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Precision and Peril, Six Miles High
It was like love at first sight: [Frank] Whittle held all the winning cards: imagination, ability, enthusiasm, determination, respect for science, and practical experience—all at the service of a stunningly simple idea: 2000 hp with one moving part.
—LANCELOT LAW WHYTE, “WHITTLE AND THE JET ADVENTURE,” HARPER’S MAGAZINE (JANUARY 1954)
When it comes to the steady and uncomplaining workings of a device such as a tricycle, a sewing machine, a wristwatch, or a water pump, mechanical perfection is naturally a good thing—but perhaps it is also a thing that is seldom essential to the preservation of life and limb. In the matter of a high-powered sports car or an elevator or a robotic operating theater, however, precision comes to be a vital necessity: mechanical failure occasioned by imprecision at a hundred miles an hour or on the sixtieth floor of a skyscraper or in the middle of heart surgery could have terrible, maybe lethal results.
Furthermore, in those situations where high speed is combined with high altitude, when paying customers are suspended unnaturally many miles above the planet’s all-too-hard surfaces, and, moreover, in a place where the human presence is inherently unwelcome and life unsustainable, the precision of the aircraft machinery that took them up there has to be utterly impeccable. Any departure from absolute perfection could have the potential for the gravest and most disastrous of consequences—as the world came to know just a few minutes after 10:00 a.m. on the sunny Singapore morning of Thursday, November 4, 2010.
Qantas Flight 32, a two-year-old Airbus A380 double-decker “superjumbo” jet aircraft, at the time the largest commercial airliner in the world, was beginning a routine seven-hour flight down to Sydney. There were four hundred forty passengers aboard, two dozen cabin crew, and a slightly unusually large number of five men in the cockpit: a captain, a first officer, a second officer, a check captain, and a supervising check captain, this last on board to check the check captain, who in turn was there to check the performance of the rest of the crew. Among them, the five had an accumulated total of seventy-two thousand hours of flight time, an amassment of experience that would be sorely needed that morning.
The aircraft had taken off at two minutes before ten from one of Changi Airport’s two southwest-heading runways, 20C. The plane’s landing gear was promptly retracted, the thrust settings on the four Rolls-Royce Trent 900-series engines were set to Climb mode, and the 511 tons of aircraft, cargo, and human passengers began to claw their relentless way upward. Within moments, the aircraft had left Singaporean airspace and entered that of the Republic of Indonesia. It was powering into the cloudless sky at a mile and a half above the mangrove swamps and small fishing villages of Batam Island when, suddenly, to the surprise, dismay, and consternation of almost everyone aboard, there were two very loud bangs, one quickly after the other.
The captain immediately overrode the automatic pilot and ordered his aircraft to cease climbing, to keep itself level at seven thousand feet, and to maintain its southerly heading. The cockpit monitors at first indicated only one event: the overheating of a turbine in the number two engine, which was on the left wing, the inboard engine, the one closer to the fuselage. Within seconds, though, this single announcement became a drizzle, then a flurry, and finally a violent storm of flashing lights and sirens and alarm bells as, one after another, systems all around the aircraft were shown to be failing. And within the number two engine, the overheating had now transformed itself into a raging fire.
The captain radioed a “pan-pan” message back to Singapore air traffic control, a message indicating a serious problem, though less than an all-out emergency. He then decided to turn back toward Singapore, to ease himself into a race track holding pattern, to use half an hour of stable flying to work out what exactly had happened to the engine, and to decide how best to deal with the cascade of problems its breakdown had occasioned. Meanwhile, fuel could be seen gushing from the rear of the engine, and a peppering of holes could be seen in the wing, where debris from an explosion of some kind had clearly smashed into it. Reports were also coming in from down below that pieces of aircraft engine had been found in villages on Batam Island, all of them clearly spewed from the damaged plane.
Takeoff is optional, they say; landings are compulsory. It took the better part of an hour for the crew to deal with the various problems afflicting their stricken aircraft, and to work out just how to land when all manner of critical parts of the aircraft were no longer working. The brakes, for example, seemed to be only partially functioning, the spoilers on the left wing could not be deployed, there was no working thrust reverser on the failed engine, and the landing gear could not be properly cranked down for touchdown. The plane would thus come in for a very fast landing, and with ninety-five extra tons of fuel aboard and badly compromised brakes, it might not be able to stop itself before running out of the almost three miles of runway. The airport was asked to scramble its fleet of emergency vehicles and wait for the approach of the giant jet.
In the event, the massive plane did manage to bring itself to a stop—the captain near-frantically pressing the pedals hard to the metal—with just over four hundred feet of runway left. What didn’t stop was the number one engine, on the left wing’s outboard. The number two had been fatally damaged and was not running, but for some reason—because the control cables and electrical connections had been severed, it later transpired, by whatever had crashed through the wings—its near neighbor still was.
Moreover, torrents of fuel were still gushing from ruptured tanks near the number two engine, and most worrisome of all, such brakes as remained on the left-hand side of the aircraft body had overheated during the high-speed, heavy landing and were now red-hot, registering almost a thousand degrees Celsius on the cockpit display.
To add to the grisly picture, the tires had ruptured and were ripped and flat, allowing the bare metal of the wheel rims to scrape along the runway for hundreds of feet. Were any wafts of the gushing fog of fuel, perhaps blown by the jet thrust from the unshutdownable number one engine, to have washed over the near-incandescent brakes or the superhot wheel rims, there would likely have been a spark, a sudden flash of fire, and then, when the wing fuel tanks were properly heated, an almighty explosion. The brief relief of the safe landing would have been replaced by the utter horror of an immobilized plane fully consumed by flames. It was a chaotic and terrifying situation—now much worse on the ground, it seemed, than ever it had been up in the air.
It took the Singapore firefighters three hours to stop the running engine, in effect by drowning it with high-powered jets of thousands of gallons of water. Engines are built to withstand rainstorms, and it is a testimony to the robust design and construction of these Rolls-Royce Trents that it took so immense a simulated rainstorm to bring this fast-spinning machine to a stop. But just as soon as it became evident that the engine would be brought under control, and once the thousands of pounds of fire-retardant foam and dry powder fire suppressor had brought the red-hot brakes back to black and reasonable cool, the passengers, who had been cooped up for two hours in what seemed like a firetrap, were let out, clambering down a set of stairs brought to the seldom-used right-hand doors. Many of the four hundred forty were terrified, but no one was hurt.
And then the crew was finally able to see what had happened. It was an ugly sight, seldom seen or experienced by even the most senior of the flight crew. They could now see that the aft third of the cowling of the number two engine had been torn away, the turbine section of the engine stripped naked, and two gaping holes were visible where part of the engine structure had been blown apart. There was soot, oil, burned wiring, smashed pipes, and parts of damaged rotor blades everywhere.
A heavy metal rotor disc, it turned out, had burst out of the engine; about half of it, torn into hot fragments, was to be found down in the villages of Batam Island. The fragments had rained down from the plane, smashing onto buildings but hitting no one.
What had happened was the nightmare of every jet engine manufacturer in the world. The Rolls-Royce Trent 900—specifically a 972–84 variant, which developed almost seventy thousand pounds of thrust and had cost Qantas Airways $13 million—had suffered what is known as an in-flight uncontained engine rotor failure. This is an exceptionally rare occurrence, but when it happens, it is invariably an exceptionally violent one, with hot metallic components from the engine fracturing and, rather than being enclosed by the metal casing, tearing through it and then being thrown out as shrapnel to tear through the wings and the fuselage of the aircraft.
Bundles of electrical cables, fuel tanks, fuel and oil pipes, hydraulic systems, mechanical systems, and a pressurized passenger compartment with highly vulnerable human bodies within—all these can be hit and damaged by ragged chunks of fast-flying metal. In the case of Qantas Flight 32, many were, and a tidal wave of destruction ricocheted through the aircraft. To the relief of all concerned, the damage and loss of control were successfully managed by a highly competent (and unusually numerous) crew on the flight deck.
