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110-638: The short-range, five-abreast airliner is powered by two aft-mounted Rolls-Royce Avon turbojet engines, allowing a clean low wing. The configuration was later retained in many narrow-body aircraft and regional jets . The initial I, III and VI variants could seat 90 to 99 passengers over 1,650 to 2,500 km (890 to 1,350 nmi). The later, slightly longer 10/11 variants could seat 99 to 118 passengers over 2,800 to 3,300 km (1,500 to 1,800 nmi) and were powered by Pratt & Whitney JT8D low-bypass turbofans. The stretched Caravelle 12 could seat 131 over 3,200 km (1,700 nmi). On 12 October 1951,

220-591: A benefit to the design, as the cabin noise was greatly reduced as a result. In July 1952, the revised X-210 design with twin Avons was re-submitted to the Secretariat General for Civil and Commercial Aviation (SGACC). Two months later, SNCASE received official notification that its design had been accepted. On 6 July 1953, the SGACC placed a formal order for the construction of a pair of prototypes along with

330-429: A combination of gravity and a hand-pump. Power was syphoned from all four engines for the hydraulics, cabin air conditioning , and the de-icing system ; these systems had operational redundancy in that they could keep working even if only a single engine was active. The majority of hydraulic components were centred in a single avionics bay. A pressurised refuelling system, developed by Flight Refuelling Ltd , allowed

440-413: A cruising speed of 400 mph (640 km/h) non-stop. Aviation company de Havilland was interested in this requirement, but chose to challenge the then widely held view that jet engines were too fuel-hungry and unreliable for such a role. As a result, committee member Sir Geoffrey de Havilland , head of the de Havilland company, used his personal influence and his company's expertise to champion

550-457: A dedicated station, with a table across from the flight engineer. 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

660-429: 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 (a DC-4 variant) piston airliner. ( Pan Am '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

770-494: A firm contract was created, the order total was revised to 10. During the next few years, the UK has an opportunity, which may not recur, of developing aircraft manufacture as one of our main export industries. On whether we grasp this opportunity and so establish firmly an industry of the utmost strategic and economic importance, our future as a great nation may depend. Duncan Sandys , Minister of Supply, 1952. A design team

880-518: A highly altered wing; an aerodynamic fairing behind the fin of the tailplane; expanded cargo capacity via raised floor support struts; and higher cabin windows. Other changes included the adoption of variable-displacement pumps for the hydraulic system and the use of AC-based generators in place of earlier DC counterparts along with an auxiliary power unit (APU). The redesigned wing was equipped with double-slotted Fowler flaps , additional and repositioned stall vanes , aerodynamic improvements to

990-618: A jet, and a BOAC de Havilland Comet 4 powered by four Avons made the first scheduled transatlantic crossing by a jet airliner . Production of the Avon aero engine version ended after 24 years in 1974. Production of the Avon-derived industrial version continues to this day, by Siemens since 2015. The current version of the Avon, the Avon 200, is an industrial gas generator that is rated at 21,000–22,000 shp (15.7–16.4 MW). As of 2011, 1,200 Industrial Avons have been sold, and

1100-470: 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 Avons were to be incorporated in pairs buried in

1210-709: 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 (BOAC) found the Type IV's specifications attractive, and initially proposed a purchase of 25 aircraft; in December 1945, when

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1320-559: A narrow fuselage and shoulder-mounted wing, similar to many regional propliners. Proposals from SNCASO included the S.O.60 with two Rolls-Royce Avon RA.7 engines, outfitted with two smaller Turbomeca Marborés as auxiliaries. SNCASE had also returned a number of designs from the X-200 to X-210, all of these being purely jet-powered. On 28 March 1952, after studying the various entries, the Comité du Matériel Civil announced that it had produced

1430-410: A pair of static airframes for fatigue testing . SNCASE's design licensed several fuselage features from British aircraft company de Havilland , the two companies already having had dealings in respect to several earlier designs. The nose area and cockpit layout were taken directly from the de Havilland Comet jet airliner, while the rest of the airliner was locally designed. A distinctive design feature

