The de Havilland DH.106 Comet was the world's first commercial
jet airliner
A jet airliner or jetliner is an airliner powered by jet engines (passenger jet aircraft). Airliners usually have two or four jet engines; three-engined designs were popular in the 1970s but are less common today. Airliners are commonly cl ...
. Developed and manufactured by
de Havilland
The de Havilland Aircraft Company Limited () was a British aviation manufacturer established in late 1920 by Geoffrey de Havilland at Stag Lane Aerodrome Edgware on the outskirts of north London. Operations were later moved to Hatfield in H ...
in the United Kingdom, the Comet 1 prototype first flew in 1949. It featured an aerodynamically clean design with four
de Havilland Ghost
The de Havilland Ghost (originally Halford H-2) was the de Havilland Engine Company's second design of a turbojet engine to enter production and the world's first gas turbine engine to enter airline service (with British Overseas Airways Corpo ...
turbojet
The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...
engines buried in the wing roots, a
pressurised cabin, and large square windows. For the era, it offered a relatively quiet, comfortable passenger cabin and was commercially promising at its debut in 1952.
Within a year of entering airline service, problems started to emerge, three Comets being lost within twelve months in highly publicised accidents, after suffering catastrophic in-flight break-ups. Two of these were found to be caused by structural failure resulting from
metal fatigue
In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts o ...
in the
airframe
The mechanical structure of an aircraft is known as the airframe. This structure is typically considered to include the fuselage, undercarriage, empennage and wings, and excludes the propulsion system.
Airframe design is a field of aerospa ...
, a phenomenon not fully understood at the time; the other was due to overstressing of the airframe during flight through severe weather. The Comet was withdrawn from service and extensively tested. Design and construction flaws, including improper
riveting
A rivet is a permanent mechanical fastener. Before being installed, a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite to the head is called the ''tail''. On installation, the rivet is placed in a punched o ...
and dangerous concentrations of
stress
Stress may refer to:
Science and medicine
* Stress (biology), an organism's response to a stressor such as an environmental condition
* Stress (linguistics), relative emphasis or prominence given to a syllable in a word, or to a word in a phrase ...
around some of the square windows, were ultimately identified. As a result, the Comet was extensively redesigned, with oval windows, structural reinforcements and other changes. Rival manufacturers heeded the lessons learned from the Comet when developing their own aircraft.
Although sales never fully recovered, the improved Comet 2 and the prototype Comet 3 culminated in the redesigned Comet 4 series which debuted in 1958 and remained in commercial service until 1981. The Comet was also adapted for a variety of military roles such as VIP, medical and passenger transport, as well as surveillance; the last Comet 4, used as a research platform, made its final flight in 1997. The most extensive modification resulted in a specialised
maritime patrol {{Unreferenced, date=March 2008
Maritime patrol is the task of monitoring areas of water. Generally conducted by military and law enforcement agencies, maritime patrol is usually aimed at identifying human activities.
Maritime patrol refers to ac ...
derivative, the
Hawker Siddeley Nimrod
The Hawker Siddeley Nimrod is a retired maritime patrol aircraft developed and operated by the United Kingdom. It was an extensive modification of the de Havilland Comet, the world's first operational jet airliner. It was originally designed ...
, which remained in service with the
Royal Air Force
The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...
until 2011, over 60 years after the Comet's first flight.
Development
Origins
![Design Studies for the DH 106 Comet](https://upload.wikimedia.org/wikipedia/commons/c/c8/Design_Studies_for_the_DH_106_Comet.jpg)
On 11 March 1943, the
Cabinet of the United Kingdom
The Cabinet of the United Kingdom is the senior decision-making body of His Majesty's Government. A committee of the Privy Council, it is chaired by the prime minister and its members include secretaries of state and other senior ministers.
T ...
formed the
Brabazon Committee
The Brabazon Committee was a committee set up by the British government in 1942 to investigate the future needs of the British Empire's civilian airliner market following World War II.Phipp, 2007, pp.15-16 The study was an attempt at defining, in ...
, which was tasked with determining the UK's airliner needs after the conclusion of the
Second World War
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
.
[Trischler and Helmuth 2003, p. 88.] One of its recommendations was for the development and production of a pressurised, transatlantic mailplane that could carry of payload at a cruising speed of non-stop.
[Birtles 1970, p. 124.] Aviation company
de Havilland
The de Havilland Aircraft Company Limited () was a British aviation manufacturer established in late 1920 by Geoffrey de Havilland at Stag Lane Aerodrome Edgware on the outskirts of north London. Operations were later moved to Hatfield in H ...
was interested in this requirement, but chose to challenge the then widely held view that
jet engine
A jet engine is a type of reaction engine discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include rocket, Pump-jet, water jet, and hybrid propulsion, the term ...
s were too fuel-hungry and unreliable for such a role. As a result, committee member Sir
Geoffrey de Havilland
Captain Sir Geoffrey de Havilland, (27 July 1882 – 21 May 1965) was an English aviation pioneer and aerospace engineer. The aircraft company he founded produced the Mosquito, which has been considered the most versatile warplane ever built,D ...
, head of the de Havilland company, used his personal influence and his company's expertise to champion the development of a jet-propelled aircraft; proposing a specification for a pure
turbojet
The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...
-powered design.
The committee accepted the proposal, calling it the "Type IV" (of five designs), and in 1945 awarded a development and production contract to de Havilland under the designation ''Type 106''. The type and design were to be so advanced that de Havilland had to undertake the design and development of ''both'' the airframe and the engines. This was because in 1945 no turbojet engine manufacturer in the world was drawing-up a design specification for an engine with the thrust and
specific fuel consumption that could power an aircraft at the proposed cruising altitude (), speed, and transatlantic range as was called for by the Type 106. First-phase development of the DH.106 focused on short- and intermediate-range mailplanes with small passenger compartments and as few as six seats, before being redefined as a long-range airliner with a capacity of 24 seats.
Out of all the Brabazon designs, the DH.106 was seen as the riskiest: both in terms of introducing untried design elements and for the financial commitment involved.
Nevertheless, the
British Overseas Airways Corporation
British Overseas Airways Corporation (BOAC) was the British state-owned airline created in 1939 by the merger of Imperial Airways and British Airways Ltd. It continued operating overseas services throughout World War II. After the passi ...
(BOAC) found the Type IV's specifications attractive, and initially proposed a purchase of 25 aircraft; in December 1945, when a firm contract was created, the order total was revised to 10.
[Jones 2010, p. 62.]
A design team was formed in 1946 under the leadership of chief designer
Ronald Bishop, who had been responsible for the
Mosquito
Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning " gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "li ...
fighter-bomber.
Several unorthodox configurations were considered, ranging from
canard to
tailless designs; All were rejected. The
Ministry of Supply
The Ministry of Supply (MoS) was a department of the UK government formed in 1939 to co-ordinate the supply of equipment to all three British armed forces, headed by the Minister of Supply. A separate ministry, however, was responsible for aircr ...
was interested in the most radical of the proposed designs, and ordered two experimental tailless
DH 108s to serve as
proof of concept
Proof of concept (POC or PoC), also known as proof of principle, is a realization of a certain method or idea in order to demonstrate its feasibility, or a demonstration in principle with the aim of verifying that some concept or theory has prac ...
aircraft for testing swept-wing configurations in both low-speed and high-speed flight.
[Watkins 1996, p. 39.] During flight tests, the DH 108 gained a reputation for being accident-prone and unstable, leading de Havilland and BOAC to gravitate to conventional configurations and, necessarily, designs with less technical risk. The DH 108s were later modified to test the DH.106's power controls.
In September 1946, before completion of the DH 108s, BOAC requests necessitated a redesign of the DH.106 from its previous 24-seat configuration to a larger 36-seat version.
With no time to develop the technology necessary for a proposed tailless configuration, Bishop opted for a more conventional 20-degree swept-wing design with unswept tail surfaces, married to an enlarged fuselage accommodating 36 passengers in a four-abreast arrangement with a central aisle.
Replacing previously specified
Halford H.1 Goblin engines, four new, more-powerful
Rolls-Royce Avon
The Rolls-Royce Avon was the first axial flow jet engine designed and produced by Rolls-Royce. Introduced in 1950, the engine went on to become one of their most successful post-World War II engine designs. It was used in a wide variety of ai ...
s were to be incorporated in pairs buried in the wing roots;
Halford H.2 Ghost engines were eventually applied as an interim solution while the Avons cleared certification. The redesigned aircraft was named the DH.106 ''Comet'' in December 1947. Revised first orders from BOAC and
British South American Airways
British South American Airways (BSAA) was a state-run airline of the United Kingdom in the mid-late 1940s responsible for services to the Caribbean and South America. Originally named British Latin American Air Lines it was renamed before serv ...
totalled 14 aircraft, with delivery projected for 1952.
[Jones 2010, pp. 62–63.]
Testing and prototypes
As the Comet represented a new category of passenger aircraft, more rigorous testing was a development priority.
[ From 1947 to 1948, de Havilland conducted an extensive research and development phase, including the use of several stress test rigs at ]Hatfield Aerodrome
Hatfield Aerodrome was a private airfield and aircraft factory located in the English town of Hatfield in Hertfordshire from 1930 until its closure and redevelopment in the 1990s.
Early history
Geoffrey de Havilland, pioneering aircraft desig ...
for small components and large assemblies alike. Sections of pressurised fuselage were subjected to high-altitude flight conditions via a large decompression chamber
A diving chamber is a vessel for human occupation, which may have an entrance that can be sealed to hold an internal pressure significantly higher than ambient pressure, a pressurised gas system to control the internal pressure, and a supply of ...
on-site and tested to failure.[ Tracing fuselage failure points proved difficult with this method,][ and de Havilland ultimately switched to conducting structural tests with a water tank that could be safely configured to increase pressures gradually.][ The entire forward fuselage section was tested for metal fatigue by repeatedly pressurising to overpressure and depressurising through more than 16,000 cycles, equivalent to about 40,000 hours of airline service.][Davies and Birtles 1999, p. 30.] The windows were also tested under a pressure of , above expected pressures at the normal service ceiling of . One window frame survived , about 1,250 percent over the maximum pressure it was expected to encounter in service.
The first prototype DH.106 Comet (carrying Class B markings
United Kingdom aircraft test serials are used to externally identify aircraft flown within the United Kingdom without a full Certificate of Airworthiness. They can be used for testing experimental and prototype aircraft or modifications, pre-del ...
