Progress in Rotorcraft Design: 1974–2024

Fundamental advancements in aircraft design over the past 50 years have enabled a range of vertical takeoff and landing (VTOL) air vehicle configurations and have significantly enhanced aircraft performance, safety, and reliability. This summary paper chronicles the evolution of rotorcraft design from 1974 to 2024. It is segregated into three key pillars of aircraft design preceded by an aircraft design overview. The three pillars are processes and tools, technology, and air vehicle configuration. The first pillar, on design processes and tools, describes advancements in technology, methodologies, and computational capabilities such as the transition from design solely by wind tunnel testing, physical models, and hand calculations to computer-aided design/synthesis and simulation in a model-based engineering digital-twin environment. The second pillar, on technology, focuses on advances in disciplinary technologies and how they have been incorporated into aircraft design. Technologies discussed include composite materials; rotor systems; propulsion systems, ranging from advancements in turbine engines to all- and more-electric propulsion technologies utilizing various energy storage systems to convertible engines; fly-by-wire systems; avionics and cockpit architectures, including digital displays, navigation aids, and communication equipment; and autonomous and semiautonomous systems. The third pillar, on air vehicle configuration, focuses on platform architectures. Major architectures discussed are high-speed VTOLs such as the thrust-vectored aircraft, tiltrotors, lift/thrust compounded helicopters, and all- and more-electric aircraft.