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Trail-blazer

As it celebrates its 55th anniversary, key.aero looks at Boeing’s 707, the ‘granddaddy’ of the modern airliner.

17-Aug-2009


The prototype Dash 80 flies past Mount Rainier. Boeing image

In the years following World War Two, the Boeing Company was primarily concerned with the production of military aircraft and the development of the B-47 ‘Stratojet’ and the B-52 in particular. The manufacturer had produced the first pressurised airliner in the Model 307 ‘Stratoliner’, which had first flown in 1938 and was roughly based on the B-17 Flying Fortress airframe. This was followed by the Model 377 ‘Stratocruiser’, first flown in 1947 - again the airframe was roughly based on a bomber, this time the B-29 ‘Superfortress’, which had the same wings and engines but a more bulbous double-deck fuselage.


During its early years, Dash 80 N-70700 was the centre of attraction in the aviation world and gave many airline pilots, airline executives, and military and government officials their first introduction to jet flying. It was retained as a Boeing test aircraft and underwent major structural and aerodynamic changes in the course of developing and testing advanced aircraft features. N-70700 was donated to the Smithsonian Air and Space Museum in Washington DC in May 1972, but was placed into storage in the Arizona desert. In May 1990, under an arrangement with the Smithsonian, Boeing returned the aircraft to Seattle for a full restoration. The refurbished Dash 80 made special flypasts of the five Boeing facilities in the Puget Sound area of Seattle on July 15, 1991, to commemorate the 75th anniversary of the Boeing Company and the 37th anniversary of its own first flight. Following its full restoration, the aircraft remained at Boeing Field until a permanent home could be found for it at the Smithsonian. In 2003, it flew again, on delivery to the museum’s new Steven F Udvar-Hazy Centre at Washington Dulles International Airport outside Washington, DC, where it now takes pride of place in the main building. It has approximately 3,000 hours of flight recorded in its logbook. Key Archive
In the United Kingdom, de Havilland had just produced the world’s first jet airliner in the shape of the Comet and the designers at Boeing saw the need for a jet-powered aircraft as being the next stage of evolution for passenger travel. However, airlines were not totally convinced as piston-powered Douglas DC-6s, DC-7s and Lockheed Constellations, with their increased ranges, had already enhanced the quality of passenger travel, and the Comet was having its problems with (at that time) unexplained crashes. Boeing was convinced that a new jet-powered aircraft was the answer and production go-ahead for the Dash 80 was announced on August 30, 1952, as a company-financed $16 million investment (there had been 79 previous variations on the design and this was the 80th, hence Dash 80). The aircraft actually rolled out of the factory less than two years later on May 14, 1954 and its first flight on July 15 also marked the Boeing Company’s 38th anniversary.

Initially, it had the same fuselage cross-section as the B-29 and lower section of the ‘Stratocruiser’, a similar swept-back wing to the B-47 and B-52 with the podded engine design of the latter. One of the initial designs incorporating paired engines on a single pylon was discontinued due to concern over the possibility of one failing and affecting the other. The company also fitted a pair of cargo doors to the Dash 80 prototype as the United States military had a need for a future transport aircraft.


The cockpit of a United States Air Force VC-137B VIP aircraft. Key – Mark Nicholls
As a ‘proof of concept’ aircraft, the Dash 80 was not fitted out as an airliner – it had few cabin windows and no provision for a galley – but the fitting of the cargo doors (and its future possible role as an air-to-air refuelling tanker) led the United States Air Force (USAF) to order 29 aircraft in September 1954. These were designated the KC-135A by the military, but the B717-100A by Boeing. Interestingly, it is the only make of refuelling aircraft to be initially designed for that purpose – all other types being conversions from aircraft built for other purposes.

With production guaranteed, Boeing looked to the civilian market for more sales, calling the aircraft the Boeing 707. However, the cabin cross-section of the Dash 80 at 132in (3.35m) was considered by airlines to be too small and even the increased cross-section required for the military of 144in (3.65m) was not enough. A final agreement of 148in (3.76m) was made, with a 10ft (3m) fuselage extension. The aircraft’s future lay in long-range intercontinental services, but at that stage, it could only just fly from New York to London without a refuelling stop – and not even that with an adverse wind – only matching the in-service piston aircraft.


In 1958, the aircraft introduced comfort-enhancing cabin features that set the industry standard. Innovations included folding armrests, opaque plastic window shades, and cantilevered seats supported by just two sets of legs for easier access and underseat stowage of carry-on articles. Boeing image
A major competitor had emerged – the Douglas DC-8 – which had more powerful engines and a longer range, though at that stage it was still on the drawing board. The proposed launch customer for the B707, Pan American Airways (Pan Am), actually ordered 25 DC-8s on October 15, 1955, though it also ordered 20 B707s as the latter was well ahead in terms of development. Boeing immediately looked at improving the B707 and announced a number of variants - the original aircraft was to be known as the B707-120, with Pratt & Whitney JT3C engines giving 12,500lb (55.6kN) of thrust (the Dash 80 had JT3s with 10,000lb (44.4kN) of thrust). Uprated versions, known as the ‘220 and ‘320, were to be equipped with the JT4A-3, giving 15,800lb (70.2kN) of thrust. Both the ‘120 and ‘220 had a choice of two different fuselage lengths, while the ‘320 was specifically designed as the long-range version, featuring a lengthened fuselage, greater wingspan and more fuel capacity. This version could be fitted with the Rolls-Royce Conway engine, changing the designation to ‘420.


