Rotorcraft Designs for the Year 2000,
UNITED TECHNOLOGIES CORP STRATFORD CT SIKORSKY AIRCRAFT DIV
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Many different types of rotorcraft and higher disk loading Vertical Takeoff and Landing VTOL concepts have been investigated in the past, but none have survived to production except for helicopters and one direct-lift turbofan VTOL. With modern technology developed in the past two or three decades, some of the earlier concepts might now be more practical and new concepts have become feasible. This paper examines some of the rotorcraft concepts that can offer higher speeds than the pure helicopters, including the compound helicopter, ABC, tilt-rotor, X-Wing, and stowed rotor configurations. All of these are potentially practical aircraft. Economic considerations will dictate that the pure helicopter is here to stay higher speed rotorcraft are not as cost-effective at short ranges. Also examined is the approach to helicopter sizing for heavy-lift applications. It is concluded that a super-large helicopter, sized to carry the heaviest payload needed, is unaffordable. A better, more cost effective solution is to develop a moderately large helicopter that will carry most of the required loads, and to use the twin-lift technique to transport the occasional extra-heavy load. NATO.