The wholly destroyed Rolls-Royce Trent number two engine after the safe landing in Singapore of Qantas Flight 32 following an “uncontained rotor failure” inside the engine a mile high over Indonesia.
Photograph courtesy of the Australian Transport Safety Bureau.
But exactly what had taken place inside the engine to bring about this near catastrophe? To appreciate that, and to enter the ultraprecise but still Hadean nightmare that is the interior of a modern jet engine, requires some history—and a return to the time, not so long past, when aviation was a propeller-driven pursuit still available to the enthusiastic amateur rather than the digitized zealotry found in today’s commercial airline cockpits.
It was Frank Whittle, the first son of a Lancashire cotton factory worker turned tinkerer, who invented the jet engine. There were other contenders, although for the kind of engine most widely recognized nowadays—the air-breathing internal combustion engine that powers most jet aircraft today, and manifestly not the non-air-breathing rocket, which is technically a jet engine also—there are really only two. One was the Frenchman Maxime Guillaume, who secured the French government’s brevet d’invention Number 534,801 for a turbojet aero engine in April 1922; the other was Hans von Ohain, from Dessau in Saxony, who, in 1933, came up with what he felt certain was a workable design for “an engine which did not require a propeller,” and actually saw it made.
Frank Whittle conceived the basic idea of a jet engine while still a young flying student, though for want of the fee was unable to renew the patent. His first propeller-less jet plane flew in May 1941.
Photograph courtesy of the University of Cambridge.
Yet neither the French idea nor the German prototype flourished. The technical requirements for an engine that was destined to function in environments of extreme physical hostility, particularly with such a fierce predicted heat that would envelop all its working parts, were just too daunting for both the materials and the engineering skills available in Europe at the time. Also, it is worth noting that American laboratories were curiously blind and deaf to the idea of a turbine-powered engine as having any utility for the aircraft industry, and the United States pursued almost no research until the 1940s.
It was left to the diminutive Frank Whittle, therefore, to pursue the dream, fired by his famous criticism of the outmoded nature of propeller-driving piston engines, a condemnation that resonates today. “Reciprocating engines are exhausted,” he declared. “They have hundreds of parts jerking to and fro and they cannot be made more powerful without becoming too complicated.* The engine of the future must produce two thousand horsepower with one moving part: a spinning turbine and compressor.”
Modern jet engines can produce more than a hundred thousand horsepower—still, essentially, they have only a single moving part: a spindle, a rotor, which is induced to spin and, in doing so, causes many pieces of high-precision metal to spin with it. Jet engines are beasts of extreme complexity bound up within a design of extraordinary simplicity. All that ensures they work as well as they do are the rare and costly materials from which they are made, the protection of the integrity of the pieces machined from these materials, and the superfine tolerances of the manufacture of every part of which they are composed. Frank Whittle had to deal with these harsh realities for ten testing years, from the moment he had his grand idea in the summer of 1928. Every imaginable obstacle was put in his way during that decade. Nevertheless, he persisted.
Frank Whittle, five feet tall, slightly Chaplinesque in appearance, neat, punctilious, and seemingly made of compressed steel springs—as a youngster, he was a daredevil stunt flier and demon motorcyclist, an irritant to his instructors, and a mathematician of rare ability—first planted the seed at the end of his stint as a flight cadet at Cranwell, the Royal Air Force academy in the English Midlands. Cadets at the time were each obliged to write a short scientific thesis on a topic that interested them, and Whittle’s paper has since become a part of aeronautical legend: with all the hubris of a young man on the make, he titled it “Future Developments in Aircraft Design.”
At the time of his graduation from Cranwell, powered flight was only a quarter of a century old. The aircraft in which cadets such as Whittle trained were mostly biplanes—they had wooden frames, were in no sense streamlined, had no enhancements such as retractable undercarriages or pressurized cabins, flew at low altitudes, and trundled through the skies at speeds seldom exceeding 200 miles an hour. RAF fighters, in many ways more advanced than most, averaged a puny 150 miles per hour, and operated at only a few thousand feet above sea level.
Science fiction was the reading rage of the day, and to a reader such as Whittle, who consumed all the H. G. Wells and Jules Verne and Hugo Gernsback he could lay his hands on, the fantastical possibilities on offer (of high-speed flight, of mass transportation, of journeying in the stratosphere, to the moon, to outer space!) presented not just a contrast, but also, in his considered view, an achievable contrast. Whittle believed that all that the fantasists were offering could actually be achieved, and yet not, he insisted, with the reciprocating engines of the moment. A new and better kind of engine was needed. He later described the ideas he advanced in his memorable Cranwell thesis.
I came to the general conclusion that if very high speeds were to be combined with long range, it would be necessary to fly at great height, where low air density would greatly reduce resistance in proportion to speed. I was thinking in terms of a speed of 500mph in the stratosphere where the air density was less than one quarter of its sea-level value.
It seemed to me unlikely that the conventional piston engine and propeller combination would meet the power plant need of the kind of high speed/high altitude aircraft I had in mind, and so in my discussion of power plant I cast my net very wide and discussed the possibilities of rocket propulsion and of gas turbines driving propellers, but it did not then occur to me to use the gas turbine for jet propulsion.
It was fifteen months later, in October 1929, that the penny finally dropped. Whittle was by now a fully qualified general duties pilot, stationed in Cambridgeshire, and while training and teaching others to fly, he obsessively ruminated and calculated and imagined the kind of engine that could possibly make aircraft go lightning fast. All his designs involved some kind of supercharged piston engine. At the same time, he could see that even a modest increase in engine power, and thus aircraft speed, would require a very much larger and heavier engine—an engine probably much too big and heavy for any aircraft to carry. He was about to abandon the quest when, suddenly, one day that October, he had his brain wave: why not, he thought, employ a gas turbine as an engine, a gas turbine that, instead of driving a propeller at the engine’s front, would thrust out a powerful jet of air from the engine’s rear? An idea that would change the world in unimaginable ways had come to Frank Whittle when he was just twenty-two years old.
His recent school days, and his later mathematical skills, reminded him that a propelling jet of the kind he was proposing would offer a working demonstration of Isaac Newton’s Third Law of Motion, propounded back in 1686. Newton (a Cambridge man, as it happens) had written that “for every force acting on a body, there is an equal and opposite reaction.” Under this law, a powerful jet being thrust from the rear of an aircraft engine would drive that aircraft forward with equal power and, in theory, at almost any imaginable speed.
Moreover, a gas turbine could also, in theory, be vastly more powerful than a piston engine, and for a very simple reason. A crucial element in any combustion engine is air—air is drawn into the engine, mixed with fuel, and then burns or explodes. The thermal energy from that event is turned into kinetic energy, and the engine’s moving parts are thereby powered. But the amount of air sucked into a piston engine is limited by, among other factors, the size of the cylinders. In a gas turbine, there is almost no limit: a gigantic fan at the opening of such an engine can swallow vastly more air than can be taken into a piston engine—as a rule of thumb, seventy times as much, in the early, Whittle-era jets. Seventy times as much air might not mean seventy times as much power—other factors come into play—but a good twenty times as much power is a reasonable and accepted figure.
Small wonder, then, that this was for the historians of inventions, of breakthroughs, a true eureka moment. It truly did represent, cliché though it may sound, a paradigm shift. And from that autumn day onward, Frank Whittle thought of little else than getting a gas turbine to work sufficiently well to propel an airplane, solving as he did so the endless raft of problems, technical and official, that kept the project from its immediate resolution. It would be ten years before the first working engine was fired up, and as so often happens, it was war that provided the spur.
