Not Much of an Engineer

by Stanley Hooker

  When in 1972 I at last visited China, I stood on the platform of the railway station at TienTsien, and my mind went back to that near miss of nearly 40 years earlier. I must say, I was more than relieved that things had happened in the way they did. Even stranger, the wheel of fate turned a full circle and, in 1974, I was invited by Li Chang, the Minister for Foreign Trade, to become an Honorary Professor of the Peking Aeronautical Institute, a distinction which I prize highly.

  In 1935 it was clear to me that Hitler was heading for war, so I decided that I must go into the Navy, in which Service I had more than the necessary qualifications to join as a Lieutenant-Commander. However, I was diverted into the Scientific and Research Department of the Admiralty. I started work in September 1935 at the Admiralty Laboratories at Teddington as a Scientific Officer at £450 a year. I had hardly settled in the place when I was suddenly summoned to Whitehall to see the Director of Scientific Research, Charles (later Sir Charles) Wright. He was a tall, rugged Canadian who had been the physicist on Scott’s fatal expedition to the South Pole. Later, when I knew him better, I tried to get him to tell me about it, but he said that it was too awful to discuss.

  When I saw him on this occasion he told me that I had been seconded to the Director of Ballistic Research and was to report to him at Woolwich Arsenal forthwith. Ballistics was concerned with the range and flight of shells and rockets. The Director, Alwyn (later Sir Alwyn) Crowe, told me that I would have been offered a job with him earlier, but his budget would not permit, so he had hijacked me from the Admiralty. This was the unexpected direct result of the report I had written on the supersonic tunnel while at Oxford.

  My first job was to work on the underlying mathematics behind the anti-aircraft (AA) rocket, which in World War II was used in vast numbers in Z-batteries. A great argument was being waged about AA guns versus AA rockets. It went thus. The great difficulty in predicting the height, speed and course of an aircraft made the chance of a lethal shot with the standard 3·7 or 4·5 inch anti-aircraft gun about 1 in 20,000. In fact, in the War they did better; if I remember correctly they scored about 1 in 10,000. To defend Britain against German aircraft attack, thousands of very expensive guns would be required, whose barrels would need frequent replacement.

  Cordite rockets were cheap, so why not fire a cloud of these at an aircraft? No expensive gun to wear out — just a bunch of simple rails to launch the rockets. But there were problems with the rocket. Nobody had ever extruded cordite to the required size of 3 in (76·2 mm) in diameter. Even once this had been done, the rockets had a tendency to burst on the launcher, and sometimes were seen sailing off in a direction at right-angles to the direction of projection.

  So the argument went on, and when war started we had not made the guns and shells, and the rockets were not ready either. When the war ended we had both in ample supply!

  Woolwich Arsenal was a remarkable place. At the main gates, there were large workshops. Once past these, large tracts of ‘country’ opened up, sloping gradually down to the river. Green fields, paths and edges were everywhere, joining the steam-heated underground bunkers where cordite was stored.

  At the end of one of these paths was a small collection of single-storey wooden huts, where the Directorate of Ballistic Research was housed. Nearby were two test houses where the rockets could be tested while clamped down, and the thrust and burning time determined. The rockets were fired by a ‘quick match’ which itself was ignited electrically. We had one nasty accident when a rocket apparently failed to ignite, and the men who went into the test bed to investigate were killed by the delayed ignition.

  I remember that the first real trials of the rocket in free flight were made at Orford Ness, Essex, and I was invited by Alwyn Crowe to be present. There was a considerable gathering of top brass to see these trials, and all appeared to go well. But the photographs showed that at least one of the rockets travelled approximately 90° in the wrong direction, so evidently the stability was marginal.

  One other job I was given in 1937 by Crowe, and that was to calculate the weight and size of a rocket which could hit Berlin. The propellants were specified as either liquid oxygen and kerosene or nitric acid and kerosene. The former was the better combination since all the constituents were combustible, whereas with nitric acid, the nitrogen therein was virtually dead weight.

