The aim of this paper is to give an outline of the background, development and V/STOL flying techniques of the Hawker P.1127. For security reasons it is not possible to release information on performance or numerical details of the control characteristics and hence it has been necessary to confine the material to a qualitative nature.

Vertical and short take-off and landing (V/STOL) ability of operational aircraft from unprepared areas enables air power to be concentrated at long range with a minimum reliance, on overseas bases. In the past such operations have been possible because of the existence of well-equipped overseas bases and long lines of communications.

In any industry, success calls not only for a tool which is well adapted to its purpose, correctly maintained and efficiently used, but also for a tool which is unsurpassed by a better one.

This is also true of air transport. C. R. Smith (President, American Airlines Inc.) noted some time ago that an aircraft ceases to be efficient as soon as another aircraft becomes available that can do its specific job better. This axiom places emphasis on the selection of aircraft as one of the primary elements of success for airlines which, in order to survive economically, must have available the right number of aircraft of the right type at the right moment.

This is the result of two essential characteristics of air transport: intense competition and marginal profits.

The earliest known boats were propelled by oars. Sails were soon discovered, probably in Egypt, where a light, but steady, north wind blows up the Nile. The Egyptians found that by stretching a large mat across the ship they could proceed up the river. However, sails remained an auxiliary source of power until about 300 A.D. because they could be used only with a following wind. Fig. 1 shows an Egyptian ship of about 1600 B.C.

The next improvement came in China, where the square sail was turned fore and aft, enabling the boat to be sailed at an angle to the wind. Unfortunately the Chinese made no further improvements, and the junk, Fig. 2, has remained basically unchanged for about two thousand years.

The art and science of re-entering a vehicle into a planetary atmosphere poses many problems, which are today on the edge of man’s mental and industrial capabilities. Re-entering a vehicle into the earth’s atmosphere incurs the following major problems: —

• (a) Kinetic heating as it passes through the denser regions of the atmosphere. Materials have to be found which can deal with the enormous amounts of heating experienced by the vehicle.

• (b) Design of a vehicle to withstand large thermal and mechanical shock.

• (c) Dynamic stability at hypersonic velocities.

• (d) Accuracy of direction of entry into the atmosphere.

• (e) Recovery of the capsule after impact, wherever it landed.

This paper deals with the kinetic heating aspect of re-entry and shows how present day materials are utilised in restricting the inside temperature of re-entry vehicles to within reasonable limits. Unmanned re-entry is specified because to re-enter a manned capsule puts large restrictions on deceleration and inside temperature limits and hence produces some unique problems which are not covered in this paper.

My Company is a small firm, situated near Colchester, Essex, operating only in the United Kingdom. It is entering its sixth year of operation, and owns seven aircraft, all Tiger Moths, five Agricultural and two Club aircraft of which, generally, only four are serviceable, the remainder being on maintenance or repair— of which more later.

Our experience is probably quite different from other operators’ as a season can vary enormously from area to area, and just a few weeks of working to capacity on something that occurs locally can make all the difference between a good year and a bad one. But although differing substantially in detail, the overall pattern is probably similar.

Aircraft have been profitably employed in a multitude of forest operations in many parts of the world. Their usefulness is, of course, greatest where the forest cover is extensive and more or less continuous and where ground access is difficult. In such situations, as, for example, in parts of the American continent and in some tropical areas, aircraft have become indispensable forest tools and are used for such varied duties as the survey and evaluation of the species composition and volume of the standing crop; the detection of outbreaks of fire, disease, and insect pests; the transport of men and materials for fire fighting; the application of chemicals, in either liquid or solid form, for the control of damaging insects, fungal disease, and rodents; the application of herbicides and fertilisers; the re-seeding of cut-over areas; and for surveys of wild life resources.

Land development through pasture improvement has made great strides in recent years in many parts of the world. This has been made possible by a better understanding of the principles of pasture production following the pioneering work of the late Sir George Stapledon and his school of grassland enthusiasts. Improved strains of pasture plants, the use of lime and fertilisers, the development of mechanical aids and a better understanding of the animal in grazing management have all been involved in the development.

The future helicopter brings to mind a vast multi-engined aircraft capable of speed in excess of 150 knots, and of payloads of 8,000 lb. or more. This is not the aircraft for agriculture.

Experience has shown that once the all-up weight of the helicopter gets beyond 3,000, 4,000 lb., its manoeuvrability is reduced to such an extent that the characteristics which make it the most ideal vehicle for aerial agriculture are lost.

Before assessing future developments of agricultural aircraft, it is interesting to study the trends of the industry over the past five years.

In England, after a promising start, which it is now apparent was occasioned by a heavier-than-normal attack of pest and disease, it soon became evident that large scale operations could not be undertaken profitably due to low fleet utilisation and numerous operational problems which arose from the use of existing fixed-wing aircraft. The major operational problems which hampered large scale operations were shortage of acceptable landing strips, small fields and a high incidence of obstacles.

In spite of the efforts by the Aircraft Industry in Europe and North America to meet the demands of agricultural aviation, there is still a need for an efficient, simple and safe range of aircraft for the treatment of crops.

When the ideal aircraft is produced to meet the needs of the small-field farmers, what form will it take–fixed-wing, helicopter, autogyro or unmanned robot?

The performance of triangular ramp vortex generators of a type used for boundary layer separation control, has been compared with that of equivalent wing or vane type of lifting generators, in a uniform velocity field, and was shown to be substantially inferior. Performance was established using a novel vortex strength measuring device of unusual simplicity, for which calibrations are given and applications are discussed.

The usefulness of vortex generators in avoiding boundary layer separation due to an adverse pressure gradient has been established. Little, however, is known of the nature of vortex modified boundary layers. As part of an investigation into convective heat transfer through such layers it was desired to compare the circulation-drag performance of two representative generator configuration types, these being the popularly used stub wing or vane type, and the edge separation, plough or wedge type.

In a recent note a method was developed for calculating the reduction in average lift of a cascade aerofoil due to trailing vortices, neglecting the interference due to blockage and stream curvature. Using the numerical values (for a rectangular aerofoil in an unstaggered cascade of finite wings) of the coefficients in the series for the circulation distribution obtained from the Liverpool University DEUCE programme referred to in the previous note, the effect of interference on the spanwise lift distribution has been studied. The analysis has been extended to predict the lift-induced drag ratio of a finite wing in a cascade.

In a previous paper charts were given which related the flow Mach numbers on either side of a wave to a dimensionless wave speed. Charts were given for shock waves, isentropic expansion waves and isentropic non-steep pressure waves in a perfect gas. In this note it is shown that the lines of constant state ratio plotted on the charts constitute families of straight lines; this fact is particularly important in the case of the shock wave chart. The wave domains are also established and compared diagrammatically.