Assuming you mean , Theres a really good Wikipedia article on it. It's got a fairly detailed animation that lets you see where the joints are. You can make these joints with the Physics behavior, but I prefer the Chipmunk Physics. Each bone in the linkage will be a separate sprite, and you'll have a motor on the central crank, powering the whole thing. Play around with it and see how it moves!
You probably want some other kind of joint to stow the legs for flight mode.