The De Havilland DH106 Comet
By Robert Waldvogel
Every time one of the pure-jet airliners from the past seven decades takes off, it carries with it the design knowledge and experience with it introduced by the de Havilland DH.106 Comet, the world’s first pure-turbine commercial aircraft.
The product of Geoffrey de Havilland, a man often described as a practical dreamer because of his ability to anticipate future aviation requirements and turn those visions into wing-sprouting realities, the Comet was to all the designs that succeeded it what the Big Bang was to the universe: a beginning, a spark, a budding.
It cleared the path all others followed. It became the light at the end of the tunnel toward which all others strove after it had bored that tunnel.
Unlike previous aircraft, the Comet was not just another design, it was the beginning of an era in commercial aviation-the jet age. In short, the Comet was the seed from which all other pure-jet airliners grew.
- DESIGN FEATURES
After a three-year development period, the sleek, silver, propellerless airliner registered G-ALVG and displaying the name “de Havilland Comet” on either of its sides, was given birth as it was silently rolled out of its Hatfield hangar on a misty Saturday morning, representing the world’s first commercial pure-jet airliner and therefore the future of passenger-carrying aviation.
The fog shrouding the airport that day was symbolic of the aircraft program, which itself had been shrouded in secrecy to avoid early publicity.
Although it still lacked its starboard engines at this point, it nevertheless modeled the sleek, aerodynamically clean lines that would become associated with high-speed, high-altitude jet flight.
Its smooth, short fuselage was lined with rectangular windows on either of its sides and it was mated to two swept wings, in which four de Havilland Ghost engines were buried at their roots. Their oval air intakes were positioned at the leading edge and led to and through the core to the trailing edge located exhaust cones. These airfoils were otherwise unobstructed by drag-producing nacelles, pylons, or propeller blades, resulting in a complete, lift-generating surface.
Sporting a conventional vertical and horizontal tail, the DH.106 rested on a tricycle undercarriage, whose main units initially retained the single wheels of the prototype. The Comet was, in every sense of the word, a piece of engineering art-especially for its time.
Its circular-section, ten-foot-wide fuselage, to which its air cleaving nose was attached, was of all-metal, semi-monocoque construction, employing 22-gauge alloy and Redux bonding to eliminate the increased weight and leak propensity holes otherwise associated with riveting methods. Overall length was 93 feet.
The 20-degree swept wings, spanning 115 feet and encompassing a 2,027-square-foot area that gave it a 52.2-pound-per-square foot loading, were equally of all-metal, two-spar construction, and they consisted of a stub wing section, which housed the engines, a center section, and an extension section.
Its aerodynamic devices included hydraulically actuated air brakes, ailerons, and hinged, trailing edge flaps. Wing deicing was accomplished by thermal means and the internal, bag-type fuel tanks, pressure introduced at a 40,000-pound-per-thirty-minute rate, had a 6,000-Imperial gallon capacity.
The cantilever tailplane, consisting of a variable-incidence horizontal surface and a rudder-installed vertical one, gave the aircraft a 28.5-foot overall height.
The four 5,000 thrust-pound de Havilland centrifugal-compressor Ghost 50 engines, passing through both the forward and rear spars at their wing root installation points, contained none of the cylinders, cylinder heads, pistons, connecting rods, valves, valve springs, tappets, carburation units, electric ignition reduction gear, or propellers hitherto associated with piston powerplants. Their inherent weight reduction, increased simplicity, and minimal drag installation produced the optimum aerodynamic configuration.
The latter was both high enough to avoid foreign object ingestion and low enough to facilitate maintenance and inspection, enabling the aircraft to employ shorter undercarriage struts, which themselves reduced structural weight. The engines’ own such reduction also enabled more fuel and/or payload to be carried, at the same time incorporating ideal anti-icing capability and fire prevention.
