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The DeHaviland Comet: The First Passenger Jet

This was a passenger airliner that changed the world – but also one that has fallen through the cracks of history. The story of the De Havilland Comet is one of both cutting edge technology that revolutionized aviation and tragic disaster. 

The world’s first passenger jet airliner which made its first flight on 27th July 1949 understandably caused one hell of a stir. At the time, traditional passenger aircraft powered by propeller were hardly the luxury air travel we have become accustomed to. Incredibly noisy and with the kind of vibrations that could shake out one’s fillings, long haul travel in one of these aircraft was a testing experience.

But that all began to change with the appearance of the De Havilland Comet. To begin with, it looked like something out of the space age, a sleek design with swept-back wings and four jet engines never before seen on a commercial airliner. Today it looks remarkably similar to our modern planes, but in the early 1950s, it might as well have come from outer space. The new, modern way to travel by air had arrived and the Comet was surely set to take the world by storm. But that’s not how things turned out. A series of fatal accidents proved that this aircraft was perhaps a little ahead of its time, and despite rallying with a newer, safer design, the aircraft was never able to recapture the same excitement or trust.     

Looking Ahead

World War II had not even finished when the British government began pondering plans for the future of their aviation industry. There was general dissatisfaction that before the war the American twin-engine Douglas DC-3 was the aircraft of choice for a huge 90% of the world’s airline passengers. In terms of aviation, the Americans had sprinted ahead and the British didn’t like that one bit. Something new was needed – something dramatic. 

Douglas DC-3
Douglas DC-3 by Towpilot is licensed under CC-BY-SA

While the first military jets had appeared out of Germany in 1939, a jet passenger airliner was an entirely different proposition. At the time, the general assumption was that jets were too unreliable and used too much fuel to be used in this way. 

Sir Geoffrey de Havilland, who was both part of the committee brought together in Britain to discuss the aviation industry, and head of the de Havilland company, an aircraft manufacturer, believed otherwise. 

It’s difficult not to overstate the complexities of the design that was first envisioned. What was initially put forward was not a passenger airliner, but a transatlantic mail plane with just six passenger seats onboard. But it would need to have a cruising altitude of 12,192 metres (40,000 ft) and cruising speed of 640 km/h (400 mph). That might not sound particularly mind-blowing in 2020, but in the late 1940s, it was nothing short of revolutionary. Nothing like this with jet engines had ever been attempted, and in truth, many weren’t convinced it was possible. 

In December 1945, the British Overseas Airways Corporation (BOAC) accepted the proposal from De Havilland and initially set out an order for 25 aircraft, which was soon reduced down to 10. Over the next year, final alterations were made with the passenger capacity expanded to 24, then 36, while the more powerful Halford H.2 Ghost 50 turbojet engines replaced the Halford H.1 Goblin which had been included in initial designs. These alterations were finalised in December 1947, with the new design becoming known as the DH.106 Comet. 

Testing 

The fact that this was very much an experimental aircraft meant that testing was both vigorous and a top priority. Countless stress tests were done on the fuselage in both pressurised and non pressurised environments. Everything onboard the plane needed to be carefully examined under the kind of pressure it would eventually face in the air. Windows, doors and everything down to the smallest components was painstakingly scrutinised. 

The first prototype was assembled in 1949 and during the first half of the year it went through further ground testing, but by 27th July, the time had come to see whether this next-generation aircraft could really fly. Piloting the aircraft that day was John Cunningham, a renowned night pilot from World War II who had earned the nickname “Cats Eyes”, along with four other members of his crew. 

The flight lasted just 31 minutes and was deemed a great success. Later that year it even appeared (on the ground) at the Farnborough Airshow – a sure sign of growing confidence. A year later, a second prototype was completed and it too began air testing. It would appear that all was progressing smoothly, and word began to spread of the Comet’s early successes. 

Design

As I mentioned earlier in the video, nothing quite like the Comet had ever been seen. This was an all-metal monoplane complete with swept wings (meaning they point further back rather than straight across) and two pairs of jet engines incorporated into the wings, with roughly 5,000 lbf each. To put that kind of number in perspective, a modern 747 carries engines producing between 46,300–56,900 lbf each.  

