"newbie" prop question
Hi All,
I have a Dynaflite Piece O' Cake that had a Black Widow .049 on it that I bought & built 20+ years ago. I broke the engine in back then, possibly didn't apply proper after-run lube, but when I finally dusted that plane off to fly it recently I can't get the Cox running right. Probably has an air leak, which I will continue to work on, but after trying a few things to get it running with no success, I ordered a new .049 OK Cub engine. I broke this engine in, then cleaned it up, screwed on the 6x3 prop from the Black Widow and headed to the flying field. Started the engine, peaked it, and hand launched the piece o' cake. It was a very calm day, and I had to fight to get the plane to 20-30 feet of altitude! I tried a few more times, seeing if I could tune a few more rpm, but it wasn't until the wind picked up a little that I was able to gain altitude to fly for a few minutes.
So, I'm no expert but I think the plane is under powered. I emailed OK Engines and they confirmed that the Cub is not as powerful/high rpm of an engine as the Cox.
Now to my question: To try to correct the situation I described (where the plane will just maintain altitude with no wind), do I need more rpm with a smaller od prop and or shallower pitch, or should I try a larger od and or larger pitch prop turning at lower rpm?
Other things I am thinking of trying is the OK Cub .06 engine, which I would hope although being heavier would have more torque to swing more prop. Of course making the plane lighter would help, but the only way I can think of to do that is to go with smaller radio gear & less battery.
Any thoughts/ideas would be appreciated.