Because of the originally intended 40-degree wing sweepback, which would have required significantly greater rotation and airborne speeds and therefore longer runways, there was provision for a jet-assisted takeoff (JATO) hydrogen peroxide sprite rocket. The 925-pound powerplant, named after its “spritely” performance, measured 84 inches long by 20 inches in diameter, was fed by a 39-gallon hydrogen peroxide fuel tank, and produced 5,000 pounds of additional thrust during a 12-second period or lesser ratings during longer intervals, particularly during short and hot-and-high field conditions.
Designed by de Havilland itself, the Sprite was the first rocket to be certificated. It would have increased the aircraft’s power output by fifty percent if a unit were installed on either side of the wing trailing edges between the existing Ghost engine exhaust cones.
The Comet’s hydraulically operated, tricycle undercarriage on production versions, fitted with equally hydraulically actuated brakes, consisted of a twin-wheel, steerable nose gear unit, which retracted rearward and was stored in its fuselage bay, and two four-wheel main units that retracted outward for nesting in under-wing bulged fairings.
Cabin access was provided by inward-opening, 4.8- by 2.6-foot aft, port passenger and forward, starboard galley servicing doors.
Cockpit vision was attained by means of four forward slit-resembling panes and two side panels, the first of which were triangular-shaped and the second of which were oblong-shaped. Only the triangular-shaped ones were openable.
Standard cockpit crew consisted of four members, who were accommodated in upholstered, bucket-like seats. The primary instruments, duplicated for both the captain and the first officer, included the instrument landing indicator, the airspeed indicator, the artificial horizon, the climb-and-descent rate indicator, the automatic direction finder (ADF), the radio navigation indicator, the altimeter, the gyro compass, the turn-and-bank indicator, the cabin pressure differential indicator, the Mach meter, the outside air temperature indicator, and the compass control panel.
The center engine instrument panel displayed four of each of the following to correspond to the four powerplants: revolutions-per-minute indicators, jet pipe temperature gauges, oil pressure and temperature indicators, rear bearing temperature indicators, and the two fuel pump isolating switches.
Each of the two forward pilots also had a control column or yoke and rudder-toe brake pedals, but only the captain had a nose wheel steering tiller on his left panel.
A center pedestal, positioned between the two pilots and extending from the instrument panel, featured the four thrust levers or throttles, the parking brake lever, the flap selector lever, the air brake lever, the automatic pilot control box, the undercarriage selector lever, the rudder trim, the aileron trim, the flap indicator and emergency lever, the high-pressure fuel cocks, and the low-pressure fuel cocks.
The second officer’s, or fight engineer’s, side-facing station, located on the starboard side, contained the undercarriage emergency lever; the cabin pressure controls; the water injection and deicing controls; the fuel cross feed cock; the safety valve; the refrigeration and mass flow controls; the cabin pressure controller; the cabin air-conditioning indicators; the temperature controller; the fuel controls and fuel panel; and the electrical supply control panel.
A similar, side-facing navigator station was located on the port side.
The DH.106 Comet used four power sources: the 5,000 thrust-pound Ghost engines, a hydraulic system, an electric system, (which itself was powered by four engine-driven generators), and two batteries.
The cockpit controls, leading to hydraulic servo tabs, operated the wing and vertical and horizontal tail surfaces, activating their screw jacks to initiate device deflection. The main hydraulic system, operating off of the number two and four engines, powered the air brakes, the ailerons, the trailing edge flaps, the horizontal stabilizers, the rudder, the undercarriage, and the wheel brakes. An emergency system, powered by an electric pump and utilizing the secondary system’s pumps, was operated by the flight engineer. The landing gear could alternatively be hand-cranked into the extended position.
Other cockpit instruments and systems included EKOO weather radar, high frequency radio controls, a very high frequency (VHF) automatic direction finder (ADF), Murphy distance measuring equipment (DME), an instrument landing system (ILS) with very high frequency omni directional range (VOR) provision, long range navigation (LORAN), two radio magnetic indictors, selective calling (SEL-CAL), an ultra-crew communication system, and a public address system.