Early aircraft on the production line at the manufacturer’s Renton facility. Key Archive
The Pan Am order ‘kick-started’ other airlines into the jet age, and both Boeing and Douglas benefited. Firstly, the then domestic-only carrier American Airlines ordered 30 ‘120s, followed by Braniff with five ‘220s, and Continental Airlines with four ‘120s. Overseas sales came from Air France (ten) and the Belgian carrier Sabena with three – and all this before the end of 1955. The following year saw the order book filling up fast, with a repeat order from Pan Am, Trans World Airlines (TWA) (33), British Overseas Airways Corporation (BOAC) (18), Lufthansa (4), Air India (3) and Qantas (7), the latter being the only orders for the short-body version of the ‘120.

It was not until the end of October 1957 that the first B707 appeared at Renton, flying for the first time on December 20. Three aircraft, all destined for Pan Am, took part in the certification programme and the Federal Aviation Administration (FAA) issued a provisional type certificate in August 1958 to allow crew training, route proving and airport familiarisation. The first visit to London Heathrow took place on September 8, 1958.


Boeing 707-430s D-ABOG (c/n 18056) and -030B D-ABOH (c/n 18057) were delivered to German carrier Lufthansa in March 1961. Key Archive
One of the main problems with aircraft was noise, as jet aircraft were louder than their piston-engined counterparts. However, a full type certificate was issued by the FAA on September 18, and the first aircraft – N710PA, c/n 17589, the fourth built – was delivered to Pan Am eleven days later. The early ‘121s were unable to achieve a non-stop service across the Atlantic, so fuel stops were made at Gander in Newfoundland, Canada, or at Shannon in Ireland. The first service by Pan Am began on October 26 from New York’s Idlewild to Paris Le Bourget, and services to London Heathrow started on November 16.

The introduction of the new, heavier, aircraft led to a number of problems at airports. Runways had to be extended to enable the aircraft to operate and taxiways and aprons strengthened to cope with the increased weight. Once at the terminal, departure lounges needed to be larger in order to process the increased number of passengers, and the way the aircraft parked was changed. Previously aircraft had parked side-on to the terminal, which eased loading and unloading as both the front and rear doors could be used. With the B707, the aircraft parked nose-in to the terminal to save space. This gave the airport more parking slots, but restricted loading and unloading as only one door was used. It also made towing vehicles necessary for pushbacks.


This aircraft was displayed at the 1998 Farnborough Airshow. It was fitted with Stage III hushkits to the engines to enable the aircraft to operate to the more stringent European Union noise rules. Key – Steve Fletcher
The added noise from the jet engines brought complaints from householders living close to airports; as a result, engine manufacturers concentrated on devices to reduce engine noise and as an offshoot of this development, engines could also be fitted with thrust reversers to reduce landing distances.

Although Boeing had produced the lighter and shorter B720 at the end of the 1950s, the aircraft was only a short-to medium-range version of the B707. This was not exactly a bad thing as a number of airlines required such an aircraft for their schedules. However, it was the longer-range ‘320 which gave the airlines what they needed – extra range. The ‘320 was designed to carry a typical load of 131 (first class) or 189 (economy) passengers non-stop across the Atlantic. With an increase in wingspan and a slight change in wing shape, an increase in wing area of nearly 20% was achieved. More powerful engines and an increase in fuel capacity resulted in a range of 4,630 miles (7,435km) being achieved.


One of the early ‘short-body’ B707-138s. Originally delivered to Qantas as VH-EBB in 1959, the aircraft is pictured while belonging to Contram International. Key Archive
The ‘320 variant entered service with Pan Am on August 26, 1959, in place of the earlier ‘121 model aircraft, and cut out the need for refuelling stops on the North Atlantic routes. Further variations of the ‘320 resulted in another wingspan extension and the fitting of further powerful engines, producing the ‘320B (and the ‘320C with a forward cargo door). A number of improvements to the flap system were also incorporated.

In the 1960s and 1970s all the major western airlines used the B707 (or its DC-8 competitor), but not until the B747 was introduced in the mid-1960s and the Airbus A300 in the early 1970s was there any real competition. Ultimately, of course, the introduction of newer and more advanced aircraft (such as the B757/B767 and Airbus A330/A340) meant that the numbers of B707s started to dwindle. The introduction of the 1985 Stage II noise regulations meant that B707s had to be ‘hush-kitted’ to reduce engine noise, and the arrival of the still more stringent Stage III regulations in 1994 led to a dramatic reduction in B707 operations. A European Union ban on non-Stage III aircraft came into effect on December 31, 1999 – along with a ban on aircraft over 25 years old – and the USA followed suit in April 2002.


B707-307C 10+01 was transferred to the NATO AEWF, becoming LX-N19997. Key - Tom Allett
Despite the effective ban in Europe and the USA, a surprising number of civilian B707s are still in use, particularly in the Middle East and Africa. A total of 59 are currently flying in civilian hands as at July 2009, and 145 in use with air forces around the world (excluding the KC-135 variant). Very few are used on passenger services, Saha Airlines of Iran being the only such operator. When the B707 production line closed at the end of May 1991, Boeing had sold 1,010 aircraft of all types (not counting the KC-135 series for the USAF).


An RAF Sentry AEW1, one of the last production 707 airframes. Key - Steve Fletcher
The B707 airframe has been used by a large number of air forces for tanking, transportation, intelligence gathering, VIP use (such as the USAF’s ‘Air Force One’), and as a platform for a wide variety of electronic missions – both gathering and emitting. Equipped with newer engines such as the CFM56, the aircraft is also used in the Airborne Warning and Control System (AWACS) role, with a large radar dish mounted on top of the fuselage.

Extracted from an article first published in Airliner World magazine July 2004

Filed Under Commercial Aviation Features.

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1 Comment

chris nunn said on the 17-Feb-2010 at 15:57

the 300 series was the best looking jet aircraft
it just looked right

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