Not at first, though. Few seemed interested: even though Whittle managed to apply for (and eventually be granted, in 1931) a patent for “Improvements Relating to the Propulsion of Aircraft and Other Vehicles,” and even though his officer colleagues at the air base spread the word that he was onto something remarkably innovative and original, he was rebuffed at every turn. The Air Ministry in particular said it had no interest, the three principal British makers of aero engines turned him away, and when, in 1935, it was time to renew his patent, he could not afford the five-pound fee—and the Air Ministry said in no uncertain terms it would not foot the bill out of government funds. Whittle was by then on the verge of giving up, and had developed plans for another kind of device altogether, one that had relevance not to air transport but to journeying by road. He let his cherished patent lapse—not, he thought grimly, that it had any residual value—except that, with the patent’s lapse, and with the release of the idea from his exclusive ownership, the world now had access to it, and that had consequences.
For, in 1935, Germany’s now-fast militarizing—and the interest in jet engines expressed by Hans von Ohain and the Heinkel Company and coincident fresh enthusiasm for turbine propulsion from the head of airframes at the Junkers factory, Herbert Wagner—placed it firmly in a position to develop a turbojet. Whether either man’s interest was spawned by the freeing of the Whittle patent has never been fully established, but the result was self-evident: come the mid-1930s, Germany had indeed become officially interested in producing an aircraft jet engine, while Britain, despite having the idea’s patented creator living with his new family and no money and no support for his ideas not fifty miles from the capital, and employed by no less than the Royal Air Force, was not.
This would all change once money was pumped into the project, and Whittle could begin translating his blueprints into test-bed engines and, eventually, see if his ideas would fly, literally. It was a firm of venture capitalists named O. T. Falk and Partners that eventually, in 1935, took the gamble. “Stratosphere plane?” was the note taken on September 11 of that year by the firm’s senior partner, Lancelot Law Whyte, who confessed to “falling in love at first sight” with the young officer. Despite the query of his notation, he later told his wife that the experience of first meeting Whittle (who by now was pursuing a doctorate at Cambridge, while on leave from the RAF) was akin to “meeting a saint in an earlier religious epoch.” Had one not known the end of the story, it might be easy to suppose that, with a beginning like this, all would inevitably end in tears. Far from it. It ends triumphantly, with the saint indeed performing all the miracles expected of him. And Lancelot Law Whyte emerges from the story as a visionary, a man undeservingly forgotten. He had once been a physicist; he was anything but a coldhearted banker, but was an almost mystical figure, who loved Whittle’s idea not because it might make money, but because of its sheer elegance, and because “every great advance replaces traditional complexities by a new simplicity. Here it was in the iron world of engineering.”
The firm offered a three-thousand-pound advance and established a company for Whittle, to be named Power Jets Limited. There was little by way of aviation experience among the principals—one of the main shareholders made cigarette vending machines—but Frank Whittle was made chief engineer, and the company’s only employee. The Air Ministry (his usual employer, as he was a serving air force officer) agreed for him to be briefly separated from his military duties, though noting that his work for Power Jets was to be spare-time employment only, with his devoting no more than six hours a week to this newfangled idea.
The ministry’s support may have been given grudgingly, but it was nonetheless given,* and it was this official “Oh, alright then” backing that convinced Whyte to get going. He placed an immediate contract with the turbine makers British Thomson-Houston† to develop an engine to Whittle’s specifications. It was to have a turbine spinning at 17,750 rpm that would drive a compressor and produce 500 hp, with the outflowing air creating enough propulsive power to fly a small mail-delivery airplane. It would be called the WU, or “Whittle Unit.” Whittle envisaged it as fast enough to carry some few tons of mail across the Atlantic Ocean, nonstop, in about six hours.
At the distance of eighty years, it is scarcely possible to appreciate the revolutionary novelty of this idea. This was no invention that was happened upon by chance. This was a well-planned, carefully thought-out, and diligently evaluated creation of an entirely new means of propulsion, of transportation. This was the moment (or the invention, or the personality) that took the standard model of precision and transported it from the purely mechanical world into the ethereal. What was about to be constructed was a device of transcendental beauty, and though it might be said that mankind has taken the invention of the jet engine and quite spoiled the world with it, the thing itself had then and has still elegance and integrity like few other modern creations.
The basic principle of the turbine engine was already well established, and turbines were already being made (not just by firms such as British Thomson-Houston, but all over the world). Gas turbines were already beginning to power ships, to generate electricity, to run factories. The simplicity of the basic idea was immensely attractive. Air was drawn in through a cavernous doorway at the front of the engine and immediately compressed, and made hot in the process, and was then mixed with fuel, and ignited.
It was the resulting ferociously hot, tightly compressed, and controlled explosion that then drove the turbine, which spun its blades and then performed two functions. It used some of its power to drive the aforementioned compressor, which sucked in and squeezed the air, but it then had a very considerable fraction of its power left, and so was available to do other things, such as turn the propeller of a ship, or turn a generator of electricity, or turn the driving wheels of a railway locomotive, or provide the power for a thousand machines in a factory and keep them running, tirelessly. Chemical energy, produced by mixing air and fuel, was thus transformed into mechanical energy. Mechanical energy was often just what was needed, to drive a ship or a factory, but if it then drove a generator, there was another level of transformation, of mechanical energy being transformed into electrical energy.
Frank Whittle was interested only in the transformation of chemical into mechanical energy. Electricity was to him of only peripheral interest. Yet he wanted the mechanical energy not simply to drive a spinning shaft. He wanted it to create a propulsive jet of gas—and further, he wanted the device that changed chemical energy into this propulsive jet to be light enough to be carried aloft, and efficient enough to make a jet engine good sense economically. This meant that the engine components had to be made with the greatest of care, to very exacting standards, and to be allowed to operate in the harshest of environments. This is what Power Jets and BTH set out to do, starting in 1936. It proved technically difficult in the extreme, and just when Hitler was starting to breathe down everyone’s neck.
Heat was probably the trickiest problem. The engine’s combustion chamber would create temperatures quite unknown to anyone then involved with burners and boiler-firing equipment. Bearings, too, presented problems—no one had ever invented a bearing that would do its work in the kind of temperatures and pressures likely to be encountered in the beating heart of a jet engine. And the experiments that BTH had to perform—testing fires at all kind of temperatures, testing bearings to their breaking point, producing billowing fumes and dangerous lakes of fuel, and explosions, explosions all the while—no one could explain what was going on, because all was classified top-secret.
It was perhaps just as well, as the first test runs of a completed engine were a near-total disaster. They took place in April 1937, with the plant outside the town of Rugby, in the English Midlands, well prepared for catastrophe—if turbine pieces fracture and get thrown out of an engine, they can be lethal. In an incident some weeks prior, a conventional turbine had exploded and hurled chunks of red-hot metal two miles away, killing several people en route. So the test engine was mounted on a truck (which, because its starter motor weighed a couple of tons, had to have its wheels removed) and was shielded by three pieces of inch-thick steel. Its jet pipe was routed out of a window, and the control for the starter motor was several yards away, with Whittle giving his orders by hand signal to the brave or foolhardy fitter employed to work it.
Whittle’s report was not exactly the cool and laconic writing of an experienced test pilot:
I had the fuel pump switched on. One of the test hands then engaged the starter coupling (which was designed to disengage as soon as the main rotor of the engine over-ran the starting motor) and I gave hand signals to the man on the starter control panel.
The starter motor began to turn over. When the speed reached about 1000 rpm I opened the control valve which admitted fuel to a pilot burner in the combustion chamber, and rapidly turned the handle of the hand magneto to ignite the finely atomized spray of fuel which this burner emitted. An observer, peering through a quartz observation window in the combustion chamber, gave me the “thumbs up” sign to show the pilot flame was alight.