The interior was considerably more spacious than what we often see today. The cabin space was divided into First and Second Class, with the seats in First Class arranged around tables, a bit like on a train. Those in Second had to live with what we would consider normal aircraft seating, but even here it was a far cry from the often cramped conditions onboard modern airliners. 

The flight deck layout was based on the Lockheed Constellation which was a popular aircraft at the time, with the reasoning being that it would add an air of familiarity to pilots. The Comet came with four hydraulic systems powered from all four engines, two primaries, one secondary and one in case of an emergency, which could still control basic functions such as lowering the landing gear (although this could also be done manually using a hand-pump). 

The aircraft also came with a new pressurised fueling system which had recently been developed by Flight Refuelling Ltd in the UK, which allowed the fuel tanks to be filled at a much faster rate than other aircraft. 

Much of the early fascination with the Comet was down to its sleek fuselage. No passenger aircraft had ever been built to fly as high and as fast as the Comet, so the fuselage was somewhat of an experiment. The thin metal skin was constructed with a combination of alloys, which were riveted and then chemically bonded to save weight. This bonding process was done using a new adhesive called Redux which had only been developed in the 1940s. 

The first Comet that appeared measured 28 metres (93ft) in length and had a wingspan of 35 metres (115ft) – making it fairly small compared to modern jumbo jets. As I’ll come to later in the video, there were subsequent Comets which gradually grew in size. 

Maiden Flight

On 2nd May 1952, the fifth production aircraft off the assembly line waited patiently on the runway at London’s Heathrow Airport. It was a misty spring morning in Britain and the crowd who had gathered to witness this historic flight heard the Comet before they saw it.

A loud shriek boomed out across the airport as the aircraft’s engines kicked into gear and moments later the Comet appeared out of the mist hurtling down the runway. Those watching held their breath as the nose slowly lifted into the sky. For the first time in history, fare-paying passengers were aboard a commercial passenger jet, which was now headed for Johannesburg in South Africa. 

And what a start to life the aircraft made. Queen Elizabeth, the Queen Mother and Princess Margret were given a special flight onboard in 1953 and in its first year alone it carried 30,000 passengers. While it doesn’t compare to our modern jet airliners, the Comet was about twice as fast as conventional propeller aircraft at the time. Not only that, it flew considerably higher meaning it could climb above adverse weather rather than having to barrel through it as had been the norm. 

The stage was set for success and by the summer of 1953, 8 BOAC Comets left London each week, three to Johannesburg, two to Tokyo, two to Singapore and one to Colombo. Orders began to pour in from all over the world especially for the impending Comet 2, which would be slightly longer than Comet 1. Airlines from France, Brazil, USA, Venezuela, Japan and many more signed up for the future of air travel. 

But amid the hype, all was not well. 

Early Problems

With all of the adulation that the Comet was receiving through 1952 and 1953, it’s worth pointing out that the first accident involving the aircraft came on 26th October 1952 when a Comet failed to get airborne while departing from Rome and skidded off the end of the runway. Despite severe damage to the aircraft, only two passengers received minor injuries and the accident was initially blamed on a pilot error.  

But it happened again on 3rd March 1953, when a Comet attempted a night take-off in Karachi, Pakistan. This time things were not so fortunate with the aircraft toppling into a dry drainage canal and colliding with an embankment. The accident killed all five crew members on board along with six passengers. Once again, the accident was attributed to pilot error (which was only later found to be false). 

Disaster  

Hindsight is a tricky animal, and no doubt some over the subsequent years questioned whether the Comet should have continued flying after those early accidents. As it happened, they did, and a full-scale disaster was only just around the corner. 

On 2nd May BOAC Flight 783 climbed into the sky above Calcutta on its way to London. Almost immediately the aircraft ran into a powerful thunderstorm, and just six minutes after take-off it began to disintegrate in mid-air. Eyewitnesses reported seeing the Comet plunge wing-less down to earth. The crash killed all 43 on board, including 6 crew members and 37 passengers. 

Sadly, this was just the start. Just over a year later, and again departing from Rome, the site of the first accident involving a Comet, the first production aircraft produced crashed into the Mediterranean 20 minutes after take-off, killing all 35 onboard. With no eye-witnesses and only a partial radio transmission received, the cause of the crash was not immediately clear. 