G-5-1) was completed in 1949 and was initially used to conduct ground tests and brief early flights.[Darling 2001, p. 18.] The prototype's maiden flight, out of Hatfield Aerodrome, took place on 27 July 1949 and lasted 31 minutes.[Green and Swanborough April 1977, p. 174.] At the controls was de Havilland chief test pilot John "Cats Eyes" Cunningham, a famous night-fighter pilot of the Second World War, along with co-pilot Harold "Tubby" Waters, engineers John Wilson (electrics) and Frank Reynolds (hydraulics), and flight test observer Tony Fairbrother
Anthony James Fairbrother (4 May 1926, Coventry – 7 December 2004) was an English engineer who was the flight-test engineer on the maiden flight of the de Havilland DH.106 Comet 1, the world's first jet airliner, in 1949.
Tony Fairbrother w ...
.
The prototype was registered G-ALVG just before it was publicly displayed at the 1949 Farnborough Airshow
The Farnborough Airshow, officially the Farnborough International Airshow, is a trade exhibition for the aerospace and defence industries, where civilian and military aircraft are demonstrated to potential customers and investors. Since its fir ...
before the start of flight trials. A year later, the second prototype G-5-2 made its maiden flight. The second prototype was registered G-ALZK in July 1950 and it was used by the BOAC Comet Unit at Hurn
Hurn is a village and civil parish in the historic county of Hampshire and the ceremonial county of Dorset, England. Situated between the River Stour and River Avon, administratively Hurn is part of Bournemouth, Christchurch and Poole unitary ...
from April 1951 to carry out 500 flying hours of crew training and route-proving. Australian airline Qantas
Qantas Airways Limited ( ) is the flag carrier of Australia and the country's largest airline by fleet size, international flights, and international destinations. It is the world's third-oldest airline still in operation, having been founded ...
also sent its own technical experts to observe the performance of the prototypes, seeking to quell internal uncertainty about its prospective Comet purchase. Both prototypes could be externally distinguished from later Comets by the large single-wheeled main landing gear
Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...
, which was replaced on production models starting with G-ALYP by four-wheeled bogies
A bogie ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transp ...
.
Design
Overview
The Comet was an all-metal low-wing cantilever monoplane powered by four jet engines; it had a four-place cockpit
A cockpit or flight deck is the area, usually near the front of an aircraft or spacecraft, from which a Pilot in command, pilot controls the aircraft.
The cockpit of an aircraft contains flight instruments on an instrument panel, and the ...
occupied by two pilots, a flight engineer, and a navigator. The clean, low-drag design of the aircraft featured many design elements that were fairly uncommon at the time, including a swept-wing leading edge, integral wing fuel tanks, and four-wheel bogie
A bogie ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transp ...
main undercarriage units designed by de Havilland.[Francis 1950, p. 99.] Two pairs of turbojet engines (on the Comet 1s, Halford H.2 Ghosts, subsequently known as de Havilland Ghost
The de Havilland Ghost (originally Halford H-2) was the de Havilland Engine Company's second design of a turbojet engine to enter production and the world's first gas turbine engine to enter airline service (with British Overseas Airways Corpo ...
50 Mk1s) were buried into the wings.[Francis 1950, pp. 100–101.]
The original Comet was the approximate length of, but not as wide as, the later Boeing 737-100
The Boeing 737 is a narrow-body aircraft produced by Boeing at its Renton Factory in Washington.
Developed to supplement the Boeing 727 on short and thin routes, the twinjet retains the 707 fuselage width and six abreast seating with two un ...
, and carried fewer people in a significantly more-spacious environment. BOAC installed 36 reclining "slumberseats" with centres on its first Comets, allowing for greater leg room in front and behind; Air France
Air France (; formally ''Société Air France, S.A.''), stylised as AIRFRANCE, is the flag carrier of France headquartered in Tremblay-en-France. It is a subsidiary of the Air France–KLM Group and a founding member of the SkyTeam global air ...
had 11 rows of seats with four seats to a row installed on its Comets.[Cookman, Aubery O. Jr]
"Commute by Jet."
''Popular Mechanics'', 93(4), April 1950, pp. 149–152. Large picture window views and table seating accommodations for a row of passengers afforded a feeling of comfort and luxury unusual for transportation of the period. Amenities included a galley
A galley is a type of ship that is propelled mainly by oars. The galley is characterized by its long, slender hull, shallow draft, and low freeboard (clearance between sea and gunwale). Virtually all types of galleys had sails that could be used ...
that could serve hot and cold food and drinks, a bar
Bar or BAR may refer to:
Food and drink
* Bar (establishment), selling alcoholic beverages
* Candy bar
* Chocolate bar
Science and technology
* Bar (river morphology), a deposit of sediment
* Bar (tropical cyclone), a layer of cloud
* Bar (u ...
, and separate men's and women's toilets.[Francis 1950, p. 98.] Provisions for emergency situations included several life raft
A lifeboat or liferaft is a small, rigid or inflatable boat carried for emergency evacuation in the event of a disaster aboard a ship. Lifeboat drills are required by law on larger commercial ships. Rafts (raft, liferafts) are also used. In t ...
s stored in the wings near the engines, and individual life vest
A personal flotation device (PFD; also referred to as a life jacket, life preserver, life belt, Mae West, life vest, life saver, cork jacket, buoyancy aid or flotation suit) is a flotation device in the form of a vest or suite that is worn by a ...
s were stowed under each seat.
One of the most striking aspects of Comet travel was the quiet, "vibration-free flying" as touted by BOAC.[Walker 2000, p. 69.] For passengers used to propeller-driven airliners, smooth and quiet jet flight was a novel experience.[Francis 1950, p. 100.]
Avionics and systems
For ease of training and fleet conversion, de Havilland designed the Comet's flight deck layout with a degree of similarity to the Lockheed Constellation
The Lockheed Constellation ("Connie") is a propeller-driven, four-engined airliner built by Lockheed Corporation starting in 1943. The Constellation series was the first pressurized-cabin civil airliner series to go into widespread use. Its press ...
, an aircraft that was popular at the time with key customers such as BOAC. The cockpit included full dual-controls for the captain and first officer, and a flight engineer controlled several key systems, including fuel, air conditioning and electrical systems. The navigator occupied a dedicated station, with a table across from the flight engineer.[Darling 2001, p. 36.]
Several of the Comet's avionics systems were new to civil aviation. One such feature was irreversible, powered flight controls, which increased the pilot's ease of control and the safety of the aircraft by preventing aerodynamic forces from changing the directed positions and placement of the aircraft's control surfaces. Many of the control surfaces, such as the elevators, were equipped with a complex gearing system as a safeguard against accidentally over-stressing the surfaces or airframe at higher speed ranges.
The Comet had a total of four hydraulic system
Hydraulics (from Greek language, Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is th ...
s: two primaries, one secondary, and a final emergency system for basic functions such as lowering the undercarriage. The undercarriage could also be lowered by a combination of gravity and a hand-pump. Power was syphoned from all four engines for the hydraulics, cabin air conditioning
Air conditioning, often abbreviated as A/C or AC, is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as 'comfort cooling') and in some cases also strictly controlling ...
, and the de-icing system
In aeronautics, ice protection systems keep atmospheric moisture from accumulating on aircraft surfaces, such as wings, propellers, rotor blades, engine intakes, and environmental control intakes. Ice buildup can change the shape of airfoils a ...
; these systems had operational redundancy in that they could keep working even if only a single engine was active.[Darling 2001, p. 17.] The majority of hydraulic components were centred in a single avionics bay. A pressurised refuelling system, developed by Flight Refuelling Ltd
Flight or flying is the process by which an object moves through a space without contacting any planetary surface, either within an atmosphere (i.e. air flight or aviation) or through the vacuum of outer space (i.e. spaceflight). This can be a ...
, allowed the Comet's fuel tanks to be refuelled at a far greater rate than by other methods.
The cockpit was significantly altered for the Comet 4's introduction, on which an improved layout focusing on the onboard navigational suite was introduced.[Darling 2001, pp. 40–41.] An EKCO
EKCO (from Eric Kirkham Cole Limited) was a British electronics company producing radio and television sets from 1924 until 1960. Expanding into plastic production for its own use, Ekco Plastics produced both radio cases and later domestic plasti ...
E160 radar
Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...
unit was installed in the Comet 4's nose cone
A nose cone is the conically shaped forwardmost section of a rocket, guided missile or aircraft, designed to modulate oncoming airflow behaviors and minimize aerodynamic drag. Nose cones are also designed for submerged watercraft such a ...
, providing search functions as well as ground and cloud-mapping capabilities,[ and a radar interface was built into the Comet 4 cockpit along with redesigned instruments.][
Sud-Est's design bureau, while working on the ]Sud Aviation Caravelle
The Sud Aviation SE 210 Caravelle is a French jet airliner produced by Sud Aviation.
It was developed by SNCASE in the early 1950s and made its maiden flight on 27 May 1955.
It included some de Havilland designs and components developed for t ...
in 1953, licensed several design features from de Havilland, building on previous collaborations on earlier licensed designs, including the DH 100 Vampire; the nose and cockpit layout of the Comet 1 was grafted onto the Caravelle. In 1969, when the Comet 4's design was modified by Hawker Siddeley
Hawker Siddeley was a group of British manufacturing companies engaged in aircraft production. Hawker Siddeley combined the legacies of several British aircraft manufacturers, emerging through a series of mergers and acquisitions as one of onl ...
to become the basis for the Nimrod, the cockpit layout was completely redesigned and bore little resemblance to its predecessors except for the control yoke.
Fuselage
Diverse geographic destinations and cabin pressurisation alike on the Comet demanded the use of a high proportion of alloys, plastics, and other materials new to civil aviation across the aircraft to meet certification requirements.["Comet Engineering: The Performance of Airframe, Engines, and Equipment in Operational Service."]
''Flight International
''Flight International'' is a monthly magazine focused on aerospace. Published in the United Kingdom and founded in 1909 as "A Journal devoted to the Interests, Practice, and Progress of Aerial Locomotion and Transport", it is the world's oldes ...
,'' 1 May 1953, p. 551. Retrieved 26 April 2012. The Comet's high cabin pressure and fast operating speeds were unprecedented in commercial aviation, making its fuselage design an experimental process.[ At its introduction, Comet airframes would be subjected to an intense, high-speed operating schedule which included simultaneous extreme heat from desert airfields and frosty cold from the kerosene-filled fuel tanks, still cold from cruising at high altitude.][
]
The Comet's thin metal skin was composed of advanced new alloys and was both riveted and chemically bonded, which saved weight and reduced the risk of fatigue cracks spreading from the rivets. The chemical bonding process was accomplished using a new adhesive
Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation.
The use of adhesives offers certain advant ...
, Redux, which was liberally used in the construction of the wings and the fuselage of the Comet; it also had the advantage of simplifying the manufacturing process.
When several of the fuselage alloys were discovered to be vulnerable to weakening via metal fatigue
In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts o ...
