BELLACAP FULL-SCALE AIRCRAFT CRASH TEST AND KRASH CORRELATION

On 27 August 1987, the Bell ACAP aircraft, designed and built under to the U.S. Army’s Advanced Composite Airframe Program, successfully completed a full-scale crash test at NASA Langley Research Center’s Impact Dynamics Facility. The test demonstrated that the all-composite airframe fully met the stringent military crash survivability design requirements of a 50-ft/s ground impact velocity (a combined impact of 42 ft/s vertical and 27 ft/s forward velocity with a rotor lift of two-thirds design gross weight) with aircraft attitudes of up to 10° roll and 10° nose-up pitch without any serious injuries to the occupants. The occupants (represented by instrumented anthropomorphic dummies) were protected in the crash test by using innovative designs of the composite energy-absorbing fuselage structure and landing gear, along with stroking seats, which together controlled impact loads to the occupants while maintaining a protective shell surrounding them. Large, potentially hazardous mass items, such as the overhead transmission and rotor, were restrained from entering the occupied areas. The fuel tank totally contained the fuel, thus reducing the risk of a postcrash fire. Comparisons of the crash test results with the KRASH computer simulation, which was used for the design of the aircraft structure, were conducted using a motion analysis of the test to determine time histories, sequence of events, and plots of structural deformations. The comparisons show good agreement between the analysis and the test, verifying that KRASH is a viable analytical tool for the design of composite airframe structures for crash impact.