Boeing 707

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Boeing 707/720
BOAC 707 at London Heathrow Airport in 1964
Type	Airliner
Manufacturer	Boeing Airplane Company
Maiden flight	December 20, 1957
Introduced	October 1958 with Pan American
Produced	1958-1991
Number built	1,010
Developed from	Boeing 367-80
Variants	C-137 Stratoliner VC-137 (Air Force One)

View of the port (left) number 1 & 2 Pratt & Whitney JT3D jet engines of a British Caledonian Boeing 707 showing the peculiarity of the number 1 engine mount which is different from the other three. June 1975.

The Boeing 707 (most commonly spoken as "Seven Oh Seven") 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 as ushering in the Jet Age, as well as being the first of Boeing's 7x7 series of airliners. Boeing delivered a total of 1,010 Boeing 707s. As of October 2006, 68 Boeing 707 aircraft (of any variant) were reported to be remaining in airline service.^[1]

[edit] History

The 707 was based on an 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 including 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.

At Seafair on August 6, 1955, Boeing test pilot Alvin "Tex" Johnston 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; for instance, the Avro Vulcan XA890 was rolled by Roly Falk on the first day of the 1955 Farnborough Air Show, but it was a bomber).

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 final major derivative was the 707-320 which featured an extended span and larger wing. The ultimate version was 707-420, a -320 equipped with 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.

The 707's engines could not supply sufficient bleed air for pressurization without a serious loss of thrust, so the aircraft instead used engine-driven turbocompressors to supply high-pressure air for this purpose. On many commercial 707's the outer port (#1) engine mount is distinctly different from the other three, as this is the only engine not fitted with a turbocompressor. The Boeing 707 was the first commercially successful airplane to use podded engines.

As the 1960s drew to a close, the exponential growth in air travel led to the 707 being a victim of its own success. 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 707's first-generation engine technology was also rapidly becoming obsolete in the areas of noise and fuel economy.

The 707 wings are swept back at 35 degrees and, 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 developed the yaw damper system on the B-47, that lent itself to later swept wing configurations like 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 Douglas DC-7 and Lockheed Constellation. On one customer acceptance flight, where the yaw damper was turned off to familiarize the new pilots with 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, a brand new 707-227 N7071 destined for Braniff, crash landed on a river bed north of Seattle at Arlington, Washington, killing four of the eight occupants.[1] In his autobiography, Tex Johnston described a Dutch Roll incident he experienced as a passenger on an early commercial 707 flight. As the aircraft's movements gradually became more severe, he went to the cockpit and found the crew frantically attempting to resolve the situation. He introduced himself and relieved the ashen-faced captain who immediately left the cockpit feeling ill. Johnston quickly stabilised the plane and later, even landed it for the crew.

Production of the passenger 707 ended in 1978. In total, 1,010 707s were built for civil use, though many of these found their way to military service. The purpose-built military variants remained in production until 1991.

Traces of the 707 are still found in the 737, which uses a modified version of the 707's fuselage, as well as essentially the same external nose and cockpit configuration as the 707. These were also used on the previous Boeing 727, while the Boeing 757 also used the 707 fuselage cross-section.

[edit] Variants

British Caledonian Boeing 707 shown at Prestwick International Airport, South Ayrshire, Scotland, circa 1972.

• 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.

RAAF 707-368C at RAF Fairford, Gloucestershire, England

• 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.

[edit] Operators

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. Use of 707s on US cargo routes has declined in recent years because the now-obsolescent engines used on many 707s remaining in service are far too loud to meet noise restrictions at many US civil airports.

In the 1980s, the USAF acquired around 250 used 707s to provide parts for the KC-135E Stratotanker program.[2] This is the major reason so few 707s are in service compared with Douglas DC-8s.

Current operators (as of August 2006) of the Boeing 707 include: African Airlines International (4), Angola Air Charter (3), Hewa Bora Airways (3), Libyan Arab Airlines (4), Iran Air (5), Sky Aviation (3), BETA Cargo (4), Saha Airlines (4) and Skymaster Airlines (5). Some 21 other airlines operate smaller numbers of the type.^[1]

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.

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

[edit] Specifications

[edit] Deliveries

[edit] Incidents

[edit] Trivia

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

• American Rock Band Bon Jovi owns, and tours the world in their own Boeing 707.

• A Boeing 720 flown by remote control was intentionally crashed at Edwards AFB as a part of the NASA Controlled Impact Demonstration program.

• The 707 is mentioned in the song "Jet Airliner" by The Steve Miller Band as well as "Early Morning Rain" by Gordon Lightfoot

See also: List of Boeing 707 operators and Airport (film)

[edit] External links

• Boeing 707 family
• Aviation-History.com on the 707, images
• Airliners.net:Boeing 707
• A proposed double-decker design for the B707
• Boeing Model 367-80
• Boeing 707 History

[edit] References

[edit] Related content

Wikimedia Commons has media related to: Boeing 707

Related development

• Boeing 367-80
• Boeing 727
• Boeing 737
• C-135 Stratolifter
• C-137 Stratoliner
• CC-137 Husky
• E-3 Sentry
• E-6 Mercury
• E-8 Joint STARS
• EC-18B (ARIA)
• VC-137 (Air Force One)

Comparable aircraft

• Convair 880
• Douglas DC-8
• Shanghai Y-10
• Vickers VC10
• Tupolev Tu-104

Designation sequence

• 367 - 377 - 701

Related lists

• List of airliners
• List of Boeing customers