Bullet planes, fatal crashes – and the top secret British project to break the sound barrier first

Days before Chuck Yeager's fateful sonic boom in the Bell X-1, an ambitious British plan had already entered all too literal free fall over the Atlantic. Nevertheless, the vexed story of the Miles M.52 still has a place in history.

Published 17 Feb 2021, 17:03 GMT, Updated 18 Feb 2021, 05:41 GMT
Aviation artist and former aerodynamics research engineer Rod Kirkby's impression of what a successful flight in the ...

Aviation artist and former aerodynamics research engineer Rod Kirkby's impression of what a successful flight in the Miles M.52 might have looked like, had the project come to fruition. In a nod to the American pilot Chuck Yeager – and the British test pilot Eric Brown, who might have beaten him to Mach 1 – Kirkby titled it 'For Yeager, read Brown.' Brown bought the original painting.  

Photograph by Rod Kirkby

On 14 October 1947, travelling 45,000 feet above the Mojave desert in California, Major Chuck Yeager of the United States Air Force broke the sound barrier.

He was flying the Bell X-1, which had been dropped from a modified B-29 bomber at 26,000 feet, before sequentially opening the taps on the aircraft’s four rockets. In the moments that followed, the aircraft – nicknamed, like all Yeager's craft, ‘Glamorous Glennis’ after his wife – reached Mach 1.05, or about 700 miles per hour. He was the first pilot to control a craft beyond the speed of sound. But he wasn't the first to try.

(Related: How Concorde pushed the limits – then pushed them too far.) 

Six days before, a very similar-looking plane was dropped from a modified de Havilland Mosquito at 35,500 feet over the Atlantic ocean, west of Land’s End. This unmanned aircraft, the A.2, was in fact a 30 per cent scale model of a British supersonic prototype jet, the Miles M.52 – and was intended to prove concept. Powered by a rocket engine from the Royal Aircraft Establishment, Farnborough, it was theoretically capable of between 800mph and 1,000mph, taking it well beyond the sound barrier.

It was not to be their lucky day: the A.2 ‘rolled slowly over on to its back, and when the rocket motor should have ignited 15 seconds after release it failed to do so’. ‘Four and a half seconds later, the chasing Meteor reported an explosion, and the A.2 disappeared into cloud. Its path as determined by the radar corresponded roughly to a bomb trajectory!’

The design of the M.52 featured short, straight wings and a bullet-shaped fuselage – attributes designed for high-speed flight, if not especially desirable at anything slower. 

Photograph by Royal Aeronautical Society / Mary Evans Picture Library

The man who wrote these words was Don Brown, the personal assistant to George Miles, the technical director of Miles Aircraft Ltd in Reading, which in 1943 was given ‘the most ambitious and advanced research project ever attempted in the history of aeronautics... the design and construction of what was to be the world's first supersonic aircraft.’

As the project evolved during the final months of 1943, Miles was told to build a single-engined aircraft capable of reaching 1,000 mph in level flight: double the 500mph top speed of aircraft then in use.

The result was the top secret Miles M.52. But was it a doomed project due to poor execution – or a stunning design ahead of its time cut short before it could prove itself?

Rockets, wings and tails  

The Miles M.52 was bullet-shaped with a pointed cone nose, cylindrical fuselage, razor-thin wings and powered by a Whittle jet engine specifically designed for supersonic speeds – due ‘to be in flight in early 1946’. Dennis Bancroft, the Miles aerodynamicist who died in 2015, oversaw the design of this revolutionary aircraft, and recalled: ‘The fuselage was based on the shape of bullets that firing tests showed [were] travelling at supersonic speeds.’

1947: The Miles A.2, a 0.3-scale prototype of the full-sized M.52, is loaded onto the running gear of a de Havilland Mosquito, used as a lifting aircraft. Shortly after launch, the model misfired and dropped on a 'bomb trajectory.' With the problematic rocket ignition system solved, a final attempt in 1948 with the A.3 was successful, reaching 1,074 mph with no sign of instability – not only vindicating the M.52 design, but outperforming expectations.  

