6. Mechanical Advantage: F-14 Wing Sweep

The gear ratio required for the actuator to produce linear output motion and the positions of the wing and actuator links can be used to calculate mechanical advantage. As expected, the mechanism reaches a maximum mechanical advantage when the wing link and actuator link are perpendicular, which occurs near the fully forward swept position. This is reasonable for the application because the wings experience increased drag in the swept forward position, and increased mechanical advantage provides greater resistance to back driving. The maximum mechanical advantage is based solely on the gearing of the linear actuator and can be calculated as the product of the worm-ring gear ratio and the inverse of the lead screw pitch.  This value is scaled according to the transmission angle between the actuator and wing links.   Plots showing mechanical advantage versus actuator link length and time over the full range of motion are shown below.

                                                        Mechanical Advantage vs Actuator Length and vs Time