Boeing 707

Template:Infobox AircraftThe Boeing 707 was a four engined commercial passenger jet airliner developed by Boeing in the early 1950s. Although it was not the first commercial jet in service (that distinction belongs to the De Havilland Comet), it was the first to be commercially successful, and is credited by many as ushering in the Jet Age, as well as being the first of Boeing's 7X7 range of airliners. Boeing delivered 1,010 Boeing 707s.

History

The 707 was based on a aircraft known as the 367-80. The "Dash 80", as it was called within Boeing, took less than two years from project launch in 1952 to rollout on May 14, 1954. The prototype was the basis for both the KC-135 Stratotanker, an air tanker used by the United States Air Force, and the 707. This was powered by the Pratt & Whitney JT3C engine which was the civilian version of the J57 used on the many military aircraft of the day incluing the F-100, F-101, F-102, and the B-52. A late and costly decision was to widen the fuselage by 6 inches (150 mm) compared to the original 367-80 and KC-135 so as to be a little wider than the Douglas DC-8.

Pan Am was the first airline to operate the 707; the aircraft's first commercial flight was from New York to Paris on October 26, 1958. American Airlines operated the first transcontinental 707 flight on January 25, 1959. The 707 quickly became the most popular jetliner of its time, edging out its main competitor, the Douglas DC-8.

In order to become a new major player in the commercial airliner business, Boeing was quick to bend to customer's desires. While the 707-120 was the initial standard model with Pratt & Whitney JT3C engines, Qantas ordered a shorter body version called the 707-138 and Braniff ordered the higher thrust version with Pratt & Whitney JT4A engines, the 707-220. The ultimate version was the 707-320 which featured an extended span and larger wing. The 707-420 featured Rolls-Royce Conway turbofan engines. Most of the later 707s featured the more fuel efficient and quieter JT3D turbofan engines and flaps on the leading edge of the wings to improve takeoff and landing performance. These were denoted with a "B" suffix such as 707-120B and 707-320B. One peculiarity of the aircraft is the outer port engine mount which is different to the other three.

As the 1960s drew to a close, the exponential growth in air travel led to the 707 being a victim of its own success. It had become obvious that the 707 was now too small to handle the increased passenger densities on the routes for which it was designed. Stretching the fuselage was not a viable option because the installation of larger, more powerful engines would in turn need a larger undercarriage, which was not feasible given the design's limited ground clearance. Boeing's answer to the problem was the first twin aisle airliner - the 747. The 707s first-generation engine technology was also rapidly becoming obsolete in the areas of noise and fuel economy.

The 707, like all swept wing aircraft, displayed an undesirable "Dutch roll" flying characteristic which manifested itself as an alternating yawing and rolling motion. Boeing already had considerable experience with this on the B-47 and B-52, and had first developed the yaw damper system on the B-47 that lent itself to later swept wing configurations including the 707. However many new 707 pilots had no experience with this phenomenon as they were transitioning from straight wing propeller driven aircraft such as the DC-7 and Lockheed Constellation. On one customer training flight, where the yaw damper was turned off to familiarize the new pilots on flying techniques, a trainee pilot exacerbated the Dutch roll motion causing a violent roll motion which tore two of the four engines off the wing. The plane crash landed on a river bed north of Seattle, killing some of the crew.

Production of the passenger 707 ended in 1978. In total, 1,010 707s were built for civil use. The military versions remained in production until 1991.

Traces of the 707 are still in some of Boeing's current products, most notably the 737, which uses a modified version of the 707s fuselage. The Boeing 727 and Boeing 757 used essentially the same fuselage stretched or shrunk to fit the needs of the particular model or sub-type. The 737 and 727 also used the same external nose and cockpit configuration as the 707.

Variants

BOAC 707 at London Heathrow Airport in 1964

File:British Caledonian Boeing 707 G-AXRS.jpg

British Caledonian Boeing 707, registration number G-AXRS shown at Prestwick International Airport, South Ayrshire, Scotland, circa 1972. This aircraft suffered engine separation during cargo flight 1998, no loss of life and was scrapped. Click to enlarge.

367-80 (Dash-80): The original prototype jet transport layout. Used to develop the 707, it was fitted with four Pratt & Whitney JT3 engines producing 10,000 lbst each. First flight was 15 July 1954.