1540-591: A result of destruction or for irreparable damage. None of these accidents and incidents are attributed to a design defect, only a few technical failures, human errors, or sabotage. The total loss of life in accidents in the Caravelle is more than 1,300. The accident rate per million flights is estimated at more than 5.5, compared with less than 1 for the most recent airliners. Related development Aircraft of comparable role, configuration, and era Related lists Rolls-Royce Avon The Rolls-Royce Avon

1650-420: A result, the Comet was extensively redesigned, with 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

1760-530: A revised windscreen design, soundproofing , a new luggage compartment door, and wing spoilers . The Caravelle 10A and 10B, which differed only in the engines used and were commonly referred to as the Super Caravelle , featured the improvements of the VI-R in addition to a high degree of further design changes. The more high-profile modifications included a stretch of the fuselage by 33 inches (84 cm);

1870-405: A second Comet 1A and never operated the type in commercial service. Both early accidents were originally attributed to pilot error, as overrotation had led to a loss of lift from the leading edge 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 , and its engine inlets also suffered a lack of pressure recovery in

1980-427: A short list of three entrants: the four-engined Avon/Marbore SNCASO S.0.60, the twin-Avon Hurel-Dubois project, and the three-engined Avon SNCASE X-210. At this point, British engine manufacturer Rolls-Royce had already begun to offer a new version of the Avon that was to be capable of developing 9,000 lbf (40 kN) of thrust, which would render the auxiliary engines of the S.O.60 and the third engine featured on

2090-438: A significantly more-spacious environment. BOAC installed 36 reclining "slumberseats" with 45 in (1,100 mm) centres on its first Comets, allowing for greater leg room in front and behind; Air France had 11 rows of seats with four seats to a row installed on its Comets. Large picture window views and table seating accommodations for a row of passengers afforded a feeling of comfort and luxury unusual for transportation of

2200-619: A smaller fin and rudder since the hazards of asymmetric thrust were reduced. The engines were outfitted with baffles to reduce noise emissions, and extensive soundproofing 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 , 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

2310-427: A total of 172 Caravelles had been sold to a range of operators. Aviation writer M.G. Douglas attributed the type's favourable early sales record to the effective marketing campaign of performing demonstrations to prospective customers using the two prototypes, as well to the Caravelle having effectively no jet-powered rivals, being the only short-haul jetliner for several years following its introduction. Several models of

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2420-556: A total of 20 different designs were ultimately received. The majority of these proposals were powered by all- turbojet engine arrangements, although Breguet had entered a number of designs that were powered by both turbojet and turboprop engines; among these was one for a Snecma Atar -powered tri-jet to be developed in association with the SNCA du Nord and a turboprop type; all of the different designs were designated as Br. 978 . Hurel-Dubois had entered several turboprop designs based on

2530-472: 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 2.75 pounds per square inch (19.0 kPa) overpressure and depressurising through more than 16,000 cycles, equivalent to about 40,000 hours of airline service. The windows were also tested under a pressure of 12 psi (83 kPa), 4.75 psi (32.8 kPa) above expected pressures at

2640-528: The Automatic Direction Finder , 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

2750-671: The Comité du matériel civil (civil aircraft committee) published a specification for a medium-range aircraft, which was later sent to the aviation industry by the Direction technique et industrielle . This called for an aircraft capable of carrying 55 to 65 passengers and 1,000 kg (2,200 lb) of cargo on routes up to 2,000 km (1,100  nmi ; 1,200  mi ) with a cruising speed of about 600 km/h (320  kn ; 370  mph ). The type and number of engines were not specified. Since 1946, various design studies for aircraft in this category had already been underway at several of

2860-841: The RM6 with 17,110 lbf (76,100 N) thrust. The RM5 powered the Saab 32 Lansen and the RM6 powered the Saab 35 Draken and all-weather fighter version of the Lansen (J 32B). 300 Avon 113s, and a larger number of Avon 203s were produced under licence in Belgium by Fabrique Nationale Division Moteurs . In the US the RA.28-49 was used in the VTOL Ryan X-13 Vertijet aircraft. In Australia,

