Ok, so I was watching the video closely with a friend and our conclusion is that you have either one or two problems.
The first problem is thrust. Lack of thrust, plus the high angle of attack (nose up) in the video is likely causing it to stall. Stalls frequently happen on the same side every time, so that could explain some or all of the roll issue. For example, when I had my first Storch, it was underpowered and I didn't get enough speed before pulling up and it kept rolling to the left and crashing, similarly to what we're seeing here. I don't remember mine <yawing> that much to the left though, so that's why I suspect there may be a second issue. In any case, if you don't have enough thrust, you need to fix that, so we may as well start there.
Possible causes of low thrust:
- Prop installed backwards. I'm not talking about the rotation direction here, I'm talking about having the numbers (8060) facing forward on the prop. If it's on backwards, it will still produce some thrust, but a lot less. Check this first.
- ESC not calibrated to throttle. To calibrate it, turn on your transmitter first. Put the throttle all the way to the highest position. Then plug in your plane. The ESC will beep. After it beeps, turn the throttle all the way down. The ESC will beep a few more times and it will be calibrated. Do that and see if you get more thrust.
- The prop nut could just be loose.
- The prop could be damaged. Check to see if it appears bent backwards a little. A friend's prop was slightly bent back and it substantially reduced thrust. Try replacing the prop and see if it makes a difference.
Lastly, to sort of test the thrust, hold the plane nose up and give it full throttle. It should have nearly enough power to support its own weight.
After the thrust, then I would start suspecting rudder/vertical stabilizer alignment. In the video it sort of looks like the tail kicks to the right before it rolls left. With the yaw/roll coupling on the Cub, a badly misaligned vertical stabilizer or rudder might cause that. The way to test that is to do a glide test. Just turn on the transmitter, plug in the plane, and throw it without giving it any throttle. It should glide, slightly nose down, without rolling. If it still rolls, then it's definitely an alignment issue. If it glides properly, then I'm guessing that you're just having a bad stall due to low thrust and too-high angle of attack.
Good luck! Post more videos!