, a detailed routine inspection process was introduced. As well as thorough visual inspections of the outer skin, mandatory structural sampling was routinely conducted by both civil and military Comet operators. The need to inspect areas not easily viewable by the naked eye led to the introduction of widespread radiography
Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeut ...
examination in aviation; this also had the advantage of detecting cracks and flaws too small to be seen otherwise.
Operationally, the design of the cargo holds led to considerable difficulty for the ground crew, especially baggage handler
In the airline industry, a baggage handler is a person who loads and unloads baggage (suitcases or luggage), and other cargo (airfreight, mail, counter-to-counter packages) for transport via aircraft. With most airlines, the formal job title is ...
s at the airports. The cargo hold had its doors located directly underneath the aircraft, so each item of baggage or cargo had to be loaded vertically upwards from the top of the baggage truck, then slid along the hold floor to be stacked inside. The individual pieces of luggage and cargo also had to be retrieved in a similarly slow manner at the arriving airport.
Propulsion
The Comet was powered by two pairs of turbojet engines buried in the wings close to the fuselage. Chief designer Bishop chose the Comet's embedded-engine configuration because it avoided the drag of podded engine
A podded engine is a jet engine that has been built up and integrated in its nacelle. This may be done in a podding facility as part of an aircraft assembly process. The nacelle contains the engine, engine mounts and parts which are required to r ...
s and allowed for a smaller fin and rudder since the hazards of asymmetric thrust were reduced.[Francis 1950, pp. 101–102.] The engines were outfitted with baffles to reduce noise emissions, and extensive soundproofing
Soundproofing is any means of impeding sound propagation. There are several basic approaches to reducing sound: increasing the distance between source and receiver, decoupling, using noise barriers to reflect or absorb the energy of the sound wav ...
was also implemented to improve passenger conditions.
Placing the engines within the wings had the advantage of a reduction in the risk of foreign object damage
In aviation and aerospace, foreign object debris (FOD), is any particle or substance, alien to an aircraft or system, which could potentially cause damage.
External FOD hazards include bird strikes, hail, ice, sandstorms, ash-clouds or obje ...
, which could seriously damage jet engines. The low-mounted engines and good placement of service panels also made aircraft maintenance easier to perform. The Comet's buried-engine configuration increased its structural weight and complexity. Armour had to be placed around the engine cells to contain debris from any serious engine failures; also, placing the engines inside the wing required a more complicated wing structure.[Francis 1950, p. 103.]
The Comet 1 featured de Havilland Ghost 50 Mk1 turbojet engines. Two hydrogen peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3% ...
-powered de Havilland Sprite
The de Havilland Sprite is a British rocket engine that was built by de Havilland in the early-1950s for use in RATO (Rocket-assisted take off) applications. A developed engine with slightly less thrust but a longer burn time was known as th ...
booster rockets were originally intended to be installed to boost takeoff
Takeoff is the phase of flight in which an aerospace vehicle leaves the ground and becomes airborne. For aircraft traveling vertically, this is known as liftoff.
For aircraft that take off horizontally, this usually involves starting with a t ...
under hot and high
In aviation, hot and high is a condition of low air density due to high ambient temperature and high airport elevation. Air density decreases with increasing temperature and altitude. The lower air density reduces the power output from the airc ...
altitude conditions from airports such as Khartoum and Nairobi.[Francis 1950, pp. 98–102.] These were tested on 30 flights, but the Ghosts alone were considered powerful enough and some airlines concluded that rocket motors were impractical. Sprite fittings were retained on production aircraft. Comet 1s subsequently received more powerful Ghost DGT3 series engines.[
From the Comet 2 onwards, the Ghost engines were replaced by the newer and more powerful Rolls-Royce Avon AJ.65 engines. To achieve optimum efficiency with the new powerplants, the air intakes were enlarged to increase mass air flow.][ Upgraded Avon engines were introduced on the Comet 3,][ and the Avon-powered Comet 4 was highly praised for its takeoff performance from high-altitude locations such as Mexico City where it was operated by ]Mexicana de Aviacion
Mexicana may refer to:
* a woman born in Mexico
* Mexicana de Aviación, a former airline of Mexico
* ''Mexicana'' (ship), a topsail schooner built in 1791 by the Spanish Navy
* ''Mexicana'' (film), a 1945 American film
* ''Mexicana'' (genus), ...
, a major scheduled passenger air carrier.
Operational history
Introduction
The earliest production aircraft, registered G-ALYP ("Yoke Peter"), first flew on 9 January 1951 and was subsequently lent to BOAC for development flying by its Comet Unit.[Davies and Birtles 1999, p. 31.] On 22 January 1952, the fifth production aircraft, registered G-ALYS, received the first Certificate of Airworthiness awarded to a Comet, six months ahead of schedule.[Davies and Birtles 1999, p. 34.] On 2 May 1952, as part of BOAC's route-proving trials, G-ALYP took off on the world's first jetliner flight with fare-paying passengers and inaugurated scheduled service from London to Johannesburg.[McNeil 2002, p. 39.]["On This Day: Comet inaugurates the jet age."]
''BBC News,'' 2 May 1952. Retrieved 26 April 2012.[Cookman, Aubrey O. Jr]
"I Rode The First Jet Airliner."
''Popular Mechanics'', July 1952, pp. 90–94. Retrieved 26 April 2012. The final Comet from BOAC's initial order, registered G-ALYZ, began flying in September 1952 and carried cargo along South American routes while simulating passenger schedules.
Prince Philip returned from the Helsinki Olympic Games with G-ALYS on 4 August 1952. Queen Elizabeth, the Queen Mother
Elizabeth Angela Marguerite Bowes-Lyon (4 August 1900 – 30 March 2002) was Queen of the United Kingdom and the Dominions of the British Commonwealth from 11 December 1936 to 6 February 1952 as the wife of King George VI. She was the l ...
and Princess Margaret
Princess Margaret, Countess of Snowdon, (Margaret Rose; 21 August 1930 – 9 February 2002) was the younger daughter of King George VI and Queen Elizabeth The Queen Mother, and the younger sister and only sibling of Queen Elizabeth ...
were guests on a special flight of the Comet on 30 June 1953 hosted by Sir Geoffrey and Lady de Havilland. Flights on the Comet were about 50 percent faster compared to advanced piston-engined aircraft such as the Douglas DC-6
The Douglas DC-6 is a piston-powered airliner and cargo aircraft built by the Douglas Aircraft Company from 1946 to 1958. Originally intended as a military transport near the end of World War II, it was reworked after the war to compete with th ...
()
vs , respectively), and a faster rate of climb further cut flight times. In August 1953 BOAC scheduled the nine-stop London to Tokyo flights by Comet for 36 hours, compared to 86 hours and 35 minutes on its Argonaut
The Argonauts (; Ancient Greek: ) were a band of heroes in Greek mythology, who in the years before the Trojan War (around 1300 BC) accompanied Jason to Colchis in his quest to find the Golden Fleece. Their name comes from their ship, ''Argo'', ...
piston airliner. (Pan Am
Pan American World Airways, originally founded as Pan American Airways and commonly known as Pan Am, was an American airline that was the principal and largest international air carrier and unofficial overseas flag carrier of the United States ...
's DC-6B was scheduled for 46 hours 45 minutes.) The five-stop flight from London to Johannesburg was scheduled for 21 hr 20 min.
In their first year, Comets carried 30,000 passengers. As the aircraft could be profitable with a load factor as low as 43 percent, commercial success was expected.[Walker 2000, p. 25.] The Ghost engines allowed the Comet to fly above weather that competitors had to fly through. They ran smoothly and were less noisy than piston engines, had low maintenance costs and were fuel-efficient above . In summer 1953, eight BOAC Comets left London each week: three to Johannesburg, two to Tokyo, two to Singapore and one to Colombo.
In 1953, the Comet appeared to have achieved success for de Havilland. ''Popular Mechanics
''Popular Mechanics'' (sometimes PM or PopMech) is a magazine of popular science and technology, featuring automotive, home, outdoor, electronics, science, do-it-yourself, and technology topics. Military topics, aviation and transportation o ...
'' wrote that Britain had a lead of three to five years on the rest of the world in jetliners.[ As well as the sales to BOAC, two French airlines, ]Union Aéromaritime de Transport
''Union Aéromaritime de Transport'' (UAT) was a French airline. It had its head office in the 8th arrondissement of Paris.[Air India
Air India is the flag carrier airline of India, headquartered at New Delhi. It is owned by Talace Private Limited, a Special-Purpose Vehicle (SPV) of Tata Sons, after Air India Limited's former owner, the Government of India, completed the sa ...](_blank)
, British Commonwealth Pacific Airlines
British Commonwealth Pacific Airlines or BCPA, was an airline registered in New South Wales, Australia in June 1946 with headquarters in Sydney. It was formed by the governments of Australia (50%), New Zealand (30%) and the United Kingdom (20% ...
, Japan Air Lines
, also known as JAL (''Jaru'') or , is an international airline and Japan's flag carrier and largest airline as of 2021 and 2022, headquartered in Shinagawa, Tokyo. Its main hubs are Tokyo's Narita International Airport and Haneda Airport, as ...
, Linea Aeropostal Venezolana
Aeropostal Alas de Venezuela C.A. is a state-owned airline of Venezuela based in Torre Polar Oeste in Caracas, Venezuela. It operates domestic services and international services in the Caribbean. Its main base is Simón Bolívar International ...
, and Panair do Brasil
Panair do Brasil was an airline of Brazil. Between 1945 and 1965 it was considered to be the largest carrier not only in Brazil but in all of Latin America. It ceased operations in 1965.
History
NYRBA do Brasil (1929–1930)
''Panair do Bras ...
. American carriers Capital Airlines, National Airlines, and Pan Am
Pan American World Airways, originally founded as Pan American Airways and commonly known as Pan Am, was an American airline that was the principal and largest international air carrier and unofficial overseas flag carrier of the United States ...
placed orders for the planned Comet 3, an even-larger, longer-range version for transatlantic operations.[Darling 2005, p. 128.] Qantas was interested in the Comet 1 but concluded that a version with more range and better takeoff performance was needed for the London to Canberra route.
Early hull losses
On 26 October 1952, the Comet suffered its first hull loss when a BOAC flight departing Rome's Ciampino airport
Ciampino () is a city and ''comune'' in the Metropolitan City of Rome, Lazio, Italy. It was a ''frazione'' of Marino until 1974, when it became a ''comune''; it obtained the city ( it, città) status (being therefore officially known as Città ...
failed to become airborne and ran into rough ground at the end of the runway. Two passengers sustained minor injuries, but the aircraft, G-ALYZ, was a write-off. On 3 March 1953, a new Canadian Pacific Airlines
Canadian Pacific Air Lines was a Canadian airline that operated from 1942 to 1987. It operated under the name CP Air from 1968 to 1986. Headquartered at Vancouver International Airport in Richmond, British Columbia, it served domestic Canadian a ...
