The first part of this survey dealt mainly with the development of the earliest ideas on air resistance and their application to flight. That part of the survey paused at the achievement of powered flight during the early years of the twentieth century. Even then, the main problem remained as that of aerodynamics, a subject only vaguely understood by those aviation pioneers endeavouring to get off the ground. For them theoretical guidelines, as yet, could offer little help. One of the earliest of those very few analytically based results to achieve general acceptance was the statement that resistance is proportional to the product of fluid density, a characteristic body area and the square of the flow's speed. This result had appeared during the seventeenth century in Newton's work and had received some experimental confirmation. Newton's concurrent ‘rare medium’ concept, viewing fluid flow as a stream of disconnected particles, gained credence at that time since its results agreed with the above resistance proportionality. Yet this concept became mistakenly applied to airflow so as to predict plate resistances proportional to the square of the sine of the plates' incidence angles, a misleading result which caused confusion for at least the next century.

We report our findings on the aerodynamic characteristics of thin slab delta wings at hypersonic speeds. We have tested wings with three sweeps (76°,70° and 65°) and four t/c ratios (0·04, 0·053, 0·066 and 0·10) using a special thin three-component balance. To date, the wing with tic of 0·040 is the thinnest wing ever tested without lee-side body at any hypersonic Mach number. The study was carried out at Mach number of 8·2, Reynolds number of 2·13 x 106 and incidence of -4° to 12°. In general, for any given t/c ratio, the increase in sweep decreased the CN whereas increased CM and CA. A possible explanation, for the effect of sweep, is given using the pressure data available in the literature. We also observed that for the sweeps considered, the t/c does not have any effect on CN and CL but increasing t/c increased CM and CA, reduced (L/D)max and moved the Xcp upstream. Blunt slab delta wings are shown to possess a unique property, wherein the CD increases with increase in sweep at higher sweep angles. This property also reflects in the (L/D) characteristics. Furthermore, the slab delta wings does not exhibit the classical CLα behaviour of sharp delta wings given in the literature. An empirical correlation has been developed to correlate CAo over a wide range of Mach number, t/c and sweep. Linearised theory has been shown to be useful in predicting the (L/D)max at Mach numbers as high as 20, for a wide range of t/c and sweep back angle.

Ladies and gentlemen, it is an honour and a great pleasure to present this Lanchester Memorial Lecture. I thank the Royal Aeronautical Society and its Aerodynamic Committee for inviting me. In preparing this lecture I greatly enjoyed the added significance of presenting it in the historical context set by Lanchester. But the real pleasure is to be here among many good friends with whom I worked together for shorter or longer periods.

“A body that in its motion through a fluid does not give rise to a surface of discontinuity.” So Lanchester defined a ‘ streamline body’ in his standard work Aerodynamics. With ‘ discontinuity’ the boundary is meant between the outer flow and the dead water region formed by fluid that departs from the surface as illustrated nicely in Fig. 1 for the flow around a cylinder.

This paper has arisen from a more general investigation aimed at identifying appropriate manned aircraft that would make suitable stand-off cruise missile platforms. One primary measure of an aircraft's ability to fulfil such a role is found in its payload-range envelope for flight profiles involving one or more payload drop. To this end, a generalisation of the Breguet Range equation is developed initially for a radius-of-action scenario in which the entire payload is ejected at altitude at the designated drop point and the aircraft returns home. The more general problem is then addressed, namely that of establishing the payload-range envelope for an aircraft flying a predefined mission profile comprising a maximum of four consecutive legs each separated by a single payload release point. The ability to include a partial payload release at any drop point is built into the model to permit planners to investigate typical ‘what if?’ effects on the overall mission.

Six numerical examples are included, all based upon the Boeing C-17 as the parent aircraft. These examples describe in detail missions of increasing complexity in order to demonstrate the versatility and efficacy of the current method.

Attention is confined to turbojet-powered aircraft cruising in the stratosphere, although the analogous case of a turboprop-powered aircraft can be simulated simply by amending a single group of constants that appears in all the formulae. Neither air-to-air refuelling policies, nor complicating atmospheric effects such as headwinds, are considered in this paper.

This paper outlines the development of flight simulators used in civil training, military training and in engineering simulation. It describes the evolution of flight simulators and the typical architecture of a modern flight simulator. The technical innovations, which have occurred in modelling, motion systems and visual systems are reviewed. The paper also reviews the transfer of training in flight simulation, the application of simulation to engineering design and outlines problems which are encountered in flight simulation. The paper concludes by reviewing the current trends in flight simulation.

The present paper addresses the problem of extracting indicial response functions from solutions of the Navier-Stokes equations. Two approaches are considered.

In the first, the indicial response is computed directly by modifying the local grid velocity to reflect the step change in plunge velocity. The computed data are then fitted using an assumed form for the response function and numerical optimisation techniques.

In the second (indirect) approach, the general form of the lift transfer operator is determined analytically from the functional form of the assumed response. Using the lift transfer operator explicit solutions of the in-phase and quadrature components of the normal force time history can be obtained. The unknown coefficients in the response function are then extracted from computed data for harmonic motion by fitting the time history using the explicit solution.

Computed response functions are presented for a range of Mach numbers and are compared with analytical results and indicial models currently used within the rotorcraft community. For the cases considered there is no significant difference between the response functions determined using the direct or indirect approach. Comparison of the computed results with existing models suggests that generalisation of the response to step changes in incidence using a two-pole approximation of the circulatory response together with the Prandtl-Glauert factor is not possible. However, comparison with higher order semi-empirical models is much improved, providing some justification for the use of such models. In addition to these observations, the extracted response functions suggest improvements to piston theory to account for thickness effects. The proposed modification of piston theory is based upon properties of the static pressure distribution and so can be used in conjunction with both CFD and experimental data.