3. Position Analysis: F-14 Wing Sweep

The actuator length data shown in the previous section was used as input to generate all of the following position plots. Because all length lengths are known, positions of all links in the 3-bar mechanism can easily be solved via a series of Cosine Law calculations. The pin joint between the actuator link and ground link was used as the origin point for calculation, and the results can then be transformed to any orientation by applying a rotation matrix. For this analysis, the mechanism was rotated to match the mechanism diagram shown previously (horizontal aligned with pitch axis of the aircraft). A plot showing the paths of the pin joint between the actuator and wing links (A) and the approximate center of mass of the wing (COM) is shown below. 

                                                    Overall Position Analysis Plot (X and Y Scales in Inches)

Individual plots of the actuator link angle and output (wing) link angle used to generate the plot above are shown below. Angle values are with respect to the coordinate origin as defined previously. The actuator link angle oscillates slightly in order to follow the circular path of point A, while the output (wing) link angle shows linear monotonic behavior with respect to the actuator length. The angular position values are also plotted versus time based on the motor input speed curve shown in Section 2.

                                                          Actuator Link Angle vs Actuator Length and vs Time

                                                    Output (Wing) Link Angle vs Actuator Length and vs Time

The actual wing sweep angle output can be calculated by adding the fixed angle between the wing link and the leading edge to the angular position of the wing link. The plots below show the resulting wing sweep angle variation from approximately 20-68 degrees versus actuator length and time.

                                                          Wing Sweep Angle vs Actuator Length and vs Time