Comet 1A, registered CF-CUN and named ''Empress of Hawaii,'' failed to become airborne while attempting a night takeoff from Karachi, Pakistan, on a delivery flight to Australia. The aircraft plunged into a dry drainage canal and collided with an embankment, killing all five crew and six passengers on board. The accident was the first fatal jetliner crash. In response, Canadian Pacific cancelled its remaining order for a second Comet 1A and never operated the type in commercial service.
Both early accidents were originally attributed to pilot error, as over-rotation had led to a loss of lift from the leading edge
The leading edge of an airfoil surface such as a wing is its foremost edge and is therefore the part which first meets the oncoming air.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, ...
of the aircraft's wings. It was later determined that the Comet's wing profile experienced a loss of lift at a high angle of attack
In fluid dynamics, angle of attack (AOA, α, or \alpha) is the angle between a reference line on a body (often the chord line of an airfoil) and the vector representing the relative motion between the body and the fluid through which it is m ...
, and its engine inlets also suffered a lack of pressure recovery in the same conditions. As a result, de Havilland re-profiled the wings' leading edge with a pronounced "droop",[Withuhn 1976, p. 85.] and wing fence
Wing fences, also known as boundary layer fences and potential fences are fixed aerodynamic devices attached to aircraft wings. Often seen on swept-wing aircraft, wing fences are flat plates fixed to the upper surfaces parallel to the wing ch ...
s were added to control spanwise flow.[Birtles 1970, p. 127.] A fictionalised investigation into the Comet's takeoff accidents was the subject of the novel '' Cone of Silence'' (1959) by Arthur David Beaty, a former BOAC captain. ''Cone of Silence'' was made into a film
A film also called a movie, motion picture, moving picture, picture, photoplay or (slang) flick is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, feelings, beauty, or atmosphere ...
in 1960, and Beaty also recounted the story of the Comet's takeoff accidents in a chapter of his non-fiction work, ''Strange Encounters: Mysteries of the Air'' (1984).
The Comet's second fatal accident occurred on 2 May 1953, when BOAC Flight 783
On 2 May 1953, BOAC Flight 783, a de Havilland Comet jetliner registered G-ALYV and operated by British Overseas Airways Corporation, broke up mid-air and crashed after encountering a severe squall, shortly after taking off from Calcutta (now Ko ...
, a Comet 1, registered G-ALYV, crashed in a severe thundersquall six minutes after taking off from Calcutta-Dum Dum (now Netaji Subhash Chandra Bose International Airport
Netaji Subhash Chandra Bose International Airport is an international airport located in Kolkata, West Bengal, India, serving the Kolkata Metropolitan Area and is the aviation hub for eastern and northeastern India. It is located approximatel ...
), India, killing all 43 on board. Witnesses observed the wingless Comet on fire plunging into the village of Jagalgori, leading investigators to suspect structural failure.
India Court of Inquiry
After the loss of G-ALYV, the Government of India
The Government of India (ISO: ; often abbreviated as GoI), known as the Union Government or Central Government but often simply as the Centre, is the national government of the Republic of India, a federal democracy located in South Asia, c ...
convened a court of inquiry to examine the cause of the accident. Professor Natesan Srinivasan joined the inquiry as the main technical expert. A large portion of the aircraft was recovered and reassembled at Farnborough, during which the break-up was found to have begun with a left elevator spar failure in the horizontal stabilizer
A tailplane, also known as a horizontal stabiliser, is a small lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters and gyroplan ...
. The inquiry concluded that the aircraft had encountered extreme negative G force
The gravitational force equivalent, or, more commonly, g-force, is a measurement of the type of force per unit mass – typically acceleration – that causes a perception of weight, with a g-force of 1 g (not gram in mass measure ...
s during takeoff; severe turbulence generated by adverse weather was determined to have induced down-loading, leading to the loss of the wings. Examination of the cockpit controls suggested that the pilot may have inadvertently over-stressed the aircraft when pulling out of a steep dive by over-manipulation of the fully powered flight controls. Investigators did not consider metal fatigue as a contributory cause.[Lo Bao 1996, p. 7.]
The inquiry's recommendations revolved around the enforcement of stricter speed limits during turbulence, and two significant design changes also resulted: all Comets were equipped with weather radar
Weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, and estimate its type (rain, snow, hail etc.). Modern weather radars are mostly puls ...
and the "Q feel" system was introduced, which ensured that control column forces (invariably called stick forces) would be proportional to control loads. This artificial feel was the first of its kind to be introduced in any aircraft. The Comet 1 and 1A had been criticised for a lack of "feel
Feel may refer to:
*Feeling
Music Bands
*Feel (New York band), a dance and R&B band
*Feel (Polish band), a pop rock band
Songs
* "Feel" (Kendrick Lamar song), 2017
* "Feel", by Phora, 2018
*"Feel", by Mahmut Orhan, 2016
* "Feel" (Kumi Koda song), ...
" in their controls, and investigators suggested that this might have contributed to the pilot's alleged over-stressing of the aircraft; Comet chief test pilot John Cunningham contended that the jetliner flew smoothly and was highly responsive in a manner consistent with other de Havilland aircraft.[Faith 1996, pp. 63–64.]
Comet disasters of 1954
Just over a year later, Rome's Ciampino airport, the site of the first Comet hull loss, was the origin of a more-disastrous Comet flight. On 10 January 1954, 20 minutes after taking off from Ciampino, the first production Comet, G-ALYP, broke up in mid-air while operating BOAC Flight 781
BOAC Flight 781 was a scheduled British Overseas Airways Corporation (BOAC) passenger flight from Singapore to London. On 10 January 1954, a de Havilland Comet passenger jet operating the flight suffered an explosive decompression at altitude an ...
and crashed into the Mediterranean off the Italian island of Elba
Elba ( it, isola d'Elba, ; la, Ilva) is a Mediterranean island in Tuscany, Italy, from the coastal town of Piombino on the Italian mainland, and the largest island of the Tuscan Archipelago. It is also part of the Arcipelago Toscano National ...
with the loss of all 35 on board. With no witnesses to the disaster and only partial radio transmissions as incomplete evidence, no obvious reason for the crash could be deduced. Engineers at de Havilland immediately recommended 60 modifications aimed at any possible design flaw, while the Abell Committee met to determine potential causes of the crash. BOAC also voluntarily grounded its Comet fleet pending investigation into the causes of the accident.[Darling 2001, pp. 28–30.]
Abell Committee Court of Inquiry
Media attention centred on potential sabotage
Sabotage is a deliberate action aimed at weakening a polity, effort, or organization through subversion, obstruction, disruption, or destruction. One who engages in sabotage is a ''saboteur''. Saboteurs typically try to conceal their identitie ...
; other speculation ranged from clear-air turbulence
In meteorology, clear-air turbulence (CAT) is the turbulent movement of air masses in the absence of any visual clues, such as clouds, and is caused when bodies of air moving at widely different speeds meet.
The atmospheric region most suscepti ...
to an explosion of vapour in an empty fuel tank. The Abell Committee focused on six potential aerodynamic and mechanical causes: control flutter (which had led to the loss of DH 108 prototypes), structural failure due to high loads or metal fatigue
In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts o ...
of the wing structure, failure of the powered flight controls, failure of the window panels leading to explosive decompression, or fire and other engine problems. The committee concluded that fire was the most likely cause of the problem, and changes were made to the aircraft to protect the engines and wings from damage that might lead to another fire.
During the investigation, the Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...
conducted recovery operations. The first pieces of wreckage were discovered on 12 February 1954 and the search continued until September 1954, by which time 70 percent by weight of the main structure, 80 percent of the power section, and 50 percent of the aircraft's systems and equipment had been recovered.[''Flight'' 29 October 1954, p. 652.] The forensic reconstruction effort had just begun when the Abell Committee reported its findings. No apparent fault in the aircraft was found, and the British government decided against opening a further public inquiry into the accident.[ The prestigious nature of the Comet project, particularly for the British aerospace industry, and the financial impact of the aircraft's grounding on BOAC's operations both served to pressure the inquiry to end without further investigation.][ Comet flights resumed on 23 March 1954.][Birtles 1970, pp. 128–129.]
On 8 April 1954, Comet G-ALYY ("Yoke Yoke"), on charter to South African Airways
South African Airways (SAA) is the flag carrier airline of South Africa. Founded in 1934, the airline is headquartered in Airways Park at O. R. Tambo International Airport in Johannesburg and operated a hub-and-spoke network, serving ten destin ...
, was on a leg from Rome to Cairo (of a longer route, SA Flight 201 from London to Johannesburg), when it crashed in the Mediterranean near Naples with the loss of all 21 passengers and crew on board. The Comet fleet was immediately grounded once again and a large investigation board was formed under the direction of the Royal Aircraft Establishment
The Royal Aircraft Establishment (RAE) was a British research establishment, known by several different names during its history, that eventually came under the aegis of the Ministry of Defence (United Kingdom), UK Ministry of Defence (MoD), bef ...
(RAE). Prime Minister Winston Churchill
Sir Winston Leonard Spencer Churchill (30 November 187424 January 1965) was a British statesman, soldier, and writer who served as Prime Minister of the United Kingdom twice, from 1940 to 1945 Winston Churchill in the Second World War, dur ...
tasked the Royal Navy with helping to locate and retrieve the wreckage so that the cause of the accident could be determined. The Comet's Certificate of Airworthiness was revoked, and Comet 1 line production was suspended at the Hatfield factory while the BOAC fleet was permanently grounded, cocooned and stored.
Cohen Committee Court of Inquiry
On 19 October 1954, the Cohen Committee was established to examine the causes of the Comet crashes. Chaired by Lord Cohen, the committee tasked an investigation team led by Sir Arnold Hall, Director of the RAE at Farnborough, to perform a more-detailed investigation. Hall's team began considering fatigue as the most likely cause of both accidents and initiated further research into measurable strain on the aircraft's skin. With the recovery of large sections of G-ALYP from the Elba crash and BOAC's donation of an identical airframe, G-ALYU, for further examination, an extensive "water torture" test eventually provided conclusive results. This time, the entire fuselage was tested in a dedicated water tank that was built specifically at Farnborough to accommodate its full length.[
]
In water-tank testing, engineers subjected G-ALYU to repeated repressurisation and over-pressurisation, and on 24 June 1954, after 3,057 flight cycles (1,221 actual and 1,836 simulated),[ G-ALYU burst open. Hall, Geoffrey de Havilland and Bishop were immediately called to the scene, where the water tank was drained to reveal that the fuselage had ripped open at a bolt hole, forward of the forward left escape hatch cut out. The failure then occurred longitudinally along a fuselage stringer at the widest point of the fuselage and through a cut out for an escape hatch. The skin thickness was discovered to be insufficient to distribute the load across the structure, leading to overloading of fuselage frames adjacent to fuselage cut outs. (Cohen Inquiry accident report Fig 7). The fuselage frames did not have sufficient strength to prevent the crack from propagating. Although the fuselage failed after a number of cycles that represented three times the life of G-ALYP at the time of the accident, it was still much earlier than expected. A further test reproduced the same results.][Withuhn 1976, p. 87.] Based on these findings, Comet 1 structural failures could be expected at anywhere from 1,000 to 9,000 cycles. Before the Elba accident, G-ALYP had made 1,290 pressurised flights, while G-ALYY had made 900 pressurised flights before crashing. Dr P. B. Walker, Head of the Structures Department at the RAE, said he was not surprised by this, noting that the difference was about three to one, and previous experience with metal fatigue suggested a total range of nine to one between experiment and outcome in the field could result in failure.
