# Launch Bar Dynamics Character Analysis of Carrier-Based Aircraft Catapult Launch
## 3 Results and Discussions
### The Effect of the Launch Bar CG Position on the Launch Bar Dynamics  
This article selected the proportionality factor (\(K_{launch}\)) of the launch bar as 20%, 40%, 60%, and 80% 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 proportionality factor of the launch bar are shown in Figure 7.  
After the launch bar automatically disengaged from the shuttle at the end of the power stroke, the key parameters are recorded in Table 4 for different proportionality factors (\(K_{launch}\)) of the launch bar.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Proportionality Factors** & **20\%** & **40\%** & **60\%** & **80\%** \\ \hline \(l_{p}^{p}\) & 0.7693 m & 0.7693 m & 0.7693 m & 0.7693 m \\ \(l_{cg}^{p}\) & 0.6555 m & 0.5294 m & 0.3912 m & 0.2408 m \\ \(l_{end}^{p}\) & 0.2035 m & 0.1711 m & 0.1393 m & 0.1085 m \\ \(l_{p}^{p}\) & 0.7414 m & 0.7414 m & 0.7414 m & 0.7414 m \\ \(h_{cg}^{r}\) & 0.6327 m & 0.5006 m & 0.3460 m & 0.1697 m \\ \(h_{end}^{r}\) & 0.1978 m & 0.1395 m & 0.0824 m & 0.0267 m \\ \(\partial_{r}^{r}\) & 67.15\({}^{\circ}\) & 64.54\({}^{\circ}\) & 61.92\({}^{\circ}\) & 59.30\({}^{\circ}\) \\ \hline \hline \end{tabular}
\end{table}
Table 4: Results of key parameter with different proportionality factors of launch bar.  
Figure 7: (**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.  
The change in proportionality factor of the launch bar had no effect on the height from the pivot point to the deck, as shown in Figure 7a. Due to the mass of launch bar being smaller than the elastic support mass, the change in proportionality factor of the launch bar had little effect on the dynamics of the elastic support mass. Therefore, the change in proportionality factor of the launch bar had no effect on the height from the pivot point to the deck.  
With the decrease in proportionality factor of the launch bar, the following values were reduced after the launch bar automatically disengaged from the shuttle at the end of the power stroke: (1) the peak value and the final value of the height between the cg position of the launch bar and the deck of the carrier; (2) the peak value and the final value of the height between the end of the launch bar and the deck of the carrier; (3) the final value of the angle between the launch bar and the nose gear. The proportionality factor of the launch bar could affect the equation of the momentum theorem for the launch bar by affecting the moment of gravity of the launch bar, the moment of the force of inertia due to longitudinal acceleration of the pivot point, and the moment of the force of inertia due to the nose landing gear's sudden extension. With the decrease in proportionality factor of the launch bar, the three above moments were reduced. Therefore, the risk of the launch bar striking the deck surface can be decreased by reducing the proportionality factor of the launch bar.  
There was an assumption that the initial height from the end of the launch bar to the deck was 5 cm. When the proportionality factor of the launch bar was 80%, the final value of the height between the end of the launch bar and the deck of carrier decreased by 7.33 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 reducing the proportionality factor of the launch bar.