Slide Rule

  And there were times when we had much to wonder at. News of the progress of the Air Ministry ship was scanty and hard to come by; by virtue of their official position they knew all about our ship but we knew little about theirs. We gleaned our technical knowledge of R.101 from patent specifications, from popular articles in the press, and from hearsay. Early in the design our calculations had disclosed a curious aerodynamic feature in the stability of these huge ships; not only could they both easily be steered by hand without the assistance of a servo motor, but no balance area was required upon the rudders although they were over a thousand square feet in area. At a comparatively late stage in the design we learned on sure authority that R.101 not only had balanced rudders but had servo motors fitted at great weight and cost to assist the helmsman in the steering of the ship. Out flared the inferiority complex; we suspended work on the rudders and spent three days in checking through our calculations to find our mistake. At the end of that time we knew that our figures were correct, and we were left dumbly staring at each other. Either these ships could be steered by hand or they could not; it was impossible that we could both be right. There must be something in this that we did not understand.

  The engine installation was another one. An airship requires engine power to go astern to check her way as she approaches the mooring mast and in R.100 we had arranged for two of our six engines to drive their propellers through a reversing gearbox for this purpose. As R.101 approached completion we were astonished to hear that her reversing propellers had proved a failure, and in consequence four of her five engines were arranged to drive ahead and the fifth one would only go astern. The fifth engine apparently was to be carried as a passenger on all her flights solely for the purpose of going astern for a minute or two at the start and finish of each flight, and with its power car it weighed over three tons. Again we were left staring at each other, speechless. It is the greatest mistake to under-rate your competitor, and in spite of their past record it was incredible to us that our competitors should perpetrate such childish follies. There must be something in this that we did not understand.

  As the years went on the same perplexities came to us very frequently on one point or another.

  The conditions imposed on the two staffs by their respective organisations provided an interesting comparison. With our capitalistic organisation we could go to no great expenditure upon experimental work; we were supposed to know our job and to be able to build an airship as a bridge might have been built. On the other hand we had freedom to change our minds and to make rapid alterations in policy and design if circumstances should require it. As an example, we changed our engine policy three times during the construction of the ship. At first it seemed expedient to design a special engine for R.100 running on hydrogen and kerosene. After a year’s work it became evident that this engine would not be fully developed before it was required for installation in the ship. The work was stopped, the design and work in progress was sold off in the most economical way, and we decided to fit diesel engines of the type that were being developed by the Air Ministry for R.101. That phase lasted for six months; it then became clear that the diesel engines would be grossly overweight and unsuitable in other ways for use in our ship. At this stage we cut clean through our difficulties and decided to use aeroplane engines running upon petrol in the normal manner. Six Rolls Royce Condor engines were selected, and the engine installation gave us no further trouble.

  At Cardington the circumstances were entirely different. A large expenditure upon research and experiment was permitted to them; if they asserted that certain research was desirable before their design could proceed, that research was invariably put in hand. In this way they built an entire experimental section of the ship, and made innumerable experiments on such accessories as gas valves, servo motors, steam heating of the passenger quarters, evaporative cooling of the engines, etc. All these researches were admirable in themselves, but unnecessary for the production of a successful airship; we bought our gas valves for R.100 from the Zeppelin company and if airships had gone on we would have made them under licence. On the other hand, it appeared that once they were committed to a definite policy with regard to R.101 it was difficult for them to change their minds; if public money had been spent upon an article for the ship, into the ship it had to go. A few months before the first flight of the R.101 her designer urged his superiors to fit petrol engines in the ship as we had done in R.100, on account of the excessive weight of the diesel engines. This petition was refused by some high civil servant in the Air Ministry whose name is now forgotten, perhaps fortunately; the diesel engines had been developed for R.101 and they had to be used. It is interesting to note these relative restrictions imposed on the two staffs; our work was hampered by the paucity of research dictated by the fixed price contract, and theirs by the inflexibility of the official system.

  My own work in the calculating office led at times to a satisfaction almost amounting to a religious experience. The stress calculations for each transverse frame, for instance, required a laborious mathematical computation by a pair of calculators that lasted for two or three months before a satisfactory and true solution to the forces could be guaranteed. To explain this for the benefit of engineers, I should say that each transverse frame consisted of a girder in the form of a stiff, sixteen-sided polygon with the flats at top and bottom; this girder was twenty-seven inches deep and up to a hundred and thirty feet in diameter. Sixteen steel cables ran from the centre of the polygon, the axis of the ship, to the corner points, bracing the polygonal girder against deflections. All loads, whether of gas lift, weights carried on the frame, or shear wire reactions, were applied to the corner points of the polygon, and except in the case of the ship turning these loads were symmetrical port and starboard. One half of the transverse frame, therefore, divided by a vertical plane passing through the axis of the ship, consisted of an encastré arched rib with ends free to slide towards each other, and this arched rib was braced by eight radial wires, some of which would go slack through the deflection of the arched rib under the applied loads. Normally four or five wires would remain in tension, and for the first approximation the slack wires would be guessed. The forces and bending moments in the members could then be calculated by the solution of a lengthy simultaneous equation containing up to seven unknown quantities; this work usually occupied two calculators about a week, using a Fuller slide rule and working in pairs to check for arithmetical mistakes. In the solution it was usual to find a compression force in one or two of the radial wires; the whole process then had to be begun again using a different selection of wires.

