Helicopter Fuel Bladder Drop Tests and Analyses

Drop tests and analyses of a civil helicopter fuel bladder were conducted to determine the effect of different constraint on the hydrodynamic pressure-time histories. Five constraints were evaluated including that of only the flexible bladder material to that provided by rigid bottom and side constraints. Tests were conducted with the bladder placed inside of a steel test box and the bladder was surrounded on the bottom and/or sides with energy absorbing or rigid materials. The pressure-time histories were recorded at different vertical locations inside the fuel tank for the different test configurations. The crushing displacements of energy absorbing materials used in some tests were measured and estimates were made of the energy absorbed through crushing. These results and their implications on design and integration of crashworthy helicopter fuel cells are discussed in the paper.