707-120: 69 of the first production 707s were built, with a longer fuselage and greater wingspan than the original Dash-80. A full set of rectangular capin windows was included for the interior, which was capable of a maximum seating for 179 passengers. The version was designed for transcontinental routes and often required a refuelling stop when used on the North Atlantic route. It was fitted with four Pratt and Whitney JT3C-6 turbojets, civilian versions of the military J57 model, which produced 12,500 lbst each, allowing a 257,000 lb TOGW. First flight was on 20 December 1954. The most important customer variant was the 707-138 for Qantas ('38' being Qantas' customer number), which had a 10 foot reduction to the rear fuselage and was capable of increased range. 13 of the 707-100s produced were -138 models. Other major orders were the launch order for 20 707-121 aircraft by Pan American and an American Airlines order for 30 707-123 aircraft. Pan Am service began the 707 career on 26 October 1958.

707-220: Designed for hot and high operations with powerful Pratt & Whitney JT4A-3 turbojets, only five of these were ultimately produced. All were for Braniff International Airways and carried the model number 707-227. This version was made redundant by the arrival of the turbofan.

707-320 Intercontinental: A stretched version of the turbojet-powered original model, powered by JT4A-3 turbojets producing 15,800 lbst each. The interior allowed for up to 189 passengers due to a 100 inch stretch, while a longer wing carried more fuel increasing range by 1,600 miles allowing the aircraft to operate as true transoceanic aircraft. Take-off weight was increased to 316,000 lb. First flight was on 11 January 1958 and 69 turbojet -300s were produced.

707-120B: The first major upgrade to the design was a reengining with JT3D-3 turbofans, which were quieter, more powerful, and more fuel efficient, producing 18,000 lbst each. The aircraft also received extra leading edge slats and the tailplane was enlarged. 72 of these were built, and many more were converted from 707-100 aircraft, including Qantas' aircraft, which became 707-138B aircraft upon conversion. The first flight of the -100B was on 22 June 1960.

707-320B: A reengining of the stretch version was undertaken in parallel with the -100B, using the same JT3D-3 turbofans and incorporating many of the same airframe upgrades as well. Take off gross weight was increased to 335,000 lb. 175 of the 707-300B aircraft were produced, as well as upgrades from original -300 models. The 707-353B was adopted by the United States Air Force and designated VC-137C for service as a presidential transport. One of the final orders was by the Iranian Government for 14 707-3J9C aircraft capable of VIP transportation, communication, and inflight refuelling tasks.

707-320B Advanced: A minor improvement made available to -300B aircraft, adding the new wing leading edge from the -300C model to earlier -300B versions.

707-320C: A convertible passenger/freight configuration which ultimately became the most widely produced variant of the 707, the -300C added a strengthened floor and a new cargo door to the -300B model. 335 of these variants were built, including a small number with uprated JT3D-7 engines and a takeoff gross weight of 336,000 lb. Despite the convertible option, a number of these were delivered as pure freighters.

707-420: A version of the 707-300C produced specifically for BOAC powered by Rolls-Royce Conway 50B turbofans, producing 17,500 lbst each. 37 were built to this configuration. As the only customer for this model, all carried the model number 707-436.

707-700: A test aircraft used to study the feasibility of using CFM International's CFM56 powerplants on a 707 airframe and possibly retrofitting them to existing aircraft. After a testing in 1979 N707QT, the last commercial 707 airframe, was refitted to 707-320C configuration and delivered to the Moroccan Air Force as a tanker aircraft. (This purchase was considered a "civilian" order and not a military one.) Boeing abandoned the program, since they felt it would be a threat to the Boeing 757 program. The information gathered in the test led to the eventual retrofitting program of CFM56 engines to the USAF C-135/KC-135R models, and some military versions of the 707 also used the CFM56. Ironically the Douglas DC-8 "Super 70" series by Cammacorp did develop commercially, extending the life of DC-8 airframes in a stricter noise regulatory environment so there are today more DC-8s in commercial service than 707s.

720: Originally designated 707-020 but later changed for marketing reasons, was a modification of the 707-120 designed for medium-range operation from shorter runways. It was lighter and faster than the Boeing 707, and had a simplified wing design. This model had few sales, but was still profitable due to the minimal R&D costs associated with modifying an existing type. At one point in the promotion stage to airlines it was known as the 717, although this model designation remained unused until it was applied to the MD-95 following Boeing's merger with McDonnell Douglas. The 720 was used before the Boeing 727 replaced it in the market. First flight was on 23 November 1959 and 64 of the original version were built.

