# Launch Bar Dynamics Character Analysis of Carrier-Based Aircraft Catapult Launch
## 3 Results and Discussions
### The Effect of the Launch Bar Mass on the Launch Bar Dynamics  
This article selected the masses of the launch bar as 10 kg, 20 kg, 30 kg, and 40 kg 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 mass of the launch bar are shown in Figure 5. \begin{table}
\begin{tabular}{c c} \hline \hline
**Simulation Conditions** & **Data** \\ \hline The type of aircraft & A3 \\ Mass of the aircraft & 31,752 kg \\ Thrust angle & 0\({}^{\circ}\) \\ Wing area & 72.37 m\({}^{2}\) \\ Mean geometric chord & 3.55 m \\ Nose tire undeflected radius & 0.4 m \\ Main tire undeflected radius & 0.559 m \\ \hline Initial steam pressure of accumulator & 1.38 MPa \\ The type of steam-powered catapult & C7 \\ Mass of piston & 3000 kg \\ Catapult stroke & 75.3 m \\ Deck edge distance & 12 m \\ The initial angle between the launch bar axis and deck & 30\({}^{\circ}\) \\ The initial angle between the holdback axis and deck & 25\({}^{\circ}\) \\ The coefficient of friction between the tire and deck surface & 0.17 \\ The coefficient of friction between the piston and cylinder wall & 0.17 \\ Air density & 1.2254 kg/m\({}^{3}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Simulation conditions of the catapult launch. After the launch bar automatically disengaged from the shuttle at the end of the power stroke, the following values are recorded in Table 2 for the different masses of the launch bar: (1) the peak value and the final value of the height between the pivot point and the deck of the carrier; (2) the peak value and the final value of the height between the cg position of the launch bar and the deck of the carrier; (3) the peak value and the final value of the height between the end of the launch bar and the deck of the carrier; (4) the final value of the angle between the launch bar and the nose gear. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Masses** & **10 kg** & **20 kg** & **30 kg** & **40 kg** \\ \hline \(h^{p}_{O}\) & 0.7693 m & 0.7693 m & 0.7693 m & 0.7693 m \\ \(h^{p}_{cg}\) & 0.4649 m & 0.4556 m & 0.4464 m & 0.4372 m \\ \(h^{p}_{grad}\) & 0.1607 m & 0.1420 m & 0.1235 m & 0.1055 m \\ \(h^{p}_{r}\) & 0.7414 m & 0.7414 m & 0.7414 m & 0.7414 m \\ \(h^{p}_{cg}\) & 0.4338 m & 0.4164 m & 0.3988 m & 0.3817 m \\ \(h^{p}_{engd}\) & 0.1266 m & 0.0917 m & 0.0572 m & 0.0212 m \\ \(\theta^{\prime}_{r}\) & 63.95\({}^{\circ}\) & 62.31\({}^{\circ}\) & 60.72\({}^{\circ}\) & 59.06\({}^{\circ}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Results of key parameters with different launch bar masses. Figure 5: (**a**) The height between the pivot point of the launch bar and the deck of the carrier; (**b**) the height between the center of gravity (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. In Table 2, \(h_{O}^{p}\) is the peak value of the height between the pivot point and the deck of the carrier, \(h_{O}^{f}\) is the final value of the height between the pivot point and the deck of the carrier, \(h_{cg}^{p}\) is the peak value of the height between the center of gravity (cg) position of the launch bar and the deck of the carrier, \(h_{cg}^{f}\) is the final value of the height between the cg position of the launch bar and the deck of the carrier, \(h_{end}^{p}\) is the peak value of the height between the end of the launch bar and the deck of the carrier, \(h_{end}^{f}\) is the final value of the height between the end of the launch bar and the deck of the carrier, and \(\theta_{r}^{f}\) is the final value of the angle between the launch bar and the nose gear. The change of the launch bar mass had no effect on the height from the pivot point to the deck, as shown in Figure 5a.