Boeing 707 Turbojet Airliner

  • By Anthony E. Pomata
  • Posted 7/03/2002
  • HistoryLink.org Essay 3890
Boeing, the oldest major aircraft manufacturer, entered the jet airliner business third, after the British and Russians. Success long eluded Boeing in the art and science of building and selling airliners (non-military airplanes for commercial air travel) at a profit. Beginning in 1928 with the model 80 trimotor airliner (a biplane with fabric covering), Boeing labored hard at producing a handful of innovative airliner designs in small, unrewarding quantities. In 1958, Boeing’s first jet airliner, the 707, proved to be the vehicle that finally changed the commercial side of the ledger from red to black ink. The 707, based on the prototype Dash-80 (1954), was the first truly successful jet airliner in service that was built in large numbers (almost twice that of the runner up Douglas DC-8) and which returned a profit to its maker.

The 707 overcame its late start with the best combination of technology, capability, and economics to out distance all of the first generation jet airliner builders, including those that followed Boeing’s design lead.

The British Were First

Britain and Germany pioneered the development of the jet-propelled airplane, and were the only nations whose jet airplanes engaged in combat during World War II. The British had long been major players in the airliner business, which appeared to them to be becoming an American dominated industry with the end of the war. Piston engine airliners being built by Douglas, Lockheed, and Boeing were far in advance in capability of their European competitors. Those West Coast manufacturers of long-range airliners were then joined by Convair and Martin covering the short haul segment.

Pondering the need the need to support its aviation industry, the British government decided to fund the development of several gas turbine (turbojet, turbofan, turboprop) engined airliners. The idea was to create a market niche for the newest technology, high-speed turbojet and turboprop-powered airliners, while the Americans were concentrating on profiting from obsolescent piston engine airliners. (The turbojet engine is the basic engine of the jet age. It works by compressing air, forcing it into a combuster, which sprays fuel on it and ignites it. The air burns continuously like a blow torch, through the turbine, which extracts energy to work the compressor, and out the back to thrust the aircraft forward.)

Aircraft and engine manufacturer de Havilland’s Comet began as a design study during mid-1941, early into World War II. By the time the DH.106 Comet flew in 1949, it had evolved into a sweptback wing, small capacity, medium range airliner with an attractive, aerodynamically clean appearance. Its four de Havilland centrifugal flow turbojet engines were positioned inside the wing, adjacent to the fuselage (the body of the aircraft). Entering service with the British Overseas Airline Corp. (BOAC) in 1952, the Comet was an immediate hit with passengers, and it quickly attracted orders from many airlines. Pan American Airlines (PAA), the trailblazer among the long distance airlines, felt compelled to order an advanced Comet variant, as there was no U.S. competitor in being or even on the horizon.

The Comet had a short-lived triumph as it tragically experienced a series of fatal accidents, which resulted in grounding in 1954 after less than two years. Careful analysis of the accidents revealed a cabin structural design flaw. Repeated pressurization cycles caused the cabin to fail, leading to explosive decompression. Other accidents were attributed to pilot error in mastering the new techniques required to fly swept wing, turbojet airliners.

A revised, much larger Comet 4 entered service in 1958, several weeks before PAA flew the first 707 across the Atlantic. It was too late and too small to compete with the faster, larger, and longer-ranged Boeing. Fewer than 125 Comet airliners were built. The Comet survives in 2002 in the form of a maritime reconnaissance variant named the Nimrod, operated by the British Royal Air Force.

Next The Russians

The Soviet aircraft industry was ordered by dictator Joseph Stalin to produce a jet airliner to match the Comet for prestige reasons and to reduce travel times across the immense 11-time-zone country. In short order, Tupolev produced a straightforward airliner adaptation of its new Tu-16 Badger twin jet bomber. The resulting Tu-104 was an attractive, rather unrefined airliner with a passenger-carrying fuselage mated to the bomber’s wings, tail, engines, and landing gear. Flying in 1955, a year after the 707 prototype, it beat the 707 into service by two years, beginning in 1956. That same year it became the first jet airliner to transport a head of state (Soviet Premier Nikita Khrushchev).

