## 4 Results and Discussions
The coefficient \(k_{c}\) gives information about the quantity of aerosols generated by each type of composition, thus observing that the composition PC1 generates the highest quantity of aerosols after burning at the highest temperature of 1390 \({}^{\circ}\)C (Figure 5). As a result, not all of the tablet's mass contributes to the generation of aerosols. The residual elements are presented as too-large particles of ash that settle on the ground rather than forming an aerosol. The proportion of each component was optimized based on these properties to form a cloud with superior characteristics. Using three types of compositions in the smoke charge provides a combination of characteristics with optimal smoke cloud formation. The purpose of laboratory testing was to determine the efficacy of screening for small-sized samples of pyrotechnic mixtures. These tests were carried out under controlled and repeatable conditions and the results are presented in Table 3. It was possible to observe the evolution of the smoke over time and the radiation disturbance by keeping the amount of screening smoke generated in a known enclosed space constant. To illustrate how the test was performed, Figure 6 shows the images received for test number five at different times from the three optical sensors used. Even if after 7 s in _MWIR_ (middle wavelength infrared) the objective can already be observed, in _LWIR_ (long wavelength infrared) and in VIS it was not yet visible. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Sample** & \(m_{pc}\) & \(m_{r}\) & \(m_{g}\) & \(k_{c}\) (\%) & **H** & **D** & \(\rho\) & \(t_{c}\) & **t\({}_{\text{VIS}}\)** & **t\({}_{\text{IR}}\)** & \(v_{c}\) & \(\dot{m}\) & **T** \\  & **(g)** & **(g)** & **(g)** & **(mm)** & **(mm)** & **(mm)** & **(g/cm\({}^{3}\))** & **(s)** & **(s)** & **(s)** & **(mm/s)** & **(g/s)** & **(\({}^{\circ}\)C)** \\ \hline PC1 & 0.51 & 0.01 & 0.10 & 78 & 5.00 \({}^{*}\) & - & 1.06 & 3.04 & 3.66 & 3.41 & 1.65 & 0.17 & 1390 \\ PC2 & 0.57 & 0.02 & 0.17 & 67 & 3.55 & 11.71 & 1.49 & 4.22 & 5.15 & 4.52 & 0.85 & 0.14 & 1368 \\ PC3 & 0.58 & 0.01 & 0.19 & 66 & 3.10 & 11.74 & 1.62 & 9.55 & 11.05 & 10.05 & 0.33 & 0.06 & 1028 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The combustion rate and combustion flow for pyrotechnics sample. Figure 5: PC1 pyrotechnic tablets combustion in the first 2 s in VIS and IR mode. IR screening time can vary slightly depending on weather conditions (low temperature, humidity > 50%, sunny or cloudy day) and contrast between target and background. These values were measured in optimal conditions as we maintained a high contrast and fixed volume inside the enclosure. Experimental values of concentration and screening time highlighted the fact that pyrotechnic mixtures based on red phosphorus have a higher screening efficiency in VIS, the screening time being given by the stability of the smokescreens dispersed in the environment (depending on the wind speed and direction). The maximum VIS screening time can only be determined under field conditions for a wind speed value less than 3 m/s [28, 29, 30]. The screening effect occurs in VIS from the  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Test** & **Sample** & \(m_{pc}\) & \(m_{a}\) & \(V_{g}\) & \(k_{oc}\) & \(\rho_{a}\) & \ \begin{tabular}{c} **Screening** \\ **Time** \\ **MWIR (s)** \\ \end{tabular}  & \begin{tabular}{c} **Screening** \\ **Time** \\ **LWIR (s)** \\ \end{tabular}  \\
**1** & PC1 & 2.25 & 1.89 & 470.25 & 0.092 & 3.69 & 3.63 & 5.12 \\
**2** & PC1 & 5 & 4.2 & 1045 & 0.204 & 8.23 & 6.21 & 8.19 \\
**3** & PC1 & 10 & 8.4 & 2090 & 0.480 & 16.40 & 11.22 & 14.32 \\
**4** & PC1 & 15 & 12.6 & 3135 & 0.612 & 24.6 & 16.01 & 19.21 \\
**5** & 2 \(\times\) PC2/2 \(\times\) PC3 & \begin{tabular}{c} 1.14 \\ 1.08 \\ 2.28 \\ 2.16 \\ 4.32 \\ 6.84 \\ \end{tabular}  & \begin{tabular}{c} 1.4 \\ 1.08 \\ 2.14 \\ 4.48 \\ \end{tabular}  & \begin{tabular}{c} 1.4 \\ 1.04 \\ 2.14 \\ 4.399 \\ \end{tabular}  &