  The conclusion was that it could be done, but the rockets would be enormously large by previous standards, weighing many tons. The report was discussed by the Secret ‘M’ Committee of the Admiralty, chaired by an Admiral, and with many important members. I attended the meetings in awe, but nothing came of it because we were just not ready to visualise such huge rockets as a practical proposition. A few years later, the German V.2s landed on London, and my calculations came back to me vividly — particularly the conclusion that the range of a single rocket was strictly limited to about 350 miles (560km) which placed much of England out of range.

  It is odd that the best scientific advice offered to the Prime Minister in 1942-44 was that such a rocket was quite impossible. Great efforts were made to stop any serious consideration of such a weapon, even after they began falling on London!

  Of course, today multi-stage rockets are used, and the launch weight is an order of magnitude greater than that of the V.2, but, back in 1937, we limited ourselves to a small rocket weighing only a few pounds. In retrospect, I think this was correct. The enormous effort that the Germans put into the V.2 never did pay off. If, instead, it had been invested in more and better aircraft, who knows what might have been the outcome?

  While at Woolwich, I worked with W. R. (now Sir William) Cook. When I met him, I was very surprised to find that he had kept well abreast of the work on supersonic airflow, which up until now I had thought was mainly of academic interest. I did not know that Woolwich had for years been photographing bullets and shells in flight, and could easily see the air shock-waves and flow in the pictures.

  Cook was a great smoker. On his desk, he had a row of seven pipes which he smoked alternately. There was also a block of opaque yellow stuff about 4 in (10 cm) cube, which sat on the desk next to the ashtray. I asked what it was.

  ‘Oh, that’, replied Cook, ‘that’s a lump of cordite’.

  ‘Good God’, I said, ‘Isn’t it very risky?’.

  ‘Not at all, it’s only dangerous when burning in a confined space’.

  Thus I learned that cordite could be extruded, carved or machined like any other plastic material. The tubes of cordite used in the rocket were about 24 in long, 3 in diameter, and had a star-shaped hole up the middle. The shape of this hole was important, because it controlled the area of the burning surface and prevented the rocket from bursting prematurely.

  Though I was very interested in all this work, I had my suspicions about its direct relevance to the war which seemed imminent. When, therefore, in the autumn of 1937 I had a letter from my friend Llewellyn Smith, asking me if I was interested in a job in the Engineering Department of Rolls-Royce, I was intrigued, and shortly afterwards I went to Derby for an interview with Colonel T. B. Barrington, who was then Chief Designer, Aero Engines. I waited in his office, from which I could see the serried rows of drawing boards and the impressive-looking men working at them.

  The door of the office opened and in came a man, slightly older than myself, with a very large and high forehead and an air of quiet confidence and authority. He shook my hand rather diffidently.

  ‘My name is Rubbra, I am the Assistant Chief Designer’.

  God knows, I did not doubt it, as I spoke for the first time with a real live Rolls-Royce engineer. Rubbra and I were destined to work together in great harmony, and with great success for many years to come, but then there seemed no way I would ever be able to equal him. I remember being shocked by his comparative youth. I expected Rolls-Royce engineers to be grizzled men with beards and at least 50 years old. Perhaps I had imprinted on my mind unconsciously the picture of Sir Henry Royce. Rubbra had the air of a qui
et, deep-thinking man, which indeed he was.

  Barrington came in, and we had a short conversation about my career to date, and he talked rather vaguely about the necessity for stressing more accurately the components in an engine. This depressed me somewhat, because although I had studied the general theory of the forces produced by the elasticity of materials, it was by no means my main subject. Then he took me to lunch at the Midland Hotel at Derby Station, with its frightful exterior and very comfortable interior, and after lunch we parted on the general line, ‘don’t call us, we’ll call you’.