2970-576: The Rolls-Royce Nene engine. Design work began in 1945. The Avon design team was initially headed by Stanley Hooker assisted by Geoff Wilde . Development of the engine was moved from Barnoldswick to Derby in 1948 and Hooker subsequently left the company, moving to Bristol Engines . The first engine ran on 25 March 1947, with a 12-stage compressor. The engine was difficult to start, would not accelerate and broke first-stage blades. Two-position inlet guide vanes and compressor bleed were among

3080-415: The airframe , 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 and dangerous stress concentrations around square cut-outs for the ADF (automatic direction finder) antennas were ultimately identified. As

3190-402: The wing root and adjustments to the leading edge that improved the performance of the wing during the crucial takeoff and landing phases of flight. Despite its commercial success, however, the Caravelle was soon displaced from being the focus of Sud Aviation's development efforts as the majority of the company's design engineers were progressively reallocated onto an entirely new project that

3300-512: The 200-unit mark. The Caravelle belongs to the first generation of passenger aircraft to use newly developed jet propulsion technology, and it was the first jet airliner developed specifically for the short/medium-range sector of the market. Early in the Caravelle's career, its chief competitors were propeller-driven aircraft, such as the British-built Vickers Viscount and the U.S.-built Convair CV-440 . Reportedly,

3410-674: 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. On 8 April 1954, Comet G-ALYY ("Yoke Yoke"), on charter to South African Airways ,

Sud Aviation Caravelle - Misplaced Pages Continue

3520-785: The Avon was used by Commonwealth Aircraft Corporation in the CA-27 Avon-Sabre . The Avon continued in production for the Sud Aviation Caravelle and English Electric (BAC) Lightning until 1974, by which time over 11,000 had been built. It remained in operational service with the RAF until 23 June 2006 in the English Electric Canberra PR.9 . Initial design work was done on the 2-spool RB.106/RB.128 as an Avon successor for large supersonic fighters. Avon Series 100 are early military versions of

3630-509: The Avon. Avon Series 200 are uprated military versions of the Avon with can-annular combustion chamber and Sapphire style compressor. Avon Series 300 are further developed military after-burning versions of the Avon for the English Electric Lightning . Avon Series 500 are civilian equivalents to the military Avon Series 200 variants. Data from "Lightning F.6 Avon 301R Specs" . lightning.org.uk. Archived from

3740-582: The Canberra B.6, Hawker Hunter and Supermarine Swift . Uprated versions followed, the RA.7/Mk.114 with 7,350 lbf (32,700 N) thrust in the de Havilland Comet C.2 , the RA.14/Mk.201, 9,500 lbf (42 kN) in the Vickers Valiant and the RA.26, 10,000 lbf (44 kN) used in the Comet C.3 and Hawker Hunter F.6. An Avon-powered de Havilland Comet 4 flew the first scheduled transatlantic jet service in 1958. The highest thrust version

3850-429: The Caravelle proved to be a highly reliable airliner during its early years of service. The low accident rate for the type led to lower than average insurance premiums for Caravelle operators. The Caravelle was typically powered by a pair of British-built Rolls-Royce Avon turbojet engines, installed in a rear-mounted position close to the tail unit. Various models of the Avon engine were adopted for different versions of

3960-463: The Caravelle were developed and produced over the lifetime of the production run, often in response to the increasing power of the available engines, which allowed higher takeoff weights to be adopted. By 1963, there were a total of six different versions of the Caravelle in production, designated III , VI-N , VI-R , 10A , 10B , and X-BIR . Of these, the Caravelle III was considered to be

4070-417: The Comet 1 with more powerful engines, the Comet 2, was being developed, and orders were placed by Air India , British Commonwealth Pacific Airlines , Japan Air Lines , Linea Aeropostal Venezolana , and Panair do Brasil . American carriers Capital Airlines , National Airlines and Pan Am placed orders for the planned Comet 3, an even-larger, longer-range version for transatlantic operations. Qantas

