The Weirdest Aero Engine Ever Built: The Half-Diesel, Half-Jet Napier Nomad

[00:00:01]If you've ever loved a machine for being cleverer than it needed to be, the Napia Nomad is the one that should break your heart. It was part diesel, part jet. A bomber once flew over Farnbor.

[00:00:15]It burned less fuel than any aero engine ever built, before or since. It came from a firm that had made bank note presses for the Bank of England, land speed record engines, and the fighter engines that fought over France. Napia survived a century and a half of everything, bankruptcy, two world wars, the loss of its own independence, and kept on building machines of impossible precision. And then, after a decade of perfecting the finest engine it ever made, the firm simply let it go, threw it away. How does the best engine anyone ever built end up scrapped, unwanted, forgotten? What happened inside those walls at Actton? Chapter 1. Four propellers stopped Farbor.

[00:00:58]September 1951, the Society of British Aircraft Constructors puts on its annual show, and the crowd strung out along the airfield has come to hear the future.

[00:01:08]The shriek of the new jets, the thunder of the last great piston engines, the sound of British aviation at the very height of its confidence. Then something comes over the field that looks wrong.

[00:01:19]An Avro Lincoln, a big 4engineed descendant of the Lancaster bomber, fat through the fuselage, honest and unhurried, makes a low pass down the runway, and its four propellers are stopped, not idling, feathered, their blades knifed edge on into the slipstream, motionless as a photograph.

[00:01:38]Four Rolls-Royce griffins, each one strong enough to haul this aircraft into the sky on its own. All four of them shut down and still. The Lincoln doesn't fall. It flies level, steady, holding its line down the field on the power of a single engine buried in its nose. An engine making a sound nobody on that airfield has heard from an aircraft before. Not the scream of a jet, not the hard bark of a Merlin, a deep industrial growl, the sound of a diesel, the sound of a lorry somehow 300 ft up and flying.

[00:02:12]At the controls almost certainly sits Napia's chief test pilot, a Danishborn airman named Michael Randre, who'd been flying the firm's experimental machines out of Luton since 1946.

[00:02:24]No contemporary record names him as the man in that particular seat on that particular afternoon. But it was his airplane, his engine, his job. If anyone was flying a Lincoln over Farmborough on a single engine, it was almost certainly Randre. The engine in the nose was called the Nomad, and it was, without much argument, the strangest aero engine anyone in Britain ever built. Here's the paradox the rest of this story turns on.

[00:02:49]The Nomad burned less fuel than any aero engine before it, and less than any aero engine built since. Not a little less, dramatically less. So far ahead of everything around it, that the men who made it believed with some justice that they'd built the most efficient aircraft engine the world would ever see. And it was a complete commercial catastrophe.

[00:03:10]It never entered production. It never powered a single operational aircraft.

[00:03:15]After the best part of a decade of work and more than5 million pounds, it was cancelled and the engines were near enough thrown away. Bill Gunston, who knew more about Aero engines than almost anyone then alive, called it one of the most interesting engines ever designed.

[00:03:31]He was right. And the tragedy is that being interesting was never the problem.

[00:03:35]It worked. It flew. It did everything its makers promised of it. It was simply a masterpiece of the wrong century.

[00:03:43]Chapter 2. Delicate as any clock, the house of Napia. To understand how a firm comes to build an engine like that, you have to go back a very long way, further than the jet age, further than aviation itself. The story begins in 1785 in Dumbartan on the Clyde with the birth of a boy named David Napia into a family of engineers, one of whom was blacksmith to the Duke of Argyle. David went south to London and apprenticed himself to Henry Mordslay, the greatest precision machinist of the age, the man who effectively invented the modern engineering workshop who first made it possible to cut a screw thread the same way twice. Whatever Napia became over the next century and a half, it carried Mordslay's obsession in its blood. The belief that a thing worth making was worth making exactly.

[00:04:33]In 1808, David Napia set up on his own in Lloyd's Court of St. Giles. He built machines, beautiful, exact machines.

[00:04:42]Steamdriven printing presses supplied to Hanzard to print the record of Parliament itself. Bullet making machinery for the Royal Arsenal from the 1830s.

