Projections of future trends in any field must be somewhat subjective; this assessment of future research on rotorcraft is no exception. However, an effort has been made at objectivity by presenting results of past and current research efforts as a foundation from which the projections are made. These projected trends are solely the opinion of the author and do not represent the policy of any agency within Government or industry, nor are they committal in any sense. Although some illustrations are derived from specific systems under investigation, the general intent of the paper is to avoid discussion of systems and to present illustrations representative of basic problems in the field of rotorcraft for which research effort can be expected to yield significant advance in performance and design.

The Matra 530 is currently called a second generation air-to-air missile. Indeed the first generation of air-to-air missiles was represented in France by the Nord 5103 which was command-guided, or the Matra 511 which was a semi-active, pure pursuit curve missile. In the second part of the 1950's the requirement was obvious for a sophisticated interception system capable of coping with the high and medium altitude threat represented by heavy and medium bombers. The destruction of this threat required a close link with an interception system composed of ground radars, ground control equipment, sophisticated high performance interceptor aircraft and, as a last link, a very high performance missile. From the French Air Force point of view, the two main characteristics of this missile as the last link of an interceptor system, were first its flexibility in different weather environment and counter measure environment; second, its capability to decrease to the maximum the penetration of the enemy bomber, which meant that the missile should be capable of attacking not only in the rear sector but also in frontal attack and in fact in all sectors around the attacking bomber.

About 13 years ago rumours began to emerge from the USA of a hitherto unknown and mysterious condition afflicting the F100 and other contemporary fighter aircraft. In fast rolls these aircraft were said to experience gyrations in yaw and in pitch which by all accounts had no right to exist, especially as aerodynamically these configurations could not be faulted. After a burst of theoretical and experimental activity the condition was explained and the terms inertia cross-coupling, roll-coupling, roll yaw coupling and other synonyms became common currency in the world of aeronautics. The mystery of these puzzling manoeuvres was essentially solved. Unfortunately the problem was not. Cross-coupling has since become a major item on the agenda of the designer of every highspeed fighting aircraft and more recently it has also made some incursions in the area of the large slender aircraft.