Photograph by Royal Aeronautical Society / Mary Evans Picture Library

Challenges included rethinking not just wing technology but also how to accommodate the pilot and reducing drag from the nose. In the end biconvex wings were used and tested on a Miles Falcon trainer plane. These had ‘a very sharp leading edge and a thickness/chord ratio less than ever before attempted,’ wrote Brown in a memorandum about the project. ‘The finished wing caused the aircraft to be known as the “Gillette Falcon” after the famous razor blade of the time.’ Bancroft noted that engineers working on the wings kept cutting themselves on the leading edges.

(Read: Sunken World War Two aircraft carrier found by deep sea expedition.)

Other hurdles were where to stow the fuel and where to locate the engine. In the end, the fuel tank was wrapped around the engine behind the pilot in the middle of fuselage – thereby increasing the diameter of the plane, but preventing centre of gravity problems. ‘It was decided, therefore, to house the pilot in a tiny conical capsule in the nose, the capsule being of smaller diameter than the fuselage, thus allowing an angular air intake immediately aft of the capsule. This capsule was far from ideal, but again it had to be accepted.’ 

The diameter was so small that the pilot was virtually lying down, ‘looking through the curved and tapering windscreen at a very flat angle’ with his feet very nearly at the same level as his shoulders. None of this sat well with the likely 160mph landing speed of the plane, but as Brown wrote, ‘there was no alternative’.

Perhaps most importantly, the Miles team had to devise a new approach to maintaining control as the plane reached high sub-sonic speeds. Significantly an all-moving tail was incorporated into the design from the outset, because at near sound barrier speeds the lifting centre of the aircraft shifting rearwards prompted a phenomenon known as ‘Mach tuck’ – forcing the nose of the plane down, with potentially devastating consequences ‘The controls had to be power operated and irreversible, and an all-moving tailplane was necessary instead of the conventional tailplane and hinged elevators,’ wrote Brown. ‘These things are commonplace today but in 1943 they had not been envisaged since the necessity had never arisen.’ Indeed all supersonic aircraft now use all-moving tail, if they aren’t delta winged.

A view of the M.52 cockpit. It was designed with a capsule that could be ejected with the pilot inside. 

Photograph by Royal Aeronautical Society / Mary Evans Picture Library

“The diameter was so small that the pilot was virtually lying down, ‘looking through the curved and tapering windscreen at a very flat angle’ with his feet very nearly at the same level as his shoulders.”

Next Frank Whittle, the inventor of the jet engine, oversaw the team supplying the engine for the aircraft. Since his Power Jet W.2/700 engine was insufficient alone, they developed afterburner technology, plus an aft turbofan, to boost its thrust and get the M.52 through the sound barrier. The craft also came with an escape capsule nose section for the pilot who would be unable to ‘bail out’ in the conventional fashion. Notably the only means of escape from Yeager's Bell X-1 was to leave the aircraft by the side hatch, and risk been sliced in two by the wing.   

(Watch: fiery crash of SpaceX's Starship ignites hopes of future spaceflight.)

“Whittle's engine was amazing,” says Rod Kirkby, a former future-projects aerodynamics research engineer turned aviation artist, who frequently presents talks on the M.52. “His design, which was part of the 1943 specification for the project, was a reheated turbofan which at high speed virtually became a ramjet engine – in a very similar fashion to the [Lockheed] SR 71 Blackbird spyplane. Unbelievable for 1943.” 

Shot down

By 1946, the detailed design work of Britain’s first supersonic aircraft was 90 per cent done and the first prototype was more than half built – and due for rollout in early summer 1946. Successful tests of the ‘all-moving tail’ had been conducted on the fastest available aircraft, the Supermarine Spitfire (reaching Mach 0.86 in trials). Meanwhile, those razor-sharp wings had been proved effective too. The firm was on course to for a maiden flight in the summer of 1946 with ace test pilot Eric ‘Winkle’ Brown lined-up for the task.

But then, out of the blue, the government cancelled the project. ‘I was hopping mad,’ recalled the test pilot. ‘We were 15 months ahead of the Americans.’ Don Brown was damning: ‘Over two years of concentrated and dedicated work on the part of the two teams was thrown away, together with over £100,000 of the taxpayers’ money: and, by this cancellation, Great Britain threw away the honour of being the first nation to achieve supersonic flight.’

The fuselage of the mockup M.52. Intended to take off and land from the ground due to the unavailability of vast lake beds onto which pinpoint landing wasn't a problem, the rocket plane would never fly, despite all components being available at time of project cancellation. The aircraft that did – the American Bell X-1 – is preserved in the Smithsonian National Air and Space Museum in Washington D.C (below).

