I consider it a great privilege to have been chosen to give the first Rex Pierson Memorial Lecture, as not only is he an outstanding figure in British Aviation, but he was also one of my close friends.

Reginald Kirshaw Pierson was born in February 1891 at Fransham, Norfolk, his father being the rector there. He was educated at Felsted School. On leaving he was destined to enter the Bank of England, but at the last moment, mainly due to the untiring efforts of his mother, he was allowed to follow his natural bent, and take up engineering instead.

In 1908, therefore, at the age of 17 he entered the Erith Works of Vickers Ltd., as an engineering pupil-apprentice, passing through the various departments and, while there, taking his Bachelor of Science Engineering degree the hard way, from evening classes.

Fatigue of aircraft parts due to small but numerous vibrations has been known about for some time, but in 1944–5 cases of structural fatigue were found which were thought to have been caused by loads greater, but less frequent, than the usual vibration loads. Such loads could be ground loads due to taxi-ing, take-off and landing or they could be air loads caused by gusts and manœuvres.

A general study of the fatigue properties of typical structures was made in the laboratory and it became apparent that the loads likely to do the most damage were those occurring about a million times in the life of the aircraft.

The rapid development of the jet engine has been responsible for a complete change of outlook in air transport. The purpose of this paper is to illustrate some of the problems and to indicate ways in which they have been solved. The subjects discussed are those of temperature control of

1. (i) Pressure cabins of aircraft

2. (ii) Engine intakes (for de-icing) and

3. (iii) Aircraft wing surfaces (for de-icing).

The normal control of engine jet pipe temperature has not been included because, until recently, it has been fully covered by the engine companies.

Jet pipe temperature control is a specialised application involving the correction of fuel flow for variations of air flow which may be due to changes in either compressor or turbine characteristics at altitude, or even the incorrect sampling of jet pipe temperature at altitude. The methods of temperature control discussed in this paper are often applicable also to engine jet pipe temperature control.

In 1949 F. H. Pollicutt, in the course of a discussion on a paper presented by P. B. Walker to the Royal Aeronautical Society, reported fatigue test results which indicated that when the aluminium alloy conforming to specification D.T.D.364 was tested, under , axial loads, in the form of Z-sections, its fatigue properties were extremely low. Z-sections with unmachined surfaces and even Z-sections with completely machined surfaces failed after short endurances at stress ranges under which small polished round test pieces would not have failed even after hundreds of millions of cycles. Pollicutt, in discussing these low values, advised that great caution should be exercised in their interpretation, warning equally against an unqualified acceptance of the testing technique and a too facile acceptance of small polished round bar test results.

The carpet and lattice methods of plotting the relationship between three and four variables respectively, developed by R. F. Sargent, of the National Physical Laboratory, have been described previously by A. H. Yates, who gave examples related to the presentation of aerodynamic and engine performance data. Outside these fields there appears to be still some lack of appreciation of the usefulness of this form of graphical representation, although it is capable of wide application. The writer has found both carpet and lattice plotting of great value in connection with the preparation of structures data sheets, and is convinced that interpolation is generally rendered easier and more accurate if graphical data are presented in this way. In one particular instance it was found possible to develop a nomogram in the form of an “ extended lattice ” plot, which gave in graphical form a direct solution to a set of equations which could be solved otherwise only by continuous approximation.

There is already in existence a fair volume of work on the subject of bending beyond the limit of proportionality, most of which requires the use of actual material stress-strain curves. This note aims to examine the problem in a more general way by using an accurate mathematical form for the stress-strain curve, strain and bending moments being expressed as functions of the ratios of various properties of the material.

The value of maximum permissible fibre stress is considered in relation to current requirements for military aircraft stressing and a guide is presented for the maximum permissible bending moment in some of the more familiar beam cross sections bending about an axis of symmetry.