ROTOR TECHNOLOGY FOR NEW GENERATION HELICOPTERS

All of the helicopters now in production in the United States have been in production for at least ten years (Fig. 1). These are the Viet Nam veterans - not designed for that purpose, but widely used there. Production of these aircraft for the U. S. Military has just about ended. A whole new family of helicopters is in development now, however, aimed at production from 1977 on (Fig. 2). These specific designs are motivated by new military requirements and increased commercial demands. However, their reason for being - the reason new aircraft are being developed in place of increased numbers of the older designs - is that new technology now permits development of significantly more cost effective aircraft. New technology in several areas has made this possible. New “advanced technology” engines consume 25% less fuel than their predecessors. Increased emphasis on low vibration levels, better handling qualities, better reliability and increased tolerance to battle damage has led to a multitude of innovations. Rivailing

all these changes in importance, however, are the advances being made in rotor design. The new generation helicopters use new airfoils and new blade materials combined in planform, twist and taper variations more complex than ever before. They offer simpler rotor head configurations, and blades better able to withstand structural damage safely. The key system attributes - performance, weight, reliability and cost - can all be improved with these new rotors.