Not Much of an Engineer

by Stanley Hooker

  So in September 1960 Bill Bedford opened the throttle, got between 10,000 and 11,000 lb thrust, and lifted the stripped-down P.1127 off its special grid at Dunsfold. The only concession Sydney made was that the aircraft should be restrained by loose tethers. This was not a good idea, because at the limit of the tethers the P.1127 swung about like a balloon on a string, out of control. But after these halting steps Bedford and his colleague Hugh Merewether got into their stride, and in September 1961 Bedford made the first accelerating transition from a VTO into high-speed horizontal flight. I asked him what it was like during the transition, and he said “The aircraft felt like a brick on ice!”

  In producing the first engine the little coterie around me — Marchant, Plumb, Lewis, Young, Quinn and Dale, for example — had come across many new problems. An obvious one was the reliable operation of the four nozzles. We were playing with the entire engine thrust and vectoring it through angles up to 100°, from horizontal to vertically downwards and 10° forward for braking. If one nozzle stuck, the result would be serious and probably disastrous. The nozzles had to rotate in unison. We bled HP air from the combustion chamber to power two air motors feeding into a differential box in such a way that, if one motor were to jam, the other would continue to drive but at half-speed. Cross-shafts from the box drove motor-cycle chains passing round the two pairs of nozzles. Normal practice would have been to use a gear-train, but I said I had not seen a broken motor-cycle chain for years, and that this was the lightest and simplest way to lock the four nozzles together.

  The nozzle drive had to rotate the nozzles quickly and lock them positively at any desired setting. For example, in making a ski take-off the pilot of today’s Sea Harrier quickly moves the lever to 55° and expects to get just that, and neither 54° nor 56°. I cannot speak too highly of the job done for us by Plessey in producing an extremely reliable operating system. Unlike all other VTOL aircraft, the single nozzle lever is the only extra control in the cockpit, and its motion is instinctive and immediate.

  Another new problem was the nozzle bearings. We did not expect any trouble with the 100°C front nozzles, but the 650°C rear nozzles were a different story. All four nozzles rotated inside giant ball bearings, but 650°C was a severe requirement for any kind of bearing and special cooling measures were necessary. To our joy, we calculated that the pressure in the cold air ducts would always be slightly higher than in the jetpipe, so that, if a pipe were to be run from the LP plenum chamber to a volute around each rear bearing, it would automatically supply cool 100°C air and keep back the hot gas. Lo, it worked just like that, and the problem of the rear bearing was solved.

  We collaborated with Sydney’s team on the special RCVs for use in hovering flight. We put these, popularly called ‘puffer jets’, in the nose, on each wingtip and in the tail, the tail jet being rotatable to give directional control like a rudder. The four puffer jets were fed with HP air from the combustion chamber. When opened, each gave about 1,000 lb of force. The opening and closing of each jet was connected to the pilot’s control column, so that, if the nose went down, he would react normally and pull the stick back, thus opening the front puffer to push the nose back up again. And the same for the wing tips and directional control, the pilot always moving the control column as he ordinarily would in normal flight. This feature has greatly contributed to the ease with which pilots can be trained to fly the Harrier.

  The earlier Rolls-Royce Flying Bedsteads had been controlled by similar puffer jets, but with an automatic stabilizing system governed by gyroscopes like an autopilot. This feature had been used in the Short SC.l research aircraft, which had four RB108 engines for lifting only, each of around 2,000 lb thrust. For safety, it is customary to use three automatic systems, in case of system failure. One might fail, two might fight against each other, whereas three provide the essential margin of safety.

  Hugh Conway, who had been Managing Director at Shorts at the time of the SC.l, made a special trip to Camm to persuade him — with a long and very technical presentation — to use the three-lane system. I saw Sydney shortly afterwards, and he told me he had said to Conway “We are ignorant buggers here at Hawkers, and don’t understand all that science”. So the Harrier was left in the hands of its pilots, with what success we all know.

  Once the transition from vertical take-off to wing-borne flight had been made, and the P.1127 shown to be a practical proposition, MWDP began, naturally, to reduce their financial contribution. However, further support from MWDP came some years later when the Tripartite squadron of nine Kestrel aircraft was formed. MWDP, the British Government and the German Government each contributed three aircraft. The purpose of this squadron, which had engines rated at 15,000 lb, was to demonstrate the capability of the aircraft to operate under actual field conditions, which it did with great success.