4180-497: The Comet appeared to have achieved success for de Havilland. Popular Mechanics 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 and Air France, each acquired three Comet 1As, an upgraded variant with greater fuel capacity, for flights to West Africa and the Middle East. A slightly longer version of

4290-654: The Comet's first flight. On 11 March 1943, the Cabinet of the United Kingdom formed the Brabazon Committee , which was tasked with determining the UK's airliner needs after the conclusion of the Second World War . One of its recommendations was for the development and production of a pressurised, transatlantic mailplane that could carry 1 long ton (2,200 lb; 1,000 kg) of payload at

4400-416: 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. An EKCO E160 radar unit was installed in the Comet 4's nose cone , providing search functions as well as ground and cloud-mapping capabilities, and a radar interface

4510-416: 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

Sud Aviation Caravelle - Misplaced Pages Continue

4620-560: 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 5,700 lbf (25 kN) Ghost DGT3 series engines. From the Comet 2 onward, the Ghost engines were replaced by the newer and more powerful 7,000 lbf (31 kN) Rolls-Royce Avon AJ.65 engines. To achieve optimum efficiency with

4730-611: The Helsinki Olympic Games with G-ALYS on 4 August 1952. Queen Elizabeth, the Queen Mother and Princess Margaret 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 twice as fast as advanced piston-engined aircraft such as the Douglas DC-6 (490 mph (790 km/h) vs 315 mph (507 km/h), respectively), and

4840-476: The Italian aircraft manufacturer Fiat Aviazione , which produced the aircraft's tailplane, fin, ailerons , and engine nacelles ; and French aviation firm Breguet Aviation , which performed the outfitting of the rear fuselage; while much of the ancillary equipment of the Caravelle originated from either British or U.S. manufacturers. Sud Aviation constructed and outfitted the nose section, along with manufacturing

4950-546: The Mediterranean off the Italian island of Elba 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

5060-669: 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. On 19 October 1954, the Cohen Committee was established to examine the causes of the Comet crashes. Chaired by Lord Cohen ,

5170-572: 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 forward aperture around

5280-483: The X-210 unnecessary. The Committee issued a request for SNCASE to re-submit its X-210 proposal as a twin-Avon design. In doing so, SNCASE decided to not remove the remaining engines from their rear-mounted position; most designs had placed the engines underneath the wing, where they could be mounted on the spar for lower overall weight, but it was felt that these weight savings were not worth the effort. This turned out to be

5390-497: The aircraft could be profitable with a load factor as low as 43 per cent, commercial success was expected. 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 30,000 ft (9,100 m). 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,

5500-403: 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. 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 and the "Q feel" system

5610-589: 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 (40,000 ft (12,000 m)), 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

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5720-520: The airliner, often with increased thrust and additional features such as thrust reversers . Alternative powerplants were adopted or proposed for some Caravelle models, such as the U.S.-built Pratt & Whitney JT8D-1 and General Electric CJ-805-23C engines. The Caravelle was designed to maximise passenger comfort and operator convenience. The rear entry door had built-in stairs that, while adding structural complexity, meant that mobile airport stairs were unnecessary. On later variants, soundproofing in

5830-463: The basic version of the airliner, while the other variants featured an increasing number of improvements. The Caravelle VI-N was equipped with more powerful Avon 531 engines and an additional heat exchanger for the air conditioning , while the Caravelle VI-R, which had come about as a result of demands by U.S. carrier United Airlines , was furnished with thrust reverser -equipped Avon 352s,

5940-426: The break-up was found to have begun with a left elevator spar failure in the horizontal stabilizer . The inquiry concluded that the aircraft had encountered extreme negative g-forces 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

6050-420: The causes of the accident. Media attention centred on potential sabotage ; other speculation ranged from clear-air turbulence 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 of the wing structure, failure of