  I was not surprised that the interview had been unsatisfactory. I still could not figure how I could get into that great engineering organisation, so I returned to the Admiralty Research Laboratory, and forgot about Rolls-Royce. This was made easier by my being promoted, at this time, to Senior Scientific Officer at £850 p.a. To reach such heights in a little over two years was very unusual, so I was not dissatisfied with prospects for the future.

  Two months later, like a bolt from the blue, came a letter from the Works Manager of Rolls-Royce, Ernest W. Hives. As I found later, he was always referred to as Hs, and he was the King of the Derby works. The letter requested my presence at Derby for an interview with Hs.

  Naturally I went, and was ushered into his office which was over the front entrance to the works. The office was half panelled in oak, had a blazing fire on one side, and Hs sat at his desk across one corner. Today that desk is one of my treasured possessions, for from it, Hs inspired, directed and led the great contribution to the war effort which Rolls-Royce was destined to make under his colossal and dominating leadership.

  I was instantly impressed by the aura of good humour yet relentless energy that seemed to surround him. I saw that he had copies of my published works on his desk. After seating me, he thumbed them through casually and asked,

  ‘What’s a Kármán Vortex Street?’

  I explained as best I could, and then he said, leaning forward ‘You’re not much of an engineer are you?’

  I had to agree and he replied:

  ‘Never mind, this place is full of the best engineers in the world and we will teach you if you have it in you. They tell me you are a mathematician of ability. Tell me about your career’.

  Which I did. He then suddenly came to life, and leaning forward said, ‘When can you start?’

  Now, I had only regarded my trips to Derby as exploratory and, in fact, I had not mentioned to my Chief in the Admiralty that I was seeing Rolls-Royce. I told Hs that I wanted to know what I should be expected to do, and for how much.

  Hs ignored this and said, ‘Whom do you work for now?’ I told him the Director of Scientific Research in the Admiralty, whereupon he picked up the telephone and said, ‘Get me Mr Charles Wright at the Admiralty in Whitehall’.

  My heart sank, because I knew now that I should be faced with an instant decision.

  The ‘phone rang, and Hs said, ‘I have a man called Hooker here, who says that he works for you, and who wants a job with us’.

  I could not hear the reply, of course, and do not remember how the conversation went from there. Finally, Hs put the ‘phone down and said, ‘He says that you are a dirty dog to leave him after he has just promoted you, but he recommends you and says that we can have you’. I said, ‘Now you have shopped me completely, and you have put me at a great disadvantage’.

  ‘I see’, he said, ‘I did not mean to do that’.

  He had a twinkle in his eye, and said:

  ‘How much do you say you are worth?’

  With great trepidation I said that it would not have been worth my while leaving the Admiralty for less than £1,000 p.a., but now I was in his hands.

  He laughed and said, ‘I’ll tell you what I will do. I will give you £1,000 for the first year, £1,100 for the second, and £1,250 for the third’, and then he added mischievously, ‘if you last that long’.

  And then he began to talk to me about the knowledge of mechanical design the company had built up, due to Henry Royce’s insistence on as near to mechanical perfection as one could get; of its great manufacturing skills; and of the loyal workforce which had a father-to-son tradition.

  ‘This door is always open to our men’, he said. ‘Only the other day a fitter came in and said, “Our Bill is leaving school on Friday”. So I said to him, “You had better send him round to see us on Monday, and we will see what we can do with him”.’

  He went on, ‘I am no mathematician or scientist, but I have a feeling that we are going to need such people in the future. We need a more technical and analytical approach to some of our engineering problems, and I am going to look to men like you to give us that lead’.

  I left his office elated. His giant strength of character, warm sense of humour, and generous approach had completely captivated me. We were destined to become great friends, ‘like father and son’ he said to me on one occasion, and he was to give me great power in Rolls-Royce in the next few years. But neither of us foresaw that. And yet, eleven years later, I was to quarrel bitterly with him, and I left Rolls-Royce to join the Engine Division of Rolls-Royce’s chief rival, the Bristol Aeroplane Company. When two people so close quarrel, the rift can be very deep, and thus it was; but, happily, some ten years later still, we were reconciled by an act of superb generosity on his part.

