The triumph of the widebody

From the first jumbo jet to today’s twin-aisle: widebodies make aviation profitable.

11.2015 | Text: Achim Figgen

Text:
Achim Figgen is a graduate engineer specializing in aerospace technology and he has written several books on aviation subjects.

Birth of the jumbo

“If you build it, I’ll buy it.”—“If you buy it, we’ll build it.” This brief ex­change be­tween Pan Am founder Juan Trippe and Boeing chief Bill Allen tran­spired in the mid-1960s, just at the start of the wide­body era. At that time, long-haul routes were served by the Boeing 707 and Douglas DC-8: quad jet aircraft with a fuselage diameter that per­mitted six seats per row, three on either side of the aisle.

With pas­sen­ger volume increasing rapidly, it was only a matter of time before this design would become too small. Douglas responded to the airlines’ requests for a larger aircraft by extending the DC-8 into the “Super Sixties” series. Boeing’s 707 sat too low to the ground to pursue this approach, which is why it decided to completely redesign the aircraft. Juan Trippe was only too happy to agree—the charis­matic and un­con­ven­tion­al head of Pan Am had searched long and hard for a revo­lution­ary solution and had little interest in one that provided only a small increase in pas­sen­ger capacity.

At this time, it was widely assumed that pas­sen­ger air transport would soon be dominated by supersonic aircraft, such as the British-French Concorde or Boeing’s planned 2707. This meant that any subsonic aircraft had to be able to double as a freighter. In re­designing the 707, Boeing based the plans on a military transport concept that lost the contract to Lockheed’s C-5 Galaxy, developed in the mid 1960s. The cockpit was moved “upstairs” to make way for a gigantic nose cargo door for freight, giving the Boeing 747, soon nicknamed “jumbo jet”, its dis­tinct­ive hump.

The C-5 Galaxy itself also played a key role in the “birth” of wide­body pas­sen­ger jets (some­times referred to as twin-aisle aircraft). For this aircraft, GE Aviation and Pratt & Whitney designed com­pletely new turbofan engines with a high bypass ratio. These laid the ground­work for the later CF6 and JT9D commercial engines, whose perfor­mance made the con­struction of the jumbo jet and sub­sequent wide­body air­craft possible in the first place.

Jets for high-volume routes

On January 22, 1970, the first scheduled flight of a Pan Am jumbo jet took off from New York for London—one day later than planned. This delay was symptom­atic of the dif­ficulties faced by Boeing as it attempted to pioneer the widebody passenger jet. Much more serious than the initial un­reliability of the JT9D engines, however, was the oil crisis of the early 1970s and the undeniable fact that, for many routes, the jumbo jet was simply too large.

Yet even the somewhat smaller wide­body models that competitors launched on the market at virtually the same time also struggled. In the mid-1960s, American Airlines executive Frank Kolk wrote a strategy paper in which he estab­lished the require­ments for a future widebody jet for high-volume medium-haul routes: a carrying capacity of about 300 passen­gers and powered by just two engines. However, McDonnell Douglas and Lockheed decided to give their new jets three engines. The DC-10 was put into service on August 5, 1971, followed almost a year later by the L-1011 “TriStar” on April 26, 1972. Both of these were initially used pre­domin­antly on U.S. domestic routes, and later branched out into inter­contin­ental travel. As they did so, they increas­ingly replaced the smaller quad-jet single-aisle model; it was substan­tially less profitable due to its lower carrying capacity, and its low-bypass engines made it a good deal louder.

Modern widebody aircraft


Boeing 787-8 Dream­liner First flight: 2009; length: 56.7 meters; wingspan/width: 60.1 meters




Boeing 787-8 Dreamliner


Twin Aisle Widebody


210-250 passengers
approx. 220 tons take-off weight



Boeing 777-300 First flight: 1997; length: 73.8 meters; wingspan/width: 60.9 meters




Boeing 777-300


Twin Aisle Widebody


370-550 passengers
approx. 300 tons take-off weight



Boeing 747-8 First flight: 2011; length: 76.3 meters; wingspan/width: 68.5 meters