  When a likely-looking solution had at last been obtained, deflection diagrams were set out for the movements of the various corners of the polygon under the bending moments and loads found in the various portions of the arched rib, and these yielded the extension of the radial wires under load, which was compared with the calculated loads found in the wires. It was usual to find a discrepancy, perhaps due to an arithmetical mistake by a tired calculator ten days before, and the calculations had to be repeated till this check was satisfied. When the deflections and the calculated loads agreed, it was not uncommon to discover that one of the wires thought to be slack was, in fact, in tension as revealed by the deflection diagrams, which meant that the two calculators had to moisten the lips and start again at the very beginning.

  The final check was to take vertical and horizontal components of the forces in every member of the frame to see that they equated to zero, that your pencil diagram was not sliding off the paper into the next room. When all forces were found to be in balance, and when all deflections proved to be in correspondence with the forces elongating the members, then we knew that we had reached the truth.

  As I say, it produced a satisfaction almost amounting to a religious experience. After literally months of labour, having filled perhaps fifty foolscap sheets with closely pencilled figures, after many disappointments and heartaches, the truth
stood revealed, real, and perfect, and unquestionable; the very truth. It did one good; one was the better for the experience. It struck me at the time that those who built the great arches of the English cathedrals in mediaeval times must have known something of our mathematics, and perhaps passed through the same experience, and I have wondered if Freemasonry has anything to do with this.

  While all this was going on, I was writing my second published novel in the evenings, So Disdained. Again I seem to have taken considerable pains over it; it took me two years to write and all of it was written through twice over, some of it three times. I used to find that the story became fixed in the first writing; I do not think that I ever altered a scene or the essentials of a piece of dialogue in a subsequent writing. A re-writing increased the length by about ten per cent; awkward phrases and sentences were eliminated, and the general style of the writing was improved. Since the first writing probably took a year, one came to the chapter fresh in the re-writing, a year older, with a year past in which one had forgotten much of the detail; this undoubtedly helped in putting the thing in to a better style. This great amount of re-writing does not seem to be necessary to me now; with increasing experience I find that I can say pretty well what I want to say the first time. Perhaps thirty per cent of my later books have been re-written; I re-write the first chapter always as a matter of principle since it is seldom in tune with the rest of the book. I do not seem to get into my stride till the first chapter is over.

  We built R.100 hanging from the roof of the shed without the use of any trestles or staging; each transverse frame was built horizontally upon the floor, lifted up with a pyramid of wires to the corners, slung by the sides to the roof railways, and the centre was then lowered till the frame hung vertically. It was then slid along into position and the longitudinal girders were put in to attach it to the next frame. The ship remained hanging from the roof of the shed until she was inflated with gas; the slings were only removed a few days before she was ready for flight. This method of erection gave us a clear floor and other advantages, but it brought its own responsibilities. Howden shed was getting old and the roof had been neglected for years; it stood in an exposed position and in heavy gales it was clear that parts of the seven and a half acres of corrugated iron were not too secure. The roof never blew off but with every gale we thought that it was going to, and in bad weather we had to keep a standing watch of riggers ready for the first sign of trouble.

  By the early summer of 1929 the ship was getting on towards completion, and the time had come to inflate her gasbags with hydrogen. Her volume was a little over five million cubic feet, giving her a gross lift of about a hundred and fifty-six tons; her tare weight was about a hundred and two tons, so that she had about fifty-four tons available for fuel and oil, ballast, crew, and passengers.

  The gas plant was just outside the shed and here the hydrogen was made, not without some danger. The gas was conveyed in a gas main which ran beneath the ground to points immediately beneath the ship; to these points each gasbag in turn was connected for inflation. Each empty gasbag hung like a curtain from the axial girder that ran through the centre of the ship; as the gas was filled into it the top of the bag bellied out and rose slowly till it reached the upper netting, and spread down the sides till it filled the whole section of the ship. There were fourteen gasbags in R.100.

  To guide these gasbags accurately into place was no mean task. We had no foremen who were experienced in this sort of work, and the financial responsibility was very large indeed. The bags were made of light fabric lined with goldbeaters-skin, easily torn by careless handling; the largest of them weighed half a ton and cost about six thousand pounds. If the bag were wrongly positioned at the first inflation it was necessary to let the gas out again till it could be shifted. The cost of the gas to fill the largest bag was about eight hundred pounds, so that mistakes cost a good deal of money.