Photograph by Royal Aeronautical Society / Mary Evans Picture Library

The Bell X-1. A formidable plane, Chuck Yeager actually broke through the sound barrier on just three of the aircraft's four rockets. While propulsion evidently wasn't a problem, stability at that speed was; with Miles ordered to share intel with the American company, some sources insist the Bell X-1 incorporated – at test stage – a baked-in element of the British M.52 design; the moving tailplane, designed to counteract a dangerous aerodynamic consequence of going supersonic. Without it, Yeager's record-breaking speed would have been impossible.   

Photograph by National Air and Space Museum / Smithsonian

When news of the cancellation broke the firm told the press that ‘practically all the items required to complete construction were in stores and the engine was already available.’ 

The project was passed to the Royal Aircraft Establishment and Vickers, and re-skinned as the R.A.E.-Vickers Transonic Rocket Research Rocket. In October 1946, The Aeroplane Spotter reported on the project and its cancellation, noting: ‘A decision at high level has been made to reduce this experimental supersonic work to the form of guided missile development, but probably the last of this Miles design has not yet been heard.’

High-speed controversy

These words were prophetic, for the shadow of the sonic boom of the Miles design was undoubtedly heard over the Californian desert on 14 October 1947.

How so? Because in 1944 the British government agreed to share the secrets of Miles’ designs and work with the Americans: Brown recalled that Bell’s ‘engineers and designers had, on the insistence of the Ministry, had access to all the drawings, calculations and design data relating to the M.52.’ At the time Bell had already begun work on its own design and was wrestling with many of the same issues as Miles, including all-important pitch (the vertical inclination of the nose) control. Crucially they had not achieved the breakthrough with the all-moving tailplane. But by the time Yeager climbed into the cockpit on 14 October – after Bell's engineers had met with the Miles design team – they had.

Most of the theories concerning how much the Bell X-1 drew on the insights of the M.52 hinge around this tailplane. According to Rod Kirkby, Bell Aircraft decided to increase the power of the tailplane trimmer after talks with the Miles design team, on the off-chance it might be required. In test flights close to Mach 1 in the X-1 Yeager had found the aircraft's pitch almost impossible to control. Fitting an electric switch that controlled the tailplane incidence – Kirkby calls the addition a 'field fix' – solved the problem.

Just how much the Miles design informed the X-1 is not known – despite much rumour – but there is no doubt that without the all-moving tailplane Yeager wouldn’t have broken the sound barrier, or lived to tell the tale. In his autobiography Yeager described flipping the switch for the tailplane “smoothed [the flight] right out... Grandma could be sitting up there sipping lemonade.” 

One important design aspect they both had in common – those straight wings – points to another possible reason for the cancellation of the Miles project, aside from the parlous state of the public finances confronting the post-war Labour government. After the defeat of Nazi Germany in May 1945, the Allies gained access to data from the Luftfahrtforschungsanstalt at Volkenrode, Hitler’s top secret aeronautical research and development centre. This showed that the Germans had conducted significant research into the importance of ‘sweepback’ wings in delaying the shock waves and the onset of aerodynamic drag in high sub-sonic speeds. ‘Orders were given to cancel immediately any high‑speed projects which did not incorporate sweepback,’ wrote Brown. ‘In vain Miles and his team pointed out that as the aircraft was designed for supersonic speeds. Furthermore, [Chuck Yeager's successful] Bell X-1 did not have sweptback wings.’ 

“Dennis Bancroft knew about swept wings when designing the M.52,” says Rod Kirkby. “Swept wings are only useful for low supersonic speeds. The drag coefficient of a straight wing actually falls when passing Mach 1; for higher speeds, thin straight wings are best.” Kirkby points out the Lockheed F104 Starfighter, introduced in 1958 and capable of sustained Mach 2, as an example of this principle in full-fledged action.  

The Bell X-1, piloted by Chuck Yeager, was the first plane to break the sound barrier. 

Photograph by Smithsonian National Air and Space Museum

Chuck Yeager, pictured next to the Bell X-1. Many believe the sound-barrier breaking X-1 design incorporated elements of the tail design of the Miles M.52. Yeager died in 2020, aged 97.

Photograph by GL Archive / Alamy

In all cases, it was too late – and anyway, the government had alighted on another candidate to meet Britain’s ambitions for supersonic flight.