6160-588: 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,

6270-401: 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 systems : two primaries, one secondary, and a final emergency system for basic functions such as lowering the undercarriage. The undercarriage could also be lowered by

6380-473: 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 . The prototype was registered G-ALVG just before it was publicly displayed at the 1949 Farnborough Airshow before

6490-513: 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. 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

6600-459: The design changes which allowed the engine, as the RA.2, to run a 25-hour test and fly in the two outboard positions on the converted Avro Lancastrian military serial VM732 , from Hucknall on 15 August 1948. The first production engine, which needed a two-stage turbine, was the RA.3, or Avon Mk 101. Several modified versions of this design were produced in the Mk. 100 series. The Avon 200 series

6710-415: The development of a jet-propelled aircraft; proposing a specification for a pure turbojet -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

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6820-510: The engine cells to contain debris from any serious engine failures; also, placing the engines inside the wing required a more complicated wing structure. The Comet 1 featured 5,050 lbf (22.5 kN) de Havilland Ghost 50 Mk1 turbojet engines. Two hydrogen peroxide -powered de Havilland Sprite booster rockets were originally intended to be installed to boost takeoff under hot and high altitude conditions from airports such as Khartoum and Nairobi. These were tested on 30 flights, but

6930-407: 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

7040-406: The form of readily removable mattress-like rolls that fixed in place via existing brackets was added to the design. In some configurations, the Caravelle's cabin was furnished with a number of rearward-facing passenger seats, which was an uncommon arrangement amongst civil aircraft. From September 1963 onwards, an autolanding capability (via two separate systems, of which one was self-contained while

7150-464: The investigation, the Royal Navy 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 per cent by weight of the main structure, 80 per cent of the power section, and 50 per cent of the aircraft's systems and equipment had been recovered. The forensic reconstruction effort had just begun when

7260-426: The jetliner flew smoothly and was highly responsive in a manner consistent with other de Havilland aircraft. 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 and crashed into

7370-401: 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 , Redux , which was liberally used in the construction of

7480-416: The large single-wheeled main landing gear , which was replaced on production models starting with G-ALYP by four-wheeled bogies . The Comet was an all-metal low-wing cantilever monoplane powered by four jet engines; it had a four-place cockpit 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

7590-526: The leading French aircraft manufacturing organisations, and had resulted in some ambitious concepts being mooted. None of these firms possessed the financial power to independently embark on the substantial development work involved, let alone to establish a manufacturing line for the construction of such aircraft. The response to the specification from the French industry was strong, it has been claimed that every major manufacturer submitted at least one proposal;

7700-413: The maiden flight, which had a total duration of 41 minutes, the crew consisted of Pierre Nadot (Captain), André Moynot (First Officer), Jean Avril (mechanic), André Préneron (radio operator) and Roger Beteille . Almost one year later, on 6 May 1956, the second prototype made its first flight. The first prototype had been fitted with a cargo door located on the lower left side of the fuselage, but this door

7810-471: The naked eye led to the introduction of widespread radiography 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 handlers 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 upward from

7920-522: 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 , a major scheduled passenger air carrier. The earliest production aircraft, registered G-ALYP ("Yoke Peter"), first flew on 9 January 1951 and

8030-486: The normal service ceiling of 36,000 ft (11,000 m). One window frame survived 100 psi (690 kPa), about 1,250 per cent over the maximum pressure it was expected to encounter in service. The first prototype DH.106 Comet (carrying Class B markings G-5-1) was completed in 1949 and was initially used to conduct ground tests and brief early flights. The prototype's maiden flight, out of Hatfield Aerodrome, took place on 27 July 1949 and lasted 31 minutes. At

8140-401: The original on 10 April 2008. Comparable engines Related lists De Havilland Comet The de Havilland DH.106 Comet is the world's first commercial jet airliner . Developed and manufactured by de Havilland in the United Kingdom, the Comet 1 prototype first flew in 1949. It features an aerodynamically clean design with four de Havilland Ghost turbojet engines buried in

