This paper describes the design and development of the Thiokol XLR99-RM-1 rocket engine for the North American X-15 research aircraft. The engine is a turbopump-driven unit of 58,000 lb. thrust at vacuum conditions utilising liquid oxygen as the oxidiser and anhydrous liquid ammonia as the fuel. The design is notable for a number of features incorporated into a rocket engine of this size, in that it is primarily an aircraft engine with all of the control and safety attributes pertaining to conventional manned flight.

The general development of the engine is reviewed on a component basis with brief digressions into the historical and political background.

An analysis is made of the stresses and strains in a loaded two-bar tie when one of the bars is subjected to heating. The material of the bars is assumed to possess linear work hardening characteristics, i.e. a constant tangent modulus in the plastic range, and these characteristics are assumed to be independent of temperature. The following cycles of loading and heating are considered: load-heat-cool-unload, load-heat-unload-cool, heat-load-unload-cool, heat-load-cool-unload, and it is shown how, and when, these cycles produce differing stresses and strains and, in particular, differing residual stresses and strains. The effect of repeated applications of these cycles, when incremental shake-down may occur, is also considered.

The development of a new commercial aircraft is a complex process spanning several years and requiring the energies of a large number of persons, both within and outside the originating organisation. Conditions for successful growth must be just right for the design to proceed to the first major accomplishment stage—that of flyable “hardware.” Conditions have to continue to be extremely favourable to reach the second stage—that of widespread airline operation. History indicates that they must be favourable to an unfortunately remote extent to reach the third stage—that of financial success for the manufacturer.

Many of the conditions involved go far beyond those under the control of the manufacturer and may even be wholly unpredictable in nature. This is why the third stage is so seldom achieved, at least in a free enterprise system.

Autogyro principles and theory are well known and only the practical aspects of design and construction of the smallest of autogyro aircraft will be considered on this occasion. Also, at this stage, it would be inappropriate to be specific about prices of such aircraft owing to the difficulty of estimating production costs. Tare weights, however, may provide some clues as to costs.

In the “thirties” the autogyro had been brought to quite a high standard of performance, mainly through the pioneering and development efforts of one man, Senor Juan de la Cierva.

During those years many ideas, which would today be regarded as novel, had been tried. Jump-start, pusher engines and tricycle undercarriages are not new.

During the period 1945-1960 many journals contained papers in which flight optimisation problems were solved by several different methods, The author has long felt that a review of these methods and the assumptions under which solutions have been obtained is needed, particularly by research workers who are new to this field of study and also because many of the techniques used for optimising flight within the atmosphere are applicable to the space flight problems of today.

Patel And Venkatraman have studied the general behaviour in bending of a thin-walled channel section (Fig. 1) made of non-linear elastic material which deforms in simple tension according to the law

where ε represents strain, σ direct stress and λ, n the relevant material properties. (It is understood that a negative sign is inserted in where this is necessary to make σ and ε have the same sign.) As Patel and Venkatraman explain, the results are, by a trivial substitution, applicable to steady creep behaviour of the channel section.

A method is presented for the analysis of a simply-supported rectangular orthotropic plate subjected to a uniformly distributed load by the application of Maclaurin's series. The solutions have practical applications in the design of interconnected beam systems because of the elastic equivalence of the grid framework to an orthotropic plate.

The application of Maclaurin's series to the analysis of beams in bending was first described by Hetényi. Recently Reddy and Gangadharan described a modified approach for beams with stepped variations in cross section. Ballesteros has extended the method to functions of two variables in the analysis of isotropic plates in bending.