[00:04:52]Coin weighing machines for the Bank of England. Automatans that could tell a good sovereign from a light one faster and more honestly than any human hand.

[00:05:00]And from 1853, the presses that printed the bank's own banknotes. So closely was Napia tied to the making of money that the firm's telegraphic address right up until 1960 was a single word, money.

[00:05:15]David's son, James Murdoch Napia, came into the business in 1837 and became a partner 10 years later and the firm took the name it would carry for more than a century. D Napia and Son. James was by every account a brilliant engineer. He was also a poor businessman and slowly over decades the great precision house shrank. By 1895 the firm that had printed the nation's money was down to seven employees. Seven. And then the grandson arrived. Montigue Napia inherited a near corpse of a company in 1895 and he had the sense to see where the world was going. He met a brash gifted salesman named Selwin Francis Edge and the two of them turned Napia towards the motorc car.

[00:06:01]In 1900, a young man called Charles Rolls, the Rolls, who would later be half of Rolls-Royce, rode as riding mechanic in a Napia in the Paris to lose and back race. In 1902, a Napia won the Gordon Bennett Cup, painted in the shade of green that would become known forever after as British racing green. In 1903, the firm moved to a new works at Actton in West London. And there, Napia built the world's first commercially successful production six-cylinder car.

[00:06:30]Smooth, powerful, expensive, exquisite.

[00:06:33]For a few years before the Great War, a Napia was a match for anything Rolls-Royce could put beside it. That was the Napia way from the very first day in Lloyd's court. precision, complexity, craftsmanship so fine that contemporaries said the firm's machines were as delicate as any clock. It was the making of them, and in the end, it would be the undoing of them. Chapter 3.

[00:06:57]The Lion, the Saber, and the fear of complexity. The First World War turned Napia into an engine maker. At first, the firm built other people's designs under contract, the RAF3A, the Sunbeam Arab, and found both of them wanting, unreliable, troublesome. So, in 1916, Montigue Napia did the thing that would define the company's next 40 years. He decided that if you wanted it done properly, you built it yourself. He funded an engine of Napia's own, designed by a gifted man named Arthur Roll. And out of the Actton drawing office came the Napia Lion. The Lion was extraordinary. Its 12 cylinders were arranged in three banks of four, spled out in a shape the engineers called the broad arrow, and it gave 450 horsepower, where rivals gave rather less. Through the 1920s, the Lion simply dominated. It powered more than 160 different types of aircraft. It raced for the Schneider Trophy, and it went hunting records on land and water. It sat in the nose of Malcolm Campbell's Bluebird in Henry Seagra's Golden Arrow in John Cobb's monstrous Napia Railton. For a decade, the Lion was one of the great names in British engineering, a byword for speed and quality both. And then in the 1930s, bigger and simpler rivals caught up and passed it. The Lion aged. Rolls-Royce with the Merlin coming was pulling ahead. Montigue Napia died in 1931. The firm needed another masterpiece and it went looking for one in the most Napia way imaginable by choosing the hardest possible road. What it built was the Saber. Designed under Major Frank Halford, the Napia Saber was a monster.

[00:08:41]24 cylinders arranged in a flat H, two crankshafts geared together. And instead of ordinary puppet valves, the simple mushroom headed valves that open and close in nearly every engine ever made, the Saber used sleeve valves. An idea championed by the great combustion engineer Sir Harry Ricardo. A sleeve valve is a lovely thing when it works. A thin machined steel sleeve that slides and rotates around the cylinder, opening and closing ports as it goes, letting the engine breathe more freely and run quieter than any puppet valve engine could. On paper, it was the future. The Saber made 3 and a half thousand horsepower in its later forms, an almost unbelievable figure for its day. It powered the Hawker Typhoon and the Tempest, the aircraft that broke the German fighter bombers over England and then hunted them across France at ground level, but it terrified the men who had to look after it. The trouble was those beautiful sleeves. To work, a sleeve valve must slide inside its cylinder with a fit measured in 10,000 of an inch, tight enough to seal, loose enough to move, and it has to hold that fit while everything around it is expanding with the heat of combustion. Get the metallurgy slightly wrong, get the machining slightly off, and the sleeve seizes solid. Early Sabers did exactly that again and again. Quality control at the works buckled under wartime pressure. There were stretches when the RAF was rejecting more sabers than it could accept, and in the cold, the oil turned against them. Ground crews on Typhoon squadrons through the winter were reduced to running the engines all night, hour after hour, in the dark and the frost, simply to stop the lubricant congealing into something like trile by the morning, because a cold saber might not start at all. The saber was a world beater that very nearly failed. Not because the idea was wrong. Ricardo's sleeve valve was in truth a superb piece of thinking, but because it was so fishly complicated that keeping it alive became a second war fought in the hangers and the workshops night after freezing night. Somewhere in that story is the warning Napia never quite heard.

