Hi. I'm a total newbie to this forum (and RC flight in general.)

I built a .40 Cub from a kit that was a gift, but decided not to smash it up learning to fly, so I scratch built an electric L19 from plans in Model Airplane News that's had a couple of spectacular crashes, and is presently waiting on a nice calm day with a break in my schedule for the next go.

In my attic I found a Cox engine that I'd salvaged from a Cox Sky Copter free flight helicopter I used to own. Since I enjoy building - I want to put it in something. Anyone recognize this and know it's size?



The tiny little fuel tank was cracked, and I dremeled the pivot mount off the bottom, so it can now act as a firewall. The photo is the engine on a test stand. It fired up, but would not run more than a few seconds on some 15% fuel (I need to find a local source for 24%.)

Thanks,
-Bill

From the size of the screw heads on the drywal screws and what I remember from the copters I think it's an 020.

If you can build something fairly light sort of like a powered glider type thing and can keep the weight down to about 10 oz then it'll fly with this engine in a very nice trainer level of performance. But a lot depends on what radio gear you have. If it's the "standard" sized stuff then you're pretty well beaten before you start. If it's something with mini to micro servos, or you don't mind buying such servos, then you're in like Flint.

Some of the speed 300 electric gliders would be great. Or lighter built electric types up to 36 inch span.

Yup, .020 "product engine" - got several of 'em. I cut the backplate down to a rectangular shape and drilled 4 holes to match the original PeeWee tank mount hole spacing...works good with eyedropper tank for FF or with a very small r/c tank.

I understand that yellow prop is the best .020 prop around (so sayith some FF guys) I think it's stiffer plastic than the black ones but not as much load as the grey composite ones. I had one but it broke, sorta brittle.

Take out the needle valve and flush some alcohol or fuel through the fuel nipple to clear out any old castor mung. Put your needle back in and try again....the 15% fuel oughta be fine if it's not old and bad. Check your 4 case screws and the glow plug for tightness. Heck, it oughta run unless the reed's gummed up but if it runs at all it's probably good enough to get it running. If you get it running, try to set it rich as possible for a while to help clean it out.

Let us know how it goes and good luck!

But not TOO tight. The backplate is only plastic and the screws are only 2-56 into aluminium.

A jeweler's screwdriver and 2 fingers without cracking any knuckles should do it. That would be 3.645 ft lbs for the scientific guys....

That's the production version PeeWee .020 off of the old Bell Free Flight Helicopter. Missing it's clear platic fuel tank.

Thanks much for the replies.

Good to hear it should work on the 15%. It's still fresh, picked it up locally.

I'll give it a cleaning with alcohol and another go.

How much voltage/amperage should I use to drive the glow-plug? I'd just clipped on my model rocket launcher (9v battery source) since it was near my workbench and had aligator clips.

I've got 3 Dymond pico servos that I picked up for my L-19, and even though my Airtronics receiver isn't the smallest in the world, it's not all that heavy.

So... It would be good to replace a 300 size electric in a glider, what about other designs? I ran across a Sopwith Camel .020 in another thread, is that only practical by using a more efficient .020 engine or uber-lightweight components? One of the planes I eventually want to model is the Curtis Jenny, because my grandfather flew one in WW-1. 1/2 A seems particularly appealing to me, due to limited work and storage space in my home.

Also - what about throttle? This engine has no throttle, is it common for folks using this sort of engine to fly without a throttle? Also, would it be a practical idea to put a brass sleeve over the cylinder with an exhaust/air intake port in it, so that it could be rotated around the cylinder, choking off the exhaust and fresh air intake to act as a throttle?

Thanks again,
Bill

Step away from the 9v batteries! The Cox glow heads are designed for 1.5 volts. If your 9v was any good, that glow head is now toast and you'll have to get another....sorry! You can get a couple of D-size flashlight batteries and wire them in parallel (pos. to pos., neg. to neg.) to make a good starting batt. I use a 5AH nicad D battery so I can recharge as needed. The Coxes require a good bit of amperage to fire up; especially in cold weather.

Fortunately it's still good :-)
9vs can't deliver much amperage.

-Bill