2. System Architecture and Inputs: F-14 Wing Sweep

During flight, the operational wing sweep angle can be varied from 20 to 68 degrees relative to the pitch axis of the aircraft. This is a relatively simple planar mechanism of three links (ground, actuator, and wing), but uses linear actuation rather than direct rotation to control the sweep of each wing. A diagram with showing the overall dimensions of the aircraft and the mechanism architecture are shown below.

F-14 Aircraft Dimensions

F-14 Wing Sweep Mechanism

The mechanism is designed to provide significant mechanical advantage and smooth, controlled motion over the full range of motion and driven by an actuator similar to that shown below, which uses a gear train and lead screw to convert rotational motor input into linear actuation.

Linear Actuator Section View

A simple animated Solidworks model of the mechanism is shown to the right (note: model is not to scale).

The following kinematic analysis is based on wing sweep system performance shown in simulations and performance characteristics of industrial long-throw linear actuators which could be used to drive the mechanism. The time required for full mechanism actuation was assumed to be 60 seconds. This is consistent with the range of motor speeds on lead screw style linear actuators of this size. The maximum motor speeds for these actuators typically range from approximately 4000-9000 rpm. The motor speed curve shown below was derived using these values. 

Input Motor Speed Curve

The gear ratio of the worm-ring pair was assumed to be 20, and the pitch of the lead screw was assumed to be 1/8 inch ACME standard. Both of these values are reasonable given the size of a typical actuator capable of providing the full range of motion of the mechanism. The resulting linear actuation motion profile used as input to the three bar mechanism is shown below.

Actuator Motion Input for 3 Bar Mechanism

Solidworks  Mechanism Animation (not to scale)