[00:10:51]The firm could build engines of dazzling brilliance. It could not always build engines that ordinary mechanics could trust and love and keep flying without heroics. Complexity was Napia's signature. It was also always its risk.

[00:11:07]There was one more thread and it mattered more than anyone knew at the time. In the 1930s, Napia had licensed two German diesel aero engines from Junkers opposed Piston two-stroke compression ignition machines of real ingenuity. Napia called them the Culverin and the Cutless. Only seven Culverins were ever built and no Cutlasses at all. Commercially, they went nowhere. But they taught the Actton drawing office something precious that almost nobody else in Britain possessed.

[00:11:37]How to make a two-stroke diesel run and run in the air. By December 1942, Napia had run out of money and independence both. The firm was bought by the electrical giant English Electric, whose chairman, Sir George Nelson, installed his own man to run it. Napia was now part of somebody else's empire, and that in time would matter more than any engine. Chapter 4. The machine that shouldn't have worked. At the very end of the war, the Ministry of Aircraft Production went looking for a particular kind of engine. Something for the long haul. A maritime patrol aircraft that might need to stay airborne for a day and a night. Quartering the gray Atlantic, hunting submarines across distances that swallowed ordinary engines whole. What they wanted was power of around 6,000 horsepower that would sip fuel rather than gulp it.

[00:12:27]Endurance, not sprint. Economy above all. Sir Harry Ricardo, the same combustion genius behind the Saber's sleeve valves, had an answer, and it was radical. The most efficient combination imaginable, he argued, was a two-stroke diesel married to a gas turbine. Think about why a diesel already rings more work out of its fuel than any petrol engine. because it burns at far higher pressures and temperatures. But even a diesel throws away enormous energy out of the exhaust pipe. Hot gas moving fast, simply lost to the air. Ricardo's insight was to stop wasting it, feed that searing exhaust into a turbine, an axial gas turbine near enough a small jet engine, and let it recover the energy that every other engine discarded. Then gear that recovered power straight back into the propeller.

[00:13:18]Nothing lost. Everything used twice. A turbo compound engine in the language of the trade where the turbine doesn't just drive the supercharger, it drives the aircraft. The Americans at Curtis Wright were chasing the same prize with a petrol engine. Ricardo and Napia were certain the diesel was the better road and they set off down it. The Actton office first schemed something enormous, a 24- cylinder H block, 75 L of engine.

[00:13:46]Then, in an act of engineering good sense, they cut it in half. What remained was 12 cylinders lying flat, horizontally opposed, six to a side.

[00:13:56]They called it the Nomad. Consider for a moment what they'd actually made, because there had never been anything quite like it in the sky, and the details are where the strange beauty of it lives. At its heart was a 12cylinder two-stroke compression ignition diesel.

