Eighty years of flight control - Triumphs and pitfalls of the systems approach

Men already know how to construct wings or aeroplanes, which when driven through the air at sufficient speed, will not only sustain the weight of the wings themselves, but also that of the engine, and of the engineer as well. Men also know how to build engines and screws of sufficient lightness and power to drive these planes at sustaining speed. . . . Inability to balance and steer still confronts students of the flying problem. . . . When this one feature has been worked out, the age of flying machines will have arrived, for all other difficulties are of minor importance. No one among our readers would doubt that, in the eighty years since then, the "age of flying machines" has indeed arrived. At the same time a certain inability to always reliably "balance and steer" still confronts us. The story of technology we will sketch here is not inevitably one of a cumulative progression, nor even necessarily one of the survival of the fittest. Instead, the history of aviation, as we see it, is one of the conciliation of courage and curiosity, challenge and response, practical ingenuity and learning. Although not always recognized as such, flight control is a systems discipline at the leading edge of aeronautics. Indeed, the triumphs and pitfalls of the systems approach to flight control design may be traced from before the first flight to the present day, and even extended in imagination to the future. So, what we intend to discuss are rises, falls, and saddle points in the fortunes and understanding of the feedback systems approach to the design of automatic feedback control systems for aircraft.