## 2 The Flying Wing Carrier-Launcher System
### Historical Data Analysis  
Table 1 shows a list of the examined flying wings with their relevant technical data. The data reported in Table 1 were collected by consulting several available sources [43; 44; 45; 46; 47; 48; 49; 50]. The analysis of historical data provided a series of graphs that summarize the following relationships: empty weight vs. wingspan (Figure 1), maximum take-off weight (MTOW) vs. wingspan (Figure 2), wing area vs. wingspan (Figure 3), wing loading vs. wingspan (Figure 4), and aspect ratio (AR) vs. empty weight (Figure 5). The wing loading W/S data are calculated considering the maximum take-off weight condition. In the figures, we also reported the linear regression curves, and red-filled triangles indicate the configuration examined in this work, which was defined thanks to a trade-off study. Even if flying wing configurations generally use airfoils with a reflected trailing edge, (as sketched in Figure 6), for flight stability reasons, (see as example [51]), we selected the Boeing BACXXx airfoil [52; 53; 54], which has a maximum thickness of 11.3% at 35% of the chord, and a maximum camber of 1.4% at 15% of the chord (Figure 7). Since, generally, the sign of the aerodynamic moment acting on an airfoil is negative (nose down effect), with a reflected trailing edge (Figure 6), the aerodynamic moment acting on the airfoil can change sign and become positive (nose up effect). This circumstance proves useful for designing a swept flying wing that is aero-mechanically stable. Figure 1: Historical data of flying wings: Empty weight vs. wingspan; red triangle represents the configuration developed in this paper. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Note** & **Flying Wing Model** & **Wingspan** & **Aspect** & **Wing Area** & **Empty** & **Max T.O.** & **Wing** & **Loading** & **Airfoil** \\  & **[n]** & **Ratio** & **[n\({}^{2}\)]** & **[n\({}^{2}\)]** & **[n\({}^{2}\)]** & **[n\({}^{2}\)]** & **[n\({}^{2}\)]** & **[n\({}^{2}\)]** \\ \hline  & Northrop B-2 Spirit [43] & 52.12 & 5.78 & 478.00 & 703.38 & 1673.59 & 3.501 & NACA 0018 \\  & Northrop YB-35 [44] & 52.00 & 7.40 & 370.00 & 533.98 & 929.99 & 2.513 & 653-018 \\  & Northrop YB-49 [45] & 52.43 & 7.20 & 370.00 & 393.54 & 862.98 & 2.322 & 653-018 \\  & Northrop XL-798 & 11.58 & 5.19 & n.a. * & 26.00 & 38.57 & 1.495 & NACA \\  & Northrop X-47B [18] & 18.90 & 4.03 & 88.59 & 62.29 & 198.31 & 2.239 & n.a.* \\  & Northrop N-1M & 11.79 & 4.21 & 33.00 & 15.70 & 20.42 & 0.732 & n.a.* \\  & Northrop N-9M & 18.30 & 7.35 & 45.50 & 26.22 & 73.01 & 1.605 & NACA 65-019 \\ Blended/UAV & Northrop Grumman & 8.50 & 2.00 & 35.98 & 17.07 & 26.27 & 0.730 & n.a.* \\  & X-4/PA Pegissa & & & & & & & \\  & McDoonel & & & & & & & \\  & Douglas/General & & & & & & & \\  & Dynamics A-12 & & & & & & & \\  & Avengeer II [16] & & & & & & & \\  & Horten Ho 229A & 16.76 & 7.80 & 52.80 & 45.13 & 79.46 & 1.505 & 13\% thickness \\  & Horten H.VIIIA [47] & 40.00 & 10.70 & 150.00 & 107.91 & 313.92 & 2.093 & 16\% thickness \\  & Intersectable XBR-1 & 15.75 & 7.40 & 33.60 & 22.62 & 56.54 & 1.683 & n.a.* \\  & DNIFA IA 38 & 32.00 & 7.70 & 133.00 & 83.39 & 184.66 & 1.388 & n.a.* \\  & Baynes Rad & 10.16 & 7.00 & 14.86 & 3.40 & 5.04 & 0.339 & n.a.* \\ Blended & Boeing X-48B & 6.40 & 4.10 & 9.34 & 1.75 & 2.62 & 0.280 & n.a.* \\ Blended & Boeing Tut-35A [46] & 10.30 & n.a.* & n.a.* & 35.60 & 14.24 & n.a.* & n.a.* \\  & Boeing Tutmah Ray & 15.00 & n.a.* & n.a.* & 64.97 & 162.41 & n.a.* & n.a.* \\ Blended & Lockheed Martin RQ-3 & & & & & & & \\  & DarkStar [50] & 21.00 & n.a.* & n.a.* & 19.42 & 44.55 & n.a.* & n.a.* \\  & Dasasult neEUROn & 12.50 & n.a.* & n.a.* & 48.07 & 80.79 & n.a.* & n.a.* \\ Supresonic & Sukhoi S-70 Okkotnik & 20.00 & n.a.* & n.a.* & 147.15 & 245.25 & n.a.* & n.a.* \\ \hline  & & & & & & & & \\ \end{tabular}
\end{table} 
Table 1: List of flying wings and data used in the present study [30]. Figure 2: Historical data of flying wings: max take-off weight vs. wingspan; red triangle represents the configuration developed in this paper.