I signalled for an increase of speed for the starter motor, and as the tachometer indicated 2000 rpm I opened the main fuel control valve.
For a second or two the speed of the engine increased slowly and then, with a rising shriek like an air-raid siren, the speed began to rise rapidly, and large patches of red heat became visible on the combustion chamber casing. The engine was obviously out of control. All the BTH personnel, realising what this meant, went down to the factory at high speed in varying directions. A few of them took refuge in nearby large steam engine exhaust casings, which made useful shelters.
I screwed down the control valve immediately, but this had no effect and the speed continued to rise, but fortunately the acceleration ceased at about 8000 rpm and slowly the revs dropped again. Needless to say this incident did not do my nervous system any good at all. I have rarely been so frightened.
It happened again the next day, sheets of flame spouting from the jet pipe, vapor from leaking joints being ignited by red-hot metal in the combustion chamber, flames dancing in midair, and the BTH workers vanishing “even more rapidly.”
But, said Whittle, after the soothing balm of several glasses of red wine taken in a local hotel, there was a simple explanation, and for a while he was confident that the combustion problem could be solved. But he was overoptimistic, and after test after test after test through that summer of 1937, all failures of one kind or another, a total redesign of the engine seemed essential. Yet, by now, there was almost no money, Whittle himself was in a near-hysterical mood, and the project seemed in dire danger of foundering. Moreover, the testing had become so dangerous that BTH insisted that any further experiments be conducted at a site seven safe miles away from its factory, in a disused foundry near the town of Lutterworth.
It was here that the project’s fortunes turned. By now, the Air Ministry had decided to throw in a modest sum, largely because Henry Tizard had written glowingly of what he believed to be Whittle’s genius, and Tizard was so widely respected that notice was taken at the highest levels of government. BTH also put in some funds, and new tests of Whittle’s redesigned engine began in April 1938. The first run ended when a cleaning rag was sucked into the engine through the compressor fan. In May, a test run achieved a speed of 13,000 rpm, though it was brought to a costly sudden shutdown when nine of the turbine blades shattered, detached themselves from the disc, and blasted their way through the engine. It took four more months to rebuild it, and this time, instead of building just one combustion chamber, the engineers built ten of them, which enveloped the turbine rotor like insulating pillows and gave the engine a look of substance and heft and symmetry, ironically not too dissimilar from the radial piston engines the jet sought to supplant.
And this engine worked, finally. On June 30, 1939, less than ten weeks before the outbreak of World War II, an Air Ministry official came up to Lutterworth to inspect it, witnessed it running for twenty-eight minutes at a sustained speed of 16,000 rpm, and made a crucially important decision. Whittle’s design was to be approved for the manufacture of a flight engine; and shortly thereafter, the Gloster Aircraft Company* was ordered to produce an experimental airplane that would be powered by it. The engine was to be designated the W1X; the plane, the Gloster E28/39.
It fell to the technical director at Gloster, a sobersided pipe-smoking engineer named George Carter, to design the new craft. The ministry wanted it to be both a flying test-bed and a warplane, so it had to have four guns and be loaded with ammunition. But Carter said it should be small and light, weighing little more than a ton, and eventually won the government’s agreement that he could leave the weaponry out of the first two prototypes. Building started in 1940, when war was fully under way and the Luftwaffe was bombing British cities with great enthusiasm, so Gloster, which had an all-too-visible factory and airfield near its home base, decided to move this highly secret project into an abandoned motorcar showroom, the Regent Garage, nearby, in the city of Cheltenham. A single armed policeman stood guard outside while, inside, a small band of craftsmen labored to finish the machine. No one, or no German, ever found out.
It is worth noting that during the run-up to the first British jet-powered flight, a German turbojet-powered aircraft had already been tested, on August 27, 1939, a week before the war’s outbreak. The plane was the Heinkel He 178, and its engine was based on the design by Hans von Ohain back in 1933, mentioned previously. The German government was unimpressed by the craft, however, deriding it for being slow and having a combat endurance of only a few minutes. Berlin then eventually bowed to advice (offered to Hitler himself by the great German aircraft designer Willy Messerschmitt) that jets used too much fuel. So the privately funded and developed Heinkel experiment, though technically the first jet-powered flight ever, proved an eventual failure.
The shrouds came off the British effort in the early spring of 1941, to reveal a sweet little aircraft, toylike in its smooth and stubby simplicity, with a foot-wide, mouthlike air intake hole for a nose—and no propeller!—a jet pipe snugged in beneath the tail, a pair of wings, a sliding-door cockpit, and little else. The undercarriage was short and retractable—there was no need to have the plane high above the runway to prevent a spinning propeller from striking the ground. In short, the Gloster E28/39—the government’s order number was 28; the production year was 1939—was simplicity itself, economical in look, in design, and in cost of materials.
It was completed some months before Whittle’s engine, which still had myriad fine-tuning problems. At one stage, the entire engine was mounted in the tail assembly of a big Wellington bomber (air inlets replacing the gun turrets) to see how it would perform at altitude. It did well, and so, unbolted from the bomber, it was taken by truck to the Gloster test airfield near the Cotswold village of Brockworth, a town better known today for its annual midsummer cheese-rolling contest, when drunken locals try to pursue a huge round cheese as it is set thundering down a local hill. There, it was finally mated into George Carter’s little aircraft: it sat directly behind the pilot, though with the fuel tank sandwiched between it and the pilot’s back.
Unlike the cheese, the aircraft was kept firmly on the horizontal for its first trials, largely to see how it handled during taxiing. But the chosen test pilot, Gerry Sayer, was apparently unable to contain himself at the smoothness of the throttle controls, and at the rapid acceleration to full power of a near-vibrationless engine, and so took the plane off for a pair of hundred-foot hops along the runway, astonishing all, and prompting an American engineer standing on the wing of a Stirling bomber almost to fall onto the ground at seeing a propellerless aircraft roaring along a runway and lifting off, if only for a few seconds. He was told to disbelieve what he had seen. German agents might have been everywhere.
In the end, it was decided to take the aircraft (now semiofficially known as the Pioneer, which, though a name of slightly greater historical portent, never took off, as it were) up to the airfield at Cranwell, Whittle’s old air force school. It was flatter (fewer cheese-rolling hills) and less populated, making it easier to keep the first flight secret.
This being Britain, it was the weather that now conspired to stall things, and the chosen day, May 15, 1941, dawned cloudy and cold. Whittle left for the engine assembly plant, where he had work to do on the next generation of engines the air force had selected to be put into what would be called Gloster Meteor fighters. He kept an eye on the skies, however, and when finally there were sufficient patches of blue sky “to mend a sailor’s trousers,” as the saying has it, he knew the evening would come clear. He drove back to Cranwell like the wind.
He was only just in time. As he suspected, Gerry Sayer already had the plane out on the long east–west runway. The breathless Whittle joined his colleagues from Power Jets and took a car to about the halfway mark, and waited there as they watched Sayer turning the doughty little craft into the bitterly cold westerly breeze.
Anticipating speed, Sayer secured his cockpit canopy. He set his trim to keep the nose slightly down, and retracted the flaps. Then he stood on the brakes and began to spool up the engine. When it was whining satisfactorily and the plane was bouncing against the brakes, he took his feet off the pedals. The craft bounded forward and began to accelerate toward the watery sun. It was 7:40 p.m. Dusk was falling. Whittle watched, clenching his fists with anxiety.
After about five hundred yards of steady acceleration, and with the engine now roaring lustily and flame spearing from the after jet pipe, Sayer eased back the stick. Effortlessly, with the aerofoils behaving in textbook style and the engine never once faltering in its delivery of a pure, whistling five hundred horses of power, the tiny aircraft rose calmly and propellerless into the evening sky. In seconds, the Pioneer was at a thousand feet, and the watchers on the ground could see as Sayer used the hydraulic accumulator to retract the undercarriage. Suddenly, the plane, by now emitting a faint trail of dark smoke, looked like a smoothly engineered bullet, vanishing into clouds that then closed seamlessly behind her.