  I would like to pay a tribute to Larry Levy, a wealthy American, who had joined MWDP, and had the political clout and dollars to persuade the American, Federal German and British governments to purchase the Kestrel aircraft and set up the field trials. The Tripartite unit began operations in 1964, dispersed as in war conditions, and the trials were literally a roaring success.

  The British Government was reluctant to pick up the cheque for the continued development of the Harrier, because the RAF continued to show little interest. Nonetheless, the programme went ahead. Chapman and Driscoll bowed out, but it must be a source of great personal satisfaction to them to see that the bread they cast upon the waters in 1958-62 returned to the US Marine Corps when they ordered more than 100 Harriers in 1969, under the enthusiastic leadership of Col. (later Lt. Gen.) Tom Miller, USMC.

  Obviously, the next step was to increase the thrust of the Pegasus so that the Kestrel could be equipped with a war load, and all the ancillary equipment involved. Accordingly, we followed the usual practice of increasing the mass flow of the fan, and raising the engine operating temperature from 970° to 1,170°C by using air-cooled cast blades in the HP turbine. Thus the thrust was increased, first to 18,000 lb and later, in production, to 21,500 lb.

  We also added a small gas-turbine starter, so that the aircraft would be completely independent of ground services. This little gas turbine gave 100 hp (as I recall), and could be run independently of the main engine so that all the electrical equipment could be checked without running the main engine — an important feature for aircraft dispersed in the field.

  To the Hawker Aircraft designers Hooper and Fozard, and to the Hawker test pilots Bedford and Merewether, must go the credit for converting the first demonstrator P.1127 into the final weapon as the Harrier. To John Dale at Bristol must go the credit for converting the early Pegasus into a reliable service engine. In fact John spent 20 years of his life developing the Orpheus and Pegasus, and gained worldwide respect for his judgment, and the firm way he ran the Pegasus development programme.

  It seems unlikely that such a programme could happen twice — Orpheus and Pegasus — where an engine and aircraft are made and tested ahead of any military specification. But miracles do sometimes happen, and the whole enterprise reaped its just reward in its contribution to the Falklands campaign. No Pegasus, no Harrier and no Task Force.

  As for the US Marine Corps, they continue to be staunch supporters of the aircraft, and Lt. General White, Deputy Chief of Staff for Aviation, USMC, recently wrote me a congratulatory letter in which he stated that the Marine Corps intended to re-equip its light attack force with the Harrier II (AV-8B) which is being jointly developed by British Aerospace and McDonnell Douglas. Such things do not happen by accident, nor without a great deal of determined and dedicated persuasion by men such as Gene Newbold from our American company. Gene came first from Fairchild, went to Curtiss-Wright, and finally joined Rolls-Royce Inc in New York. He dedicated his efforts to the Pegasus and the Harrier, and is held in such great respect by all in the Pentagon that he had the entree to the low and the high. He continues to be a key man in the efforts we have made to sell the Harri
er to the US Air Force and Navy. This is no mean task, considering the great production facilities that exist in the USA, and which will naturally favour the production of American-designed aircraft and engines.

  Chapter 11

  The Mergers and my first Retirement

  Few can doubt that in the 1950s Britain had too many aircraft companies, and too many military aircraft development programmes. It was inevitable that both should sharply diminish, but perhaps this should have been possible without either suggesting that military aircraft were obsolete or that companies failing to merge should no longer be considered for government contracts.

  The pressure on companies to merge grew from late 1957. Westland, the helicopter builder, took over Fairey, Saunders-Roe and the helicopter programmes from Bristol. Hawker Siddeley, by far the largest existing group, progressively swallowed up Folland, Blackburn Aircraft and de Havilland Aircraft. Bristol Aircraft joined with the successful TSR.2 contractors, Vickers-Armstrongs and English Electric, to form BAC (British Aircraft Corporation), which also absorbed Hunting Aircraft. On the engine side Rolls-Royce took over D. Napier & Son, while Bristol Aero-Engines and Armstrong Siddeley Motors merged to form BSEL (Bristol Siddeley Engines Ltd) to provide engines for TSR.2, thereafter taking over de Havilland Engines and Blackburn Engines.

  It was a time of great turmoil, rarely equalled in any industry. People in the great pioneering companies of this British industry were passionately proud and loyal to their great names, and powerful emotions had to be eroded if the mergers were to succeed. At top levels of management tough and astute tycoons fought for various interests — their employees, their company names, their aircraft projects, the financial deals and the fine print in the agreements. But at the technical and engineering levels it all took place with scarcely a ripple.

