Abstract
Aircraft design begins with dreams and design requirements, and eventually proceeds to detailed drawings of every part of the aircraft being fabricated. To the outside world, the disciplines of aerodynamics and structures often seem most important – they lead to the overall shaping of the aircraft and to the design of the parts that, when fabricated and assembled, comprise the physical geometry of the aircraft. These are obviously important, but without some other things inside, the aircraft could never fly. These ‘other things’ – more properly known as ‘aircraft subsystems’ or just ‘systems’ – play a crucial role in aircraft design and operation.
Systems turn an aerodynamically shaped structure into a living, breathing, flying machine. Systems include flight control, hydraulics, electrical, pneumatic, fuel, environmental control, landing gear, and the evermore- capable avionics. In the early stages of conceptual or preliminary design the systems must be initially defined, and their impacts must be incorporated into design layouts, weight analyses, and performance calculations. Anyone seeking to become a good aircraft conceptual designer must learn about all types of systems. During detail design the systems are fully defined, including system architecture, functional analysis, component design, and safety and failure analysis. This is done by highly experienced systems specialists.

Introduction

Flight controls have advanced considerably throughout the years. In the earliest biplanes flown by the pioneers flight control was achieved by warping wings and control surfaces by means of wires attached to the flying controls in the cockpit. Such means of exercising control was clearly rudimentary and was usually barely adequate for the task in hand. The use of articulated flight control surfaces followed soon after but the use of wires and pulleys to