OK Cub .024

Would be classic if you could pull it off

Good you brought up this little considered OK Cub .024, @duaneh. It appears to use the same tank mount bolt pattern as the Pee Wee?

I did a little reading of it and the Pee Wee in Sceptre Flight,

https://sceptreflight.com/Model%20Engine%20Tests/OK%20Cub%20.024%20%282%29.html

It produced 0.034 BHP at 14,000 RPM.

https://sceptreflight.com/Model%20Engine%20Tests/Cox%20Pee%20Wee%20020%20%282%29.html

Pee Wee produced 0.035 BHP at 18,500 RPM on 25% nitro fuel. Fuel used on the OK was not specified, but for its power to be similar to the Pee Wee given its slight upsizing in displacement, can't imagine it to be less than 25% nitro. It peaks at a lower RPM than the Pee Wee, which is typical for OK's.

That tells me that one may want to experiment with prop pitches and diameters slightly greater than with the Pee Wee, to extract most of its power.

Peter used OK's 5 inch prop, which I imagine was probably 3 inch pitch but could be different, maybe a 2. I don't have OK props to compare with. This lends credence to supporting the OK's power peaking at lower RPM's.

Duane, I am interested to hear futher of how well your plane flies on OK power.

Cool , Have you flown the undersize /resized Kingpin ? I was chasing the OK .024 at one time but never got one , I hope you enjoy and share the running with us .

Hi duaneh and gang,I have a cub .024 bench ran a couple years ago.actully ran good,I think all I had was 15 percent nitro.when I get some fresh fuel I will pull it out.i think they deserve more credit that some give them

I have flown the Cub .024 about a dozen years ago. Mine seem to be one of the better running .024's. I had it was mounted on a Scientific, Baby Stunt Master, the plans show a Cub .024 mounted to the plane. I flew it on 20' or 25' foot lines at the time. OK Cub fuel used to be 20% Nitro with 22 % Castor. I believe I used a 4 1/2 " by 2 Cox prop. I think the Baby Stunt Master was suited just right for the Cub .024 with a light built up body an 16in. wing span. It was more of a novelty to me, it could have looped, but I didn't. I had bought a couple of spare glo heads from Ted along with a few extra Reeds, but never needed them. I still have the Baby Stunt Master plans. Eddy

Well, I got a chance to run the Cub .024, but did not go as well as I hoped. I hooked up the glow battery, primed it, and could hear a good sizzle from the plug. I started flipping with high hopes, but nary a pop. Removed the plug and attached the clip. Sizzle, and even a wisp of smoke, but no glow. Bad glow head.

With nothing to lose, I removed the center post and D&T'ed the head to 1/4-32.




Now we've got a good glow! Back on the test stand, it will run on an exhaust port prime, but won't continue running. I have already replaced the fuel line, and verified the fuel passage to the venturi is clear. It looks like a PeeWee reed will fit, I will try one. After that, I am about out of ideas.

Great work on the .024 duaneh….I think you are on the right track to go after fuel delivery issues if it’s burning the prime out OK….Hopefully it’s successful and your fix can turn into a common repair for unobtainable heads for this neat little engine….

Good repair, @duaneh, I'm sure that soon you'll have the other problems sorted out so the OK becomes a reliable runner.

If you really want to turn heads, putting a venerable Champion glow plug of the 1950's that looks like their miniature spark plug would really turn heads!