Aeroelasticity of nonconventional airplane configurations past and future

At the end of the first century of manned, powered flight, it is worthwhile to look backward to understand how innovation in airplane design required developments in aeroelasticity and how aeroelasticity has played a role in shaping the first 100 years of aircraft design. The insights gained will help to predict how and where aeroelasticity and aeroservoelasticity will influence the future development of efficient, more capable, innovative air vehicles, and define the needs for technology and tools to enable this future. By definition, all new aircraft begin as unconventional to a certain extent. Designs that never see universal use remain curiosities, but still help our quest for better vehicles and guide the development of analysis, design, and testing tools. Innovative, nontraditional designs affected by aeroelastic considerations have included oblique wing aircraft, forward-swept wing aircraft, X-wings, flying wings, and large joined wings. Designs that were unusually innovative at the time of their introduction but later became widespread include the swept-back wing jet, the T-tail, and the fly-by-wire control configured vehicle. Control and exploitation of aeroelasticity depends on the continued development of new materials, new structural and aerodynamic concepts, sensors, actuators, and active control techniques. Such developments must be accompanied by proper integrated analysis\design tools, and, most importantly, by the same human inquisitiveness and creativity that has driven aircraft design for over a century. This paper uses the history of nonconventional airplane configurations to review some of the steps taken during the past century to establish aeroelastic effects as integrated design features that must be anticipated, controlled, and exploited. The paper goes on to discuss the potential impact of past lessons on emerging airplane configurations currently in various stages of study and development.