All that Whittle and his colleagues could then hear was the even roar of the engine—a jet engine, the first-ever confection of precisely engineered compressor blades and turbine blades and hot-sprayed fuel and Newton’s Third Law to rise and to fly in England, and the first ever in the world to enjoy the support of a national government. For the coming minutes, there may have been nothing to see but the clouds overhead, but the timbre and volume and direction of the sound indicated to all below that, up there, Gerry Sayer was having fun, was putting the little craft through her paces, was being the exemplar of an old-school test pilot, and was inaugurating, officially, the Jet Age.
Then, after maybe a quarter of an hour, Whittle and his men heard the sound grow louder from the east, and then they could see her, glinting in the low sun and preparing to land. They saw the undercarriage come down; the flaps and spoilers were lowered, the speed reduced, the glide path achieved—until the plane was no more than ten feet above the rain-damp runway, moving so slowly and decorously it was almost hovering. At this point, Sayer cut the power way back, and the craft settled down for the final seconds of her first flight, then dropped gently onto the center line with the wheel supports bouncing under the weight, and then he turned his charge toward the waiting car and stopped, turning the throttle back to stop and silence the engine. All was quiet: there was no sound now except for faint residual radio chatter with the control tower, the creak of cooling metal on the fuselage—it was cold that night, and the engine parts had been very warm—the susurrus of blowing airfield grass as the breeze kicked up a little, and then, suddenly, the unmistakable sound of frantically running feet.
They were racing toward the plane. Frank Whittle, who thirteen years before had dreamed up the idea of an engine and had battled long and hard to get it made, and George Carter, who had designed the tiny craft that would be hoisted by it into the sky, and into the history books, ran without thinking across the taxiway, and together they reached up and grasped Gerry Sayer’s hand and shook it with congratulations and expressions of relief. It was the spring of 1941. A new era had begun.
Yet there was no Ministry of Information film crew to take note, no journalist on hand, no one from the BBC, no photographer, save for one amateur who took a blurry picture of a grinning Whittle reaching up to the lip of the cockpit and offering his congratulations and thanks.
IT WAS NOT until the New Year of 1944, fully two years and eight months later, that the British public was told of the new invention, of the new age that had stolen up on them, unbeknownst to almost all. “Jet Propelled Aeroplane,” said the Times, on page 4. “Success of British Invention”: “After years of experiments Britain now has flying a fighter aeroplane propelled by a revolutionary type of power unit, the perfection of which represents one of the greatest steps forward in the history of aviation. The new system, known as jet propulsion, does away with the need for an orthodox engine and also for an air-screw.”
Frank Whittle’s name is mentioned four paragraphs in, as is the fact that the U.S. government was apprised of the success of the first flight within weeks of its occurrence, in July 1941. Yet the British public, which had footed the bill, was kept firmly in the dark. Likewise the American public, who were told the news of the new engine on the same day: January 6, 1944.
Frank Whittle, initially honored—King George VI conferred a knighthood—and somewhat revered, did not have as happy a time in postwar England as one might think he deserved. Power Jets was nationalized, and its chief engineer sidelined, put out to pasture. He traveled, he lectured, he wrote, and he particularly savored his election to a fellowship of the Royal Society. He won prizes, the most valuable of which, at around half a million dollars, he decided generously to split with Hans von Ohain, the German inventor whose Heinkel-powered plane had been the true first to fly with a turbojet engine. Whittle argued often for the good sense of building a supersonic passenger plane, and badgered officials long before Concorde was a drawing board dream. But no one listened, and by 1976, with his marriage failed, he decided to light out for America, and spent his final years in a suburb of Washington, DC.
Occasionally he was called back home. He returned to be presented with the Order of Merit by Queen Elizabeth in 1986; and again when there was a bit of a fuss around the fiftieth anniversary of his former engine company’s creation, in 1987; and then, with his son Ian Whittle piloting, he came to London and flew happily on a Cathay Pacific 747 passenger aircraft nonstop to Hong Kong.
It was in one small and curious way a memorable flight. For, back then, when Kai Tak Airport was the only commercial airfield in the then–British colony, most inbound flights had to make an alarming last-minute course change in order to land safely. Standing instructions for the approach required that the plane come into the colony’s airspace from the west and, losing height rapidly, head directly toward an enormous red-and-white checkerboard that had been obligingly painted onto the rockface of a mountainside. When the plane was just a mile distant, less than twenty seconds from closing hard with the rocks, the pilot had to make a sudden sharp, thirty-seven-and-a-half-degree turn to starboard, a maneuver that, if faultlessly performed, then allows for a direct low-altitude approach onto Kai Tak’s runway 013.
Anyone not warned beforehand about this maneuver can be severely alarmed—and Frank Whittle, who had been sitting calmly in the cockpit behind his son during the cruise and was now preparing for a routine landing, was indeed somewhat bothered by what, for a few seconds, seemed an inevitable crash. But the required maneuver, invariably perfectly timed and precisely accomplished by pilots of long experience with this most exotic of eastern approaches (his son this day included), put the aircraft down a few moments later, and with customary exactitude.
THE PLANE THAT day had been powered by four Rolls-Royce jet engines,* all of which had fired perfectly to complete this dramatic maneuver. It was also a Rolls-Royce jet engine, but a very much more powerful variant, and built for a very much larger aircraft, that, almost a quarter of a century later, failed so dramatically over Indonesia. The official postmortems, published three years later in Australia, went some way toward illuminating the formidable technical problems and challenges involved in the making of a modern high-power, high-performance jet engine.
Although a modern jet engine is, upon close inspection, a thing of the most fantastic complexity, it is easy to believe this is not so. Its exterior cowling is so clean and smooth; the fan blades at its open mouth turn with such slow elegance; the sounds it emits, even at full throttle, have such a sonorous harmony about them, that it is tempting to imagine all is the purest simplicity within. In fact, once the covers are removed, everything inside is a diabolic labyrinth, a maze of fans and pipes and rotors and discs and tubes and sensors and a Turk’s head of wires of such confusion that it doesn’t seem possible that any metal thing inside it could possibly even move without striking and cutting and dismembering all the other metal things that are crammed together in such dangerously interfering proximity. Yet work and move a jet engine most certainly does, with every bit of it impressively engineered to do so, time and again, and under the harshest and fiercest of working conditions. And nowhere is the environment more harsh or more fierce than in the high-pressure section of the turbine, the fattest, smoothest, and, to the outsider, most innocent-looking part of a jet engine, with nothing (such as a fan) to be seen moving and nothing (such as a hot exhaust blast) to be felt or heard to any degree.
There are scores of blades of various sizes in a modern jet engine, whirling this way and that and performing various tasks that help push the hundreds of tons of airplane up and through the sky. But the blades of the high-pressure turbines represent the singularly truest marvel of engineering achievement—and this is primarily because the blades themselves, rotating at incredible speeds and each one of them generating during its maximum operation as much power as a Formula One racing car, operate in a stream of gases that are far hotter than the melting point of the metal from which the blades were made. What stopped these blades from melting? What kept them from disintegrating, from destroying the engine and all who were kept aloft by its power? It seems at first blush so ludicrously counterintuitive: that a piece of normally hard metal can continue to work at a temperature in which the basic laws of physics demand that it become soft, melt, and turn to liquid. How to avoid such a thing is central to the successful operation of a modern jet engine.
For, very basically, it turns out to be possible to cool the blades by performing on them mechanical work of a quite astonishing degree of precision, work which allows them to survive their torture for as many hours as the plane is in the air and the engine is operating at full throttle. The mechanical work involves, on one level, the drilling of hundreds of tiny holes in each blade, and of making inside each blade a network of tiny cooling tunnels, all of them manufactured at a size and to such minuscule tolerances as were quite unthinkable only a few years ago.