[00:14:13]two-stroke so that every downward stroke of every piston was a power stroke. No wasted turns. It breathed by loop scavenging. Fresh air swirled in through ports in the cylinder wall as the piston uncovered them, pushing the burnt gas out ahead of it. No valves needed at all for the business of breathing. The connecting rods were fork and blade paired so that two rods could work on a single crankpin, one straddling the other. The whole assembly packed tighter than seemed possible. And the pistons, the pistons were the thing. They were built in two pieces because no single metal could survive what happened inside those cylinders. The crown, the top face staring straight into the fire was ostinitic stainless steel, and at full power it glowed at something like 1300° F, 700 on the C scale. Below it, a body of aluminium alloy cooled from within by jets of oil sprayed up inside the piston to carry the heat away. There was a single spark plug in each cylinder, and it was used for one thing only, to light the engine on a cold morning. Once it was running, the diesel did what diesels do and ignited its fuel by the sheer violence of compression. The plug just sat there redundant, its work done.

[00:15:30]Bolted to this diesel was the turbo machinery, an axial compressor and an exhaust driven turbine lifted from the aerodynamics of Napia's own Niad turborop. A diesel and a jet welded into one machine, each feeding the other. The first version, the Nomad one, was almost two engines pretending to be one. And it showed. It drove a pair of contraotating propellers. The diesel turning one and the turbine assembly turning the other with fuel injected into the turbine like an afterburner for extra thrust on takeoff, then shut off in the cruise to save fuel. It first ran complete in October 1949. It weighed something over 4,000 lb and it worked. 860 hours on the test bench. Then the contra rotating propellers went on and hundreds more hours followed. Then at last into the nose of that Avro Lincoln and up into the air, the machine the crowd watched over Farnra with its four griffins feathered and still. But the men who built it, Herbert Sammons who ran the turbine side and Ernest Chatterton who ran the piston side with specialists like Arthur Penn on the supercharging and Lionel Elford on the compressor aerodynamics knew it was too complicated. Two propellers, an afterburner, a separate supercharger and a separate turbine. So they did the rarest thing an engineering team can do.

[00:16:52]They looked at their own creation and they simplified it. The Nomad 2 was the machine as it should always have been.

[00:16:59]Out went the contra rotating propellers and the afterburner.

[00:17:03]In came a single propeller, a single 12 stage axial compressor delivering a boost pressure of some 89 lb per square in. A three-stage exhaust turbine and one device that made the whole thing sing. The biogear. The biogear invented by a doctor buyer was an infinitely variable coupling. a stack of thin steel discs spinning together in a film of oil, able to link the turbine directly to the engine's crankshaft at any ratio you cared to ask for. This mattered enormously because the turbine spun at 18,200 revolutions a minute, near enough, n times crankshaft speed.

[00:17:41]Ordinary gears could never have reconciled the two smoothly across the whole range of the engine. The buyer gear could. When the engine loafed along at low power, the crankshaft drove the compressor. When it worked hard, the turbine repaid the debt, pouring every scrap of surplus power back into the propeller shaft. It was in miniature one of the loveliest ideas in the history of the piston engine. A machine that balanced its own books moment to moment without anyone touching a lever. The Nomad 2 first ran in December 1952. It made over 3,000 horsepower dry, and with water injection, later versions reached beyond 3,000. It weighed 1,000 lb less than its predecessor, and it would run on almost anything you poured into it.

[00:18:24]Diesel, kerosene, wide cut petrol. And then there was the number, the one figure this entire story turns on. The Nomad 2 burned 0.345 lb of fuel for every horsepower it produced every hour. And in the thin, cold air high above the weather, it did better still, down towards 0.326 at more than 22,000 ft. The Napia Power Heritage Trust, the men who later kept the firm's memory alive, put it as plainly as it can be put, a misly fuel consumption unmatched by any aero engine to this day. Bill Gunston, weighing it against every engine he had ever studied, judged that its overall efficiency was of an altogether higher order than anything else that had flown.

[00:19:09]This was not a crank's folly. It was not a clever machine that didn't quite work.

[00:19:14]It was a rigorously reasoned thermodynamic masterpiece that delivered precisely everything it had promised.