With the Comet grounded, the larger, faster (600+ mph) Tu-104 was the only turbojet airliner in service for more than two years until the Comet 4 and 707 joined it in 1958. As the first successful turbojet airliner, the Tupolev was untroubled by pressurization problems, and it introduced the axial flow turbojet engine to airline service. Its Mikulin engines produced twice the thrust of any Western engine at the time, and it took more than five years for U.S. and British companies to equal its power. The Tu-104 series served Soviet Bloc airlines well for nearly 20 years. Just over 200 airliners were built.

The Dash-80 Begins a Dynasty

Having lost out to Douglas and Lockheed with the disappointing sales of its highly regarded, but comparatively expensive 377 Stratocruiser, and with the Comet in service, Boeing decided to compete anew with a jet airliner. The plan was to satisfy the Air Force need for a jet powered air-refueling tanker and to provide the airlines with a large jet airliner, using essentially the same airframe. Boeings’ concept was to use Air Force development funding to help defray costs, and to economize by building both types on the same assembly line.

When the mid-1952 decision was made to build a company-funded jet propelled prototype to the tune of $16 million, Boeing was well positioned to succeed. At the time it had built thousands of pressurized aircraft and was the only maker of large, 600 mph jet aircraft. The B-47 Stratojet bomber was in production, and the recently flown YB-52 Stratofortress bomber was well received by the Air Force. Boeing’s development of the successful Flying Boom air refueling system, in use aboard KB-29 and KC-97 propeller-driven tankers, made its jet tanker proposal extremely attractive to the Air Force.

Beginning in 1946, Boeing studied a series of turboprop and turbojet powered modifications of its C-97 Stratofreighter and Stratocruiser. Perhaps Boeing was influenced by an Air Force experiment wherein two pairs of B-47 inboard jet engines, complete with pylons, were hung on a straight-winged transport glider and successfully tested. The Chase XCG-20A was flown on April 20, 1951, thus becoming the first U.S. jet transport and the first transport to use axial flow jet engines. Ultimately, however, a fresh approach incorporating B-47 and B-52 design elements was selected. Designated as model 367-80 to disguise the new aircraft as a variant of the C-97 for competitive reasons, the prototype became known the Dash-80 or Dash Eighty.

Emerging in 1954 as a chocolate and yellow painted sweptback winged beauty with four under-slung engines, the Dash-80 owed little to any previous jet airliner. Indeed, the Dash-80 can be considered to this day to be the granddaddy of most of the following large jet airliners built in the U.S., Europe, Russia, and even China, as they adopted its general configuration for their own.

Flown on July 15, 1954, the Dash-80 proved to be an immediate winner in terms of flying qualities and technology. The real battle then began as Boeing tried to sell the Air Force and the airlines on its new product. Urgently needing a fast, jet powered tanker to refuel its speedy jet bombers and fighters, the Air Force stepped up to the plate first and ordered 29 KC-135 Stratotankers to replace its propeller-driven tankers. Assured of the soundness of its gamble by the September 1, 1954, tanker order for an enlarged Dash-80 development, Boeing prepared to produce it.

That Pivotal Inch

At this time Douglas and Lockheed essentially owned the world long-haul airliner market that Boeing wanted a big piece of. Douglas, in fact, had announced plans to build its own jet airliner, which would materialize in mid-1958 as the DC-8, a near twin of the 707. Airlines weren’t anxious to enter the jet age just yet. Piston engine airliners were profitable, the Comet saga indicated that more development was necessary, and the high cost of jet airliners and their required infrastructure all conspired against Boeing.

Meanwhile, the British were first again. The Vickers Viscount four-turboprop airliner entered into service in early 1953. Vickers turboprop would prove to be the first successful turbine-engine airliner in service that was built in large numbers (444). Several U.S. airlines placed orders for larger capacity variants.