Five conjoined high-pressure turbine blades in a jet engine, fashioned from single-crystal titanium alloy and peppered with tiny holes that allow a rush of cool air to prevent them from melting in the chamber’s lethally hot atmosphere.
Photograph courtesy of Michael Pätzold/Creative Commons BY-SA-3.0 de)
Inevitably, it was commerce that provided the spur for all this work—although the jet engine makers who worked secretly for “the dark side,” creating technologies for bombers and stealth fighters and their like, made as-yet-unacknowledged contributions, too, and about which plane makers still cannot talk. The start of work on turbine blade efficiency began in the 1950s, just as soon as piston-engined aircraft began to be eased out of the world’s main skyways, and as soon as jet engines, initially developed for military use, were being redesigned in ways that made economic sense for hauling passengers and freight over long distances at high speed. Aircraft such as the Viscount, the Comet, the Tupolev Tu-104, the Convair 880, the Caravelle, the Douglas DC-8, and, from 1958, the best known of all narrow-bodied jets, the Boeing 707, began to sweep the field. The engines with which they were equipped (the De Havilland Ghost; Pratt and Whitney’s JT3C and JT3D; Rolls-Royce’s Avon, Spey, and Conway; and for the two hundred Tupolev Tu-104s that Moscow built, the little-known Mikulin AM-3 turbojet) were all of their time state-of-the-art high-precision machines.
By today’s standards, these older engines were relatively primitive, being noisy, fuel-hungry, underpowered, and inefficient. Yet all this started to change, once again in the 1970s, as more and more aircraft were needed to fly over greater and greater distances and at higher and higher speeds. To produce the necessary thrust for the big and more economical wide-bodied jetliners that growing numbers of passengers and hard-pressed airline accountants alike were demanding, and to produce that thrust quietly and efficiently and with something of a nod to the growing environmental concerns of the latter half of the century, the new jet engines had to be huge and astonishingly powerful. They had to compress their inswept air (as much as one ton of it sucked in every second) to unimaginable pressures, they had to burn their fuel at unimaginable temperatures, and they had to create an interior holocaust, a maelstrom of fire, that tested every molecule of every metal piece that whirled and careened around inside.
This is where Rolls-Royce’s internal Blade Cooling Research Group, founded in the early 1970s, plays its part in the saga. The group’s mission was simple enough: solve the problem of keeping those high-pressure turbine blades from melting, and then jet engines could be made that would give out all the power anyone might need. For the axiom of turbinology is a simple one: the hotter the engine is run, the greater the spare pressure, and the higher the jet velocity. The hotter, in other words, the faster.
At the same time, though, the hotter the engine environment, the bigger the problem for the turbine blades. For while one might suppose the first task of a turbine blade is to drive the engine’s compressor, it actually is not. That is its secondary task. Its first task is quite simply to survive.
In Whittle’s engines, and the military jets that were built immediately after his invention turned out to be a proven success (and in the civilian world’s turbojet engine of the Vickers Viscount and the pure jet engines of the Comet, which was to become the first-ever commercial jetliner), the survival of the turbine blades was not a major issue.
They were critically important components, of course. The first blades that Whittle made were of steel, which somewhat limited the performance of his early prototypes, since steel loses its structural integrity at temperatures higher than about 500 degrees Celsius. But alloys were soon found that made matters much easier, after which blades were constructed from these new metal compounds in ways that met most of the challenges of the earliest engines. They were shaped to meet and extract energy from the peculiar violent vortices of the hot gases that swirled about them. They were fixed to the disc that carried them in a way that could manage the otherwise intolerable stresses of being whirled around at hundreds of revolutions each minute. Their shape was such that they managed to extract with remarkable efficiency the power from the chemical reaction between the hot compressed air and the fuel (gasoline in Whittle’s first laboratory, kerosene later on) delivered to them. They did not run the risk of melting, though, because the temperatures at which they operated were on the order of a thousand degrees, and the special nickel-and-chromium alloy from which they were made, known as Nimonic, remained solid and secure and stiff up to 1,400 degrees Celsius. There was adequate leeway between the temperature of the gas and the melting point of the blades. That would change, though, in the 1960s and ’70s. The leeway steadily diminished, and soon it finally vanished altogether.
For, by then, the demands made on the next generation of engines required that the gas mixture roaring out from the combustion chamber be heated to around 1,600 degrees Celsius, and even the finest of the alloys then used melted at around 1,455 degrees Celsius. The metals tended to lose their strength and become soft and vulnerable to all kinds of shape changes and expansions at even lower temperatures. In fact, extended thermal pummeling of the blades at anything above 1,300 degrees Celsius was regarded by early researchers as just too difficult and risky—unless someone could come up with a means of keeping the blades cool.
A team of about a dozen Rolls-Royce engineers promptly did just that. They worked out that it should be possible, with highly precise machining and the mathematical abilities of very powerful computers, to create an ultrathin film of relatively cold air that would swaddle each blade as it whirled around inside the engine, and which would protect it, thermally, from the hellish atmosphere beyond. The layer of cold air need be less than a millimeter thick, but if it managed to maintain its own integrity as the blade spun around, then the swaddled blade would also.
But where to acquire the cold air, inside a jet engine? The source was hidden, it turns out, in plain sight. After much pondering and experimenting, it was realized that the cooler air could come directly from the huge tonnage of atmosphere being sucked in by the fan at the engine’s front. Most of that air bypasses the engine (for reasons that are beyond the scope of this chapter), but a substantial portion of it is sent through a witheringly complex maze of blades, some whirling, some bolted and static, that make up the front and relatively cool end of a jet engine and that compress the air, by as much as fifty times. The one ton of air taken each second by the fan, and which would in normal circumstances entirely fill the space equivalent of a squash court, is squeezed to a point where it could fit into a decent-size suitcase. It is dense, and it is hot, and it is ready for high drama.
For very nearly all this compressed air is directed straight into the combustion chamber, where it mixes with sprayed kerosene, is ignited by an array of electronic matches, as it were, and explodes directly into the whirling wheel of turbine blades. These blades (more than ninety of them in a modern jet engine, and attached to the outer edge of a disc rotating at great speed) are the first port of call for the air before it passes through the rest of the turbine and, joining the bypassed cool air from the fan, gushes wildly out of the rear of the engine and pushes the plane forward.
“Nearly all” is the key. Some of this cool air, the Rolls-Royce engineers realized, could actually be diverted before it reached the combustion chamber, and could be fed into tubes in the disc onto which the blades were bolted. From there it could be directed into a branching network of channels or tunnels that had been machined into the interior of the blade itself. And now that the blade was filled with cool air—cool only by comparison; the simple act of compressing it made it quite hot, about 650 degrees Celsius, but still cooler by a thousand degrees than the post–combustion chamber fuel-air mixture. To make use of this cool air, scores of unimaginably tiny holes were then drilled into the blade surface, drilled with great precision and delicacy and in configurations that had been dictated by the computers, and drilled down through the blade alloy until each one of them reached just into the cool-air-filled tunnels—thus immediately allowing the cool air within to escape or seep or flow or thrust outward, and onto the gleaming hot surface of the blade.
