Commercial Aircraft Directory - Aircraft Specification

Boeing - 707-100

The Boeing 707 was the world's first practical intercontinental jet airliner and its design configuration of swept wing with engines in pods suspended from pylons was to become the dominant configuration for large and medium jet airliner design.

This configuration had been proven in military service with the B-47 and in the Boeing 367-80 prototype which first flew in 1954. The 367-80 was the result of a USAF competition for a jet tanker which could refuel B47 and B52 bombers within the receiver aircrafts optimum operational envelope. Boeing was awarded the Jet Tanker contract in August 1954 and the 367-80 was developed into the Boeing KC-135, of which Boeing hoped to sell a commercial derivative to US airlines.

As it had been with the Boeing KC-97 derived Stratocruiser and B17 derived Stratoliner, initial airline reaction to the Boeing Jetliner was cool. Unfavourable comparisons were drawn with the Douglas DC-8 , a larger and heavier aircraft which crucially had a wider cabin. As a result the design which emerged as the Boeing 707 was a significantly different aircraft from the 367-80 and KC-135.

The 707 was larger, had a wider cabin, was constructed from heavier gauge aluminium and built to meet FAA certification requirements. The fuselage at its widest point was 3.759m which became the standard for successive Boeing narrow body aircraft designs such as the 727,737 and 757.

The 707-100 was marketed as Boeing 707-120; each operator who ordered a new aircraft from the production line was assigned a one digit customer suffix which was appended to the ‘dash number’. Pan American’s aircraft were therefore Boeing 707-121s and American Airlines 707-123s.

The practice continues to this day for Boeing commercial aircraft, although from a Boeing internal design perspective and the FAA the aircraft are known just by their generic ‘dash number.

The first order for the initial model of the 707 the -100, was placed in October 1955 by Pan American for 20 aircraft (who also ordered 25 DC-8-30s) and the first flight took place on December 20 1957.

Pan American was not only the launch customer for the 707 but was instrumental in the development of the aircraft throughout its production cycle.

Another major carrier which selected the 707-100 was American Airlines, which ordered 26 examples; however the third major American carrier United Airlines opted for the DC-8. The initial engine for the 707-100, the Pratt & Whitney JTC-3C-6 turbojet produced 60.5 kN thrust and was a civil derivative of the J57 which powered the KC-135. The engine was fitted with water injection to deliver increased thrust at take off, and was (even by the standards of the time) considered noisy, and to ameliorate this, the JTC-3 was fitted with noise suppressors.

The 707-100 entered service with Pan American on 26 October 1958 from New York to Paris, however with a maximum fuel range of 7483 km the 707-100 was an inadequate performer on transatlantic routes, requiring a fuel stop westbound. The same problem was being encountered during US transcontinental services which commenced in December 1958 with aircraft leased from Pan American by National Airlines, and followed by American Airlines in January 1959.

Range/payload performance was particularly crucial for the Australian airline QANTAS during transpacific operations, and to meet their requirements and to show that Boeing was determined to cast off its legacy of non responsiveness to airlines needs, Boeing developed the 707-100 Short Body, a model of which only 7 were built, specifically for QANTAS. The 707-100 Short Body was a 707-100 which had sections of fuselage removed reducing the fuselage length by 3.05m, and consequently reduced the empty weight of the aircraft by some 3175kg, allowing QANTAS range/payload requirements to be met. The penalty incurred was a reduction in passenger capacity to 120 in a one class configuration. Boeing again showed its willingness to produce limited quantities of specialised variants for individual airlines when it produced 5 707-200s for Braniff airlines. The 707-200 was a 707-100 powered by the Pratt & Whitney JT4A-3 an engine which produced 70.8 kN, and was also being offered on the DC-8. Braniff needed the extra power for ‘hot and High’ take offs which were a feature of its South American operations.

The 707-100 however was not a intercontinental aircraft and Pan American (in confidential meetings) told Boeing that the initial order for 20 707s would be the last, and that future purchases would involve the more capable DC-8.

It was always intended that an intercontinental variant of the 707 would be produced the result of which was the 707-300 and Pan American’s order for 20 707s was to consist of only 8 707-100s, the remainder were for 707-300s. As a result of the 707-100s limited appeal to international carriers only 56 were produced.

Pratt & Whitney however were developing the JT3D, a derivation of the JT3C which resulted in a turbofan engine with considerably more power, reduced fuel consumption, noise and emissions The JT3D-1 produced 76 kN and the later JT3D-3 80.2kN, with the same fuel flow as the JT3C. The JT3C became a turbofan by changing the two front stages of the LP compressor for larger stages and by adding an additional turbine stage to drive the larger front ‘fan’. The core of the engine remained a JT3C and Pratt & Whitney was able to offer a conversion kit for operators to convert their JT3Cs to JT3Ds. The JT3D was also fitted with thrust reversers which reduced landing runs. The JT3D enhanced the performance of the 707-100 which became (when fitted with these engines) the 707-100B. Compared with the 707-100 the 707-100B had a 27% better maximum payload range and a 30% reduction in take off run.

The 707-100B became the standard production version of the 707 and most operators upgraded their aircraft to this standard. Another modification to the 707-100/100B was an increase in the height of the fin and on some aircraft a ventral fin, was fitted as a result of UK certification requirements for the 707-420. These modifications were adopted for production and retroactively fitted to all 707s.

The 707 (like most swept wing aircraft) had a proclivity to Dutch Roll and after several incidents during airline training flights Boeing developed the yaw damper; a device which has been fitted to every commercial aircraft of similar configuration since. Despite these improvements, on intercontinental operations the 707-100B still didn’t meet the requirements of Pan American and other international carriers. The problem was the wing. It was simply too small, a problem that would be rectified with the 707-300.

A total of 72 707-100Bs were built including a repeat order for Qantas who ordered 6 700-100B Short Bodies The last 707-100B was delivered to American Airlines on 22 April 1969 having accepted delivery of 56 707-100/100Bs in total. The other major operator to operate the 707-100/100B was Trans World Airways (TWA) who also operated 56. By mid-2008,only two 707-100s remained flying; a short body 707-100B initially delivered to QANTAS on 10 September 1964 and now owned and operated by actor/pilot John Travolta, and another aircraft delivers to Qantas on 18 September 1959 now operated by the Peoples Democratic Republic of Congo.

Lloyd Dunning-Mitchell

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