Good evening. I've never flown an RC plane in my life, however, when cleaning out the wife's grandma's attic I found an old control-line plane. Intrigued, i took it home and cleaned it up. Now that it's cleaned up and moving again. I'd like to get it running. From what i can gather, it's a Fox .15, they (my in-laws) flew it in the '70's and it probably stayed in the attic for the last 30+ years after they grew bored with it.

So, my question is, what the heck do i need to get it running again?

As far as materials, I've got it mounted to a test stand of sorts, but I'm not sure where to mount a fuel tank. i went to the last remaining hobby shop in the area and found a glow plug that fits and works. I got an igniter, so I know the plug will heat up.

What about fuel? I know nothing about RC plane fuel.

And...does this thing have a carb? I've worked on old mopeds, so i've seen and cleaned a few small carbs, but nothing this tiny. How do I set it to run or even start? it looks like it only has a screw/spring assembly on the side that turns the needle. Is that the only fuel adjustment possible?

Last question, which way does it turn? Clockwise or Counter-clockwise?

I'll put up a few pictures of that i took tonight, if something is amiss, please let me know. i'd love to get it running for my own boys, and me, to enjoy.

This is, indeed, a control-line (CL) Fox .15 for the 60's or 70's. Engine's easy - truly. There is no carb, just the venturi (intake) in the front. Through the venturi is the needle valve (long screw with the spring on it) and on the other side is where you plug in the fuel line from the tank.

The engine, as you face it, turns counter-clockwise.

Any decent glow fuel (same fuel works for control-line or RC) works just fine in these engines. My own Fox .15's run regularly on 0% nitro. Nitro percentages is how you determine what fuel to use - in the CL world 0% works for most of us common flyers but some guys will use 5% with the smaller engines like a .15 Fox. I can't think of any reason (other than speed planes) for a nitro more than 10% for CL engines, and a Fox is nothing close to a "speed" engine. Your only challenge with the modern fuels is to find one that has enough castor oil. The old Fox iron engines used 28-30% castor and few fuels have that much today. You mentioned that you have a local hobby shop (LHS), talk to them about getting a small bottle of castor oil to add to whichever fuel you get - it's nothing to simply pour it in and shake it.

OK, first - you've got one issue - the propeller. From the photo, it looks like you've got the old white plastic prop - GET RID OF IT! Even new, these props were dangerous and had to be "pretreated" by boiling before first use. 30+ years old, there's no chance it will hold together while running today. You're probably going to be hand-cranking the engine - I would suggest a wood 8x4 or 8x6 prop. 8x4 and 8x6 is the size and thrust (8" long, 4 being a weaker thrust than 6). For bench running an 8x4 will do nicely. What you don't want is a carbon fibre prop - it'll cut your fingers to ribbons.

Speaking of fingers, safer crank starting would be to use what us old-timers call a "chicken stick", simply a broom handle end (maybe 8" long or so) to turn the prop. Saves the fingers a lot. They're made commercially but for your purposes an old broom handle will do fine.

When you mount the new propeller, try to mount it so it's horizontal when resting against the piston compression. As you turn the propeller on the engine, there's a point at which it gets harder to turn - this is the compression working against your turn. This is the point you want the prop horizontal. Not a critical item, just makes hand-cranking easier - is more important when the engine's on the plane. When flying and fuel runs out, a horizontal prop is much less likely to be damaged on landing.

Fuel tank isn't mounted to the engine, it sits behind it and can be mounted simply by a couple eye-screws and a couple rubber bands holding it in place. Your LHS should have lots of them, and a 2 or 3 ounce tank is more than enough for a .15 - a 2 ounce tank will run you for about 6-8 minutes. You need one fill/feed hole, and one vent hole. Old CL tanks have 3 tubes - on top is the fill tube, bottom has the vent/overflow, center is the feed to the engine.

I strongly suggest you find a place outside to run the engine. First, there's no muffler so she's LOUD!!!! She also exhausts a fair amount of smoke, oil, and fumes. That's normal.

