Impact dynamics of different cabin solutions of small airplanes

Novel technologies in numerical computation enable to investigate the emergency landing conditions for light airplanes. An important matter concerning this kind of airplanes is the crashworthiness of the vehicle impacting the ground, thereafter the parachute opening. The current regulations for the emergency landing dynamic conditions CS 23.562 expect that seat design satisfies the requirements in vertical and horizontal test conditions. In particular, the aim of this work is to compare two different aircraft configurations: a low-wing metallic and a high-wing composite one. Both the airplanes are two-seaters and single-engine equipped. The target of the analysis is the check of the compliance with human tolerance to injury criteria by the seats and the restraint system, and the determination of the possible strikes of the occupants inside the habitable space as a consequence of the impact loads. A finite element analysis of a partial section of the fuselage for both the configurations has been performed through the use of the commercial solver LS-Dyna. The models include seats, restraints, dummies and the structural elements that could intercept the trajectory of the passengers during the crash events. In Figure 1 the finite element model of the metallic fuselage is represented. A parametric analysis is performed in order to find out the best attack angle in terms of the lumbar loads and the loads transmitted by the belts as a consequence of the contact between the aircraft and the ground, so to improve the level of safety. The performed investigation could be an important indication for the parachute system design