Boeing 747-8


Twin Aisle Widebody,
partial double-deck


470-600 passengers
approx. 450 tons take-off weight



Airbus A380 First flight: 2005; length: 72.7 meters; wingspan/width: 79.8 meters




Airbus A380


Twin Aisle Widebody, double-deck


540-850 passengers
approx. 575 tons take-off weight


Crossing the Atlantic on two engines

Twin-jet aircraft of the sort Kolk envisioned were then indeed built—not by one of the estab­lished U.S. manufacturers, but by a newcomer from the other side of the Atlantic. The A300 was de­veloped within the Airbus consortium led by France and Germany with British and eventually Spanish in­volve­ment. It took off on its maiden flight on October 28, 1972 and was in regular service as of May 1974.

Hardly anyone at the time could have guessed what funda­mental changes the arrival of this European jet would trigger in the industry. For one thing, Boeing and its peers were confronted with a competitor that conquered half the global market within about four decades and also proved to be a deciding factor in Lockheed’s with­drawal from the commercial market and McDonnell Douglas’s being forced to seek refuge in a merger with Boeing. For another, the A310 (based on the A300) and, to an even greater extent, the Boeing 767, which appeared on the market at roughly the same time, made it pos­sible to fly long-haul routes with twin-jet aircraft. Airlines could now offer nonstop con­nections outside of the major aviation hubs.

THE FIVE LARGEST AIR PASSENGER HUBS IN THE WORLD (NUMBER OF PASSENGERS)

Dubai, UAE (DXB)
71.548.061

London, GB (LHR)
68.310.701

Hong Kong, HK (HKG)
64.767.139

Paris, FR (CDG)
58.780.759

Amsterdam, NL (AMS)
55.537.414

International passenger traffic The figures comprise all passengers boarding and disembarking at the respective airport over the period from April 2014 to April 2015.

THE FIVE LARGEST AIR CARGO HUBS IN THE WORLD (MEASURED IN TONS)

Hong Kong, HK (HKG)
360.000

Incheon, KR (ICN)
212.097

Dubai, VAE (DXB)
204.075

Shanghai, CN (PVG)
202.865

Taipeh, TW (TPE)
174.013

International freight traffic The volumes comprise the total freight and airmail loaded and unloaded at the respective airport in tons during the month of April 2015.

Source: Airports Council International, July 2015

Measured in flight time, the distance that a twin-engine jet is allowed to be from an alter­native airport in the case of engine failure increased steadily, thanks primarily to the major boost in the reliability of the modern turbofan engines. The first trans­atlantic flights were flown with the A310 and B767 in the mid-1980s; today it is possible to receive ETOPS (extended-range twin-engine operational performance standards) certifi­cation for five hours and longer, depending on the type of air­craft. This means that even jets equipped with only two engines can fly virtu­ally any route in the world without making a detour.

Timeline

WIDEBODY AIRCRAFT AND ENGINES FROM 1960S TO TODAY

Bigger and farther

But the engines didn’t just get more reliable; they also became more powerful, so that the aircraft size at which two engines were no longer suf­ficient kept getting bigger and bigger. Twin-jet models were soon able to hold their own when it came to range, as well. In the early 1990s, Airbus put the quad-jet A340, which can theoret­ically transport up to 440 passen­gers, on the market beside the A330. The latter was just as large but had only two engines, and actually sold much better. Another major twin-engine success was Boeing’s “Triple Seven,” which made its debut in the mid-1990s. In the engines they developed for the air­craft, GE Aviation, Pratt & Whitney, and Rolls-Royce pushed dimen­sions and per­form­ance to hitherto unseen levels.

This trend became par­ticu­larly evident when new versions of the A340 and Boeing 777 were launched on the market at the start of the millen­nium. In terms of range and passen­ger capacity, they were clearly designed as suc­cessors to previous 747 models. The twin-engine 777-200LR and -300ER performed as well as or better than the A340-500 and -600, and did so at lower cost. Airbus took this lesson and imple­mented it in the A350 XWB; since then, models smaller than the A380 are also based solely on a twin-engine design.

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Spacious The view of the upper deck bar and economy class of an A380.

widebodys_1

Spacious The view of the upper deck bar and economy class of an A380.

Where to next?