[00:19:21]The tragedy of the Nomad is not that it failed. The tragedy is that it succeeded. Chapter 5. An engine of outstanding efficiency. The high water mark came in 1954. On the 30th of April that year, the magazine Flight published Bill Gunston's landmark account of the engine under a title that said everything, "An engine of outstanding efficiency." Gunston himself wrote that the description which followed was the most extensive engine study the magazine had ever published. Page after page of glossy cutaway diagrams laying bare the nomad's beautiful complications, the fork and blade rods, and the disc stack of the biogear rendered in loving line drawings. On the very same day, the airplane carried its own piece. A fortnight later, the story crossed the Atlantic into the American press, and Salmons and Chatton wrote the whole design up for the Society of Automotive Engineers. A paper that stands to this day as the definitive record of what Napia had done. For one brief season, the trade press treated the Nomad not as a curiosity, but as a triumph, as the future, and there was an aircraft waiting for it. the Avro Shackleton, the great 4engineed maritime patrol aircraft the RAF was building to hunt submarines across the North Atlantic. The aircraft the crews would come to call the Growler. AVO drew up a version, the Type 719, with all four thirsty Griffins replaced by Nomads and another version carrying just two. The Royal Canadian Air Force's longrange Argus was in the frame as well, and this was no paper exercise. A prototype Shackleton was handed over to Napia at Luton. arriving in January 1953 so the engine could be fitted into a real wing in real metal and made ready to fly. Picture it as the men at Actton pictured it in that spring of 1954. An aircraft that could stay up for a day and a night keeping watch over the sea lanes, sipping fuel where every rival gulped it. The most efficient aero engine in the world in the nose of the aircraft it had been designed for at the exact moment the world seemed ready to want it. The neat Nomad installation fared cleanly into the Shackleton wing with leading edge radiators that put the old hands in mind of a mosquito. This was the golden hour, the engine perfected, the press admiring, the application chosen. Nobody standing in that drawing office, looking at the tidy nomad tucked into the Shackleton's wing, could quite see the shadow already lengthening across the whole enterprise.

[00:21:53]Because while Napia had spent the best part of 10 years perfecting the most complicated aero engine ever conceived, thousands of moving parts, each one machined to the tolerance of a fine watch. A quieter, crudder idea had been growing up alongside it. An engine with essentially one moving part, and it was about to win.

[00:22:14]Chapter 6. The one moving part.

[00:22:18]Here is the thing the nomad's makers could not undo, however brilliantly they machined it. While Napia built an engine of thousands of moving parts, a rival idea had arrived that had, for all practical purposes, one. The pure jet was a shaft with a compressor on one end and a turbine on the other spinning in a single straight line. The turborop, a jet geared to a propeller, was very little more. Rolls-Royce had the dart.

[00:22:45]Bristol had the Proteus. Rolls-Royce had the AA, which would soon be pushing airliners across the Atlantic at heights and speeds no propeller could touch.

[00:22:54]Against the nomad's forest of pistons, connecting rods, gears, discs, and shafts, these engines were almost insolently simple. A jet could be stripped and understood by a young national serviceman in a way the Nomad never could. And simplicity, it turned out, was worth more than economy. The Nomad's whole case rested on fuel. burn less, fly further, stay up longer. But for most of what aviation now wanted to do, fuel economy was no longer the thing that mattered most. What mattered was power for weight, and the Nomad was heavy, the better part of 3,600 lb, and bulky and complicated and slow to build.

[00:23:33]A simple jet was lighter, cheaper to manufacture, and could win back range another way entirely by climbing higher and flying faster than any diesel-driven propeller could dream of. The sums that had looked so commanding in 1945 looked a little worse with every year that passed. Worse still, the market the Nomad had been born to serve was quietly disappearing beneath it. The age of the large piston aero engine was ending.

[00:23:58]Everyone in the industry could feel the ground shifting and nobody felt it more sharply than Napia itself because Napia, extraordinary as it sounds, was busy killing its own engine from the inside.

[00:24:10]The firm had thrown itself into gas turbines with all the restless ambition that had built the Lion and the Saber.

[00:24:16]There was the Niad turborop. There was the nymph, the eland, the gazelle turbo shaft, and even ramjet work besides.

