  The 707's jet speed, long range, high seating capacity and operating economics revolutionised airliner travel when it was introduced into service in 1958. The 707 also laid the foundations for Boeing's dominance of the jet airliner market.
Recognising the jet engine's potential for commercial aviation, Boeing (at great financial risk) decided to develop a jet powered transport that could fulfil military tanker transport roles but be easily adapted to become an airliner. The resulting prototype, known as the 367 Dash 80, flew for the first time on July 16 1954. Impressed, the US Air Force ordered a larger version, with a wider fuselage (12 ft, vs 11 ft for the Dash 80) into production as the KC-135 tanker/transport (more than 800 were built). At first, Boeing wanted to sell the same size aircraft to the airlines, but the airlines insisted on an even larger airplane, which Douglas promised to build (this became the DC-8). Boeing finally relented, designing the 707 as a longer aircraft with a slightly wider fuselage (12 ft 4 in).
The first production 707 (a 707-120 for Pan Am) flew on December 20 1957, and entered service later the following year. Developments of the 707-120 include the similar 707-220, the shorter 138 for Qantas, and the stretched 707-320, which flew in July 1959. The 707-120 and 320 were later reengined with JT3D turbofans (in place of the original JT3 and JT4 turbojets) to become the 707-120B, and the 707-320B respectively. The 707-320C was a convertible model, the 707-420 was powered by RollsRoyce Conways, while the proposed CFM-56 powered 707-700 upgrade was flight tested in the late 1970s but never entered production.
Most civil 707s in service today have been converted to freighters, while a number are used as corporate transports.
Many air forces have bought 707s, new or converted second-hand aircraft, for general transport, aerial refuelling, and electronic warfare. The E-3 Sentry is a dedicated airborne warning and control system (AWACS) platform with a large rotodome above the fuselage. The E-6 Mercury performs the TACAMO (Take Charge and Move Out) role with the US Navy, maintaining communication with the ballistic missile submarines. The E-8 J-Stars (Joint Surveillance Target Attack Radar System) performs the battlefield control role. Other military 707s received the designations C-137, or C-18, but many others have no special military designation.
707 Weights
707-120B - Operating empty 55,589kg (122,533lb), max takeoff 116,575kg (257,000lb).
707-320B - Empty 66,406kg (146,400lb), max takeoff 151,315kg (333,600lb).
707 Performance
707-120B - Max speed 1010km/h (545kt), max cruising speed 1000km/h (540kt), economical cruising speed 897km/h (484kt). Range with max payload 6820km (3680nm), range with max fuel 8485km (4580nm).
707-320B - Max speed 1009km/h (545kt), max cruising speed 974km/h (525kt), long range cruising speed 885km/h (478kt). Range with max passengers 6920km (3735nm), range with max fuel and 147 passengers 9265km (5000nm).
707 Dimensions
707-120B - Wing span 39.90m (130ft 10in), length 44.07m (144ft 6in), height 12.94m (42ft 5in). Wing area 226.3m2 (2433sq ft).
707-320B - Wing span 44.42m (145ft 9in), length 46.61m (152ft 11in), height 12.93m (42ft 5in). Wing area 283m2 (3050sq ft).
707 Powerplants
707-120B - Four 75.6kN (17,000lb) Pratt & Whitney JT3D-1 turbofans.
707-320B - Four 80kN (18,000lb) JT3D-3s or four 84.4kN (19,000lb) JT3D-7s.
707 Variants
- 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 lbf (44 kN) 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 cabin windows was included for the interior, which was capable of a seating 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 lbf 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 707-120s 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 obsolete 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 -320s 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 lbf 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 707-120 aircraft, including Qantas' aircraft, which became 707-138B aircraft upon conversion. The first flight of the -120B was on 22 June 1960.
- 707-320B: A re-engining of the stretched version was undertaken in parallel with the -120B, 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 -320 models. The US military designation for the cargo version of the 707-320B is C-18. 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 -320B aircraft, adding three-section leading edge flaps. These reduced takeoff and landing speeds, and also altered the lift distribution of the wing allowing the ventral fin found on earlier 707s to be removed. The same wing was also used on the -320C.
- 707-320C: A convertible passenger/freight configuration which ultimately became the most widely produced variant of the 707, the -320C added a strengthened floor and a new cargo door to the -320B 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 707-320 originally produced at specific request for BOAC and powered by Rolls-Royce Conway 508 turbofans, producing 17,500 lbf each. Although BOAC initiated the programme, Lufthansa was the launch customer and Air India was the first to receive a 707-420 on February 18 1960. A total of 37 were built to this configuration.
- 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 lbf each. Takeoff gross weight was increased to 235,000 lb. 88 of these were built in addition to conversions of existing 720 models.
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