Hi, thank you for all of your comments.
This post is actually started when I shared my Lazy 8 practice video with my Vector 40
and I was suggested that I should work with the tank height. I was told that the engine sounded leaning when performing the outside loop when in the lazy 8. Well, to be honest, I didn’t really aware of that when flying.
I didn’t feel much different in control when transitioning from the inside loop to the outside loop. Most probably it's because of my flying experience so I can't really tell the difference, yet.
But after reading your responses here, I think I'm gonna hold the decision to play with the tank height at the moment because:
1. From what I've read from various resources and comments, I need to settle into inverted flight for at least 5 level laps and time those compared to the upright. Dan also wrote "It may take a lap or so for the setting to show itself." -- I’m still learning to be able to fly inverted more than 1 full lap, that's why there's no inverted flying on my video. I guess it's still hard to tell if the tank is in the wrong height or not since the only 'evidence' I have now is the lazy 8 video.
2. Dan wrote "But you still can listen to the engine run as you go through the eight, and see how it changes in each looping direction." What I hear is the engine leans out throughout the lazy 8, from the inside to outside loops, and back to the richer sound when back on level upright (I might be wrong though, I'm still not that good at judging how the engine sounds). -- I think this might be because of I'm still learning to fly inverted and feel less confident when upside down, so I'm turning tighter outside than inside. From what I've read, that will change the relative way the motor runs too because the load on it through the prop is higher when I turn tighter.
3. And as Ken said, "It would be natural for an engine to lean out going into inverted from a loop but it should go back to rich once level inverted." -- I think if I only do the Lazy-8 which means I only go for an inside loop and then directly an outside loop, I wouldn't have the chance to hear if the engine go back to rich, would I?
4.
I note that with many modern engines (and some ancient ones), running it too slowly greatly exacerbates this tendency. Just about any modern engine on a stunt plane needs to have a 4" pitch prop, and the associated relatively high RPM. Or at least high by stunt standards - 11,000 - 12,000 in the air. That's because everything inside it is sized for running at high speeds, not chugging around at 8500 rpm like it was 1955 all over again.
I fly my Vector with ENYA 35XS, APC 10.5x4.5, 10,500-ish RPM, and 5.4 sec lap time. I might try to close the needle a bit by a click or two and see the difference.
In conclusion, rather than tinkering with the current tank setup, I think I would try to focus to fly the loops and Lazy-8 better first and do the inverted flights for more than 2 or 3 laps consecutively. I'll try to time the laps when I can do the inverted flights.
Does it sound a good plan?
Looking forward to hearing more from you guys!
Best,
Kafin