In case you're interested. On a pan flute, the pipes increase in length in exponential order. If you want a quick, but good way of getting it right, make the longest pipe twice as long as the shortest (you're not quite there yet). Let the lengths increase in a straight line (the way you've done) then shorten the middle pipes so that you have a gentle curve, like a tilted bow. Not doing well describing this, I should draw it. The diameter should be constant on the entire pipe, so you won't have them touching at the bottom yet having enough gaps at the top for you to see her chin through the pipe.