Like you said the cannon was the focus so I'll start with that. You don't need two detachers for each dummy. I tested it using just one and they flew just as far as when using two detachers. The dummies don't make great projectiles because they slow down very quickly. This is actually pretty fun because now you have to try to avoid a midair collision (or not and just watch the fireworks lol). You said the plane was just a means of testing the cannon but it's a pretty decent plane. One thing to remember though is that once you fire you dummy missiles, the center of mass shifts towards the rear and in this plane that means it moves behind the center of lift. That's why you lose control of the plane after you've shot all missiles.