  Russell’s aircraft design team, led by Bill Strang and Mick Wilde, still reigned intact at Bristol. On the engine side my team received a small influx of valuable talent from Armstrong Siddeley, together with a large increase in knowledge and experience. Only later did I learn how large had loomed the fears of others that the chief engineers, all strong personalities, would indulge in a head-on collision. In fact there was little argument and I carried on as before. Dr Eric Moult of DH Engines took over helicopter engines, a growth area, at his factory at Leavesden, outside Watford. Pat Lindsey, of Armstrong Siddeley, took over the new Industrial and Marine Division at a former ASM plant at Ansty, outside Coventry. We had all been friends since the early days of jet engines, and hardly had a cross word.

  Thus BSEL was, from the word go, a happy ship. As Technical Director I was nominally able to direct Moult and Lindsey, but they were so competent and self-propelled that no interference from me was necessary. We contented ourselves with mutual sharing of technical expertise and mutual support to overcome any serious problem.

  No better example of this policy could be given than the changes made to the Olympus and Pegasus combustion chambers. I had previously been only too happy to stick to the Lucas system, in which the fuel is fed under high pressure to atomizing jets which spray it in a cloud of fine droplets into the burning region. For many years palliatives had been sought for the most severe disadvantage of this method, which is the fact that it is not possible to maintain the high pressure needed for proper atomization, except at maximum fuel flow. Thus, at take-off the fuel flow is 100 per cent and the fuel pressure may be 1,000 lb/sq in, giving good atomization; but at flight-idling, or low power at high altitude, the fuel flow may be 10 per cent and the pressure only 10 lb/sq in, a hundred-fold reduction. This low pressure results in the burner emitting a spluttering jet containing small, medium and large droplets, which need highly variable periods of time in which to burn. This can wreck the desired fuel distribution and air/fuel ratio, lay down carbon deposits, cause a smoky jet and promote flameout whenever the pilot opens or closes the throttle.

  From the beginning, Armstrong Siddeley had concentrated on vaporizing burners rather like a Primus stove or common blowlamp. In their system the fuel was supplied at low pressure and metered into a curved tube like the handle of a walking stick, located in the burning zone of the combustion chamber. The fuel was vaporized by the heat surrounding the short walking-stick tube and emerged as a vapour which mixed readily with the airflow and gave uniform and consistent combustion under all conditions.

  Of course the ASM system had its problems, one of which was melting of the metal of the walking-sticks, but brilliant work by that company’s engineers — notably former rocket designer Sid Allen — overcame them completely. When we at Bristol inherited the system in 1960 it was free from any significant trouble. I had a careful evaluation made against the traditional high-pressure atomizing burners, and the vaporizing method emerged as clearly superior.

  I had no hesitation in deciding that both the Olympus and Pegasus should forthwith be changed to vaporizing combustion, with the assistance of the former ASM combustion engineers. The change not only gave perfect behaviour under all conditions but eliminated visible smoke and gave sundry other valuable improvements.

  All liquid fuel must be turned into a vapour and mixed with the correct amount of oxygen from the air before it will burn. It seems obvious that to do the vaporizing separately under controlled conditions is better than squirting droplets into the burning zone and leaving them to do it on their own. Why did it take until 1960 for the blinding light to dawn on me? My defence is that I was so busy dragging Bristol into the jet age that I was only too happy to leave combustion to Lucas.

  That great firm, under Sir Bertram Waring, a mighty supporter of the aircraft industry, had from the early Whittle days developed gas-turbine combustion chambers and fuel systems. It did the chambers at Burnley under Clarke and Morley, and the fuel systems at Shaftmoor Lane, Birmingham, under Dr Watson and Dick Iffield. As far as possible it was a case of ‘fit and forget’ the Lucas system where I was concerned; but equally there was no doubt of the superiority of the vaporizing system.

  Whilst we were changing over to vaporizing combustion, in the early 1960s, the technology of the jet engine was poised for a giant new leap. Though 20 years earlier the so-called ducted-fan engine, again first envisaged by Sir Frank Whittle, had attracted only very limited interest, it was obvious from the way Pratt & Whitney beat the Rolls-Royce Conway, simply by going to a much higher bypass ratio in their JT3D turbofan, that the subsonic transport engines of the future were going to have much higher bypass ratios, in the region of 3 to 7, and would thus be much quieter and much more fuel efficient.

