I mounted the fuel tank with the stopper forward. I was going to mount it like the manual says, but if I was low on fuel and went inverted, how is the clunk to follow the fuel. I don't think the length of the fuel lines will be too long. I hope not.

as for how it takes off, you might try a lightly higher nose angle. This is what I had to do to a Yellow F-16 as it would do the same. I think the rec. like 2deg or so. Maybe something to try.