[00:24:24]Napier's drawing office was now split against itself. Half of it laboring over the most sophisticated piston engine in the world, while the other half chased the very turbines that would make it obsolete. And there had been a defeat that cut deep. Napia had gone after the engine contract for the Vicar's Vic Count, the world's first turborop airliner, a genuine British triumph in the making, and lost it to the Rolls-Royce Dart. That loss did a permanent injury to Napia's standing as a maker of arrow engines. The Viccount and its darts went on to sell around the world, and every one of them was a quiet reminder of the future Napia had failed to seize, steering the firm ever further from the piston work the Nomad represented. Above it all sat English Electric and its chairman, Sir George Nelson. From as early as 1947, Nelson had been pulling Napia's center of gravity steadily away from aircraft pistons, towards turbochargers, towards diesel electric traction for the railways, towards the marine engines that would keep the firm profitable long after the aerero business was gone. The men perfecting the most efficient piston engine in aviation history were working inside a company that had already quietly decided its future lay somewhere else entirely. The Nomad was a masterpiece, but it was a masterpiece that nobody in charge much needed anymore.

[00:25:48]Chapter 7. Killed by a vacuum. The cancellation of 1955.

[00:25:55]There was no villain. That is the hardest part of the nomad's ending to accept. And the truest, nobody set out to destroy it. No boardroom cabal, no vengeful minister, no rivals sabotage.

[00:26:08]It was killed by a vacuum, by the slow, grinding discovery that there was no longer any aircraft that would carry it, and no one left in a position of power who cared enough to change that. Watch how the vacuum forms. It forms in three quiet stages, and not one of them looks on its own like a death sentence. It begins with the Shackleton. The great maritime patrol aircraft, the one the Nomad had been designed for from the very start, had already gone into service with Rolls-Royce griffins and contraotating propellers. But the Nomad conversion was taken seriously and by serious people. Avo drew up the four Nomad and two Nomad versions with real care, each promising the enormous patrol endurance that only the diesel turbine could deliver, the ability to loiter over the ocean for hour upon hour. That was the whole point of a submarine hunter and the ministry acted on it. In October 1952, the Ministry of Supply authorized the transfer of the second Shackleton prototype, the aircraft serial VW131 to Napia. In January 1953, it arrived at Luton. Through 1953 and into 54, the work went on. Dummy nomads fitted first to prove the installation, then vibration trials in the spring of 54. Then flight cleared engines bolted into the wing. Men spent years of their working lives on that conversion. It was real. It was nearly ready. And then the will simply drained out of it. The RAF ordered the next mark of Shackleton, the MR3 for coastal command, and ordered it once again with the Griffin. A separate requirement for a great longrange flying boat faded and died at about the same time, taking another possible home for the nomad down with it. And here is the bitter irony buried in that choice, the detail that turns a business decision into something closer to tragedy. The Griffin the RAF chose to keep was itself a thirsty, demanding, highmaintenance engine. In service, some Shackleton squadrons were tearing into their Griffins for top overhauls every 400 hours. Engines threw their spark plugs clean out. A single squadron flying six aircraft could find itself changing a whole engine on average every single day. The Nomad had been built precisely to cure that kind of misery, to fly further, longer, on less, and to keep flying. And still, as the historical record notes, with a flatness that says more than any lament could, the potentially beneficial Nomad re-engine did not happen. That is the first stage.

[00:28:44]The aircraft it was made for chose the engine it was made to replace. The second stage came from across the Atlantic. The Royal Canadian Air Force needed a long range maritime patrol aircraft of its own, the Canada Argus.

[00:28:57]And here surely was the Nomad's second chance. But when Canada chose its engines, it reached for the American right R335 O. And this is the crulest single fact in the whole story. The right R3350 was near enough the very engine the Nomad had been created to beat. The thirsty conventional piston giant that Ricardo's brilliant diesel turbine was supposed to render obsolete. The Nomad lost its last realistic application to precisely the kind of engine it had been designed to make extinct. There was now nothing left in the sky for it to power. Not one aircraft, not in Britain, not in Canada, not anywhere. So the third stage was almost a formality. In April 1955, after something over 10 years of work and an expenditure of £5.1 million, work on the Nomad simply ended. The month is worth pausing on and pausing on carefully because it is where legend can so easily grow. April 1955 was also the month Britain changed its minister of supply.