8250-430: The original SE designation assigned to the airliner was retained. In May 1959, the Caravelle received its airworthiness certification, enabling the type to enter passenger service. On 26 April 1959, the Caravelle performed its first flight with paying passengers on board for Scandinavian operator SAS; shortly thereafter, the type commenced operations with Air France as well. Within four years of entering airliner service,

8360-436: The other was integrated with the airliner's autopilot ), was made available for the Caravelle by Sud Aviation. The final assembly line for the Caravelle was at Sud Aviation's factory at Blagnac Airport near Toulouse . Much of the aircraft was manufactured at other sites across France and in other countries, however. The production of large portions of the Caravelle had been subcontracted to other manufacturers; these included

8470-491: The period. Amenities included a galley that could serve hot and cold food and drinks, a bar , and separate men's and women's toilets. Provisions for emergency situations included several life rafts stored in the wings near the engines, and individual life vests were stowed under each seat. One of the most striking aspects of Comet travel was the quiet, "vibration-free flying" as touted by BOAC. For passengers used to propeller-driven airliners, smooth and quiet jet flight

8580-475: 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. The cost of solving the Comet mystery must be reckoned neither in money nor in manpower. Prime Minister Winston Churchill , 1954. During

8690-408: The same conditions. As a result, de Havilland re-profiled the wings' leading edge with a pronounced "droop", and wing fences were added to control spanwise flow. 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 in 1960, and Beaty also recounted

8800-574: 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

8910-654: 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 from April 1951 to carry out 500 flying hours of crew training and route-proving. Australian airline Qantas 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

9020-493: 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 , 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 ), India, killing all 43 on board. Witnesses observed

9130-506: 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 downward and rearward 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,

9240-764: The tailcone, rudder, Fowler flaps , both the leading edges and trailing edges of the wing, and the majority of the fuselage. The Caravelle served with airlines on every continent except Australia. In 1957, Trans-Australia Airlines (TAA) sought to order two Caravelles, to service its longest routes, Perth-Sydney and Perth-Melbourne, from 1960. However, the Australian government blocked the order, saying that any further diversity in full-size airliners used on domestic routes would have an adverse impact on aircraft servicing within Australia. For 45 years of commercial operation, 67 Caravelles have been withdrawn from service as

9350-418: The time, including a swept-wing leading edge, integral wing fuel tanks, and four-wheel bogie main undercarriage units designed by de Havilland. Two pairs of turbojet engines (on the Comet 1s, Halford H.2 Ghosts, subsequently known as de Havilland Ghost 50 Mk1s) were buried in the wings. The original Comet was the approximate length of, but not as wide as, the later Boeing 737-100 , and carried fewer people in

9460-441: 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. 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 engines and allowed for

9570-534: The type has established a 60,000,000 hour record for its class. The engine was initially a private venture put forward for the English Electric Canberra. Originally known as the AJ.65 for Axial Jet, 6,500 lbf the engine was based on an initial project concept by Alan Arnold Griffith . which combined an axial compressor with a combustion system and single-stage turbine using principles proven in

9680-486: The type received its first order from Air France; it was followed by Scandinavian Airlines System (SAS) in 1957. More orders followed, which had been partially driven by a campaign of direct presentations held at airshows and dedicated flight demonstrations using the two prototypes to potential customers. Also during 1956, SNCASE (Sud-Est – Southeast) had merged with SNCASO (Sud-Ouest – Southwest) and several other French aircraft manufacturers to become Sud Aviation; however,

9790-432: The wing roots, a pressurised cabin , and large 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 the airliner's entry into service, three Comets were lost in highly publicized accidents after suffering catastrophic mishaps mid-flight. Two of these were found to be caused by structural failure resulting from metal fatigue in

9900-414: 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 totalled 14 aircraft, with delivery projected for 1952. As the Comet represented a new category of passenger aircraft, more rigorous testing

10010-473: The wingless Comet on fire plunging into the village of Jagalgori, leading investigators to suspect structural failure. After the loss of G-ALYV, the Government of India 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

10120-471: 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, 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