The RAE also reconstructed about two-thirds of G-ALYP at Farnborough and found fatigue crack growth from a rivet hole at the low-drag fibreglass
Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clo ...
forward aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane.
An opt ...
around the Automatic Direction Finder
An automatic direction finder (ADF) is a marine or aircraft radio-navigation instrument that automatically and continuously displays the relative bearing from the ship or aircraft to a suitable radio station. ADF receivers are normally tuned to ...
, which had caused a catastrophic break-up of the aircraft in high-altitude flight. The exact origin of the fatigue failure could not be identified but was localised to the ADF antenna cut out. A countersunk bolt hole and manufacturing damage that had been repaired at the time of construction using methods that were common, but were likely insufficient allowing for the stresses involved, were both located along the failure crack. Once the crack initiated the skin failed from the point of the ADF cut out and propagated downwards and rearwards along a stringer resulting in an explosive decompression.
It was also found that the punch-rivet construction technique employed in the Comet's design had exacerbated its structural fatigue problems; the aircraft's windows had been engineered to be glued and riveted, but had been punch-riveted only. Unlike drill riveting, the imperfect nature of the hole created by punch-riveting could cause fatigue cracks to start developing around the rivet. Principal investigator Hall accepted the RAE's conclusion of design and construction flaws as the likely explanation for G-ALYU's structural failure after 3,060 pressurisation cycles.
Earlier structural indications
The issue of the lightness of Comet 1 construction (in order to not tax the relatively low thrust DeHavilland Ghost engines), had been noted by DeHavilland test pilot John Wilson, while flying the prototype during a Farnborough flypast in 1949. On the flight, he was accompanied by Chris Beaumont, Chief Test Pilot of the DeHavilland Engine Company (that made the Comet 1's Ghost engines) who stood in the entrance to the cockpit behind the Flight Engineer. He stated "Every time we pulled 2 1/2-3G to go around the corner, Chris found that the floor on which he was standing, bulging up and there was a loud bang at that speed from the nose of the aircraft where the skin 'panted' (flexed), so when we heard this bang we knew without checking the airspeed indicator, that we were doing 340 knots. In later years we realised that these were the indications of how flimsy the structure really was."
Square window myths
Despite findings of the Cohen Inquiry, a number of myths have evolved around the cause of the Comet 1's accidents. Most commonly quoted are the 'square' passenger windows. While the report noted that stress around fuselage cut-outs, emergency exits and windows was found to be much higher than expected due to DeHavilland's assumptions and testing methods the passenger windows shape has been commonly misunderstood and cited as a cause of the fuselage failure. In fact the mention of 'windows' in the Cohen report's conclusion, refers specifically to the origin point of failure in the ADF Antenna cut-out 'windows', located above the cockpit, not passenger windows. The shape of the passenger windows were not indicated in any failure mode detailed in the accident report and were not viewed as a contributing factor. A number of other pressurised airliners of the period including the Boeing 377 Stratocruiser, Douglas DC-7, and DC-8 had larger more 'square' windows than the Comet 1 and experienced no such failures. [The DeHavilland Comet Disaster - Aerospace Engineering - Paul Withey Professor of Casting at the University of Birmingham School of Metallurgy - Video presentation retrieved 30NOV22] In fact, the Comet 1's window general shape resembles a slightly larger Boeing 737 window mounted horizontally. They are rectangular ''not square'', have rounded corners and are within 5% of the radius of the Boeing 737 windows and virtually identical to modern airliners. Paul Withey, Professor of Casting at the University of Birmingham School of Metallurgy states in a video presentation delivered in 2019, analysing all available data that: "The fact that DeHavilland put oval windows into later marks, is not because of any 'squareness' of the windows that caused failure." "DeHavilland went to oval windows on the subsequent Marks because it was easier to Redux them in,(use adhesive) - nothing to do with the stress concentration and it's purely to remove rivets." (from the structure)
Surviving Comet 1s can be seen on view at the RAF Museum Cosford and the DeHavilland Museum at Salisbury Hall, London Colney.
Response
In responding to the report de Havilland stated: "Now that the danger of high level fatigue in pressure cabins has been generally appreciated, de Havillands will take adequate measures to deal with this problem. To this end we propose to use thicker gauge materials in the pressure cabin area and to strengthen and redesign windows and cut outs and so lower the general stress to a level at which local stress concentrations either at rivets and bolt holes or as such may occur by reason of cracks caused accidentally during manufacture or subsequently, will not constitute a danger."
The Cohen inquiry closed on 24 November 1954, having "found that the basic design of the Comet was sound", and made no observations or recommendations regarding the shape of the windows. De Havilland nonetheless began a refit programme to strengthen the fuselage and wing structure, employing thicker-gauge skin and replacing the rectangular windows and panels with rounded versions, although this was not related to the erroneous 'square' window claim, as can be seen by the fact that the fuselage escape hatch cut-outs (the source of the failure in test aircraft G-ALYU) retained their rectangular shape.[Davies and Birtles 1999, pp. 30–31.]
Following the Comet enquiry, aircraft were designed to "Fail safe" or "Safe Life" standards, though several subsequent catastrophic fatigue failures, such as Aloha Airlines Flight 243
Aloha Airlines Flight 243 (IATA: AQ243, ICAO: AAH243) was a scheduled Aloha Airlines flight between Hilo and Honolulu in Hawaii. On April 28, 1988, a Boeing 737-297 serving the flight suffered extensive damage after an explosive decompression ...
of April 28, 1988 have occurred.
Resumption of service
With the discovery of the structural problems of the early series, all remaining Comets were withdrawn from service, while de Havilland launched a major effort to build a new version that would be both larger and stronger. All outstanding orders for the Comet 2 were cancelled by airline customers.[Darling 2001, p. 33.] All production Comet 2s were also modified with thicker gauge skin to better distribute loads and alleviate the fatigue problems (most of these served with the RAF
The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...
as the Comet C2); a programme to produce a Comet 2 with more powerful Avons was delayed. The prototype Comet 3 first flew in July 1954 and was tested in an unpressurised state pending completion of the Cohen inquiry.[ Comet commercial flights would not resume until 1958.
Development flying and route proving with the Comet 3 allowed accelerated certification of what was destined to be the most successful variant of the type, the Comet 4. All airline customers for the Comet 3 subsequently cancelled their orders and switched to the Comet 4,][ which was based on the Comet 3 but with improved fuel capacity. BOAC ordered 19 Comet 4s in March 1955, and American operator Capital Airlines ordered 14 Comets in July 1956. Capital's order included 10 Comet 4As, a variant modified for short-range operations with a stretched fuselage and short wings, lacking the pinion (outboard wing) fuel tanks of the Comet 4.] Financial problems and a takeover by United Airlines
United Airlines, Inc. (commonly referred to as United), is a major American airline headquartered at the Willis Tower in Chicago, Illinois. meant that Capital would never operate the Comet.
The Comet 4 first flew on 27 April 1958 and received its Certificate of Airworthiness on 24 September 1958; the first was delivered to BOAC the next day.[Lo Bao 1996, p. 11.] The base price of a new Comet 4 was roughly £1.14 million (£ million in ). The Comet 4 enabled BOAC to inaugurate the first regular jet-powered transatlantic services on 4 October 1958 between London and New York (albeit still requiring a fuel stop at Gander International Airport
Gander International Airport is located in Gander, Newfoundland and Labrador, Canada, and is operated by the Gander International Airport Authority. Canadian Forces Base Gander shares the airfield but is a separate entity from the airport. The ...
, Newfoundland, on westward North Atlantic crossings). While BOAC gained publicity as the first to provide transatlantic jet service, by the end of the month rival Pan American World Airways was flying the Boeing 707
The Boeing 707 is an American, long-range, narrow-body airliner, the first jetliner developed and produced by Boeing Commercial Airplanes.
Developed from the Boeing 367-80 prototype first flown in 1954, the initial first flew on December 20, ...
on the New York-Paris route, with a fuel stop at Gander in both directions, and in 1960 began flying Douglas DC-8's on its transatlantic routes as well. The American jets were larger, faster, longer-ranged and more cost-effective than the Comet. After analysing route structures for the Comet, BOAC reluctantly cast-about for a successor, and in 1956 entered into an agreement with Boeing to purchase the 707.
The Comet 4 was ordered by two other airlines: Aerolíneas Argentinas
Aerolíneas Argentinas, formally Aerolíneas Argentinas S.A., is Argentina's largest airline and the country flag carrier. The airline was created in 1949 from the merger of four companies and started operations in . A consortium led by Iberia ...
took delivery of six Comet 4s from 1959 to 1960, using them between Buenos Aires and Santiago, New York and Europe, and East African Airways
East African Airways Corporation, more commonly known as East African Airways, was an airline jointly run by Kenya, Tanzania, and Uganda. It was set up on 1 January 1946, starting operations the same year. The airline was headquartered in the Sa ...
received three new Comet 4s from 1960 to 1962 and operated them to the United Kingdom and to Kenya, Tanzania, and Uganda.[Darling 2005, p. 114.] The Comet 4A ordered by Capital Airlines was instead built for BEA as the Comet 4B, with a further fuselage stretch of and seating for 99 passengers. The first Comet 4B flew on 27 June 1959 and BEA began Tel Aviv to London-Heathrow services on 1 April 1960. Olympic Airways
Olympic Airlines ( el, Ολυμπιακές Αερογραμμές, ''Olympiakés Aerogrammés'' – OA), formerly named Olympic Airways for at least four decades, was the flag carrier airline of Greece. The airline's head office was located ...
was the only other customer to order the type.[Jackson 1987, p. 459.] The last Comet 4 variant, the Comet 4C, first flew on 31 October 1959 and entered service with Mexicana in 1960. The Comet 4C had the Comet 4B's longer fuselage and the longer wings and extra fuel tanks of the original Comet 4, which gave it a longer range than the 4B. Ordered by Kuwait Airways
Kuwait Airways ( ar, الخطوط الجوية الكويتية, ) is the national carrier of Kuwait, with its head office on the grounds of Kuwait International Airport, Al Farwaniyah Governorate. It operates scheduled international services th ...