[00:30:04]Selwin Lloyd handing over to Reginald Mling who arrived with a brief to streamline the country's sprawling expensive aviation industry. It is tempting to draw a straight line between the two events, to imagine a new minister sweeping into office and striking the nomad from the books with a stroke of the pen, but no surviving record names, any minister, any official, any single hand as the one that killed it. That is the honest truth, and it is somehow harder to bear than a villain would have been. The most efficient aero engine ever built was not struck down. It was let go. abandoned in the gap between an industry that had already moved on and a white hall full of turbine enthusiasm where no one could quite be found to make the case that it was worth saving. The engine data was filed away at Napia, set aside, in the words of one account, in the hope that renewed interest might one day reignite the work. It never came. The second Shackleton prototype lingered at Luton.

[00:31:04]Its nomads bolted into a wing they would never lift. In January 1956, its fuselage was carted off to Avro's Bracebridge Heath site to be used for ditching experiments, dropped into water again and again to see how airframes behaved when they came down in the sea.

[00:31:20]The rest of it was scrapped where it stood at Luton, a flight cleared engine of unmatched efficiency, and the aircraft built to prove it, broken up for salvage. And here the tragedy sharpens into something almost unbearable because the idea itself did not die. It simply changed clothes.

[00:31:39]English Electric and Napia poured all their ingenuity into the Deltic. A triangular three crankshaft 18cylinder diesel of astonishing power for its size. Designed in the same Actton office by the same men who had built the Nomad.

[00:31:53]And after the Nomad was canled, Napia even built a compound Deltic. A Deltic married to a turbine recovering its exhaust energy running on the exact principle the Nomad had proved. The thinking survived, the engineering survived, the engine did not. The corporate endgame came quickly after that. In 1961, the aero business was reorganized as Napia Aero Engines Limited, owned jointly now by English Electric and Rolls-Royce. Within a year, Rolls-Royce had taken the one Napia turbine it actually wanted, the Gazelle, and dropped everything else. And in 1963, the company that had built printing presses for Hansard and banknotes for the Bank of England stopped making Aero engines altogether forever. The Nomad had been the warning and the epitap, both at once. Napia's genius had always been for glorious complexity. In an age that had fallen in love with the simple turning shaft, that genius had nowhere left to go. Chapter 8. The green door closes. The engines went for scrap. The tooling went with them. What survived was a handful of test units and two flight cleared nomads. Engines certified fit to fly that never would. Filed away in a store.

[00:33:10]set aside, one account has it, in the hope that interest might one day revive and the whole great enterprise begin again. It never did. They simply waited in the dark for a future that never came for them. The people went in stages the way people always do. The Aero Engine Company closed its doors in 1963. But the Actton works themselves. The red brick heart of Napia in West London, where the Lion and the Saber and the Nomad had all been born, held on for a few years more until the end of the decade. In 1968, English Electric was swallowed by the electrical giant GEC, and the last of Actton went down with it. There is a phrase the old workers used for the moment it ended. They called it the closing of the green door.

[00:33:55]The scale of the loss reached Parliament. On the 8th of March 1963, the member for Actton, Philip Holland, rose in the House of Commons to speak about the closure of the Napia factory in his own constituency. He described the joint statement from English Electric and Rolls-Royce that had announced the shutdown and the redundancy of more than 2,000 employees.

[00:34:17]He spoke of those involved trying to move heaven and earth to save what they could. He spoke above all of highly qualified engineers. Men of rare and specific skill, the kind of skill that takes a working lifetime to build, who now could not find work anywhere near their own homes. 2,000 of them. In one West London burough, men whose hands and minds had built some of the finest machinery this country ever produced, reading their redundancy notices and wondering quietly what on earth came next. The Deltic outlived the company that had bred it. Its design and manufacturer were handed in 1970 to Paxsman at Colchester and the first Colchester built Deltic ran in 1972.

[00:35:01]The Napia name itself lingered on for another decade in a smaller, humbler form until in December 1974, the last of it became simply Napia Turbochargers Limited. 160 years of engineering from the automatons that weighed the Bank of England's sovereigns through the record cars and the fighter engines to the most efficient aero engine the world had ever seen ended as a brand name stamped on a turbocharger.

