Inverse simulation is becoming a more widely used technique in flight mechanics studies. The ability to predict control and response time histories for a predefined manoeuvre or task has obvious benefits in certain applications (handling qualities studies related to the ADS-33 requirements for helicopters, for example). The main criticisms of the technique have always been concerned with the numerical problems usually encountered when solving the equations of motion in the inverse manner. In this paper these problems are highlighted and a simple technique which overcomes them is presented. This technique provides a robust mechanism whereby reliable and consistent inverse simulations are possible.

It is widely accepted that the effectiveness of cannon in the air-to-air combat scenarío depends on the rate of fire. Present firing rates for 20-30 mm aircraft cannon range from 600 to 1500 rounds per minute. New developments are aimed towards even higher rates of fire. With these higher rates of fire more energy is likely to be transferred to the aircraft fuselage, resulting in possible structural fatigue damage. To absorb the recoil forces several types of recoil system have been developed and are presently in use. Conventional recoil systems are not, however, ideal for very high rates of fire and hence alternatives must be investigated.

With this work the use of an anti-resonant device to reduce the transmission of forces to the aircraft fuselage for a high rate of fire is investigated. Antiresonant isolators operate on the principle that a condition of little or no motion may be enforced at specific points of interest on a system at particular frequencies, through suitable tuning of the system. This is essentially achieved by designing the isolator system in such a way that inertial forces are used to react spring forces under stationary conditions.

The paper is focuses on the study of the profile optimisation of a unidimensional structure in idealised critical flutter conditions. The problem has been addressed already by other authors, but here an original technique is used to search for some variables at the left hand end of a simply supported vibrating beam, the knowledge of which is necessary for the numerical integration of the governing equations. Additionally, the frequency is considered as a control parameter. A composite orthotropic symmetric panel with four layers is considered and the optimised profiles of all the structural components determined.

A knowledge-based computer system has been developed to automatically scan and interpret graphical displays of vibration data taken from strain gauges mounted on the blades of gas turbines performing acceleration tests. The various characteristic lines which appear on these displays are recognised and classified and the lines representing modes of vibration are examined to determine which mode is being excited and the severity of the excitation. All lines are compared, by a “blackboard” technique, against those predicted by the system working from the engine specification, laboratory tests and finite element analyses. Any unexpected features are reported for manual inspection.

Several series of tests have now been made on the system. In the first test on 130 diagrams, every one of over 3000 features visible to the human eye was detected and then classified.