Low Cost, Flexible Pultruded Design for Helicopter Tail Booms

The Flexible Pultruded Design (FPD) for composite helicopter tail booms utilizes low cost adjustable tooling and the automated pultrusion process to provide very high quality and very low part unit cost. FPD is ideal for early fabrication of flightworthy structure during SDD and LRIP program phases. FPD is comprised of sandwich construction utilizing X-Cor core (comprised of a multitude of fine pins) that provides Z-direction thru-thickness reinforcement as well as shear strength and stiffness. FPD sandwich construction provides high structural efficiency (i.e. lightweight) and features a structural shape that allows four identical pultruded details to be trimmed and assembled to form a completed tail cone assembly, including taper if needed, where the width and height dimensions can be independently accomplished without affecting the pultrusion die. The panel features a molded (pultruded) panel joint that is tooled and designed for optimum joint quality and strength using a bonded/bolted construction. The Z-pins in the core provide enhanced ballistic tolerance, which offers considerable benefit in applications such as helicopter tail cones where small enclosed volume and nonredundant load paths often exhibit ballistic vulnerability. Phase I will generate full scale proof-of-concept Demonstration hardware.