Guy, nice video. I've got that same camera and like it a lot. You're doing the half roll during the reverse half cuban pretty well, as in not much attitude deviation before and after the roll. Unless you're trying to draw a perfect competition figure, I would focus on a perfect attitude before and after the roll, and maintaining perfect heading during the roll rather than drawing an inverted line after the roll. Drawing a line is the easy part - it's the roll itself that is the challenge. So if you're doing that well, the figure will look good whether you draw a line or not. You'll just lose a couple points if you did it in a contest.
Most folks doing this figure in non-inverted system aircraft actually vary their pitch a lot more than you're doing, as in letting the nose drop during the half roll.
The biggest thing I saw, which you've already picked up on, is your pitch rate through the loop. Again, unless you want to fly a perfectly round loop, anything else is just varying degrees of an egg-shaped loop, which is just fine for recreational acro. But if you did want to draw a round loop, you'll need to pull quite a bit harder up as as well as down. Looks like you're deliberately flying it with very little G load. Looks like it might be in the 2.5G territory up and down. This is fine for fun, but if you want to round it out, you'll probably need to pull at least 4G up, float the top a lot longer than you're doing, and pull at least 4G down.
Almost everyone first moving from recreational acro to competition that I've critiqued from the ground will fly a loop with a flat spot on the second quarter. You need a pretty good pull to get the first quarter started round, and then you need to increase your pull (more stick movement, not G force) as you pass through vertical to keep the second quarter round. Then you need to float it a good bit from about 30 degrees before inverted level, to about 30 degrees nose down in the third quarter of the loop. Then just a steadily increasing G pull through the rest of the loop down will round it out. Think about pitch rate in a round loop as speed is changing. At the top you're very slow...maybe half the speed of your entry/exit speed. So in this example, your pitch rate at the top should be half of what you'd see at the bottom if the loop is to have any chance at being round. If your pitch rate is the same throughout the loop, or even faster at the top, you know it's pinched, or egg-shaped. An even pitch rate could physically only produce a round loop if your speed never changed through the loop. This would take a wee bit more power than what you've got.
Also, if you have a fixed pitch prop, enter the loop at cruise power setting, add full power on the way up, and return to your cruise power setting on the way down. I see lots of folks pull power to idle at the top for fear of overspeeding and stressing the plane on the way down. This is physically impossible to do, even with power maintained, as long as you exit the loop fairly close to your starting altitude.
One more thing about video critiquing aerobatics is that your camera angle only captures pitch. I use this same camera, but mount it to my head using the strap provided. This allows the camera to capture my head movements during figures, which of course is to monitor different axes as needed. This allows me to critique accuracy of both heading and pitch, instead of just one or the other.
I know this video is not RV-related, but it's just an example of me using your same camera mounted in a way that captures both axes as I turn my head. It's been helpful for me to pick up on certain things after a practice session.
http://www.youtube.com/watch?v=0eibTyZAb0c&feature=channel