If the mathematics is performed correctly—and it is here that the awesome computational power that has been available since the late 1960s comes into its own, becomes so crucially useful—and if the placing of all these pepperings of minute holes is correctly achieved, with some holes on the blade’s leading edge, some on its chubby little body, some along the trailing edge, then this cool air will form an unimaginably thin film of comforting relative frigidity, wrapping itself around the blade and coating its whirling surface like a silvery insulating jacket. It is this, then, that allows the blade to survive the blistering heat of the onrushing fuel-air mixture, which the combustors have just set alight.*
All who see such a jet engine turbine blade, and who know something of its manufacture, see in its making the most sublime of engineering poetry, much like the finest of Rolls-Royce motorcars, one might say—the Silver Ghosts of eighty years before had many of the qualities of perfection that are engineered into today’s better aircraft engines. Each of the Rolls-Royce nickel alloy blades (which weigh less than a pound, are mostly hollow but sensationally strong, can fit easily into the palm of the hand, and, as it happens, are also, for now, essentially made by hand) is cast in a top-secret factory near Rotherham, in northern England. The most proprietary and commercially sensitive aspect of the blades, aside from the complex geometry of the hundreds of tiny pinholes, is the fact that the blades are grown from, incredibly, a single crystal of metallic nickel alloy. This makes them extremely strong—which they need to be, as in their high-temperature whirlings, they are subjected to centrifugal forces equivalent to the weight of a double-decker London bus, of around eighteen tons.
There is a delicious irony here, however. For although, as one might expect, to make such a blade requires techniques displaying the very highest order of precision and computational power, they are combined with another means of manufacturing that is of the greatest antiquity. The “lost-wax method” was known to the Ancient Greeks, for whom precision was a wholly unfamiliar concept.* It is employed specifically in this case to allow the creation of the cooling tunnels within the blade; and the wax is melted out, as in Athenian days, just before the molten alloy is poured into the ceramic mold, which is now, absent the wax, busy with the network of voids for the eventual cooling air.
Creation of the blade’s single-crystal structure is encouraged at this very point in the long and cumbersome manufacturing process, and is the company’s most closely guarded secret. Very basically, the molten metal (an alloy of nickel, aluminum, chromium, tantalum, titanium, and five other rare-earth elements that Rolls-Royce coyly refuses to discuss) is poured into a mold that has at its base a little and curiously three-turned twisted tube, which resembles nothing more than the tail of P. G. Wodehouse’s Empress of Blandings, the fictional Lord Emsworth’s prize pig. This “pigtail” is attached to a plate that is cooled with water, and the whole arrangement, once it is filled with liquid metal, is slowly withdrawn from the furnace, allowing the metal, equally slowly, to solidify.
This it does, first, at the cool end of the pigtail, but because the mold here is so twisted, only the fastest-growing crystals and those with their molecules distributed with what is called a face-centered cubic arrangement, for complex reasons known only to students of the arcana of metallurgy, manage to get through. And through this magic of metallurgy, the entire blade then assembles itself from the one crystal that makes it along the pigtail, and ends up with all its molecules lined up evenly. It has become, in other words, a single crystal of metal, and thus, its eventual resistance to all the physical problems that normally plague metal pieces like this is mightily enhanced. It is very much stronger—which it needs to be, considering the enormous centrifugal forces that dominate its working life.
Having now created the single-crystal blade, it remains only to dissolve away any of the substances that remain in its core, and then to use a technique called electrical discharge machining to drill the hundreds of tiny holes down into the cooling channels. Electrical discharge machining, or EDM, as it is more generally known, employs just a wire and a spark, both of them tiny, the whole process directed by computer and inspected by humans, using powerful microscopes, as it is happening. The process is all but silent, and it is in many ways more melting than drilling.
Here, however, comes an important moment in the story, one that has crept into the narrative all too stealthily.
The making of high-pressure turbine blades has long required the absolute concentration of legions of workers, men and women with decades of experience in hand-eye coordination and a studiously learned degree of extreme manual dexterity. These “blade runners,” as it were, have for years past learned to manage, for instance, the complexities and eccentricities of the cooling-hole drilling machines—and the more complex the engines, the more holes need to be drilled into the various surfaces of a single blade: in a Trent XWB engine, there are some six hundred, arranged in bewildering geometries to ensure that the blade remains stiff, solid, and as cool as possible.
Despite the apparent fantastical complexity of a modern jet engine—here a Rolls-Royce Trent, four of which power the enormous Airbus A380 double-decker superjumbo jets—there is essentially only one moving part, a rotor that passes through the entire length of the engine, from fan to exhaust.
Yet human lives, those of the aircraft passengers and crew, are dependent on the engine’s not self-destructing in flight. The vanishingly small number of occurrences of this kind of incident is based to a large degree on the integrity of these human-made engine blades. Because there is no doubt of the blades’ immense importance, it is worth noting that their integrity owes much to the geometry of the cooling holes that are being drilled, which is measured and computed and checked by skilled human beings. No tolerance whatsoever can be accorded to any errors that might creep into the manufacturing process, for a failure in this part of a jet engine can turn into a swiftly accelerating disaster.
This stark realization, that lives depend on the perfection of these blades, brings this one industry to a critical moment, a crucial development—the first in the story, perhaps, and one that would be unimaginable to precision’s originators, to engineers such as John Wilkinson or Joseph Bramah, Henry Maudslay or Joseph Whitworth, or indeed, to Henry Royce himself. Engineering, in this one field to start with, seems now to have reached a degree of sophistication in which the rigorous demands of modern precision have come for the first time to outstrip the abilities of humankind to meet them.
Up until this point, the processes—whether it is the making of a cylinder or a lock or a gun or a car; the boring or the milling or the grinding or the filing; the directing of the lathe or the tightening of a screw or the measuring of flatness or circularity or smoothness—invariably involve some kind of human agency. Yet now, in this one field to begin with, but in many more as the tolerances shrink still further and limits are set to which even the most well-honed human skills cannot be matched, automation has to take over. The Advanced Blade Casting Facility can perform all these tasks (from the injection of the losable wax to the growing of single-crystal alloys to the drilling of the cooling holes) with the employment of no more than a handful of skilled men and women. It can turn out one hundred thousand blades a year, all free of errors—or as far as anyone knows.
Once, the most troubling consequence of the introduction of precision machinery was the displacement of unneeded workers, who were understandably vexed. Nowadays, it is perhaps the relative paucity of human supervision in engineering fields where human lives are at stake that has steadily become a more pressing concern.
“Our people are fantastically skilled,” remarked the manager of manufacturing at the new plant, “but they’re human, and no human is going to produce the same quality of work at the end of a shift as they do at the beginning.” Precision engineering, in this industry in particular, does now appear to have reached some kind of limit, where the presence of humans, once essential to maintaining the attainment of the precise, can on occasion be more of a drawback than a boon—as the investigation into the Qantas Airways jet engine failure amply illustrates.
IN THE IMMEDIATE aftermath of the incident, the airline grounded all six of the Airbus A380s in its fleet, and angrily threatened lawsuits against Rolls-Royce because of the commercial impact of the accident. Yet anger plays no part in an investigation into an aircraft accident, and the Australian government’s Transport Safety Bureau then took the lead in determining what or who was at fault. The official report, issued almost three years after the accident, in June 2013, turned out to be a damning indictment of an industrial culture that had taken for granted the need for absolute precision to be applied consistently in the making of every single part of a modern high-performance jet.
For it transpired that the fate of this engine, of this plane, of these passengers and crew, of the reputation of an airline and of the engine maker, all turned on the performance of one tiny metal pipe. It was a pipe no more than five centimeters long and three-quarters of a centimeter in diameter, into which someone at a factory in the northern English Midlands had bored a tiny hole, but had mistakenly bored it fractionally out of true.
The engine part in question is called an oil feed stub pipe, and though there are many small steel tubes wandering snakelike through any engine, this particular one, a slightly wider stub at the end of longer but narrower snakelike pipe, was positioned in the red-hot air chamber between the high- and intermediate-pressure turbine discs. It was designed to send oil down to the bearings on the rotor that carried the fast-spinning disc. It needed to have a filter fitted into it, so the stub end of it had to be reamed out to make certain it could accommodate the metal ring of this filter.