The deadly Swallow

The creator of the Mosquito, the aviation giant de Havilland, was asked to look into sweepback designs in October 1945, leading to the creation of the DH108. This was similar to the tailless swept-wing rocket-powered Messerschmitt Me 163, used by the Luftwaffe as an interceptor during the latter stages of the war. According to Rod Kirkby, the plane had an infamy for introducing the term 'graveyard dive' into the vernacular of the pilots of the time – given their hopelessness of recovery when the plane found itself in a steep dive. The first tail-less DH108 prototype – nicknamed the Swallow – took to the skies in May 1946 piloted by Geoffrey de Havilland Junior, the test-pilot son of the company owner. Over the months that followed modifications were made and the second prototype was launched in July that year for high speed testing. 

On 27 September, de Havilland died while trying to break the then speed record of 616 mph in flights over the Thames Estuary: the aircraft broke up mid-flight at around Mach 0.9. The wreckage was discovered on mud-flats near Egypt Bay, north east of Gravesend on the Kent coast.

The first of the boundary-breaking De Havilland DH108 aircraft, a low-speed prototype. Further work on the design would yield the first British piloted aircraft to break the sound barrier – and high-speed crashes in the aircraft would kill the founder of the company's son, Geoffrey de Havilland, Jr., and test pilot John Derry.   

Photograph by Royal Aeronautical Society / Mary Evans Photo Library

The third DH108 prototype – piloted by John ‘Cats Eyes’ Cunningham – flew ten months later in July 1947, just three months before the X-1’s victorious bid in California. After successful speed record attempts de Havilland’s chief test pilot John Derry inadvertently took the DH108 north of Mach 1 in an uncontrolled dive on 6 September 1948, making it the first British aircraft to break the sound barrier and earning him fame as Britain’s first supersonic pilot – though not in level flight, as the X-1's had been; Derry survived this 'graveyard dive' only due to the plane regaining enough aerodynamic control due to the thickening of the air (and an increase in the ambient speed of sound) as it descended.  

‘The DH108 was instrumental in the development of modern jet aircraft of both military and civil design and was the epitome of an era when great advances were made through those brave men who were “pushing the envelope”,’ states BAE Systems, a successor firm to de Havilland. John Derry was to die at the controls of a later iteration of the aircraft, the DH110, in 1952.

One final shot

Meanwhile, staff at the Royal Aircraft Establishment had continued to work on the Vickers-built model of the original M.52.

After losing the second model (the A.2) they spent months perfecting on the rocket engine before further attempt was made in October 1948 to trial A.3. Released over the Atlantic: ‘After six seconds the rocket motor started and A.3 accelerated smoothly with no sign of instability. The rocket burned for about a minute, the maximum speed attained being a Mach 1.4, 62 seconds after release.’ On it ‘continued happily westwards’ wrote Brown, ‘After eight minutes and at a range of about 70 miles, radio contact was lost and it was never known how far the model M.52 continued on its flight towards the USA: the point of real importance, however, was the fact that the design of the M.52 was finally and irrefutably vindicated.’ It's possible that the design would have exceeded hopes: according to Rod Kirkby, “not only was it stable throughout the flight, but drag measurements showed that Miles's estimates were likely pessimistic. The M.52's performance would have been better than predicted.”

Peter Amos, an aviation historian who has written the authoritative multi-volume history of the Miles Aircraft company and shared Don Brown’s document with National Geographic, adds: ‘The M.52 would have given Britain the lead in supersonic flight, if the government of the day hadn’t cancelled it when it had been partially built, and then wasted much more money on a long-winded series of only partially successful rocket propelled scale models of the M.52.’

We can never know if British aviators would have broken the sound barrier first. What we do know is that they did on celluloid. David Lean’s 1952 film, The Sound Barrier, was inspired by the story of Geoffrey de Havilland Jr’s death in the DH108, and then Derry’s successful bid to break the sound barrier. It was an international box office success.

Chuck Yeager – who died in December 2020, aged 97 – went to the American premiere, but wasn’t amused. He liked it even less when he reportedly kept meeting people who had seen the film and thought the Brits had broken the sound barrier first. Irony? The truth, as ever, is rather more complicated.

Alec Marsh is a journalist and author of the Drabble and Harris books

Additional reporting by Simon Ingram

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