The investigation into this second crash took some time, with the Royal Navy attempting to salvage the wreckage. In the meantime, BOAC grounded their Comet fleet as a committee began looking into the crash. 

Quite astonishingly, no fault was found with the aircraft after either of their recent fatal crashes. This had since led some to question whether this prestigious British project received a degree of protection from the government. There seems to be little to no evidence of this, but as we shall see, it didn’t take long for this decision to backfire spectacularly. On 23rd March 1954, BOAC Comet’s once again took to the skies – but not for long. 

Just over two weeks later, a Comet operated by South African Airways was travelling from Rome to Cairo (yes it’s truly bizarre that we keep coming back to the Italian capital) crashed off the coast of Naples, killing all 21 onboard. The Comet was once again grounded, and its Certificate of Airworthiness eventually revoked. 

Investigation 

This time investigators had to get to the bottom of the causes of the crashes. A dedicated water tank was constructed in the UK in which a Comet airframe was placed. Here, the fuselage underwent countless repressurisation and over-pressurisation tests to see how it would cope – and for a while, everything seemed fine. 

On 24th June 1954, the test fuselage split open, originating from a bolt hole. It was quickly discovered that the fuselage did not have enough strength to prevent the crack from growing. Investigators summarized that such a split could occur anywhere between 1,000 and 9,000 cycles (one cycle being one take-off and one landing). The aircraft involved in the first major crash in the Mediterranean had completed 1,290 cycles.   

They also found that the way windows had been installed was a recipe for disaster, with the punch riveting method not strong enough to prevent fatigue cracks from spreading around these points. Punch riveting, in which the hole is punched out by the rivet itself, may have sped up the process, but the holes created were imperfect and contributed to the overall weaknesses within the aircraft.  

The Return

The findings of the investigation had been damning, but would not be terminal. All Comet 1s were immediately withdrawn from service and major rethink took place on how to strengthen the aircraft. It may have taken a few years, but eventually, De Havilland felt they had got it right. This involved a thicker alloy skin, a complete redesign and strengthening of the windows and thicker gauge materials used in the pressure cabin area. 

The Comet 2, which was slightly larger and had flown for the first time on 27th August 1953, was also withdrawn and completely re-built, while Comet 3 was very much a development aircraft and was never mass manufactured. 

Comet 4 on the other hand would become the most successful aircraft in the series. It measured 5.64 metres (18 ft 6 in) longer than Comet 1 and could typically seat between 74 and 81 passengers. By 1958, deliveries of the Comet 4 were going out around the world at a cost of £1.14 million (£24 million today) each. There was also a change in engines with the Rolls-Royce Avon Mk 524 turbojet added, boosting the power output to 10,500 lbf per engine. It’s fairly astonishing that despite the catalogue of disaster, not only was the aircraft able to return, it came back bigger than ever.

But the Americans had caught up, and while the Comet had made a return, it would struggle. By the end of the 1950s, American passenger airliners, which included the Boeing 707 and Douglas DC-8 were bigger, faster and more cost-effective. The Comet was unable to keep up and BOAC ceased flights using the Comet 4 in 1965, but around the world, they flew until 1981.

Legacy

As I mentioned right at the start of the video, the name De Havilland Comet has somewhat fallen through the cracks when it comes to aviation history. While Boeing and Douglas have gone on to become household names, De Havilland has not. 

The reasons for this are of course quite obvious. The disastrous series of fatal accidents that occurred during the 1950s should have been enough to finish off the company, the fact that it came back at all was almost unbelievable. 

But let’s set those disasters aside for the time being. The De Havilland Comet was a truly extraordinary breakthrough in terms of aviation technology and should be remembered as such. The world’s first passenger jet airliner was certainly not perfect and there are questions over whether it should have been allowed to fly after the early accidents, but make no mistake about it, aviation before and after the Comet was almost entirely different. 

What’s interesting is that those who worked for Boeing and Douglas on their early jet airliners have since said that if the structural failures hadn’t happened to the Comet, they would have most likely happened with their aircraft. This was a painful right of passage that the airline industry had to experience as they moved into the jet age. 

The De Havilland Comet was a deeply flawed masterpiece, but one that should be remembered as the aircraft that completely changed air travel.

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