I think I may have found the real design intention behind RTS Lugnut's missile launcher. If this is right, the launcher part was incorporated to make the feature playable, and the position was for a different purpose. It's a midair refueling boom. Lugnut's a flying fortress - a large command type plane that can be used to refuel smaller fighters from a boom in the tail section. Lugnut's missile launcher is in the exact right place to fulfill this function: I think this goes some way to explaining the otherwise random positioning of this part.