, Middle East Airlines
Middle East Airlines – Air Liban S.A.L. ( ar, طيران الشرق الأوسط ـ الخطوط الجوية اللبنانية ''Ṭayyarān al-Sharq al-Awsaṭ – al-Khuṭūṭ al-jawiyyah al-lubnāniyyah''), more commonly known as Middle ...
, Misrair
Egyptair (Egyptian Arabic: , ') is the state-owned flag carrier of Egypt. The airline is headquartered at Cairo International Airport, its main hub, operating scheduled passenger and freight services to 81 destinations in the Middle East, Europ ...
(later United Arab Airlines), and Sudan Airways
Sudan Airways ( ar, الخطوط الجوية السودانية) is the national airline of Sudan, headquartered in Khartoum. Since 2012, the company has been fully owned by the Government of Sudan.
One of the oldest African carriers, it was ...
, it was the most popular Comet variant.
Later service
In 1959 BOAC began shifting its Comets from transatlantic routes and released the Comet to associate companies, making the Comet 4's ascendancy as a premier airliner brief. Besides the 707 and DC-8, the introduction of the Vickers VC10
The Vickers VC10 is a mid-sized, narrow-body long-range British jet airliner designed and built by Vickers-Armstrongs (Aircraft) Ltd and first flown at Brooklands, Surrey, in 1962. The airliner was designed to operate on long-distance route ...
allowed competing aircraft to assume the high-speed, long-range passenger service role pioneered by the Comet. In 1960, as part of a government-backed consolidation of the British aerospace industry, de Havilland itself was acquired by Hawker Siddeley, within which it became a wholly owned division.["De Havilland – Post War"]
, ''rafmuseum.org.uk''. Retrieved 30 May 2012
In the 1960s, orders declined, a total of 76 Comet 4s being delivered from 1958 to 1964. In November 1965, BOAC retired its Comet 4s from revenue service; other operators continued commercial passenger flights with the Comet until 1981. Dan-Air
Dan-Air (Dan Air Services Limited) was an airline based in the United Kingdom and a wholly owned subsidiary of London shipbroker, shipbroking firm Davies and Newman. It was started in 1953 with a single aircraft. Initially, it operated cargo a ...
played a significant role in the fleet's later history and, at one time, owned all 49 remaining airworthy civil Comets. On 14 March 1997 a Comet 4C serial ''XS235'' and named ''Canopus'',[ which had been acquired by the British ]Ministry of Technology
The Ministry of Technology was a department of the government of the United Kingdom, sometimes abbreviated as "MinTech". The Ministry of Technology was established by the incoming government of Harold Wilson in October 1964 as part of Wilson's am ...
and used for radio, radar and avionics trials, made the last documented production Comet flight.[Walker 2000, p. 169.]
Legacy
The Comet is widely regarded as both an adventurous step forward and a supreme tragedy; the aircraft's legacy includes advances in aircraft design and in accident investigations. The inquiries into the accidents that plagued the Comet 1 were perhaps some of the most extensive and revolutionary that have ever taken place, establishing precedents in accident investigation; many of the deep-sea salvage and aircraft reconstruction techniques employed have remained in use within the aviation industry. In spite of the Comet being subjected to what was then the most rigorous testing of any contemporary airliner, pressurisation and the dynamic stresses involved were not thoroughly understood at the time of the aircraft's development, nor was the concept of metal fatigue. Though these lessons could be implemented on the drawing board for future aircraft, corrections could only be retroactively applied to the Comet.
According to de Havilland's chief test pilot John Cunningham, who had flown the prototype's first flight, representatives from American manufacturers such as Boeing
The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and product ...
and Douglas
Douglas may refer to:
People
* Douglas (given name)
* Douglas (surname)
Animals
*Douglas (parrot), macaw that starred as the parrot ''Rosalinda'' in Pippi Longstocking
*Douglas the camel, a camel in the Confederate Army in the American Civil W ...
privately disclosed that if de Havilland had not experienced the Comet's pressurisation problems first, it would have happened to them. Cunningham likened the Comet to the later Concorde
The Aérospatiale/BAC Concorde () is a retired Franco-British supersonic airliner jointly developed and manufactured by Sud Aviation (later Aérospatiale) and the British Aircraft Corporation (BAC).
Studies started in 1954, and France an ...
and added that he had assumed that the aircraft would change aviation, which it subsequently did. Aviation author Bill Withuhn concluded that the Comet had pushed "'the state-of-the-art' beyond its limits."[Withuhn 1976, p. 88.]
Aeronautical-engineering firms were quick to respond to the Comet's commercial advantages and technical flaws alike; other aircraft manufacturers learned from, and profited by, the hard-earned lessons embodied by de Havilland's Comet.[Trischler and Helmuth 2003, p. 90.] The Comet's buried engines were used on some other early jet airliners, such as the Tupolev Tu-104
The Tupolev Tu-104 (NATO reporting name: Camel) is a retired twinjet, medium-range, narrow-body turbojet-powered Soviet airliner. It was the second to enter regular service, behind the British de Havilland Comet, and was the only jetliner operat ...
, but later aircraft, such as the Boeing 707 and Douglas DC-8, differed by employing podded engines held on pylons beneath the wings. Boeing stated that podded engines were selected for their passenger airliners because buried engines carried a higher risk of catastrophic wing failure in the event of engine fire. In response to the Comet tragedies, manufacturers also developed ways of pressurisation testing, often going so far as to explore rapid depressurisation; subsequent fuselage skins were of a greater thickness than the skin of the Comet.
Variants
Comet 1
The Comet 1 was the first model produced, a total of 12 aircraft in service and test. Following closely the design features of the two prototypes, the only noticeable change was the adoption of four-wheel bogie main undercarriage units, replacing the single main wheels. Four Ghost 50 Mk 1 engines were fitted (later replaced by more powerful Ghost DGT3 series engines). The span was , and overall length ; the maximum takeoff weight
The maximum takeoff weight (MTOW) or maximum gross takeoff weight (MGTOW) or maximum takeoff mass (MTOM) of an aircraft is the maximum weight at which the pilot is allowed to attempt to take off, due to structural or other limits. The analogous ...
was over and over 40 passengers could be carried.[Walker 2000, p. 190.]
* An updated Comet 1A was offered with higher-allowed weight, greater fuel capacity,[ and water-methanol injection; 10 were produced. In the wake of the 1954 disasters, all Comet 1s and 1As were brought back to Hatfield, placed in a protective cocoon and retained for testing. All were substantially damaged in stress testing or were scrapped entirely.]
* Comet 1X: Two RCAF Comet 1As were rebuilt with heavier-gauge skins to a Comet 2 standard for the fuselage, and renamed Comet 1X.[Jones 2010, p. 68.]
* Comet 1XB: Four Comet 1As were upgraded to a 1XB standard with a reinforced fuselage structure and oval windows. Both 1X series were limited in number of pressurisation cycles.[Walker 2000, p. 40.]
* The DH 111 Comet Bomber, a nuclear bomb-carrying variant developed to Air Ministry specification
This is a partial list of the British Air Ministry (AM) specifications for aircraft. A specification stemmed from an Operational Requirement, abbreviated "OR", describing what the aircraft would be used for. This in turn led to the specification i ...
B35/46, was submitted to the Air Ministry on 27 May 1948. It had been originally proposed in 1948 as the "PR Comet", a high-altitude photo reconnaissance adaptation of the Comet 1. The Ghost DGT3-powered airframe featured a narrowed fuselage, a bulbous nose with H2S Mk IX radar, and a four-crewmember pressurised cockpit under a large bubble canopy. Fuel tanks carrying were added to attain a range of . The proposed DH 111 received a negative evaluation from the Royal Aircraft Establishment
The Royal Aircraft Establishment (RAE) was a British research establishment, known by several different names during its history, that eventually came under the aegis of the Ministry of Defence (United Kingdom), UK Ministry of Defence (MoD), bef ...
over serious concerns regarding weapons storage; this, along with the redundant capability offered by the RAF's proposed V bomber
The "V bombers" were the Royal Air Force (RAF) aircraft during the 1950s and 1960s that comprised the United Kingdom's strategic nuclear strike force known officially as the V force or Bomber Command Main Force. The three models of strategic ...
trio, led de Havilland to abandon the project on 22 October 1948.
Comet 2
The Comet 2 had a slightly larger wing, higher fuel capacity and more-powerful Rolls-Royce Avon
The Rolls-Royce Avon was the first axial flow jet engine designed and produced by Rolls-Royce. Introduced in 1950, the engine went on to become one of their most successful post-World War II engine designs. It was used in a wide variety of ai ...
engines, which all improved the aircraft's range and performance; its fuselage was longer than the Comet 1's.[ Design changes had been made to make the aircraft more suitable for transatlantic operations.][Jackson 1980, p. 175.] Following the Comet 1 disasters, these models were rebuilt with heavier-gauge skin and rounded windows, and the Avon engines featuring larger air intakes and outward-curving jet tailpipes.[Munson 1967, p. 155.] A total of 12 of the 44-seat Comet 2s were ordered by BOAC for the South Atlantic route.["Comet Service To South America Planned" (News). ''The Times'', Saturday, Issue 52516, 10 January 1953, col G, p. 3.] The first production aircraft (G-AMXA) flew on 27 August 1953.[Jackson 1987, p. 456.] Although these aircraft performed well on test flights on the South Atlantic, their range was still not suitable for the North Atlantic. All but four Comet 2s were allocated to the RAF, deliveries beginning in 1955. Modifications to the interiors allowed the Comet 2s to be used in several roles. For VIP transport, the seating and accommodations were altered and provisions for carrying medical equipment including iron lungs were incorporated. Specialised signals intelligence
Signals intelligence (SIGINT) is intelligence-gathering by interception of ''signals'', whether communications between people (communications intelligence—abbreviated to COMINT) or from electronic signals not directly used in communication ( ...
and electronic surveillance capability was later added to some airframes.
* Comet 2X: Limited to a single Comet Mk 1 powered by four Rolls-Royce Avon 502 turbojet engines and used as a development aircraft for the Comet 2.
* Comet 2E: Two Comet 2 airliners were fitted with Avon 504s in the inner nacelles and Avon 524s in the outer ones. These aircraft were used by BOAC for proving flights during 1957–1958.
* Comet T2: The first two of 10 Comet 2s for the RAF were fitted out as crew trainers, the first aircraft (XK669) flying initially on 9 December 1955.[Swanborough 1962, p. 48.]