You did a good job cleaning her (they're not super high performance engines) and as long as she's turning fairly easily with no fuel in her you should probably be good to go. Let's look at that needle valve first though. Unscrew the needle with the spring completely out of the tube and take a look through the tube to make sure it's completely clear - that's got to be clear in order for fuel to flow through it. The tube has a tiny hole in the side that you can't see by looking down the intake - hopefully. It's probably a good idea to unscrew the nut on the other side and remove the tube to make sure this hole is clear too. When you re-install it, make sure that hole is facing down, into the engine.

Screw the needle back in - all the way closed - and then unscrew it 3 full turns. Being Fox, there's probably a tiny notch on the head of the needle - that's a reference notch so you know how much it's turned. It's just a case of paying attention while turning.

OK, fuel tank's loaded and hooked to the engine. Without hooking up the glow plug to power, put your finger over the intake and turn the prop two or three turns to suck/syphon fuel from the tank - you'll actually be able to see the fuel coming up the line to the engine. Then, finger off the intake, flip the prop to hear the engine "pop". No power, so it'll just be a chug. Hook up the power line and turn it again, slowly, to try to get a "kick" out of it. If/when she kicks, you'll know, no doubt whatever. Turn the prop one more revolution, and on the 2nd turn - as the propeller gets into the compression stage - flip it smartly.

It'll probably take a few tries to get her started. A 2-cycle engine at low speed only "fires" every other revolution, which is why one turn gives you the kick and the next one doesn't - you want to be "flipping" on that "fire" revolution.

Once started, she'll be running slow, what we call "4-cycling" - maybe 5,000-6,000 RPM. Reach around behind the engine (stay away from that prop) and slowly screw in the needle valve. You'll hear the engine speeding up. The point will come when the speed/sound jumps slightly and she'll really be screaming - that's when she'll be truly singing - a glorious (and loud) sound. With a 8x4 prop, it's also about 10,000-11,000 RPM - her designed running speed. If you screw in just a tiny bit more she'll start to die off. She's too lean (fuel vs air) at that point. Just back off a little bit (maybe 1/8 turn or so) to the point she's screaming again, and then back off just a little bit more. A little extra fuel (and smoke, and oil) going in while on the bench means she'll stay just a bit cooler while running.

However, on your first bench runs, consider that she hasn't been run in maybe 30 years. Once you get her up to screaming speed, you'll want to back off a bit more to slow her down a bit - higher than when she first started but still 4-cycling. There'll be smoke all over the place, oil all over the place - and she'll be happily purring along.

Once the engine quits, she's going to be HOT! Give it about 4-5 minutes to cool down to the point where you can touch it safely.

A quick note about the smoke. Castor oil does not burn. The oil coming out the exhaust, and the smoke, are the same thing. The fuel consists of alcohol (the actual FUEL that burns to run the engine), castor oil (lubricant) and nitro-methane (you could call it "octane boost"). 0% nitro = 87 octane fuel in your car. 10% would be equivalent to about 90 octane or so, 15% is high-test. To an old-timer like me, there's nothing better than the smell of castor in the morning.

Good luck with her!! If you have any problems at all, I, and a lot of other guys most likely, am here.

As a safety tip, paint the outer 1/2" of each prop blade yellow or white. While running, that prop becomes invisible. The paint will remind you of where the blades are. It only takes a split second to sustain a lifelong injury!

For a short run with the fuel setting on the rich side any glow model engine fuel will do. But if you want to run the engine flat out for more than a second or two then that engine needs more caster oil than is found in modern fuels.

Duke Fox recommended the use of 28% all caster oil and some nitro say 10%. for his engines that had plain bearings.

If I wanted to use that engine I would take a regular 15% model fuel and add 6 oz of Klotz caster to a gallon.

Thank you all so very much for the help and information. I'll update here as soon as I get the little engine running!

Hi!
A suitable prop size for the old FOX .15 (2,5cc ) is a 8x4 or 8x5 prop.APC is a good choice.
fuel: 25-25% castor oil, 5-15% nitro and the rest methanol.

You can flip start that engine! All of us old-timers used that metod when we started decades ago
, and we still use it, using the long finger! Or...using a modern electric 12V starter.