The passenger cabin, blanketed in sound-suppressing insulation to minimize internal penetration of the Ghost engines’ scream, was standardly configured with 36 four-abreast first class seats in a two-two arrangement with a central aisle and was subdivided into forward and aft sections. A two-unit galley was installed adjacent to the forward, right servicing door, while two lavatories and a garment storage closet were installed in the aft vestibule.
Pressurization and air conditioning were provided by engine compressor air and a control valve.
Baggage, cargo, and mail were carried in a single main deck compartment, located immediately behind the flight deck, and two underfloor heated, lighted, and pressurized holds.
Designated the DH.106 Comet 1 in its initial production version, the aircraft featured 12,500- and 105,000-pound payload and gross weights, respectively, achieving a 1,500-statute mile range with 36 passengers and fuel reserves. Cruise speed varied between 450 and 465 mph at 28,000- to 40,000-foot altitudes.
IN SERVICE
Amid anticipatory excitement, fanfare, and ceremony, the DH.106 Comet 1 slated to operate the world’s first commercial jet service and draped in BOAC’s white and dark blue livery, was boarded through its aft, port door on May 2, 1952, its history-making and marking patrons greeted in the cabin by then-designated stewardesses in their crisp, equally-blue uniforms.
Piloted by Captain Mike Majendie, First Officer J. G. Woodmill, Flight Engineer Wally Bennett, and Radio Officer Bob Chandler, and served by steward Edward Charlewood and stewardess Joan Nourse, the Comet 1 slated for the inaugural passenger-carrying service, registered G-ALYP, taxied from the excited crowd with the aid of its four high-pitched Ghost 50 engines, positioning itself on the runway’s threshold and unleashing itself, like a stallion stampeding out of the starting gate, with a thunderous roar. Rapidly accelerating, it rotated and disengaged itself at 15:12, plunging skyward and, in the process, taking its passengers into the jet age.
Touching down in Rome, Beirut, Khartoum, Entebbe, and Livingston, and changing crews at the second and third of these intermediate airports, it landed three minutes early in Johannesburg, its destination, after a record 23.5-hour flight, despite a 30-minute refueling delay in Entebbe and the need to twice circle before being given clearance.
Taxiing to its parking position, it was inundated with enthusiastic throngs of awaiting people.
BOAC placed the aircraft into service on a second route-in this case, from London to Colombo-on July 11, which required 16.35 hours to cover the 6,000-mile distance with intermediate stops in Rome, Beirut, Bahrain, Karachi, and Bombay. A third stretching 7,761 miles, connected London with Bangkok and necessitated a 20.15-hour flying time, along with an additional seven hours, to complete, with refueling stops in Rome, Cairo, Bahrain, Karachi, Calcutta, and Rangoon. It was later extended to Tokyo.
By April of 1963, BOAC operated nine Comets, thus qualifying it as having the world’s only pure-jet airliner fleet-and after a year of service had carried 27,700 passengers in them, having covered more than 104,600,000 miles during 9,443 airborne hours with an average 80-percent load factor. Sixty-one percent of all arrivals were within two hours of their scheduled arrival times, which was considered phenomenal considering the fact that they entailed a new design, a new powerplant type, and, in essence, a new era.
THE COMET 1A
Nevertheless, scheduled passenger service logically and inevitably indicated the need for improvements-considering the type’s innovation-and these were applied to a modified variant designated Comet 1A and would be subsequently incorporated in an even more extensively modified Comet 2.
Although it retained the 5,000 thrust-pound Ghost 50 engines, they were now equipped with water methanol injection during takeoff, enabling them to generate between ten and twelve percent more thrust and therefore facilitate higher passenger capacities, of 44, or gross weights, of 115,000 pounds. But a slight decrease in payload, to 11,800 pounds, coincided with these changes. Nevertheless, a 6,906-Imperial gallon fuel capacity increased the type’s range-in this case, to 1,770 statute miles.
