Composites give copters a lift

Design, fabrication, and analysis of a tail rotor blade made of composite laminated materials for a heavy transport helicopter.

High-performance composites generally exhibit high strength and stiffness, low density, and good resistance to fatigue and corrosion, properties that make them well suited for many aircraft and aerospace applications. The use of fiber-reinforced composites in flight-critical structures in helicopters is growing rapidly. But the introduction of composites has not been without problems. These include development of entirely new design, fabrication, and qualification discipline, as well as difficulty in analyzing internal stresses, demonstrating this technology to certifying agencies, determination of adequate test criteria, and quantifying environmental degradation.

Development and qualification of helicopter components and systems includes a heavy emphasis on a full-scale test approach independent from the design process. In the case of fatigue-loaded, flight-critical components, a laboratory fatigue program is conducted, supported by static and vibratory tests, stress surveys, and coupon or sub-element programs.