[00:35:28]But the people did not let the memory close with the door. The works secretary at Actton was a woman named Joyce Finch.

[00:35:35]After the green door shut in 1968, it was Miss Finch who kept the old naperians together, organizing annual reunions, holding a scattered, redundant community in place by nothing more than force of will and affection. And out of those reunions, in the early 1990s, the very first meeting seeded at her own home in October of 91, a group of former Napia men founded the Napia Power Heritage Trust. Their purpose was simple and urgent. To rescue the firm's story and the firm's machines before the last of the men who actually remembered them were gone. They were saving something the wider country had never even known it possessed.

[00:36:14]In 1996, a digger clearing the old Napia ground at Luton turned up the firm's buried photographic archive. A lost record of the whole enterprise come back out of the earth. In 2012, more paper records surfaced in a forgotten storeroom at Actton. The history of one of Britain's great engineering houses, quietly returning from the ground and the walls, decades after the men who made it had clocked off for the last time and gone home. Chapter nine. Glass storage and three museums. Go looking for Napia in Actton now, and there is very little left to find. The great works on Actton Veil are gone. The test houses out at Park Royal, where the nomad was run up and roared against its mountains, are gone. One building survives from the whole vast estate, an office block put up in 1916, now refaced in glass and given over to self-s storage. People pay by the month to keep their cardboard boxes where Napia once kept its drawing offices, where men once bent over boards and drew the fork and blade rods and the disc stack of the buyer gear. And on land that was once Napias, there now stands a modern housing development. Someone at some point had to choose its name. They called it Napia Square. The word survives on an estate agent's board on the very ground where the Lion and the Saber and the Nomad were dreamed up and built. The engines themselves outlasted almost everything else. Three of them remain. The prototype Nomad rests in Scotland at the National Museum of Flight at East Fortune. A Nomad 2 crossed the Atlantic to the Smithsonian's great hanger at the Udvah Hazy Center in Virginia. And a third sits in the collection of the Science Museum in London, given to the nation by a college that had used it once to teach young engineers how such a thing was made. The most fuelefficient aero engine ever built, ending its days as three silent exhibits under gallery lights, cutaway, cold, admired by a handful of enthusiasts, and unknown to very nearly everyone else who walks past. That should be the end of it. A brilliant, doomed machine, forgotten. But it isn't quite, because Napia's real monument turned out not to be its most efficient engine at all, but its strangest sister, the Deltic. That triangular diesel from the same Actton office under the same Ernest Chatterton who had run the nomad's piston side went on to become a genuine legend. 22 of the great Deltic locomotives were built for British railways in the early 1960s. The most powerful single unit diesel locomotives in the world when they appeared and the engines that brought the first regular 100 mph diesel passenger services to Britain hauling expresses up the East Coast mainline. Deltic engines went to sea as well, driving the Royal Navy's fast patrol boats and tonclass mine hunters right into this century. Six of the locomotives are preserved today.

[00:39:11]They still run at heritage galers and grown men who remember them as boys will stand at the line for an hour in the rain just to hear that unmistakable Deltic growl come rolling down the track towards them. So this is where Napia's long story finally settles. The engine everyone remembers is the one that hauled the trains. The engine that was the far greater achievement, the most efficient thing that ever flew, sits silent in a museum, and hardly anyone alive knows its name. Napier's gift, from David Napier's first workshop in Lloyd's Court, to the last drawing pinned up at Actton, was for complexity so fine that contemporaries called it delicate as any clock. That gift built the presses that printed the nation's money. It built the record cars and the Lion and the Saber. And it built the Nomad, the purest, cleverest, most beautiful expression of everything the firm could do. An engine that used its fuel twice and wasted almost nothing.

[00:40:09]The world, in the end, wanted something simpler. And so, the most brilliant engine Napia ever made was let go. Not with a scandal, not with a fight, but quietly in the spring of 1955 for want of anyone left who would stand up and say that it should be saved.