720B: The turbofan powered version of the 720, with JT3D-1-MC6 turbofans producing 17,000 lbst each. Takeoff gross weight was increased to 235,000 lb. 88 of these were built in addition to conversions of existing 720 models.

Operators

A KC-135 Stratotanker refuels a F-22 Raptor

Although 707s are no longer employed by major US airlines, many can still be found in service with smaller non-US airlines, charter services and air cargo operations.

The first two aircraft built to serve as Air Force One were custom-built Boeing 707s, with designation VC-137; these were also used by high-ranking federal officials on official trips. Many other countries use the 707 as a VIP transport, including Argentina, Brazil, Chile, the Republic of Congo, Egypt, Indonesia, Israel, Italy, Jordan, Libya, Morocco, Pakistan (PAF), Romania, Saudi Arabia, Sudan, and Venezuela. The Royal Australian Air Force (RAAF) operated a number of 707s that were specially modified for VIP use before replacing them with modified BBJs. Other military operators of the Boeing 707 have included Angola, Canada, Colombia, Germany, India, Iran, Paraguay, Peru, Portugal Spain, Taiwan, Togo, United Arab Emirates and Yugoslavia.

The U.S. and other NATO-aligned countries, as well as South Africa and Israel, have used the 707 platform for aerial refueling (KC-135) and AWACS (E-3 Sentry), although many of these aircraft are now being phased out. The Royal Australian Air force (RAAF) operates 707s as refuellers for Australia's F/A-18 Hornets; these are soon to be replaced by Airbus A330 MRTTs. The 707 is also the platform for the United States Air Force (USAF)'s Joint STARS project, and the United States Navy's E-6 Mercury. USAF acquired around 250 used 707s to provide parts for the KC-135E Stratotanker program.[1] This is the major reason so few 707s are in service compared with Douglas DC-8s.

The current list of customer codes used by Boeing to identify specific options and trim specified by customers was started with the 707, and has been maintained through Boeing's current models. Essentially the same system as used on the earlier Boeing 377, the code consisted of two digits affixed to the model number to identify the specific aircraft version. For example, Eastern Airlines was assigned code '25'. Thus a 707-200B sold to Eastern would carry the model number 707-225B. The number remained constant as further Boeings were purchased, thus an Eastern 737-300 would carry the number 737-325.

Trivia

American actor John Travolta owns, and is qualified to fly, an ex-Qantas 707-138, registration N707JT.

At Seafair on August 6, 1955, Boeing test pilot Alvin "Tex" Johnston twice performed a "barrel roll" in the Dash-80 at 500 feet. This story appears on a video called 'Frontiers of Flight - The Jet Airliner', produced by the National Air and Space Museum in association with the Smithsonian Institution in 1992. The roll can be viewed on video at AviationExplorer.com. To date Johnston is the only pilot to have performed this in a four engine jet transport. (Other big four engine jet aircraft have done barrel rolls, the Avro Vulcan XA890 was rolled by Roly Falk on the first day of the 1955 Farnborough Air Show, but it was a subsonic bomber).

The Chinese government sponsored development of the Shanghai Y-10 during the 1970s, which was a near carbon-copy of the 707.

Specifications

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General characteristics

	707-120B	707-320B
Passengers (2 class)	110	147
Passengers (1 class)	179	202
Max. takeoff weight	257,000 lb (116,570 kg)	333,600 lb (151,320 kg)
Empty weight	122,533 lb (55,580 kg)	146,400 lb (66,406 kg)
Operating range (Max Payload)	3,680 nautical miles (6,820 km)	3,735 nautical miles (6,920 km)
Crusing speed	540 kt (1000 km/h)	525 kt (972 km/h)
Length	144 ft 6 in (44.07 m)	152 ft 11 in (46.61 m)
Wingspan	130 ft 10 in (39.90 m)	145 ft 9 in (44.42 m)
Tail height	42 ft 5 in (12.93 m)
Powerplants	Four 75.6 kN (17,000 lbf) Pratt & Whitney JT3D-1 turbofans.	Four 80 kN (18,000 lbf) JT3D-3s or four 84.4 kN (19,000 lbf) JT3D-7s.