* Comet C2: Eight Comet 2s originally destined for the civil market were completed for the RAF and assigned to No. 216 Squadron.
* Comet 2R: Three Comet 2s were modified for use in radar and electronic systems development, initially assigned to No. 90 Group (later Signals Command) for the RAF. In service with No. 192 and No. 51 Squadrons, the 2R series was equipped to monitor Warsaw Pact
The Warsaw Pact (WP) or Treaty of Warsaw, formally the Treaty of Friendship, Cooperation and Mutual Assistance, was a collective defense treaty signed in Warsaw, Poland, between the Soviet Union and seven other Eastern Bloc socialist republic ...
signal traffic and operated in this role from 1958.
Comet 3
The Comet 3, which flew for the first time on 19 July 1954, was a Comet 2 lengthened by and powered by Avon M502 engines developing .[ The variant added wing pinion tanks, and offered greater capacity and range.][Jackson 1987, p. 457.] The Comet 3 was destined to remain a development series since it did not incorporate the fuselage-strengthening modifications of the later series aircraft, and was not able to be fully pressurised.[Birtles 1970, p. 129.] Only two Comet 3s began construction; G-ANLO, the only airworthy Comet 3, was demonstrated at the Farnborough SBAC Show in September 1954. The other Comet 3 airframe was not completed to production standard and was used primarily for ground-based structural and technology testing during development of the similarly sized Comet 4. Another nine Comet 3 airframes were not completed and their construction was abandoned at Hatfield. In BOAC colours, G-ANLO was flown by John Cunningham in a marathon round-the-world promotional tour in December 1955. As a flying testbed, it was later modified with Avon RA29 engines fitted, as well as replacing the original long-span wings with reduced span wings as the Comet 3B and demonstrated in British European Airways
British European Airways (BEA), formally British European Airways Corporation, was a British airline which existed from 1946 until 1974.
BEA operated to Europe, North Africa and the Middle East from airports around the United Kingdom. The a ...
(BEA) livery at the Farnborough Airshow in September 1958. Assigned in 1961 to the Blind Landing Experimental Unit (BLEU) at RAE Bedford, the final testbed role played by G–ANLO was in automatic landing system
In aviation, the instrument landing system (ILS) is a precision radio navigation system that provides short-range guidance to aircraft to allow them to approach a runway at night or in bad weather. In its original form, it allows an aircraft to ...
experiments. When retired in 1973, the airframe was used for foam-arrester trials before the fuselage was salvaged at BAE Woodford, to serve as the mock-up for the Nimrod
Nimrod (; ; arc, ܢܡܪܘܕ; ar, نُمْرُود, Numrūd) is a biblical figure mentioned in the Book of Genesis and Books of Chronicles. The son of Cush and therefore a great-grandson of Noah, Nimrod was described as a king in the land of ...
.
Comet 4
The Comet 4 was a further improvement on the stretched Comet 3 with even greater fuel capacity. The design had progressed significantly from the original Comet 1, growing by and typically seating 74 to 81 passengers compared to the Comet 1's 36 to 44 (119 passengers could be accommodated in a special charter seating package in the later 4C series).[Winchester 2004, p. 109.] The Comet 4 was considered the definitive series, having a longer range, higher cruising speed and higher maximum takeoff weight. These improvements were possible largely because of Avon engines, with twice the thrust of the Comet 1's Ghosts.[Davies and Birtles 1999, p. 62.] Deliveries to BOAC began on 30 September 1958 with two 48-seat aircraft, which were used to initiate the first scheduled transatlantic services.
* Comet 4B: Originally developed for Capital Airlines as the 4A, the 4B featured greater capacity through a 2m longer fuselage, and a shorter wingspan; 18 were produced.
* Comet 4C: This variant featured the Comet 4's wings and the 4B's longer fuselage; 23 were produced.
The last two Comet 4C fuselages were used to build prototypes of the Hawker Siddeley Nimrod maritime patrol aircraft.[ A Comet 4C (SA-R-7) was ordered by Saudi Arabian Airlines with an eventual disposition to the Saudi Royal Flight for the exclusive use of King Saud bin Abdul Aziz. Extensively modified at the factory, the aircraft included a VIP front cabin, a bed, special toilets with gold fittings and was distinguished by a green, gold and white colour scheme with polished wings and lower fuselage that was commissioned from aviation artist John Stroud. Following its first flight, the special order Comet 4C was described as "the world's first executive jet."
]
Comet 5 proposal
The Comet 5 was proposed as an improvement over previous models, including a wider fuselage with five-abreast seating, a wing with greater sweep and podded Rolls-Royce Conway
The Rolls-Royce RB.80 Conway was the first turbofan engine to enter service. Development started at Rolls-Royce in the 1940s, but the design was used only briefly, in the late 1950s and early 1960s, before other turbofan designs replaced it. H ...
engines. Without support from the Ministry of Transport
A ministry of transport or transportation is a ministry responsible for transportation within a country. It usually is administered by the ''minister for transport''. The term is also sometimes applied to the departments or other government age ...
, the proposal languished as a hypothetical aircraft and was never realised.
Hawker Siddeley Nimrod
The last two Comet 4C aircraft produced were modified as prototypes (XV148 & XV147) to meet a British requirement for a maritime patrol aircraft
A maritime patrol aircraft (MPA), also known as a patrol aircraft, maritime reconnaissance aircraft, or by the older American term patrol bomber, is a fixed-wing aircraft designed to operate for long durations over water in maritime patrol roles ...
for the Royal Air Force
The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...
; initially named "Maritime Comet", the design was designated Type HS 801.[Haddon-Cave 2009, p. 17.] This variant became the Hawker Siddeley Nimrod and production aircraft were built at the Hawker Siddeley
Hawker Siddeley was a group of British manufacturing companies engaged in aircraft production. Hawker Siddeley combined the legacies of several British aircraft manufacturers, emerging through a series of mergers and acquisitions as one of onl ...
factory at Woodford Aerodrome
Woodford Aerodrome is a former airfield and aircraft factory at Woodford, Greater Manchester, England, north of Macclesfield. It was opened by the Avro company after the First World War and became an important production centre for military ...
. Entering service in 1969, five Nimrod variants were produced. The final Nimrod aircraft were retired in June 2011.["Nimrod R1 makes final flight"]
''Defence Management Journal'', 28 June 2011. Retrieved 28 June 2011.
Operators
The original operators of the early Comet 1 and the Comet 1A were BOAC, Union Aéromaritime de Transport and Air France. All early Comets were withdrawn from service for accident inquiries, during which orders from British Commonwealth Pacific Airlines, Japan Air Lines, Linea Aeropostal Venezolana, National Airlines, Pan American World Airways and Panair do Brasil were cancelled. When the redesigned Comet 4 entered service, it was flown by customers BOAC, Aerolíneas Argentinas, and East African Airways,[Darling 2001, pp. 47–61.] while the Comet 4B variant was operated by customers BEA and Olympic Airways [ and the Comet 4C model was flown by customers Kuwait Airways, Mexicana, Middle East Airlines, Misrair Airlines and Sudan Airways.]
Other operators used the Comet either through leasing arrangements or through second-hand acquisitions. BOAC's Comet 4s were leased out to Air Ceylon
Air Ceylon was the former flag carrier airline of Ceylon (now Sri Lanka). The airline discontinued flights to Europe in early 1978 and finally ceased all local services on 31 August 1979, when it was replaced by Air Lanka and then rebranded to Sr ...
, Air India
Air India is the flag carrier airline of India, headquartered at New Delhi. It is owned by Talace Private Limited, a Special-Purpose Vehicle (SPV) of Tata Sons, after Air India Limited's former owner, the Government of India, completed the sa ...
, AREA Ecuador, Central African Airways
Central African Airways (CAA) was a supranational airline corporation serving as flag carrier for Southern Rhodesia, Northern Rhodesia and Nyasaland (respectively the present day countries of Zimbabwe, Zambia and Malawi), which were organised as ...
and Qantas Empire Airways
Qantas Airways Limited ( ) is the flag carrier of Australia and the country's largest airline by fleet size, international flights, and international destinations. It is the world's third-oldest airline still in operation, having been founded ...
;[Darling 2005, p. 119.] after 1965 they were sold to AREA Ecuador, Dan-Air
Dan-Air (Dan Air Services Limited) was an airline based in the United Kingdom and a wholly owned subsidiary of London shipbroker, shipbroking firm Davies and Newman. It was started in 1953 with a single aircraft. Initially, it operated cargo a ...
, Mexicana, Malaysian Airways
Malaysian may refer to:
* Something from or related to Malaysia, a country in Southeast Asia
* Malaysian Malay, a dialect of Malay language spoken mainly in Malaysia
* Malaysian people, people who are identified with the country of Malaysia regard ...
, and the Ministry of Defence. BEA's Comet 4Bs were chartered by Cyprus Airways
Cyprus Airways (Greek: Κυπριακές Αερογραμμές) is the flag carrier airline of Cyprus, based at Larnaca International Airport. It commenced operations on 1 June 2017.
History
Cyprus Airways resumed operations in 2016 after win ...
, Malta Airways and Transportes Aéreos Portugueses.[Darling 2005, p. 117.] Channel Airways obtained five Comet 4Bs from BEA in 1970 for inclusive tour charters.[Darling 2005, p. 138.] Dan-Air bought all of the surviving flyable Comet 4s from the late 1960s into the 1970s; some were for spares reclamation, but most were operated on the carrier's inclusive-tour charters; a total of 48 Comets of all marks were acquired by the airline.
In military service, the United Kingdom's Royal Air Force
The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...
was the largest operator, with No. 51 Squadron RAF, 51 Squadron (1958–1975; Comet C2, 2R), No. 192 Squadron RAF, 192 Squadron (1957–1958; Comet C2, 2R), No. 216 Squadron RAF, 216 Squadron (1956–1975; Comet C2 and C4), and the Royal Aircraft Establishment
The Royal Aircraft Establishment (RAE) was a British research establishment, known by several different names during its history, that eventually came under the aegis of the Ministry of Defence (United Kingdom), UK Ministry of Defence (MoD), bef ...
using the aircraft. The Royal Canadian Air Force also operated Comet 1As (later retrofitted to 1XB) through its No. 412 Squadron RCAF, 412 Squadron from 1953 to 1963.
Accidents and incidents
The Comet was involved in 26 hull loss, hull-loss accidents, including 13 fatal crashes which resulted in 426 fatalities.["de Havilland Comet hull-losses."]
''Aviation Safety Network.'' Retrieved: 28 May 2012. Pilot error was blamed for the type's first fatal accident, which occurred during takeoff at Jinnah International Airport, Karachi, Pakistan, on 3 March 1953 and involved a Canadian Pacific Airlines
Canadian Pacific Air Lines was a Canadian airline that operated from 1942 to 1987. It operated under the name CP Air from 1968 to 1986. Headquartered at Vancouver International Airport in Richmond, British Columbia, it served domestic Canadian a ...