UAT Union Aeromaritime de Transport, which had placed an order for two of the new variants on May 1, 1951, inaugurated them into service on its Paris-West African route line two years later, on February 19, but it was extended as far south as Johannesburg in November. Since South African Airways did not initiate its own leased Comet 1 service until that October, UAT’s operation constituted the world’s second pure-jet one.
The Royal Canadian Air Force, which ordered two DH.106-1As itself, inaugurated them into North American service on March 18 and April 13, 1953, marking the first time the type was operated in that hemisphere.
In Europe, Air France, which had made a two-strong Comet 1A order, placed the first in service on the Paris-Rome-Beirut route on August 26, 1953. The second was flown to Algiers.
Although Canadian Pacific also placed an order for a single Comet 1A, it never operated the type for reasons that shall be shortly discussed.
When deliveries were completed by the end of 1953, pure-jet Comet service was being offered to and within North America, Europe, Africa, the Middle East, and the Far East. De Havilland, because of its vision and gamble, had ushered in the jet age.
In all, 21 preproduction and production DH.106-1s and -1As were built, as follows.
THE COMET 2
The Comet 1 and 1A were succeeded by the Comet 2. Featuring a three-foot fuselage stretch ahead of the wing that gave it a new, 96-foot overall length, but retaining the previous version’s 44-passenger capacity, it introduced a new powerplant type-in this case, the 7,100 thrust-pound Rolls Royce RA25 Avon 503, whose capacity was later increased to 7,300 thrust pounds.
As the first pure-jet airliner to offer a sound suppressing nozzle and a thrust reverser, it ensured immediate weight transfer from the wings to the undercarriage upon touchdown, decreasing declaration rolls, particularly on wet and contaminated surfaces, and minimized skidding. Its additional thrust facilitated both payload and takeoff weight increases, to 13,500 and 120,000 pounds, respectively, the latter increasing wing loading to 59.1 pounds per square foot.
Range, the aircraft’s principle deficiency, was increased to 2,535 statute miles, enabling carriers to eliminate some enroute stops and decrease travel times. Cruising speed, at 35,000 feet, increased to 480 mph.
Initially retrofitted with 6,500 thrust-pound Rolls Royce RA7 Avon 502 engines and registered G-ALYT, the prototype, designated Comet 1X, first flew on February 16, 1952 and was followed by the first production example on August 27 of the following year, at which time 28 orders for the advanced version had been received.
BOAC, its launch customer, had already submitted a letter of intent for 12 aircraft, five of which were intended to replace the original Comet 1s. British Commonwealth Pacific Airlines ordered half a dozen in January of 1952 for trans-Pacific service between Auckland, New Zealand, and Vancouver, British Columbia. Japan Air Lines, which then only maintained a domestic route system, equally ordered two DH.106-2s for intended international sectors, and LAV Linea Aeropostal Venezolana, placing its order for two on August 1, 1952, foresaw them as connecting South with North America, specifically Caracas with New York. And on March 20, 1953, Panair do Brasil placed its own order tor three. By the end of the year, 35 aircraft had been ordered.
The new variant spoke for itself. On January 22, 1954, for instance, it closed the gap between London and Khartoum in 6.22 hours, having averaged 481 mph.
Final approach, at about 130 knots, required a 4,500-rpm engine setting, but the powerplants themselves responded to throttle advances in as few as five seconds. Touchdown speed, depending upon enroute fuel burn and its resulting landing weight, varied between 82 and 92 knots, and deceleration was achieved by means of thrust reverser and brake applications.
THE COMET 3
Because the Comet sparked what could be called the jet revolution and shrank the world, in terms of travel time, by some 40 percent, overwhelming demand was created, leaving de Havilland little choice but to offer an even larger successor to its two basic versions, the Comet 3.
Introducing a 15.5-foot fuselage stretch over the Comet 2, which increased its overall length from 96 to 111.5 feet, it offered four-abreast first class and five-abreast economy passenger capacities of, respectively, 58 and 78.