As twin-engine aircraft become ever more efficient—seat kilo­meter costs of the A350-1000 and Boeing 777-9 models currently in develop­ment are expected to match those of the A380—it raises an important question: Are aircraft like the A380 or the only slightly smaller 747-8, the latest jumbo jet, even neces­sary? “Sales of wide­body aircraft with two decks are not going as well as they were forecast to ten years ago,” states Dr. Marc Le Dilosquer, Director, Market Analysis at MTU Aero Engines. In fact, airlines are currently holding off on new orders, although this may also have to do with changes in the market environ­ment. The rapid growth of Persian Gulf airlines has shifted traffic flows; passen­gers wishing to travel from Europe to destin­ations in the Asia-Pacific region no longer auto­matically fly via Hong Kong, Singapore or Bangkok. They are also no longer limited to Qantas Airways, Singapore Airlines, Thai Airways International or Cathay Pacific, carriers that dominated these routes for decades. But if Airbus equips the A380 with new engines, thus regaining the former operating cost advantage over the smaller twinjets, then the A380’s biggest customer, Emirates, will purchase still more of the world’s largest passen­ger airliner.

At any rate, John Leahy, Head of Sales at Airbus, remains confident. The number of mega-cities, which Airbus defines as cities that see more than 10,000 passen­gers a day on long-haul flights, is expected to nearly double over the next 20 years from 47 today to 91. Leahy makes a clear case that this will create demand for air­craft like the A380. But Randy Tinseth, Vice President Marketing at Boeing Commercial Airplanes, counters this with arguments that are just as convincing. In the past ten years, the number of flights to places such as Tokyo’s Haneda and Narita Airports or Seoul’s Incheon International—in other words, airports in precisely such mega-cities—has grown between 26 and 33 percent. At the same time, the number of avail­able seats declined at a double-digit rate. Tinseth concludes that the market is demanding higher frequency rather than larger aircraft.

That the lion’s share of long-haul passen­ger routes will be handled in the future by twin-jet aircraft might indeed be indisput­able. However, it’s still too soon to bid the A380 adieu. Don’t forget that the jumbo jet didn’t become the best seller it is remem­bered as today until the completely redesigned 747-400 version went on the market—more than 20 years after the first proto­type made its maiden flight.

WIDEBODY AIRCRAFT AND ENGINES FROM 1960S TO TODAY

Inside MTU Widebody engine expertise at MTU Aero Engines

For more than four decades, MTU Aero Engines has actively partici­pated in developing and manu­facturing wide­body engines, and during that time, its role has only increased in import­ance. Its story began in the early 1970s with GE Aviation CF6, one of the most success­ful turbofan engines of all time. Now used in the A330, B747 and MD-11, to name just a few, the engine features MTU parts in its turbine and compressor.

GE competitor Pratt & Whitney is involved in production of the PW4000, one of three engines for the original versions of the Boeing 777. MTU was able to land the contract for developing the low-pressure turbine, which it manu­factures to a large extent in house.

For the A380’s engine, the GP7200, MTU developed and now manu­factures the low-pressure turbine and the turbine center frame. In addition, MTU produces components for the engine’s high-pressure turbine, putting its program share at a proud 22.5 percent (see “The GP7000 engine for the A380”).

MTU develops and builds the turbine center frame for GE’s GEnx engine (used in Boeing’s 787 and 747-8) and the GE9X, which will power Boeing’s new long-haul models 777-8 and 777-9 (see “In the middle: The turbine center frame for large aircraft engines”).

But MTU does more than just develop and manu­facture wide­body engines—these also currently account for about a third of all overhaul work at MTU Main­tenance in Hannover. The CF6 is the most important product at the moment and is expected to remain so for some time, according to Norbert Möck, Director GE Programs at MTU Main­tenance. The halls in Hannover have also already seen more specimens than planned of the GE90, which was added to the port­folio three years ago.

widebodys_3

Proven technology a CF6-80C2 at MTU Maintenance.

widebodys_3

Proven technology a CF6-80C2 at MTU Maintenance.

widebodys_4

Putting a giant through its paces a GP7000 on a test rig.

widebodys_4

Putting a giant through its paces a GP7000 on a test rig.

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