The problem of transferring a space vehicle between two points in a given gravitational field such that the minimum amount of fuel is used has been called the fundamental navigational problem of astronautics. In such a problem it may be required to find the optimum thrust magnitude and thrust direction which yields a minimum fuel trajectory. Furthermore, certain end conditions may be specified which the optimal trajectory must satisfy. In a large number of published papers the velocity of the vehicle is supposed known both at the beginning of the transfer and at the end whereas the time taken to complete the manoeuvre may or may not be given. Also, other performance criteria have been chosen besides minimum fuel. For example, minimum time of transit or maximum orbital altitude at perigee.

Papers mentioned in this review deal mainly with flight in two dimensions apart from those sections on general theory. Furthermore, all space vehicles considered are assumed to have a fixed exhaust velocity unless otherwise stated.

In past years, flying a basic X-15 from launch through a dead stick landing on a precise speed and altitude profile was considered a demanding piloting task. The success of each mission was determined by the pilot's ability to perform under the physiological and psychological stresses of flight into a hostile flight environment of high Mach numbers, high accelerations, high altitude, and limiting temperatures. Today the aircraft has been extensively modified to qualify the X-15 as a test bed vehicle for a ramjet engine, which will be carried in place of the movable ventral, providing real time flight environment for testing and developing an operational prototype ramjet for use on future hypersonic cruise vehicles. The additional systems pictured in Fig. 1 (external tanks, ramjet, external window, and ablative coating), their associated emergency procedures and the degraded flying characteristics of the X-15A-2 have increased the pilot's workload significantly over the standard X-15 mission.

In delivering the 1968 British Commonwealth Lecture I am conscious of the honour bestowed upon me by the Council of the Royal Aeronautical Society and mindful of the responsibilities attached to addressing such an eminent body as are assembled here tonight.

My subject—The Development and Future of Air Cargo—is, I believe, worthy of our attention at this particular time, not only because it is in itself an interesting special aspect of the general history of civil and military aviation, but because we have reached a critical point in that development at the very moment when air cargo service is beginning to show its potential contribution to the expansion of World Trade, including the badly needed expansion of Britain's own export trade. As we proceed, we shall see that the big expansion in air cargo has only recently begun. The formative years of aviation were more concerned with development of the vehicle, in creating public acceptability of this new form of transport and in fostering the growth of the more immediately profitable passenger traffic.

This paper is based on a lecture given to a meeting in June 1967 sponsored by the Royal Aeronautical Society and Business Operations Research Ltd. It describes the activities of the operations research functions in Aer Lingus and is based on the work both of the central Operations Research Unit and, also, on studies carried out by management science specialists in the Aer Lingus Economic Planning Department.

The recently developed theory of modal control has so far been mainly applied to the design of process control systems. This theory is, however, capable of much wider application and it is the principal object of this paper to illustrate its use as a basis for the synthesis of aircraft control systems. The particular illustrative problem considered is that of synthesising a lateral autopilot for bank-angle and roll-rate mode control. Typical aerodynamic data for an aircraft flying at M=0·9 and at altitudes from sea level to 40 000 ft (12 km) are used in the calculations.

The results of a series of shear buckling tests on shallow, flat-sided, corrugated webs are presented, and a comparison made with a theoretical analysis in which the web is assumed to buckle either as an orthotropic plate or in a local mode. An expression is derived for the efficiency of a corrugated web in shear, and used to compare the four shapes of cross-section tested.

Calvert has considered alternative methods of estimating the blockage corrections for blunt-based bodies of revolution in closed wind tunnels at low Mach numbers. His models were all of maximum diameter 152 mm, with an ellipsoidal nose section 203 mm long followed by a cylindrical afterbody. The ratio of overall length L to maximum diameter d varied from about 1.5 to 5.5. For each model the base pressure was measured in wind tunnels of two different sizes, so that the blockage correction factor e for the smaller tunnel could be derived for each model from the experimental results. These experimental values of e were compared with alternative theoretical estimates, using the methods given by Evans, Maskell and Pank-hurst and Holder.

I am especially honoured to be invited to deliver the inaugural address of the newest branch of the Royal Aeronautical Society here in Ireland, with your exceptional contribution and involvement in both the pioneering and progress of commercial air transport. It is also a great pleasure to have my old friend Captain Jack Kelly-Rogers, one of the world’s truly great aviators and most appropriately your first Chairman, officiating tonight. As President of the Weybridge Branch of the Society I also bring you their greetings and best wishes.

In this note it is suggested that the three-tube yaw probe be placed on the boundary and used as a Preston tube to measure the boundary shear stress when both its magnitude and direction are unknown. The calibration results necessary for this method are also presented herein.

We envisage here that it is desired to evaluate (using a digital computer) the integral of a function f (x, y) with respect to x (say), along a curve γ in the xy-plane; the value of the function and of the co-ordinates of the curve being known only at discrete, and possibly irregularly spaced, points of γ. Such a problem frequently arises, especially where γ is a closed curve: as for instance in aerodynamics when it is desired to estimate the force components and pitching moment inferred from an experimentally determined set of pressures taken over an aerofoil; here the function values are related to the pressure measurements and γ is the aerofoil contour.

The slender-body theory of Ward is applied to a configuration consisting of a slender, pointed wing, carrying directly beneath it a pointed half-body of revolution divided along a meridian plane.

Expressions for lift and drag due to incidence are found which are valid in both subsonic and supersonic flow if the flow is attached. The lift result can be used to find pitching moment. For the supersonic case the drag at zero incidence is also found and the expressions for a conical configuration are developed so that a limiting form of these can be compared with the results of ref. 3.

The analytical construction of displacement functions for plate elements subject to bending was discussed at some length in ref. 1. Attention was thereby drawn to both triangular and quadrilateral elements available in the ASKA system, which satisfy either all kinematic compatibility conditions or are deficient in the continuity of the gradient normal to the edge. The most rudimentary elements of the triangular set consist of the so-called fully compatible TRIB 3C and the TRIB 3, which satisfies the slope condition only at the vertices. The TRIB 3C corresponds in principle, but not in detail, to the element evolved by Bazeley et al but allows, however, also for linear taper.

The response of a P1a fighter aircraft to vertical and lateral harmonic gusts is calculated, and the predicted spectra for response accelerations at many points on the structure compared with previous flight measurements in continuous turbulence. The frequency range for the comparison is 0.45 c/s to 30 c/s and the response includes the short period pitching and the dutch roll rigid–body modes as well as oscillations in five symmetric and four anti–symmetric flexible modes. Structural flexibility is represented by measured vibration modes and aerodynamic forces are calculated by an oscillatory lifting surface theory.