**Abstract**

The Multifunctional Structures for High Energy Lightweight Load-bearing Storage (M-SHELLS) research project goals were to develop M-SHELLS, integrate them into the structure, and conduct flight tests onboard a remotely piloted small aircraft. Experimental M-SHELLS energy-storing coupons were fabricated and tested for their electrical and mechanical properties. In this chapter, finite element model development and structural analyses of two small test aircraft candidates are presented. The component weight analysis from the finite element model and test measurements were correlated. Structural analysis results with multifunctional energy storage panels in the fuselage of the test vehicle are presented. The results indicate that the mid-fuselage floor composite panel could provide structural integrity with minimal weight penalty while supplying electrical energy. Structural analyses of the NASA X-57 Maxwell electric aircraft and an advanced aircraft fuselage structure are also presented for potential application of M-SHELLS. Secondary aluminum structure in the fuselage subfloor and cargo area are partially replaced with reinforced five-layer composite panels with M-SHELLS honeycomb core. The fuselage weight reduction associated with each design without risking structural integrity are described. The structural analysis and weight estimation with composite M-SHELLS panels in the fuselage floor indicates 3.2% structural weight reduction, but with increased stress.

**Keywords:** advanced composite, multifunctional structure, green aviation, electric flight vehicle design, finite element analysis, honeycomb panel, electrical energy storage, structural weight estimation and reduction, aircraft design