Two wingtip pinion tanks, installed on the existing airfoils, increased their area to 2,121 square feet and loading to 68.4 pounds per square foot, while the new 8,360-Imperial gallon fuel capacity they provided took the type’s range to 2,700 statute miles. Power was provided by four 10,000 thrust-pound Rolls Royce RA26 Avons, which facilitated payload and gross weights of, again respectively, 20,200 and 145,000 pounds-the latter 40,000 pounds more than the original Comet 1’s capability. Cruising speed, at 29,000 feet, eclipsed the 500-mark for the first time, reaching 516 mph.
Registered G-ANLO, the Comet 3 prototype first took to the air on July 19, 1954. BOAC, logically the launch customer for the previous versions, followed suit with the long-fuselage one, ordered five. But the aircraft’s greatest achievement was Pan American’s milestone three-firm and seven-optioned order for the type on October 20, 1952. Innovative and globe girdling, it could only remain so by entering the jet age with the latest and fastest equipment, no longer able to maintain its image with its slower, piston-powered Boeing B377 Stratocruisers, Douglas DC-6s, and Lockheed Constellations.
Aside from the Comet’s acceptance by carriers such as Pan American, it equally penetrated the US market, where Boeing’s 707 had still only been an idea, demonstrating the fact that the country had not been able to keep pace with turbine airliner advancement. It would enable Pan American to offer both transatlantic range and acceptable passenger capacities.
Air India’s order for two and the Ministry of Supply’s order for one rounded out the initial commitments for the definitive version, whose superlative performance was demonstrated during its test flights. Between October 23 and 24, 1957, for instance, it covered the distance between London and Johannesburg in 12 hours, 59 minutes at an average 433-mph speed.
THE COMET 4
For passenger services, de Havilland considered producing modified versions of its existing DH.106-1s, -1As, and -2s, but increased traffic demand could not be met with their low capacities that ranged from 36 to 42. Although the more ambitious Comet 3 offered greater power, range, and capacity, it had been designed with the type’s original flaws and would have required a modification too extensive and costly to bring them up to safe standard.
The solution lay in the proposed and definitive Comet 4, which would incorporate the fuselage strengthening and round cutouts of the Comet C Mark 2s, but the greater dimension of the Comet 3.
Subjected to a demonstration tour in December of 1956 in order to collect range, speed, performance, and operating cost data during simulated airline service, it landed in Sydney, Australia, after a 23-minute hold, during which an overenthusiastic crowd, numbering some 35,000, was water hose forced to relocate so that it could safely touchdown. The elongated version, the first time it ever landed down under, was inundated by the reception.
Later in its tour, it covered the 3,350-mile distance between Montreal and London in six hours, `18 minutes, averaging 548 mph, achieving the distinction of being the first pure-jet airliner ever to cross the Atlantic without stopping and demonstrating the type’s potential.
Although, as a prototype, it maintained a four-psi internal pressure to reduce fuselage skin loads and the 20,000-foot equivalent atmosphere consequently necessitated crew oxygen, it nevertheless succeeded in performing 80 percent of the tests required for Comet 4 certification, accelerating its development program. It had, at this time, not even been built.
Its urgency was prudent. Unlike the Comet 1, which did not face competition at the time of its conception, the longer-fuselage Comet 4 did so across the Atlantic, since the Boeing 707’s prototype, the 367-80, had already taken to the skies on July 15, 1954 and Douglas’s DC-8 counterpart was in advanced blueprint form.
Equally important in the Comet 4’s development program was the Comet 2, which provided initial operating experience with the 10,500-thrust-pound Rolls Royce RA29 Avon 524 engines, two of which were installed in the outboard positions, and these were fed by larger, almost rectangular-shaped air intakes. So-configured, it was designated Comet 2E and first flew in August of 1957. BOAC and the Ministry of Supply each ordered one.
Registered G-AMXK, the former’s example otherwise retained the 7,300-thrust-pound RA9s in the inboard positions and was intended to amass 3,500 hours of engine experience by May of 1958. Between September 16 of the previous year and May 31 of the following, it operated eleven weekly roundtrips to Beirut, which covered 4,500 miles in an attempt to simulate routine airline service.
