Boeing 707
The Boeing 707 is an early American long-range narrow-body airliner, the first jetliner developed and produced by Boeing Commercial Airplanes.
Developed from the Boeing 367-80 prototype, the initial first flew on December 20, 1957.
Pan Am began regular 707 service on October 26, 1958.
With versions produced until 1979, the 707 is a swept wing quadjet with podded engines. Its larger fuselage cross-section allowed six-abreast economy seating, retained in the later 720, 727, 737, and 757 models.
Although it was not the first commercial jetliner in service, the 707 was the first to be widespread, and is often credited with beginning the Jet Age. It dominated passenger air-transport in the 1960s, and remained common through the 1970s, on domestic, transcontinental, and transatlantic flights, as well as cargo and military applications. It established Boeing as a dominant airliner manufacturer with its 7x7 series.
The initial, was powered by Pratt & Whitney JT3C turbojet engines.
The shortened, long-range and the more powerful entered service in 1959.
The longer-range, heavier 707-300/400 series has larger wings and is stretched slightly by.
Powered by Pratt & Whitney JT4A turbojets, the 707-320 entered service in 1959, and the with Rolls-Royce Conway turbofans in 1960.
The 720, a lighter short-range variant, was also introduced in 1960. Powered by Pratt & Whitney JT3D turbofans, the 707-120B debuted in 1961 and the 707-320B in 1962. The 707-120B typically flew 137 passengers in two classes over, and could accommodate 174 in one class. With 141 passengers in two classes, the 707-320/420 could fly and the 707-320B up to. The 707-320C convertible passenger-freighter model entered service in 1963, and passenger 707s have been converted to freighter configurations. Military derivatives include the E-3 Sentry airborne reconnaissance aircraft and the C-137 Stratoliner VIP transport. In total, 865 Boeing 707s were produced and delivered, not including 154 Boeing 720s.
Development
Model 367-80 origins
During and after World War II, Boeing was known for its military aircraft. The company had produced innovative and important bombers, from the B-17 Flying Fortress and B-29 Superfortress to the jet-powered B-47 Stratojet and B-52 Stratofortress, but its commercial aircraft were not as successful as those from Douglas Aircraft and other competitors. As Douglas and Lockheed dominated the postwar air transport boom, the demand for Boeing's offering, the 377 Stratocruiser, quickly faded with only 56 examples sold and no new orders as the 1940s drew to a close. That venture had netted the company a $15 million loss. During 1949 and 1950, Boeing embarked on studies for a new jet transport and saw advantages with a design aimed at both military and civilian markets. Aerial refueling was becoming a standard technique for military aircraft, with over 800 KC-97 Stratofreighters on order. The KC-97 was not ideally suited for operations with the USAF's new fleets of jet-powered fighters and bombers; this was where Boeing's new design would win military orders.As the first of a new generation of American passenger jets, Boeing wanted the aircraft's model number to emphasize the difference from its previous propeller-driven aircraft, which bore 300-series numbers. The 400-, 500- and 600-series were already used by their missiles and other products, so Boeing decided that the jets would bear 700-series numbers, and the first would be the 707. The marketing personnel at Boeing chose 707 because they thought it was more appealing than 700.
The project was enabled by the Pratt & Whitney JT3C turbojet engine, the civilian version of the J57 that yielded much more power than the previous generation of jet engines and was proving itself with the B-52. Freed from the design constraints imposed by limitations of late-1940s jet engines, developing a robust, safe, and high-capacity jet aircraft was within reach for Boeing. Boeing studied numerous wing and engine layouts for its new transport/tanker, some of which were based on the B-47 and C-97, before settling on the 367-80 "Dash 80" quadjet prototype aircraft. Less than two years elapsed from project launch in 1952 to rollout on May 14, 1954, with the first Dash 80 flying on July 15, 1954. The prototype was a proof-of-concept aircraft for both military and civilian use. The United States Air Force was the first customer, using it as the basis for the KC-135 Stratotanker aerial refueling and cargo aircraft.
Whether the passenger 707 would be profitable was far from certain. At the time, nearly all of Boeing's revenue came from military contracts. In a demonstration flight over Lake Washington outside Seattle, on August 7, 1955, test pilot Tex Johnston performed a barrel roll in the 367-80 prototype. Although he justified his unauthorized action to Bill Allen, then president of Boeing, as selling the airplane with a 1 'g' maneuver he was told not to do it again.