In 1955, Boeing, with its Dash-80 flying prototype and its first jet tanker under construction, was locked in a sales battle with Douglas, which had never built a large jet airplane of its own design, and which was pitching an un-built airplane to the airlines, and winning. Douglas, with a solid reputation as an airliner manufacturer, was offering DC-8 models with more powerful engines, greater passenger capacity, and longer range than the proposed 707. PAA and American Airlines wanted six-across passenger seating, longer range, and more powerful engines.

The DC-8 was offered with an overall fuselage width of 147 inches, sufficient for six across seating, while Boeing wanted a common airliner and tanker fuselage width of 144 inches (to economize on tooling costs), which was too narrow for the airlines.

Boeing’s president Bill Allen made the costly decision to widen the 707 for six-across seating. At 148-inch fuselage width, the 707 design was now one inch wider than the DC-8, and PAA bought 20 of these, as well as 25 DC-8s. Boeing was behind. To secure additional orders, Boeing offered several fuselage lengths, larger wings for more range, and more powerful engines. By developing a family of 707 models, Boeing unknowingly set the stage for its great success in the jet airliner business.

First 707 Service

The Comet 4 raced across the Atlantic carrying passengers on October 4, 1958, three weeks before PAA flew the first 707 passenger flight from New York City to Paris, on October 26, 1958. It was a hollow victory for the new Comet version as it lacked true trans-Atlantic capability, as evidenced by the need to refuel in Canada en route to New York. BOAC, a British national airline, was among the first to order 707s.

Domestic U.S. airline service began that year when National Airlines flew a leased PAA 707 from Miami to New York. The order flood gates opened, Boeing became the jet airliner manufacturer of choice, selling hundreds of 707s around the world. Within a short period, 707s were flying passengers and cargo throughout the Free World.

Some firsts. Boeings’ first turbine engine transport in service were two Air Force YC-97Js turboprop test aircraft flown in 1956 to gain operating experience. During July 1955 the first turbine engine airliner in U.S. service, a Vickers Viscount turboprop, carried passengers for Capital Airlines. On September 27, 1958, a Fairchild Friendship twin turboprop airliner (Dutch designed, U.S. built with British engines) flew revenue service for West Coast Airlines in California. Douglas flew its DC-8 on May 30, 1958; it entered service less than a year after the 707 on September 18, 1959. The first supersonic airliner was a Douglas DC-8-43 that dived past Mach one (a figure representing a very high rate of speed) during a test on August 21, 1961.

Turbofan Transformation

Early 707 turbojet engines lacked power, were noisy, prodigious fuel burners, and environmentally dirty. The British again stepped forward and introduced the turbofan engine. It differed from the turbojet by having an enclosed set of large compressor blades added, which moved volumes of cool air along the core engines’ exterior. The effect was near miraculous -- increased power, lower fuel consumption, less noise and pollution, for a slightly heavier, more expensive engine. All current production jet airliners use turbofan engines. British Rolls-Royce Conway turbofans powered a 707-420 into the air on May 20, 1959, but it was a Douglas DC-8-40 using similar engines that entered airline service first on April 1, 1960.

And yet again an American company seized the initiative, and wrested the turbofan market away. Pratt & Whitney, the turbojet supplier to both Boeing and Douglas, rapidly developed its superior JT3D turbofan engine, which became the most reliable airplane engine in history. The JT3D transformed the 707 into a stellar performer, and the orders poured in. Pratt & Whitney went on to furnish the vast majority of engines for the 707, 720, 727, 737 (first generation), 747, DC-8 and DC-9 airliners, and U.S. and foreign military transports.

Presidential Airplanes

Teddy Roosevelt was the first of our Presidents to fly aboard an airplane (and ride in an automobile), on October 1, 1910, years after he left office. Boeing had the distinction of carrying the first sitting President aloft on January 14, 1943, when its 314 Clipper flying boat flew Franklin D. Roosevelt to the Casablanca Conference in North Africa. In the following period, a series of propeller-driven airliners served the President. With the Soviet Premier flying in jet aircraft and the 707’s entry into service, the time was ripe for the Presidency to enter the jet age. The Air Force ordered three 707-120s, designated as VC-137As, for White House use, as well as for other VIPs. When the President is aboard a VC-137A, it is called Air Force One. President Eisenhower inaugurated White House jet travel in 1959.