  Chapter 2

  The Merlin

  And so, in January 1938, here I was seated in my Spartan little office in Nightingale Road, Derby. After a few days, I resolved that I must end my isolation and go forth to explore the surroundings. I discovered that just across the corridor was a door marked ‘Library’, so in I went and found the Librarian very friendly and helpful. He explained the surrounding geography, and who was who.

  The overall Chief Engineer was A. G. Elliott, who was primarily a design engineer, and had been Royce’s right-hand man for many years. Under him were Barrington as Chief Designer, and Jimmy Ellor as Chief Experimental Engineer. All people who designed and made drawings were responsible to Barrington, and all people who tested engines and components or did other experimental work were responsible to Ellor. The information that Ellor’s department produced was fed to the Design department, who incorporated it into modified designs to improve the engines.

  Since I knew nothing of design, it was clear that I must direct my attention to the work being done in the Experimental Department. So, one afternoon after lunch, I took my courage in both hands, and wandered diffidently into the next office, which I knew housed the engineers responsible for testing the single-cylinder research engines. In it were about half-a-dozen highly efficient-looking young men, all busy at reports or examining blueprints. Over in the corner sat a quiet grey-haired man gazing into space, and since he looked the most innocuous, I went over and asked him what he did. He replied, ‘I am in charge of testing superchargers’.

  ‘What does that mean?’, I asked.

  ‘Well, we have a rig back there in the test area, driven by two electric motors each of 250 horsepower, on which we can drive a test supercharger, and measure its performance independently of the engine. In fact, this is a typical set of curves that we get’.

  He picked up a bunch of sheets from his desk, and showed them to me. Plotted on them was the amount of air that the supercharger pumped, the pressure it produced, and the temperature rise of the air due to its compression.

  I asked, ‘Could I borrow one of these curves?’ ‘Certainly’, he replied, ‘take a complete set’.

  I bore them back in triumph to my office. By the grace of God I had stumbled on the one man whose job it was to produce test results which were right up my street, namely, the flow and compression of air.

  I was not to know that Hs, under advice from Llewellyn Smith, had given instructions that I was to be left to soak in the atmosphere of Rolls-Royce for the time being, in the hope that I would find my own feet in an area to which I could contribute. His attitude was that I was not to be deviated into any routine task unti
l I had had a chance to settle down, and get some idea of what went on. And, although I felt neglected, it happened in just the way he had hoped.

  I had never even seen a supercharger, and had no idea how it managed to compress air by centrifugal action. I rushed to the Library and borrowed two books, The Internal Combustion Engine, by D. R. Pye and Stodola’s great work on Steam Turbines. Both contained chapters on the elementary theory of centrifugal compression, and I was soon able to compare the theory with the experimental results which Frank Allen had given me. There were wide disagreements.

  In both Stodola and Pye the theory was very sketchy, and I was soon able to extend it to include the separate efficiencies of the rotor and the diffuser. Briefly, a centrifugal supercharger consists of a rotor carrying a number of equally spaced radial vanes. In the case of the Merlin supercharger, which I was examining, the rotor was 10.25 in (260 mm) in diameter and had 16 vanes. It was driven by the engine through a step-up gear, and revolved at 28,000 rpm. The air entered at the centre of the rotor, moved out radially under the centrifugal force, and was flung off the rim into a stationary 12-vaned diffuser, the object of which was to convert the velocity of the air into the pressure which forced greater masses of air into the cylinders of the engine.

  If one thinks of the cylinders and pistons of an engine as the heart which converts the force of the burning air and petrol mixture into mechanical power by the downward motion of the piston, then the supercharger is the lungs of the engine, and by its efficiency controls the power output.