I hope that it will be clear from the brief accounts you have just heard that not only have the universities in the UK made a major contribution to the status and health of the aerospace industry but, given a modicum of encouragement, they can continue to do so. Indeed, I maintain for reasons that I shall make clear that the part that they can and should play is of greater importance now than ever.

Reliability testing for GW systems can be considered as comprising five categories of test:

1. 1. Development testing, including environmental testing, to ensure that the design is capable of performing to the technical requirements.

2. 2. Reliability demonstration testing, to provide assurance that the reliability requirements will be, or are being, met.

3. 3. Production Testing.

4. 4. Acceptance testing, to provide assurance that production missiles are achieving the required reliability.

5. 5. In-service testing, to ensure that reliability is maintained during Service conditions.

This paper surveys the particular problems experienced when applying these categories of reliability testing to guided weapons. The paper considers only the equipment in the missile, and not GW sub-systems fitted to launch vehicles, since such sub-systems are basically the same as other avionic, ground or ship-based systems from the reliability test point of view.

Previous analysis of the operation of the counterspun nutation damper has been restricted to small nutation angles and to axisymmetric spacecraft. This paper develops equations for the dynamics of nutation damper/spacecraft combinations in which the spacecraft is non-axisymmetric and may adopt large nutation angles. In addition, a mechanism to model the growth of nutation due to energy dissipative mechanisms on board the spacecraft is introduced.

The dynamic equations were programmed in a digital simulation language. The effects of three probable imperfections in the construction and operation of nutation dampers on the operating characteristics of the dampers were investigated by simulation. The implications of these non-ideal conditions for the design of counterspun nutation dampers are identified.

A number of panel methods are now currently in use for solving potential flow about single and multi-element aerofoils. All these methods use a combination of singularities, both source and vorticity, on or inside the aerofoil surface and solve the singularity strengths by satisfying the boundary condition of zero normal flow on the surface of the aerofoil.

In this note the method developed by Basu for solving single aerofoil problem using the concept of internal singularity distribution has been applied to the case of multi-element aerofoil problem.

Reference 1 provides the stimulus for this note, containing, as it does, a trap into which many engineers and statisticians fall. Referring to Fig. 6 of that paper (this was incorrectly labelled — it should have been Fig. 4), a set of observed data is presented on normal probability paper, together with a straight line representing the fitted normal distribution. Since none of the points is far from the line, the conclusion is drawn that the data are well-fitted by a normal distribution.

However, a closer look at the figure shows that the scatter of the ‘observed’ points about the fitted line is not random, but systematic; the first four points all lie above the line, the next six below the line, the next eight above the line, and the last two below the line.

The purpose of this note is to bring to attention a result which seems to have been long forgotten — indeed it may never have been widely known — and to present a parallel new result.

The ‘long forgotten’ result is that, for a simple cantilever thin walled torsion tube of area A(y) the torsional deflection θ at the tip when subjected to a torque T(y) is a minimum, for constant tube weight, if the skin thickness t(y) is proportional to , where y is the spanwise co-ordinate.

In shock wave turbulent boundary layer interaction, upstream influence is defined as the distance from the inviscid shock wave to where the incoming boundary layer is first disturbed. The latter position is generally taken as being where the mean wall pressure first increases above the undisturbed value. Wall pressure fluctuation measurements in two Mach 3, high Reynolds number interactions have shown that unsteadiness of the separation shock wave structure results in the instantaneous upstream influence varying over a range of values. Upstream influence as defined above is actually the maximum of this range and, at this distance upstream of the shock wave, the probability of finding the flow disturbed is correspondingly low. The minimum value of the range is the distance from the inviscid shock wave to where the incoming flow is always disturbed. In all of the cases studied the latter station was found to be just upstream of the separation point.

The problem of potential flow about two-dimensional aerofoils undergoing general unsteady motion at low speeds has been studied by Giesing and by Basu and Hancock using the method of surface singularities, both source and vorticity, distributed on the aerofoil surface, satisfying the boundary condition of zero normal flow on the instantaneous aerofoil surface. These two methods differ in the application of the Kutta condition.

A rotor concept is described that enables the generation of a controlled thrust vector in any direction within the rotor’s sphere of action. It is suggested that a rotor of this kind might replace the entire tail unit of the ‘conventional’ single-rotor helicopter to provide a lighter, more compact layout of improved performance. An active control system might be required for the ‘flying-tail’ layout envisaged.

Some of the structural and mechanical design problems that are posed by a vectored-thrust (VT) rotor are briefly discussed and are seemingly tractable by exploiting the potential of advanced composite materials.

No assessment is made of the aerodynamic performance of a VT rotor, nor of the helicopter configurations or operational scenarios where a VT rotor might prove advantageous. Some limited assessments of this kind seem merited.

Ever since the birth of the aircraft industry the universities have been making a continual contribution to research and development in aerodynamics. For example between the wars the work of Professor Melvill Jones and his school had a direct impact on the design of aircraft as illustrated by the classical paper (see Fig. 1) ‘The Streamline Aeroplane’ which was presented to the Royal Aeronautical Society by Melvill Jones in January 1929. In the immediate post-war years the work of Professors Lighthill, Ward and others laid the foundation of calculation methods for supersonic aerodynamics which eventually led to the design of practical supersonic aircraft. In addition staff in the universities have produced a continuous stream of theoretical and experimental results which have been useful, both in design, and in the overall research programme of the aircraft industry. In particular this work has resulted in a large number of new test techniques including the design and development of wind tunnels for special purposes. It is this aspect of current work which will be discussed first.