A Skin-Stringer Design for a Crashworthy Composite Fuselage for the Hughes 500E Helicopter

The design of the lower fuselage of the Hughes 500E helicopter is part of the Composite Fuselage program of Hughes Helicopters, Inc. The objectives of the program are to design, fabricate, test and fly a composite fuselage which will meet the vertical impact requirements of MIL-STD-1290 with a minimum of 22 percent savings in weight over the metal design. The design approach used on the crashworthy composite lower fuselage assembly is a simple skin-stringer design without honeycomb structural elements, but which is similar to the existing metal design. The decision to use this approach is a result of trade-off studies, design development tests, and the requirement of mating existing support components, such as the landing gear, to the composite fuselage. The design has been evaluated through impact tests and KRASH analyses. The results of the tests show that the crashworthy objectives can be met with 26 percent savings in weight and 39 percent fewer parts.