A fourth jet, a turbofan 707-320B/VC-137C tail #62-6000 (now at the Air Force Museum, Dayton, Ohio) was ordered for the use of President John F. Kennedy (1917-1963). It figured tragically as the location where Vice President Lyndon B. Johnson was sworn in as President following Kennedy’s assassination on November 22, 1963. A final jet, VC-137C tail #72-7000 served as the principal Air Force One until 1990. Boeing has a lock. The newest and current Air Force One is a 747-200, designated as VC-25A.

Medium Range 720

With the 707 solidly in service, two serious competitors appeared on the scene offering medium range jet airliners. By 1959, the Convair 880 (another 707 look-a-like) and the French twinjet Caravelle had flown. Boeing defended its market share by introducing the new 720 airliner. While appearing as a 707 variant, the 720 was a new design aerodynamically and structurally, optimized to cover the medium range segment of the market. The 720 entered service during 1960.

Special Missions

Boeing satisfied an Air Force requirement for a flying radar station and command post by modifying a 707-320B with an overhead rotating radar rotodome. The resulting production aircraft designated as E-3 Sentry AWACS (Airborne Warning and Control System), was the final 707 airframe built. This occurred in 1991. The navy also procured modified 707-320Bs, designated as the E-6A Mercury, to function as a communication platform for land and sea based ballistic missile operations. Both of these special mission aircraft remain in front line service in 2002. Canada and Iran purchased 707s modified for the airborne refueling tanker role.

Mass Production

The 707 is no longer in first tier airline service, but several foreign airlines provide third tier and charter service. Private individuals operate 707s, including actor/pilot John Travolta. Dash-80 progeny include the manufacture of nearly 2,000 707s, 720s, and C-135s, all in Renton, Washington, truly mass production on a grand scale, greatly rewarding Boeing for its $16 million gamble.

Several 707 design elements survive today in the form of the similar appearing nose of the current production 737 Next Generation airliner, and in the identical fuselage width of the 737 and the contemporary 757 airliner. The Dash-80 presently resides in Boeing’s Plant 2, awaiting the completion of its new home at the National Air and Space Museum, located in Washington, DC. Boeing has delivered more than 10,000 jet airliners.


Sources: Boeing Archives; Robert J. Serling, Legend and Legacy: The Story of Boeing and Its People (New York: St. Martin’s Press, 1992); Boeing Public Relations; Alfred Price, The Boeing 707, Profile no. 192 (Surrey, U.K.: Profile Pub. Ltd., 1967); Barry J. Schiff, The Boeing 707 (New York: Aero Pub. Inc., 1967); Bill Gunston, The Illustrated Encyclopedia of Commercial Aircraft (New York: Exeter Books, 1982); William Green and Gordon Swanborough, The Illustrated Encyclopedia of the World’s Commercial Aircraft (New York: Crescent Books, 1997); William F. Smith, Jr., "The Supersonic Dive of a DC-8", American Aviation Historical Society Journal (Spring 1992); Paul Duffy & Andrei Kandalov, Tupolev, The Man and His Aircraft (Warrendale, PA: Society of Automotive Engineers, Inc., 1996); Dependable Engines Since 1925(Hartford: United Technologies/Pratt&Whitney, 1982); Bill Gunston, The Development of Jet and Turbine Aero Engines (Somerset, U.K.: Patrick Stephens Ltd., 1995); Kenneth Munson, The Vickers Viscount 700, Profile no. 72 (Surrey, U.K.: Profile Pub. Ltd., 1966); Air Force Museum Website (www.wpafb.af.mil/museum); Seattle TV station KING 5 News Department; Author visits aboard the Dash-80 N70700 in Boeing’s Plant 2, VC-137B #58-6970 at the Seattle Museum of Flight, and numerous passenger flights in 707s.

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