# Launch Bar Dynamics Character Analysis of Carrier-Based Aircraft Catapult Launch
## 3 Results and Discussions
### The Effect of the Restoring Moment of the Launch Bar on the Launch Bar Dynamics  
This article selected the restoring moments of the launch bar as 50 N-m, 150 N-m, 250 N-m, and 350 N-m when the simulation was carried out. The height of the pivot point of the launch bar, the height of the cg position of the launch bar, the height of the end of the launch bar, and the angle between the launch bar and the nose gear with the change in restoring moment of the launch bar are shown in Figure 6.  
After the launch bar automatically disengaged from the shuttle at the end of the power stroke, the key parameters are recorded in Table 3 for different restoring moments of the launch bar.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Restoring Moments** & **50 N-m** & **150 N-m** & **250 N-m** & **350 N-m** \\ \hline \(h_{O}^{p}\) & 0.7693 m & 0.7693 m & 0.7693 m & 0.7693 m \\ \(h_{cg}^{p}\) & 0.4372 m & 0.4491 m & 0.4618 m & 0.4752 m \\ \(h_{end}^{p}\) & 0.1055 m & 0.1289 m & 0.1551 m & 0.1836 m \\ \(h_{O}^{p}\) & 0.7414 m & 0.7414 m & 0.7414 m & 0.7414 m \\ \(h_{cg}^{c}\) & 0.3814 m & 0.4035 m & 0.4261 m & 0.4492 m \\ \(h_{end}^{p}\) & 0.0212 m & 0.0655 m & 0.1108 m & 0.1570 m \\ \(\theta_{r}^{f}\) & 59.04\({}^{\circ}\) & 61.13\({}^{\circ}\) & 62.23\({}^{\circ}\) & 65.33\({}^{\circ}\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Results of key parameters with different restoring moments of the launch bar.  
The change in launch bar restoring moment had no effect on the height from the pivot point to the deck, as shown in Figure 6a. This phenomenon occurred because the restoring moment of the launch bar was smaller than the load in the catapult launch system. Therefore, the change in launch bar restoring moment had little effect on the dynamics of the elastic support mass.  
Upon increasing the restoring moment of the launch bar, the following values increased after the launch bar automatically disengaged from the shuttle at the end of the power stroke: (a) the peak value and the final value of the height between the cg position of the launch bar and the deck of the carrier; (b) the peak value and the final value of the height between the end of the launch bar and the deck of the carrier; (c) the final value of the angle between the launch bar and the nose gear. This phenomenon occurred because the launch bar restoring moment could affect the equation of the momentum theorem for the launch bar, whereby a larger launch bar restoring moment resulted in a larger angular acceleration of the launch bar. The risk of collision between the launch bar and the deck can be reduced by increasing the restoring moment.  
There was an assumption that the initial height from the end of the launch bar to the deck was 5 cm. When the restoring moment of the launch bar was 50 N-m, the final value of the height between the end of the launch bar and the deck of the carrier decreased by 7.88 cm, whereby the launch bar would strike the deck surface of the carrier. Therefore, the risk of the launch bar striking the deck surface can be decreased by increasing the restoring moment of the launch bar.  
Figure 6: (**a**) The height between the pivot point of the launch bar and the deck of the carrier; (**b**) the height between the cg position of the launch bar and the deck of the carrier; (**c**) the height between the end of the launch bar and the deck of the carrier; (**d**) the angle between the launch bar and the nose gear.