# Prediction Method of Blast Wave Impact on Crew Module for Liquid Rocket Explosion on Launch Pad
## 3 Definite of Explosive Yield  
### Definite Method of Explosive Yield forLiquid Propellant  
TNT equivalent model is to convert the explosive materials into equivalent TNT according to the equal energy, and then the explosive law of TNT is applied to predict the effect of liquid propellant explosion [20]. It is widely used in the field of explosive characteristics of liquid propellant all over the world because of the ease of use [21]. Given that the mass of liquid propellant \(M_{0}\) and explosive yield \(Y\) of different modes, the TNT \(M_{\mathrm{T}}\) can be calculated by using Equation (1). \[M_{\mathrm{T}}=Y\cdot M_{0} \tag{1}\]  
where, \(M_{\mathrm{T}}\) represents mass equivalent to TNT, kg. \(Y\) stands for explosive yield, dimensionless. \(M_{0}\) is the total mass of the liquid propellant, kg. It is very difficult to obtain accurate explosive yield theoretically under different explosion modes, because the chemical reaction mechanism of liquid propellant is different from that of solid explosive, and is affected by various factors such as the type, mass, detonation time of propellant, \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Time** & **Country** & **Rocket** & **Mass/t** & **Why \&How** & **Location** & **Consequences** \\ \hline \multirow{4}{*}{1983} & \multirow{4}{*}{Soviet Union} & \multirow{4}{*}{Soyuz} & \multirow{4}{*}{303} & One of the boosters & \multirow{4}{*}{booster} & Rocket and \\  & & & exploded before the launch, & & & \\  & & & causing a full rocket to & & & \\  & & & explode. & & & \\ \hline \multirow{4}{*}{2003} & \multirow{4}{*}{Brazil} & \multirow{4}{*}{VLS} & \multirow{4}{*}{50} & During the pre-launch & \multirow{4}{*}{stage-1} & Rocket and \\  & & & maintenance test, an engine & & & \\ \cline{4-5}  & & & misfire caused an & & & \\ \cline{4-5}  & & & explosion. & & & \\ \cline{4-5}  & & & & & & \\ \hline \multirow{4}{*}{2016} & \multirow{4}{*}{USA} & \multirow{4}{*}{Falcon9} & \multirow{4}{*}{549} & The cryogenic helium & \multirow{4}{*}{stage-2} & Rocket and \\  & & & system in the secondary & & & payload are \\ \cline{4-5}  & & & oxygen tank leaked and & & & destroyed, \\ \cline{4-5}  & & & caused an explosion during & & & launch pad \\ \cline{4-5}  & & & the pre-launch test and & & & destroyed, no \\ \cline{4-5}  & & & refuelling. & & & casualties \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._ \begin{table}
\begin{tabular}{c c c} \hline \hline
**Scenarios** & \multicolumn{2}{c}{**Process Description**} \\ \hline \multirow{3}{*}{1} & Structure destruction of propellant tank of stage-3 causes propellant leakage and explosion, which results in the structure destruction of the propellant tank of the stage-1, stage-2 and boosters and the explosion. \\ \cline{2-2}  & & Structure destruction of stage-2 propellant tank causes propellant leakage and explosion, which results in the structure destruction of the propellant tank of the stage-1 and boosters and simultaneous explosion of the vertically falling stage-3. \\ \hline \multirow{3}{*}{3} & \multirow{3}{*}{Structure destruction of propellant tank of stage-1 causes structure destruction of booster tank, which results in stage-2 and stage-3 falling vertically, and then all propellants explode at the same time} \\ \cline{4-5}  & & Structure destruction of propellant tank of stage-1 causes propellant leakage and explosion, which leads to stage-2 falling vertically and explosion with boosters, and then stage-3 falls vertically and explodes. \\ \hline \hline \multirow{3}{*}{4} & \multirow{3}{*}{Structure destruction of propellant tank of stage-1 causes propellant leakage and explosion, which leads to stage-2 falling vertically and explosion with boosters, and then stage-3 falls vertically and explodes.} \\ \cline{4-5}  & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Scenarios setting of the rocket explosion on launch pad. falling speed and ground property, etc.