4. Velocity Analysis: F-14 Wing Sweep
The following velocity analysis is based on the input shown in Section 2 and the position analysis shown in Section 3. The linear actuation speed can be directly calculated from the actuator gear ratio, lead screw thread pitch, and the input motor speed curve. The resulting linear actuation speed curve shown below is a direct scaling of the rotational motor input speed.
Linear Actuation Speed vs Time
The resulting rotational velocities of the input (actuator) and output (wing) link are plotted versus actuator link length and time below. The equations used to calculate these values were derived from the 3-bar position loop closure equation. This results is a two-by-two system of linear equations which was solved over the full input domain. Although the actuator link rotational velocity shows an interesting curve shape, the magnitude suggests that this is negligible for purposes of analysis. However, this motion is necessary to allow motion of the mechanism. Regardless, these values will be kept to maintain accuracy of further analysis. The wing link rotational velocity follows a curve similar in shape to the linear actuation speed curve.
Input (Actuator) Link Rotational Velocity vs Actuator Length and vs Time
Output (Wing) Link Rotational Velocity vs Actuator Length and vs Time
The linear velocities of point A and the COM of the wing are scaled versions of the output link rotational velocity based on distance from the pin joint between the wing and ground links. These distance between point A and the ground pin is 36 inches, and the distance between the COM and the ground pin is 96 inches. This results in a COM linear velocity that is approximately three times that of point A.
Point A Linear Velocity vs Actuator Length and vs Time
Wing COM Linear Velocity vs Actuator Length and vs Time