The Ministry of Supply’s test vehicle, registered G-AMXD and conforming to the same powerplant configuration, was subjected to a similar schedule. Collectively, the pair flew 3,344 miles, averaging more than 14 daily airborne hours, in the process demonstrating the type’s reliability, despite an increase in engine rpm from 7,100 to 7,400. Only a single, unscheduled engine change, necessitated by the failure of an auxiliary unit, was carried out during this grueling period.
So reliable, in fact, was the new powerplant, that the Air Registration Board granted it its full normal category approval before the DH.106-4 even flew, extending its time-between-overhauls interval from 250 to 750 hours ten months later and, still later, to 1,000 hours.
The Rolls Royce Avon 524 engines introduced exhaust nozzle silencers that reduced their audible output five to six decibels below that of comparable Douglas DC-7 and Lockheed Constellation piston airliners, resulting in Port Authority of New York clearance for operation of the Comet 4 to Idlewild International Airport, its intended destination.
BOAC, having played a major role in its design configuration and development program, never lost faith in the aircraft, without which it may never have been built. Indeed, forced to operate a motely fleet of antiquated piston types, most of which it had since disposed of, it lost 500,000 pounds Sterling during the grounding and now heavily relied on the long-range, higher-capacity version for its transatlantic operations and to restore it to profitability.
Its eventual, 19-strong Comet 4 fleet would progressively replace the Boeing B377 Stratocruisers it temporarily deployed, six of which it had ordered, another six of which had been operated by United Airlines, four of which had been intended for SAS, and one of which had been flown by Pan American. It had also been left with no choice but to reinstate the Handley Page HP81 Hermes 4 piston airliners it had retired after delivery of its first DH.106-1s.
The jetliner which ultimately emerged from the wreckage of defeat to the structural integrity of victory during its Phoenix-like reincarnation, featured a 111.5-foot overall length, oval passenger windows, three overwing emergency exits on either side, thicker fuselage skins, and greatly increased integrity to withstand the pressurization forces against it during a 30,000-hour operational life.
The wings, still with their original 20-degree sweepback, were increased in span, resulting in a 115-foot one and a 74.4-pound-per-square-foot loading, and housed an 8,900-Imperial gallon fuel capacity. The pinion tanks, installed on the still-born Comet 3 and located three-fourths from the root, were retained.
The four 10,500 thrust-pound Rolls Royce RA29 Avon Mark 524 engines were equipped with larger air intakes, noise suppressors, and thrust reversers, and were subdivided into three temperature zones, each of which was formed by a bulkhead, ventilators, and fire extinguishers. The thrust reversers themselves, whose 1,002-pound deflector units ducted the thrust 45 degrees forward and 20 degrees sideways by means of louvered openings, decreased landing runs, provided more positive deceleration during wet and contaminated surface conditions, and reduced brake and tire wear. Their ducting precluded fuselage or undercarriage interference.
Single-class arrangements, depending upon density, varied from 70 to 81 passengers, although accommodation was later increased to 100. An 8.75-psi pressure differential produced an 8,000-foot atmosphere at a 43,000-foot cruise altitude.
The way the Comet 1 had launched the jet age and inaugurated scheduled jet service, it only seemed logical, to do the same across the Atlantic, perhaps demonstrating the aircraft’s rightful accomplishment.
Piloted by Captain Roy Millichap, aircraft G-APDC was accessed by a mobile boarding stair, in front of which was an arch that proclaimed, “BOAC Comet 4: First-Ever Transatlantic Jet Service.” Disppendaged from these access stairs, the airliner started its screaming, wing root-installed Rolls Royce turbines and inched aware from its parking position at 09:55, taxiing to the runway’s threshold, during which the pre-takeoff checklist was completed and the trailing edge flaps were extended.