The wide fuselage of the Dash 80 was large enough for four-abreast seating like the Stratocruiser. Answering customers' demands and under Douglas competition, Boeing soon realized this would not provide a viable payload, so it widened the fuselage to to allow five-abreast seating and use of the KC-135's tooling. Douglas Aircraft had launched its DC-8 with a fuselage width of. The airlines liked the extra space and six-abreast seating, so Boeing increased the 707's width again to compete, this time to.
Production and testing
The first flight of the first-production 707-120 took place on December 20, 1957, and FAA certification followed on September 18, 1958. Both test pilots Joseph John "Tym" Tymczyszyn and James R. Gannett were awarded the first Iven C. Kincheloe Award for the test flights that led to certification. A number of changes were incorporated into the production models from the prototype. A Krueger flap was installed along the leading edge between the inner and outer engines on early 707-120 and -320 models. This was in response to de Havilland Comet overrun accidents which occurred after over-rotating on take-off. Wing stall would also occur on the 707 with over-rotation so the leading-edge flaps were added to prevent stalling even with the tail dragging on the runway.Further developments
The initial standard model was the 707-120 with JT3C turbojet engines. Qantas ordered a shorter-bodied version called the 707-138, which was a -120 with six fuselage frames removed, three in front of the wings, and three aft. The frames in the 707 were set apart, so this resulted in a shortening of to a length of. With the maximum takeoff weight the same as that of the -120, the -138 was able to fly the longer routes that Qantas needed. Braniff International Airways 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 wing and JT4A engines, while the 707-420 was the same as the -320, but with Conway turbofan engines.Though initially fitted with turbojet engines, the dominant engine for the Boeing 707 family was the Pratt & Whitney JT3D, a turbofan variant of the JT3C with lower fuel consumption and higher thrust. JT3D-engined 707s and 720s were denoted with a "B" suffix. While many 707-120Bs and -720Bs were conversions of existing JT3C-powered machines, 707-320Bs were available only as newly built aircraft, as they had a stronger structure to support a maximum takeoff weight increased by, along with modifications to the wing. The 707-320B series enabled nonstop westbound flights from Europe to the West Coast of the United States and from the US to Japan.
The final 707 variant was the 707-320C,, which had a large fuselage door for cargo. It had a revised wing with three-sectioned leading-edge flaps, improving takeoff and landing performance and allowing the ventral fin to be removed. The 707-320Bs built after 1963 used the same wing as the -320C and were known as 707-320B Advanced aircraft.
In total, 1,010 707s were built for civilian use between 1958 and 1978, though many of these found their way to military service. The 707 production line remained open for purpose-built military variants until 1991, with the last new-build 707 airframes built as E-3 and E-6 aircraft.
Traces of the 707 are still found in the 737, which uses a modified version of the 707's fuselage, as well as the same external nose and cockpit configurations as those of the 707. These were also used on the previous 727, while the 757 also used the 707 fuselage cross-section.
Design
Wings
The 707's wings are swept back at 35°, and like all swept-wing aircraft, display an undesirable "Dutch roll" flying characteristic that manifests itself as an alternating combined 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 would be applied to later swept-wing configurations like the 707. However, many pilots new to the 707 had no experience with this instability as they were mostly accustomed to flying 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's actions violently exacerbated the Dutch roll motion and caused three of the four engines to be torn from the wings. 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.
In his autobiography, test pilot Tex Johnston describes a Dutch roll incident he experienced as a passenger on an early commercial 707 flight. As the aircraft's movements did not cease and most of the passengers became ill, he suspected a misrigging of the directional autopilot. He went to the cockpit and found the crew unable to understand and resolve the situation. He introduced himself and relieved the ashen-faced captain who immediately left the cockpit feeling ill. Johnston disconnected the faulty autopilot and manually stabilized the plane "with two slight control movements".
Johnston recommended Boeing increase the height of the tail fin, add a boosted rudder as well as add a ventral fin. These modifications were aimed at mitigating Dutch roll by providing more directional stability in yaw.