This paper will consider the various types of data links to Remotely Piloted Vehicles. The factors affecting their design will be explained and the important parameters and problems highlighted.

The actual and potential roles for RPVs are well established, whether they be military or civil surveillance, or crop spraying. The information to be transferred between the ground terminal and the RPV or between RPV and RPV will depend largely upon the type of mission. This will impose the biggest constraint on the link design.

The developments in the use of composite honeycomb in passenger aircraft structures has been growing rapidly over the past ten years. Starting with its use in the semi-structural internal use as a flooring material such as the cross plied UD glass-nomex cored floors of the wide body jet aircraft — 747 — L1011 and DC10, to the external uses for control surfaces, fins, undercarriage doors, engine pods, etc, and the ultimate all-composite fuselage of the LearFan project.

The progress in the light aircraft field by comparison, is almost non-existent, the major use of composites is restricted almost entirely to the manufacture of sailplanes and the majority of these use foam stabilisation rather than honeycomb.

In the absence of a criterion for maximum wingtip deflection, the estimation of wing weight is a straightforward technical problem, for conventional planform shapes. Shear force and bending moment are integrated from the wing-tip to the wing root; using the known aerofoil shape, and the maximum allowable stress or strain, the skin thickness is determined at each station, and hence the mass of the entire wing is found.

It is safe to assume constant wing-loading per unit area along the span. If less than this constant value is used near the root, then some of this load must be transferred to stations further outboard; the bending moment at the wing-root is increased, and the skin-thickness and hence the wing weight will also be increased.

Throughout its existence the organisation now known as British Aerospace, Warton Division has been primarily concerned with the design and manufacture of advanced combat aircraft. Often it is in this class of aircraft that the advantages of developments in structures and materials are first realised on a production basis.

This paper briefly describes some of the currrent involvement of Warton structural engineers in material selection, technology demonstrators and future projects for the next generation of combat aircraft.

It has been pointed out by a number of investigators that aerofoils with blunt trailing edges have many advantages, both structural and aerodynamic, at transonic and supersonic speeds. However, a profile with a blunt trailing edge unfortunately creates a high base drag at subsonic speeds and this could result in the total drag being considerably higher than that for a profile with a sharp trailing edge. This base drag arises due to the periodic vortex shedding from the blunt base which causes low pressures in the wake thus creating the base drag.

In order to reduce the base drag of a blunt trailing edge at subsonic speeds, this periodic vortex shedding must be suppressed. This has been achieved by various methods — a splitter plate behind the base, the base bleed, base cavities — and these have shown varying degrees of drag reduction.

The theory of optimal flight paths goes back to 1951, when Tsien and Evans found the optimal thrust program for a vertically ascending sounding rocket. Hibbs, in 1952, solved the problem of the optimal burning program for horizontal flight of a winged, rocket propelled vehicle. Miele has carried out much work in this field, mostly using*the assumption of constant thrust, and working without the aid of a digital computer, (which is necessary to achieve results). Reference 3 gives a summary of early work in this field.

Recently, the problem of optimal climb paths of a ballistic rocket, away from the vertical, has been shown in Ref. 4 to have a simple analytic solution. The problem of a winged supersonic rocket missile, assuming the thrust acts along flight path, has been solved in Ref. 5.