  BSEL and Rolls-Royce studied such engines but lacked funds to build one. In the United States, however, the USAF organised the CX-HLS programme for a gigantic long-range cargo aircraft, and this led to the Lockheed C-5A Galaxy and to new-generation HBPR (high bypass ratio) turbofan engines at General Electric and Pratt & Whitney. GE got the contract for the C-5A engine, but Pratt & Whitney decided to go it alone and constructed the JT9D engine to power the first of today’s wide-body commercial transports, the Boeing 747, ‘Jumbo Jet’. Rather suddenly it was a whole new ball game.

  Rolls-Royce boldly gambled company money on the design and prototype manufacture of a large HBPR engine, the RB178. After careful planning BSEL planned to join with our existing French partner, SNECMA, in the JT9D programme. In view of what has happened in the past 20 years, this US/UK/France programme would clearly have been an excellent step towards collaboration in the largest projects, but it was not to be.

  In 1966 Rolls-Royce ran a demonstrator RB178 engine and to strengthen its hand, the main board at Derby made a successful bid for the entire BSEL assets and business with the result that in October 1966 we were bought up by Rolls-Royce at the substantial price of £63.6 million.

  Although I was quite happy with the basic principle of amalgamating Bristol Siddeley with Rolls-Royce, I was sad that these two famous names were to disappear. I was not so pleased with what this entailed for myself and my team of engineers. Derby had Sir D
enning Pearson as Chairman and Chief Executive, Sir David Huddie as Managing Director of Derby Aero Engines, and F. T. Hinckley as Commercial Director. I asked Pearson to appoint me to the main Rolls-Royce Board but his feeling at that time was that I was no longer acceptable to the engineers at Derby. My request was turned down and so I decided to retire at the earliest convenient date, which was my 60th birthday on the 30 September 1967. The negotiations to obtain the best possible financial terms for me were aided by two of my friends at Derby, Don Pepper, Director of Personnel, and Trevan Hawke, Financial Director.

  Chapter 12

  The RB211 and the Prodigal’s Return

  When I decided to retire in September 1967, Hugh Conway, who had been appointed to the Rolls-Royce main board whilst remaining managing director at Bristol, asked me to stay on as a consultant. This I willingly agreed to do. Having no executive responsibilities I was able to sit back and survey the various Rolls-Royce engine programmes. The one that stood out like a sore thumb — in size, importance, technical and financial risk, and lack of progress — was the RB211 at Derby.

  The RB211 was the giant High By Pass Ratio engine that the main board finally chose to build. The reasons behind the giant HBPR engines now need explaining in more detail. Back in 1958 Pratt & Whitney had shown, in meeting the competition of the Conway bypass jet, that it was possible to add on the front of an existing turbojet a large fan, with a diameter much greater than the rest of the engine, driven by extra turbine stages (or an additional turbine driving a separate LP shaft). Such a fan would both supercharge the rest of the engine, called the gas-generator or core, and also greatly raise the propulsive mass flow and reduce the mean jet velocity, a system which we had also used in the Pegasus in 1958.

  In all gas-turbine jet engines the central core can be regarded as a ‘boiler’ producing hot gas under pressure. In a simple turbojet this flow is allowed to escape through the propulsive nozzle, producing thrust. The higher the pressure ratio and the higher the operating temperature, the greater the efficiency of the boiler — provided, of course, that the efficiency of each compressor and turbine can be maintained. On the other hand, the higher the ‘boiler efficiency’, the greater the velocity of the jet, the kinetic energy of which is wasted on being released to the atmosphere. The propulsive efficiency therefore falls. Propulsive efficiency is equal to 2Va divided by Vj plus Va, where Va is the velocity of the aircraft (relative to still air) and Vj is the velocity of the jet (relative to the aircraft). In round figures Va may be 850 ft/sec (580 mph) and Vj 2,000 ft/sec, giving a propulsive efficiency of 60 per cent. For Concorde we do better because Va is much greater. The only way to do better with subsonic aircraft is to reduce Vj. If we could get it down to 1,500 ft/sec, by augmenting the airflow, we could raise the propulsive efficiency to 72 per cent, thus — other things being equal — cutting the fuel burn by at least 20 per cent.