[Joseph Smith]

In '11, our team along with 1718 used a pair of gas shocks to balance our arm, mounted on either side of our tower. The arm was balanced in the stowed position, about 30 degrees from our vertical tower. Since the mounting point of the gas shocks moved with the arm, the force that they apply on the arm increases when it reaches horizontal and decreases when it is above or below horizontal, so that the arm is balanced at all points of rotation. I'm not going into the physics behind this, but from my personal experience it works.