10230-475: The work on the Super-Caravelle would be merged with similar work that had been undertaken by Britain's Bristol Aeroplane Company , and would result in the development of Concorde . In total, 282 Caravelles of all types were manufactured (2 prototypes or pre-production aircraft and 280 production aircraft); reportedly, Sud Aviation's projected break-even point for the type had been forecast to be around

10340-585: Was a complete redesign having very little in common with earlier Marks. Differences included a completely new combustion section and a 15-stage compressor based on that of the Armstrong-Siddeley Sapphire . The first application was the Vickers Valiant . The engine entered production in 1950 as the RA.3/Mk.101 with 6,500 lbf (29 kN) thrust in the English Electric Canberra B.2 . Similar versions were used in

10450-528: 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 for small components and large assemblies alike. Sections of pressurised fuselage were subjected to high-altitude flight conditions via a large decompression chamber 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

10560-542: Was a novel experience. 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 , 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

10670-495: Was a write-off. On 3 March 1953, a new Canadian Pacific Airlines 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

10780-538: 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 derivative, the Hawker Siddeley Nimrod , which remained in service with the Royal Air Force until 2011, over 60 years after

10890-462: Was built into the Comet 4 cockpit along with redesigned instruments. Sud-Est 's design bureau, while working on the Sud Aviation Caravelle 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

11000-582: Was formed in 1946 under the leadership of chief designer Ronald Bishop , who had been responsible for the Mosquito fighter-bomber. Several unorthodox configurations were considered, ranging from canard to tailless designs; All were rejected. The Ministry of Supply was interested in the most radical of the proposed designs, and ordered two experimental tailless DH 108s to serve as proof of concept aircraft for testing swept-wing configurations in both low-speed and high-speed flight. During flight tests,

11110-465: Was intended to produce a successor to the Caravelle. The project was relatively ambitious, having the aim of producing a viable supersonic transport that possessed the same general size and range as the Caravelle. It was decided that the envisioned supersonic airliner should be naturally named after the firm's recent success, thus the Super-Caravelle name was applied to the design. Ultimately,

11220-465: 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. On 26 October 1952, the Comet suffered its first hull loss when a BOAC flight departing Rome's Ciampino airport 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,

11330-466: 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 " 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

11440-820: Was modified by Hawker Siddeley 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. 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. The Comet's high cabin pressure and high 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

11550-488: 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 (RAE). Prime Minister Winston Churchill tasked

11660-490: Was removed in the second prototype in favour of an all-seating arrangement. By October 1956, both prototypes had accumulated in excess of 1,000 flight hours. By the end of 1956, the two aircraft had visited various locations across Europe and North Africa ; and trials were already underway for French carrier Air France . During 1957, the second prototype accumulated roughly 2,500 flight hours across various flights conducted throughout North America and South America . In 1956,

11770-713: Was subsequently lent to BOAC for development flying by its Comet Unit. 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. 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 . 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

11880-449: Was the RA.29 Mk.301/2 ( RB.146 ) used in later versions of the English Electric Lightning . It produced 12,690 and 17,110 lbf (56,400 and 76,100 N) with afterburning. Other aircraft to use the Avon included the de Havilland Sea Vixen , Supermarine Scimitar and Fairey Delta 2. The RA.3/Mk.109 was produced under licence by Svenska Flygmotor as the RM5 , and an uprated RA.29 as

11990-488: Was the cabin windows in the shape of a curved triangle , which were smaller than conventional windows but gave the same field of view downwards. On 21 April 1955, the first prototype of the Caravelle (F-WHHH), launched by Madame de Gaulle , was rolled out. On 27 May 1955, the first prototype conducted its maiden flight , powered by a pair of British Rolls-Royce RA-26 Avon Mk.522 , capable of providing 4,536  kgf (44,480  N ; 10,000  lbf ) of unitary thrust. For

12100-436: 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 aircraft, both military and civilian, as well as versions for stationary and maritime power. An English Electric Canberra powered by two Avons made the first un-refuelled non-stop transatlantic flight by

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