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As part of the European Space Agency (ESA) Future Launchers Preparatory Programme (FLPP), SONACA (BELGIUM) and BRM (USA) companies joined their competences to develop a new concept of structural European launcher cryogenic upper inter-stage composite ring. This challenging program targeted the replacement of an ARIANE traditional aluminum ring by a lighter and affordable multi-functional composite structure. The ARIANE 5 aluminum specification was used as the basis of the design concepts, with adaptation to a future launcher 4.3 m diameter. After a preliminary design phase, involving selection of different manufacturing routes, material and processes by elementary tests made at coupon level, the 3D orthogonal weaving process was selected as the best candidate to realize a full scale ring demonstrator. The structure was designed, stressed and verified by test by SONACA, and the 3D weaving was optimized in close collaboration with BRM. Five 90° segment carbon fiber dry preforms were produced by BRM using the most advanced weaving automated technology. All these segments were injected by SONACA using their expertise in RTM process. The parts were controlled both geometrically and wrt internal defects by NDT. A 30° segment was successfully submitted to five static load cases up to failure, showing a TRL of 5. Four 90° segments were assembled by CFRP splices to exhibit a full ring demonstrator. [ABSTRACT FROM AUTHOR]