Now poised on it, it symbolically represented the threshold of the re-established jet age and the beginning of yet another new era-that of pure-jet service across the Atlantic Ocean. Opening its throttles, which unleashed a thunderous roar from its four, 10,500 thrust-pound engines, it began its acceleration roll, a journey which had taken more than four years in the making since the early-Comet groundings. Generating sufficient lift, it teetered on its main wheels as its nose pointed skyward and surrendered itself to the sky, now North America-bound, only leaving the four fading smoke trails behind to hint of its existence. Its extended wings would carry it across the ocean.
In many ways, the event was reminiscent of Geoffrey de Havilland’s namesake “The de Havilland,” which had initially failed, but later rose to victory, incorporating the lessons it taught. Both triumphed over the elements, the airplanes of other manufacturers, and their own shortcomings. Although the Comet 1 was now history, it was nevertheless, in a strange way, present in spirit and innovation. Like people, it strove to become the best version of itself and far superior to its original conception.
Briefly alighting in Gander, Newfoundland, to refuel. It proceeded to New York-Idlewild, successfully completing its second triumph. Aircraft G-APDB, operating the first eastbound transatlantic crossing, did so nonstop, touching down in London after a mere six hours, 12 minutes, competing with and beating Pan American, which inaugurated its own 707-121 jet service three weeks later on October 26, 1958 with “Clipper America,” powered by four Pratt and Whitney JT3C-6 engines and registered N711PA. Destined, instead, for Paris, it also made a refueling stop in Gander.
By November 13, the London-New York route was operated daily and the Comet 4 also spread its wings to Montreal, Tokyo, Hong Kong, Malaya, Australia, South Africa, and South America by the time all 19 ordered aircraft had been delivered on January 11, 1960. They collectively logged 4,700 monthly airborne hours, covering 487,000 weekly miles.
BOAC flew its Comet 4 fleet until November 24, 1965, at which time it was replaced with Rolls Royce Conway-powered 707-420s, and they were acquired by AREA of Ecuador, Dan-Air of London, and Malaysia-Singapore Airlines.
PROGRAM PERSPECTIVE
The de Havilland DH.106 Comet story is an intriguing one tell, but a difficult one to conclude, since its early history was plagued with doubt and fatality, questioning the integrity of its engineering and design. The darkness of defeat, of course, ultimately led to the light of victory.
While aircraft, as assessed, are invariably compared to others, there were no others to which the Comet could be equated for evaluation, since it was the first and became, to a degree, the standard by which others were compared. As a pure-jet airliner, it was the first, the trailblazer, and the catalyst to the jet age. When placed in the shadow of previous pistonliners, it offered leaps in technology, speed, and altitude. However, when placed next to the jet airliners that followed it, it became their shadow because of its limited range, excess noise and fuel consumption, and small payload.
As a result, being first renders and reduces any comparison to one without validity or significance. Paving the way, even in the air, often entails unexpected falls, as the aircraft certainly experienced, since it was based upon the aerodynamics and technology then known and sadly needed first hand, if not fatal, experience, to expose the limitations based upon it and the flaws that surfaced to alert of them.
But it certainly set standards of speed and comfort, redefining the ratio and relationship between distance and time, and proved the overwhelming passenger demand for and acceptance of the jet engine over all ranges.
De Havilland crossed the piston-pure-jet powerplant line with the DH.106 Comet, culminating with the 4C, which offered a one-third increase in gross weight, a more than double increase in engine thrust and range, and a two-third increase in passenger capacity, and reduced its 36-hour, eight-stop flight from London to Tokyo to a 26-hour, four-stop one.
Shrinking the world by forty percent, the Comet revolutionized commercial aviation, reducing travel times; transforming formerly inaccessible parts of the world into reachable realities; changing the concept of distance; and intermingling cultures, languages, politics, business, economics, ideas, and attitudes by means of high-speed altitudes.
Although only a beginning, its spirit and the lessons it taught continue in every jetliner that has since entered service. Without it, there may never have been a jet age.
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