  Because of this responsibility the gasbags were inflated and hung in position by the design staff. I took one squad of riggers on to the girders of the ship—we had lost all fear of heights by then—and the chief draughtsman took another squad; the operation was directed by B. N. Wallis talking to us through a megaphone. This unconventional teamwork answered admirably and was much admired by a representative of the Zeppelin company who happened to be with us at the time, and to whom an office worker was an office worker, and a foreman a foreman. He had never seen anything like that in Germany. Neither had we in England, but it worked. All fourteen gasbags were positioned in the ship after a fortnight’s sweat and toil with only one small tear.

  Throughout the summer of 1929 the gasbags were inflated, the manufacture of the gas itself taking a considerable time. Finally came the day when the ship floated in the shed; the roof suspensions became slack and the ship swung from trays of balance weights upon the ground. The completion of the outer cover now that the gasbags were in place took some time, and there was an immense amount of final detail work to be carried out before the ship could fly. Perhaps the most important feature was the engine trials.

  These trials were a very grave responsibility. R.100 had three power cars slung outside the contour of the hull, each housing two Rolls Royce Condor engines developing between them 1400 horsepower, and one six-cylinder motor car engine driving a dynamo. Each power car had to pass a test of running for two hours ahead at cruising power and half an hour astern; these tests had to be carried out in the shed before the ship could fly. I have been connected with a great number of first flights of aeroplanes as well as all the flights that R.100 made, but I have never seen a test more dangerous or terrifying than these power car trials. The clearance of the great wooden propellers from the concrete floor was no more than fifteen inches, and whatever precautions we took it was impossible to keep the hull of the ship from surging up and down in the fierce air currents generated by the thrust of the propellers in the shed. The noise of these engines running with open exhausts within the corrugated iron shed made ear defenders necessary and it was impossible to communicate except by writing. Wallis or I stood by the car throughout each trial watching the pointers that we had arranged to indicate the ship’s movement and the propeller clearance; we had a system of signalling to stop all engines if the surging of the ship grew dangerously large. All my life I shall remember the sight of those engine cars leaping and straining at their cable drag wires with terrific force, suspended from a hull that was completely full of hydrogen, each car with smiling men gesticulating with thumbs up out of the window in the deafening clamour, myself gesticulating back thumbs up to them with a cheerfulness I could not feel. If a propeller had hit the floor or if a suspension cable had parted under that test the issue could only have been sheer disaster and the loss of many lives. We had made no mistakes, however, and nothing happened, and at last these engine trials came to an end; but it is my firm conviction, looking back upon those days, that if it is possible to compare dangers R.100 was never in so great danger as she was three months before she flew. I do not think that anything the ship did in her flights was so dangerous to her as those engine trials. We were restricted in this matter by the Airworthiness authorities, which meant, in practice, by our competitors at Cardington; if we had had our way we should have done things differently.

  That summer So Disdained was published in England, and Watt succeeded in negotiating an American publication for it under a title that I disliked very much but had to accept, The Mysterious Aviator. This was the start of title troubles which have pursued me throughout my writing career; I seldom seem to see eye to eye with my publishers on what constitutes a good title for one of my books. I have now reached the stage when I can generally get my own way by putting on a display of bad temper, but young authors can’t play it that way, and I had to take The Mysterious Aviator or give up publication in the United States. I took it, needless to say, and tried to forget about it on the principle of taking the cash and letting the credit go; I had, moreover, many more important things to th
ink about that summer.

  R.101 flew before we did, making her first flight on October the 14th 1929; from that point we started to learn details about her, mostly from the newspapers. It was quite true that she was carrying an engine as a passenger for astern running only; it was quite true that she had servo motors to work her rudders. Details of her weights gradually leaked out to us; she had a gross lift of only 148 tons and a tare weight of 113 tons, so that she had only 35 tons useful load as compared with our 54 tons. The Air Ministry press department, of course, was in full blast telling the world what a marvellous ship she was; in our offices at Howden a faint sense of impending disaster was stirring in us, I think, even in those early days. An airship is safe in proportion to its useful lift, in proportion to the weights that it can jettison in an emergency, and by that standard R.101 was definitely dangerous. In our view, also, she was considerably underpowered.

  By this time the crew of R.100 were at Howden. The captain and first officer, Squadron Leader Booth and Captain Meager, proved to be most helpful in the later stages of the construction and soon became great friends; we had our troubles with R.100 but they were obviously pleased right from the start that they had not been allocated to the other ship. The other members of the crew were as mixed a crowd as it would be possible to find. About one third of them were old, experienced airship hands, mostly of naval origin. Another section of them were premium apprentices from Rolls Royce, young men from good public schools and with influential connections. The remainder were fitters and riggers from our own workshops, recruited on account of their competence and intimate knowledge of the ship. There was no discipline among this airship crew in the normally accepted sense. Each man had been carefully picked, and taken as a whole they were a very good crew indeed. About twenty-five men constituted a full crew for the ship, excluding officers, wireless operators, and stewards, but we had over forty men as crew members, I think for training; when we flew to Canada we sent a spare crew over to meet us in Montreal.