Comet 1A.[Roach and Eastwood 1992, pp. 331–335.] Three fatal Comet 1 crashes due to structural problems, specifically BOAC Flight 783
On 2 May 1953, BOAC Flight 783, a de Havilland Comet jetliner registered G-ALYV and operated by British Overseas Airways Corporation, broke up mid-air and crashed after encountering a severe squall, shortly after taking off from Calcutta (now Ko ...
on 2 May 1953, BOAC Flight 781
BOAC Flight 781 was a scheduled British Overseas Airways Corporation (BOAC) passenger flight from Singapore to London. On 10 January 1954, a de Havilland Comet passenger jet operating the flight suffered an explosive decompression at altitude an ...
on 10 January 1954 and South African Airways Flight 201 on 8 April 1954, led to the grounding of the entire Comet fleet. After design modifications were implemented, Comet services resumed on October 4, 1958 with Comet 4s.
Pilot error resulting in controlled flight into terrain was blamed for five fatal Comet 4 accidents: an Aerolíneas Argentinas crash near Asunción, Paraguay, on 27 August 1959, Aerolíneas Argentinas Flight 322 at Campinas near São Paulo, Brazil, on 23 November 1961, United Arab Airlines Flight 869 (1962), United Arab Airlines Flight 869 in Thailand's Khao Yai mountains on 19 July 1962, a Saudi Arabian Government crash in the Italian Alps on 20 March 1963, and United Arab Airlines Flight 844 in Tripoli, Libya, on 2 January 1971. The Dan-Air Flight 1903, Dan-Air de Havilland Comet crash in Spain's Montseny range on 3 July 1970 was attributed to navigational errors by air traffic control and pilots. Other fatal Comet 4 accidents included a British European Airways crash in Ankara, Turkey, following instrument failure on 21 December 1961, a United Arab Airlines Flight 869 (1963), United Arab Airlines Flight 869 crash during inclement weather near Bombay, India, on 28 July 1963, and the terrorist bombing of Cyprus Airways Flight 284 off the Turkish coast on 12 October 1967.
Nine Comets, including Comet 1s operated by BOAC and Union Aeromaritime de Transport and Comet 4s flown by Aerolíneas Argentinas, Dan-Air, Malaysian Airlines and United Arab Airlines, were irreparably damaged during takeoff or landing accidents that were survived by all on board.[ A hangar fire damaged a No. 192 Squadron RAF Comet 2R beyond repair on 13 September 1957, and three Middle East Airlines Comet 4Cs were destroyed by Israeli troops at Beirut, Lebanon, on 28 December 1968.]
Aircraft on display
Since retirement, three early-generation Comet airframes have survived in museum collections. The only complete remaining Comet 1, a Comet 1XB with the registration G-APAS, the very last Comet 1 built, is displayed at the RAF Museum Cosford.[ Though painted in BOAC colours, it never flew for the airline, having been first delivered to ]Air France
Air France (; formally ''Société Air France, S.A.''), stylised as AIRFRANCE, is the flag carrier of France headquartered in Tremblay-en-France. It is a subsidiary of the Air France–KLM Group and a founding member of the SkyTeam global air ...
and then to the Ministry of Supply
The Ministry of Supply (MoS) was a department of the UK government formed in 1939 to co-ordinate the supply of equipment to all three British armed forces, headed by the Minister of Supply. A separate ministry, however, was responsible for aircr ...
after conversion to 1XB standard;["de Havilland Comet 1A."]
''Royal Air Force Museum Cosford''. Retrieved 1 November 2010. this aircraft also served with the RAF as XM823. The sole surviving Comet fuselage with the original square-shaped windows, part of a Comet 1A registered F-BGNX, has undergone restoration and is on display at the de Havilland Aircraft Museum in Hertfordshire, England. A Comet C2 ''Sagittarius'' with serial ''XK699'', later maintenance serial 7971M, was formerly on display at the gate of RAF Lyneham in Wiltshire, England since 1987.[Araujo, Ignacio]
GB-High Wycombe: "Dismantlement and relocation of Gate Guardian Comet C2 XK699."
''Defence Equipment & Support''. Retrieved 31 May 2012. In 2012, with the planned closure of RAF Lyneham, the aircraft was slated to be dismantled and shipped to the RAF Museum Cosford where it was to be re-assembled for display. The move was cancelled due to the level of corrosion and the majority of the airframe was scrapped in 2013, the cockpit section going to the Boscombe Down Aviation Collection at Old Sarum Airfield
Six complete Comet 4s are housed in museum collections. The Imperial War Museum Duxford has a Comet 4 (G-APDB), originally in Dan-Air colours as part of its Flight Line Display, and later in BOAC livery at its AirSpace building. A Comet 4B (G-APYD) is stored in a facility at the Science Museum at Wroughton in Wiltshire, England. Comet 4Cs are exhibited at the ''Flugausstellung Peter Junior'' at Hermeskeil, Germany (G-BDIW), the Museum of Flight Restoration Center near Everett, Washington (N888WA),[ and the National Museum of Flight near Edinburgh, Scotland (G-BDIX).
The last Comet to fly, Comet 4C ''Canopus'' (XS235),] is kept in running condition at Bruntingthorpe Aerodrome, where fast taxi-runs are regularly conducted."DH106 Comet 'Canopus' 'Fast Taxi Run' - Bruntingthorpe Cold War Jets (May 2018)"
''youtube.com''. Retrieved 28 July 2020. Since the 2000s, several parties have proposed restoring ''Canopus'', which is maintained by a staff of volunteers, to airworthy, fully flight-capable condition.[Darling 2001, p. 5.] The Bruntingthorpe Aerodrome also displays a related Hawker Siddeley Nimrod MR2 aircraft.[
]
Specifications
In popular culture
See also
*Arnold Alexander Hall
*Seymour Collection, an aerophilately collection relating to the Comet in the British Library.
References
;Notes
;Citations
;Bibliography
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* ''Antennas and Propagation, Part 1.'' London: Institution of Electrical Engineers, 1978. .
* Atkinson, R. J., W. J. Winkworth and G. M. Norris
"Behaviour of Skin Fatigue Cracks at the Corners of Windows in a ''Comet'' I Fuselage"
. Ministry of Aviation via Her Majesty's Stationery Office, 1962.
* Avrane, A. ''Sud Est Caravelle''. London: Jane's Publishing, 1981. .
* Beaty, David. ''Strange Encounters: Mysteries of the Air''. London: Atheneum, 1984. .
* Bibel, George D. ''Beyond the Black Box: The Forensics of Airplane Crashes''. Baltimore, Maryland: JHU Press, 2008. .
* Birtles, P.J. ''Classic Civil Aircraft 3: De Havilland Comet''. Shepperton, UK: Ian Allan, 1990. .
* Birtles, P.J. "The de Havilland Comet Srs. 1–4." ''Aircraft in Profile, Volume 5.'' New York: Doubleday, 1970, first edition 1967.
* Bray, Robin. ''The Comet that Fell to Earth''. Cumbria, UK: Hayloft Publishing, 2015. .
* Cacutt, Len. ''The World's Greatest Aircraft''. Devon, UK: Exeter Books, 1989. .
"The Comet Accidents: History of Events: Sir Lionel Heald's Introductory Summary at the Enquiry"
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"Comet Resurgent: A decade of D.H. Jet Transport Design"
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*
* Darling, Kev. ''De Havilland Comet''. North Branch, Minnesota: Specialty Press, 2001. .
* Darling, Kev. ''De Havilland Comet''. Ramsbury, Marlborough, Wiltshire, UK: Crowood Press, 2005. .
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* Lane, Peter
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* Stewart, Stanley. ''Air Disasters.'' London: Arrow Books, 1989, First edition 1986. .
* Stroud, John. ''Soviet Transport Aircraft since 1945.'' London: Putnam, 1968. .
* Swanborough, F. G. ''Civil Aircraft of the World.'' London: C. Scribner's Sons, 1980. .
* Swanborough, F. G. ''Turbine-engined Airliners of the World.'' London: Temple Press Books, 1962.
* John W. R. Taylor, Taylor, John W. R. ''Jane's All The World's Aircraft 1965–66''. London: Sampson Low, Marston & Company, 1965.
* Taylor, John William Ransom. ''The Lore of Flight.'' New York: Barnes & Noble, 1996, First edition 1988. .
* Tegler, Jan
''B-47 Stratojet: Boeing's Brilliant Bomber'' (Walter J. Boyne Military Aircraft Series).
New York: McGraw-Hill Professional, 2000. .
* Trischler, Helmuth and Stefan Zeilinger, eds
''Tackling Transport, Volume 3'' (Artefacts Series: Studies in the History of Science and Technology).
London: NMSI Trading Ltd, 2003. .
* Walker, Timothy. ''The First Jet Airliner: The Story of the de Havilland Comet''. Newcastle upon Tyne, UK: Scoval Publishing Ltd., 2000. .
* Watkins, David. ''de Havilland Vampire: The Complete History.'' Thrupp, Stroud, UK: Budding Books, 1996. .
* Winchester, Jim, ed. "De Havilland DH.106 Comet." ''Civil Aircraft (The Aviation Factfile)''. London: Grange Books plc, 2004. .
* Withuhn, Bill. "Triumph, Tragedy and Triumph Again... The Comet Story." ''Air Classics Airliner Special No. 2'', Summer 1976.
External links
De Havilland DH106 Comet 1 & 2
from BAE Systems site
* [http://www.flightglobal.com/pdfarchive/view/1949/1949%20-%201356.html "Comet in the Sky" a 1949 ''Flight'' article on the Comet's maiden flight]
Film of BOAC De Havilland Comet 3 G-ANLO at Vancouver International Airport in December 1955
The de Havilland Comet in RCAF Service
a 1951 ''Flight'' article
*[http://www.flightglobal.com/pdfarchive/view/1953/1953%20-%200539.html "Conversion to Comets" a 1953 ''Flight'' article on the Comet's handling]
"Comet Engineering" a 1953 ''Flight'' article
by Bill Gunston
"The Comet Accidents: History of Events," a 1954 ''Flight'' article of Sir Lionel Heald's summary of the enquiry
* [https://web.archive.org/web/20121001190510/http://www.kbtc.org/page.php?id=795 Project Comet] Documentary produced by Full Focus
"The Comet is Twenty"
a 1969 ''Flight'' article
a 1989 ''Flight'' article on the Comet's influence
{{Authority control
De Havilland Comet,
1940s British airliners
Aircraft first flown in 1949
De Havilland aircraft, Comet
Low-wing aircraft
Quadjets