The fractured oil feed stub pipe that failed due to metal fatigue caused by slightly misaligned machining that left the pipe a little thinner on one side. Fatigue cracking probably began upon takeoff in Los Angeles, and worsened after takeoff from London. A minute after takeoff from Singapore, the pipe broke open and spewed hot oil over the rapidly spinning rotor.
Photograph courtesy of the Australian Transport Safety Bureau.
The tube and the assembly around it had been manufactured in a Rolls-Royce plant, Hucknall Casings and Structures, sometime in the spring of 2009. In normal circumstances, it would have been trivially easy to machine the pipe for the filter fitting, and to do so to the exacting standards laid down by the designers of the engine. But for this particularly complicated part of this particular engine, it was decided to complete first the entirety of the hub assembly that separates the high-pressure from the intermediate-pressure areas of the engine—and then and only then, once the pipe had been fitted into place in this assembly, to drill out the tube to its design specifications. This proved to be exceptionally difficult, however, because now parts of the pipe could not be readily seen, as other parts of the fully assembled hub and newly made welds of its various pieces obscured the engineers’ clear sight of it.
These engineers did the best they could, but in the end, the tiny pipe that would eventually go into the turbine of the engine that would be suspended from the port side wing of the Qantas A380 was machined improperly: the drill bit that did the work was misaligned, with the result that along one small portion of its circumference, the tube was about half a millimeter too thin.
The assumption is that, during manufacture, the hub assembly somehow moved a tiny amount as it was being drilled, with the result that the drill bit moved fractionally closer to one wall of the pipe, reducing it to what would be dangerously vulnerable thinness. More dangerously still, the quality-control departments at Hucknall Casings, and the computer-driven machines that check the conformance of all critical parts of an aircraft, passed the tube as being satisfactory. The badly made part should have thrown up all manner of red flags. It should have been discarded—a high-pressure turbine blade, deemed to be an absolutely critical and safety-critical part of an engine, would have been tossed out and smashed for an error far less significant than the error in this tube.
Yet, for reasons that have much to do with what is euphemistically called the “culture” of that particular facility within Rolls-Royce’s immense engineering establishment, the stub pipe passed all its inspections. A potentially weakened engine component made its way all along the supply chain until it was placed into the engine, and there to await its inevitable breakage—and the equally inevitable destruction of the entire engine. It should have failed inspection, but it didn’t. It just failed in real life.
Metal fatigue is what did it. The aircraft had spent 8,500 hours aloft, and had performed 1,800 takeoff and landing cycles. It is these last that punish the mechanical parts of a plane: the landing gear, the flaps, the brakes, and the internal components of the jet engines. For, every time there is a truly fast or steep takeoff, or every time there is a hard landing, these parts are put under stress that is momentarily greater than the running stresses of temperature and pressure for which the innards of a jet engine are notorious.
And from what can be divined, the weakness in the wall of the stub pipe gradually transformed itself into a fatigue crack. That crack first opened, very slightly, investigators believe, when the plane took off from a short runway in Los Angeles two days prior to its takeoff from Singapore. The fissure then began to spread and to open a little more when the plane landed in London; it came under still further stress when the plane took off from Heathrow bound for Singapore, and once again when it landed at Changi Airport hours before its departure for Sydney.
Ninety seconds after this midmorning takeoff, with the plane climbing steeply and the engine running at 86 percent of full power, throwing out more than 65,000 pounds of thrust, the crack finally opened fully and the pipe ruptured. A spray of hot oil immediately hissed out into the void between the high- and intermediate-pressure turbines, where the temperature was already at some 400 degrees Celsius. The auto-ignition temperature of the oil was 286 degrees, and the jet of oil mist became like a high-powered flamethrower, pouring fire against the huge, heavy, rapidly spinning turbine disc.
After a few seconds of such ferocious heating, the disc expanded, lost its shape, began to wobble furiously, and then eventually broke, and hurled its fractured segments at hundreds of miles an hour out through the engine and out of the casing and, in two instances, through the left wing of the plane and, in a third, clear through the bottom of the fuselage. A brief flash fire broke out inside the left wing, but mercifully did not spread; the damage to the hydraulics and electrics occasioned by the shrapnel caused a series of major failures to the aircraft systems. All ended well, thanks in large part to the crew, as the Australian government report noted.
What the report also noted, however, were the failures within Rolls-Royce: the failure to machine a critical part properly, the failure to keep proper records, the failure to inspect properly, and the failure to reject what were called “non-conforming” parts, and to allow them to pass into service, with potentially lethal consequences. The delivery of such engines to Qantas was far from unique: hasty inspection soon after the accident revealed that scores of Hucknall made oil pipes with misaligned walls thinner than half a millimeter had already gone into service, with the consequence that no fewer than forty engines, in use by Singapore Airlines and Lufthansa, and on all the remaining five Qantas aircraft, needed to be withdrawn from use and repaired.
It was a costly mistake by Rolls-Royce, for not only were there internal repercussions, expensive repairs, staff changes, procedural reforms, and public relations nightmares, but also Qantas was paid some eighty million dollars in compensation; the Rolls-Royce balance sheet for the year after the event showed a net loss to the company of seventy million dollars. The firm insists that such an error is unlikely to happen again, and that all necessary precautions have been taken, at Hucknall and elsewhere.
BURIED DEEP WITHIN the Australian government report on the accident is one paragraph that seems especially relevant to the wider issues posed by the ever-increasing precision of modern machinery. Like much of the 284-page report, the paragraph is rich with jargon, but the basic message shines through nonetheless:
Large aerospace organizations are complex sociotechnical systems made up of organized humans producing highly technical artefacts for complex systems, such as modern aircraft. Due to the inherent nature of these complex sociotechnical systems, their natural tendency is to regress if not constantly monitored—and occasionally even when monitored vigorously. This natural regression can occur due to the pressure applied via global economic forces, the requirement for developing growth, profit and market share . . .
“Highly technical artefacts for complex systems”—shorthand, or rather, bureaucratic longhand, for ultraprecise machines, such as the Trent 900-series jet engine. Maybe, this incident will suggest to some, modern machines of certain specific kinds are being made now with just too much precision, with too much complexity, for it to be prudent for humans to participate in the making of them. If this is true, it might reasonably prompt the question: could we be seeing here the beginning of the upper limits of our ability to manage the kind of precision we think we need?
Or maybe precision is itself reaching some kind of limits, where dimensions can be neither made nor measured—not so much because humans are too limited in their faculties to do so but, rather, because as engineering reaches ever downward, the inherent properties of matter start to become impossibly ambiguous. The German theoretical physicist Werner Heisenberg, in helping in the 1920s to father the concepts of quantum mechanics, made discoveries and presented calculations that first suggested this might be true: that in dealing with the tiniest of particles, the tiniest of tolerances, the normal rules of precise measurement simply cease to apply. At near-and subatomic levels, solidity becomes merely a chimera; matter comes packaged as either waves or particles that are by themselves both indistinguishable and immeasurable and, even to the greatest talents, only vaguely comprehensible.*
In the making of the smallest parts for today’s great jet engines, we are reaching down nowhere near the limits that so exercise the minds of quantum mechanicians. Yet we have reached a point in the story where we begin to notice our own possible limitations and, by extension and extrapolation, also the possible end point of our search for perfection. There may be an event horizon coming into view—and if so, then the work being performed at the jet engine makers of the world, where so much depends on such a testing level of precision, acts as a signpost, a warning that an end of sorts may be in sight.
Perhaps this sense of technical foreboding is true—as far as the making of machines and devices that are directly applicable to human-scale activities is concerned. Then again, to go beyond this, to venture into other worlds and to deal with other universes, maybe the limits that seem about to challenge human competence can in fact be pushed even higher and higher. Maybe, in these other worlds, precision can be further and further refined, with no end to its limits in sight.
Out in space, for example, all may be very different.