also BB so it can survive on less lube. Still, were I to use it, I would add extra castor to make it about 22%.

For 1/2A use, I've heard folks tout Sig 25% and Byron's 1/2A fuel. I still have some Norvel 15%, to which I still add some castor. I would use 15% for general 1/2A purposes, 25% if racing. I have been able to use 10% OK but when I tried 5%, starting was more difficult. I like the lube to be 20%-22% of all or mostly castor.

One thing to remember is to try different fuel combos. Since fuel is one of the glow timing factors (also compression ratio, prop, plug, and location (humidity, altitude, etc.)) one fuel mix may be better for your plane.

Also remember that these are just my opinions and preferences, individual results may vary.

One final thought: The reference article above suggests a 7x4 or 7x6 prop for a baffle Fox .15. Mine all run fine on an 8x4 or a 7x6. I would not go down to 7x4 on that engine. I DID try an 8x6 and it was too much. The statement that they do not like to be over-propped is true. Again, my opinion.

George

combatpigg

My Feedback: (3)

I was sort of kidding....I just think it is the coolest sounding brand name, the can itself is a work of art, a collectors' item. I didn't know that they had changed the recipe. I normally just buy any old 15% fuel at the LHS for about $16, then add $2 worth of castor to it, shake it up, then start guzzling.

Sneasle

ok, i was wondering cause i have looked at a few of the fuels at my LHS and most dont say what kinda oil is in them and a few dont even list their fuel contect, atleast not that i could see.

combatpigg

My Feedback: (3)

That's why I don't care what I buy, as long as I top off the gallon jug with pure caster, it's all good.

Tim Wiltse-RCU

I know guys will laugh at me..... but my Cox engines LOVE Sig Champion 10% nitro 25% straight castor lube. That is what I was test running my Sniper DR's on and they were running 22,000+ rpm on it. On straight out he bottle Norvel NVX 35% they ran 20,000 if I was lucky....it's all about the castor bean!

Later,
Tim

OzMo

My Feedback: (3)

one REALLY good reason to use castor oil based fuel is because .....MOLES HATE IT!!

gcb

sneasle,

Most of the unlisted fuels are formulated for large BB ABC engines that don't need a lot of nitro or lube.

Many (most?) CL flyers will not buy fuels whose formula is not listed. Additionally, some fuels list by weight, so if they say 18% lube it may be 14% by volume.

If you need to use unlisted, off the shelf, at least try to look up the contents on the web. You may save an engine that way. If in doubt, add some castor.

Watch out also for car fuel. Some cars run very high RPM and can get by with less lube than a prop engine.

Oil from the good old castor bean burns at a higher temp than most synthetics. As engines run, the top of the piston gets very hot. On cox engines, just below that piston top is the ball socket. Castor will keep some lube on that surface well after most synthetics have vaporized (very lean run). Castor is insurance.

George

KidEpoxy

Castor is insurance
IF you never run lean, sythetic does ~ok
IF you ever run lean, sythetic may destroy your engine.

Castor is cheap insurance compared to buying a new motor... well, $7 SureStarts may be an exception, just how much castor $ will you spend a year to not buy another $7 motor- $5? $8? $20? But Norvies or other non-cheapo engines, I'd take the insurance.

combatpigg

My Feedback: (3)

$8 worth of castor [1 qt.] will treat 4 gallons of fuel, which works out to about 250 flights with my 1/2A planes, which also works out to just over 3 cents per flight for the extra lube. That's why I look at it like cheap insurance..

Sneasle

agreed.. i will keep that in mind once i start flying