I am just brainstorming here, but I am wondering about the following: Look at this picture of the payload bay doors on the space shuttle. http://commons.wikimedia.org/wiki/F...tory_inside_the_Space_Shuttle_payload_bay.jpg Each door has a torque shaft driven by an actuator. Lets say the required torque to drive the shaft is around 500 in-lb while the shuttle is in orbit. If I know the angle that the door rotates from closed to open and the dimensions, can I solve for the force required for that torque? Is the correct equation T=r*F*sin(deg)? Do I even need to know any thing about the door itself since this is zero G? Or would I need the dimensions of the torque shaft? If I am just making a rough estimate (very rough) would it be possible to solve this? This is not homework, this is just for my personal gain in engineering knowledge. Any ideas, insults, etc, are welcome.