Nevil Shute Norway Foundation


Metal fatigue and the real Mr.Honey.

"No Highway" remains a great favourite amongst Nevil Shute's readership and one of the few of his books to be made into a film. In a sense it is a technical novel; there is a good deal of technical detail included in it but it also demonstrates Shute's ability "par excellence" to weave it into a good solid story which appeals to both the technical and non-technical reader. But also it is renowned because, within a few years of its publication, real crashes of new jet aeroplanes happened due to fatigue failures in a similar manner to that described in the book. So "No Highway" acquired the nature of a prophetic book.

You will all be familiar with the story. Mr.Honey in the Structural Department of the Royal Aircraft Establishment (RAE) develops a novel theory of metal fatigue based on changes within atoms that occur after a period of time due to fluctuating loads. To test his theory he is using the spare tailplane of the Reindeer aircraft, oblivious of the fact that his work might have serious practical consequences. At the time "No Highway" was written RAE were indeed carrying out fatigue tests and there was debate about whether fatigue could be significant in aircraft [6]. In a discussion on the paper quoted in Ref 6. during a meeting at the Royal Aeronautical Society in 1949 the following comment was made by Dr.D.Williams of the Structures Department at the RAE. "Specimens of the same component having a mean life of 10,000 hours could depart from that mean by thousands of hours. This was not only known to metallurgists but had been proved at the Royal Aircraft Establishment on built up structures such as tailplanes" and also "cracks in the skin were easily seen but a stringer could break clean through without immediately betraying the fact" the cover illustration of my PAN copy of "No Highway" depicts a man looking anxiously at the tail of an aircraft through a magnifying glass.

Metal fatigue was not a new problem. In essence materials can break by fatigue where loads fluctuate or reverse at stresses lower than when the load is constant. Railway engineers for example found that axles could fail by fatigue. This was discovered in the late nineteenth and early twentieth century. Early aircraft were of wooden construction and fatigue was probably not considered very much if at all. Crashes were mostly caused by failure of the structure due to overloading. By the 1930's aircraft construction had changed to metal with the use of aluminium for the airframe and with thin aluminium panels used in place of fabric.

In reality the basic research work behind the modern understanding of metal fatigue was done by a engineer at the RAE by the name of Dr.A.A.Griffith ( Fig 6 ). He laid the foundations of the growth of cracks in materials on which the science of fracture mechanics came to be based. Griffith work was carried out in the 1920's and he was, by all accounts, a "man whose thinking was way ahead of his time" and he has also been described as a "curious loner" [2]. Metal fatigue depends on the conditions that govern the propagation of tiny cracks and how such cracks can develop beyond the "critical crack length" and lead to fracture. So failure by metal fatigue is a phenomenon that depends on surface defects, stress concentrations around holes etc and at a scale that is many times larger than that of atoms.

So why did Shute have Mr Honey's theory based on the behaviour of atoms? Well atomic theory after the war was new and exciting and was something that could fire the public imagination. If you were casting about for a theory for an eccentric scientist to have in a novel, then something based on atoms and nuclei would be just the thing. Also, being new and controversial, it is just the theory that can be put up to an independent committee (the ISARB in "No Highway") and for them to equivocate about, as they did.

Incidentally Dr Griffith became Head of the Engine Department at RAE and had a significant impact on the development of jet engines during and after the war. He was a very well respected engineer and a Fellow of both the Royal Aeronautical Society and the Royal Society [7]. So his career surpassed anything the fictitious Mr Honey could have dreamed of, yet Griffith was the real Mr Honey in the sense that his pioneering work on fracture laid the foundations for the theoretical contemporary understanding of metal fatigue. However it is most unlikely that Shute ever met Dr.Griffith, or if he did, that he based Mr.Honey on him. With visits to Farnborough Shute would probably have met characters who were prototypes for his Mr.Honey.

The de Havilland Comet crashes of 1953 and 1954 caused consternation in the British aircraft industry. The Comet was the first British jet airliner to enter service. The design was conceived in the late 1940's and the Comet was built using aluminium alloys. Probably there was not enough account taken of the danger of fatigue occurring at stress concentrations in the metal of the fuselage. Very detailed examinations of the wreckage from all the crashed was carried out at RAE Farnborough and it was ultimately established that small fatigue cracks began around a hole close to the windows. These spread slowly and undetected until they reached the "critical Griffith length" whereupon the skin tore catastrophically and the fuselage exploded like a blown up balloon [8].

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