IMPROVING FUSELAGE CRASHWORTHINESS

An innovative composite concept for light aircraft has been developed to provide better passenger protection.

Two primary design goals for light-aircraft crashworthiness are to limit the impact forces transmitted to the occupants and maintain the structural integrity of the fuselage to ensure a minimum safe occupant volume. To meet these objectives, an aircraft fuselage must be designed for high stiffness and strength to prevent structural collapse during a crash. Yet, the fuselage must not be so stiff that it transmits or amplifies high-impact loads to the occupants. The design should contain some crushable elements to help limit the loads transmitted to the occupant to survivable or non-injurious levels.

In 1997, a three-year research program was initiated at NASA Langley Research Center to develop a fuselage concept for potential application to light aircraft. During the first two years of the research program a 1/5-scale model fuselage was fabricated and tested. This was followed with the fabrication of a 60-in diameter full-scale fuselage section during the third year of the program. Drop tests of the fuselage section were performed at 372-in/s vertical velocity for both 0° and 15° roll impact attitudes to evaluate the crashworthy features of the fuselage design. The primary impact design goal was to achieve an average floor-level acceleration of 25 g for a 372-in/s vertical impact velocity. The secondary impact requirement was to maintain a high level of crash protection for a vertical impact at 372 in/s velocity with a 15° roll attitude. The experimental data were correlated with analytical predictions from a crash simulation developed using the nonlinear, explicit transient dynamic finite-element code, MSC/DYTRAN.