Development and test verification of the Ariane 4 interstage 2/3 in CFRP

The interstage 2/3 configuration of the Ariane 4 launcher has been redesigned, using the CFRP composite (instead of aluminum) for the curved blade-stiffened panels, in order to reduce weight. Verification analysis of the design was performed using NASTRAN and BOSOR4 models. In experimental tests, flat stiffened panels were tested in compression to verify the selected design details of the cylinder. Three different sizes of subcomponent panels were tested with the objectives of determining the local buckling behavior at room temperature and at 180 C, assessing the strength of the panel to end-ring connections, and establishing the global panel buckling behavior between ring frames. As a result of the tests, the stiffener run-out configuration was modified to prevent premature separation at the tip.