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Boeing 2707

By Wikipedia,
the free encyclopedia,

http://en.wikipedia.org/wiki/Boeing_2707

2707
Model of a Boeing 2707.
Role Supersonic transport
Manufacturer Boeing Commercial Airplanes
Status Cancelled
Number built 0 completed

The Boeing 2707 was developed as the first American supersonic transport (SST). After winning a competition for a government-funded contract to build an American SST, Boeing began development at its facilities in Seattle, Washington. Rising costs and the lack of a clear market led to its cancellation in 1971 before two prototypes had been completed.

Development

Early studies

Boeing had worked on a number of small-scale SST studies since 1952. In 1958, it established a permanent research committee, which grew to a $1 million effort by 1960. The committee proposed a variety of alternative designs, all under the name Model 733. Most of the designs featured a large delta wing, but in 1959 another design was offered as an offshoot of Boeing's efforts in the swing-wing TFX project (which led to the purchase of the General Dynamics F-111 instead of the Boeing offering). In 1960, an internal "competition" was run on a baseline 150-seat aircraft for trans-Atlantic routes, and the swing-wing version won.

By mid-1962, it was becoming clear that tentative talks earlier that year between the Bristol Aeroplane Company and Sud Aviation on a merger of their SST projects were more serious than originally thought. It appeared there was a very real chance the combined companies would be offering a design. In November, the two companies announced that a design called "Concorde" would be built by a consortium effort. This set off something of a wave of panic in other countries, as it was widely believed that almost all future commercial aircraft would be supersonic, and it looked like the Europeans would start off with a huge lead.

National commitment

On June 5, 1963, President John F. Kennedy formed the National Supersonic Transport program, which committed the government to subsidizing 75% of the development costs of a commercial airliner to compete with Concorde. The director of the Federal Aviation Administration, Najeeb Halaby, decided Concorde was too far ahead in development to bother building a direct competitor, and instead selected a much more advanced standard as their baseline. The American SST was intended to carry 250 passengers (more than twice as many as Concorde), fly at Mach 2.7–3.0, and have a trans-Atlantic range of 4,000 miles (6,400 km). The high speed demanded that the aircraft be made out of either stainless steel or titanium, because skin friction at speeds above Mach 2.2 would cause conventional aircraft duralumin (an aluminum alloy) to lose its temper and strength. The target speed thus significantly inflated the price. This decision would dramatically increase costs, and calculations later showed this would have only cut 20 minutes from a journey across the Atlantic over Concorde due to acceleration time and similar issues.

Requests for Proposals were sent out to airframe manufacturers Boeing, Lockheed, and North American for the airframes; and Curtiss-Wright, General Electric and Pratt & Whitney for engines. The FAA estimated that there would be a market for 500 SSTs by 1990.

Design competition

Preliminary designs were submitted to the FAA on January 15, 1964. Boeing's entry was essentially identical to the swing-wing Model 733 studied in 1960; it was known officially as the Model 733-197, but also referred to both as the 1966 Model and the Model 2707. The latter name became the best known in public, while Boeing continued to use 733 model numbers. The design had an uncanny resemblance to the future B-1 Lancer bomber, with the exception that the four engines were mounted in individual nacelles instead of the box-like system mounted in pairs on the four-engined Lancer.

A "downselect" of the proposed models resulted in the North American NAC-60 and Curtiss-Wright efforts being dropped from the program, with both Boeing and Lockheed asked to offer SST models meeting the more demanding FAA requirements and able to use either of the remaining engine designs. In November, another design review was held, and by this time Boeing had scaled up the original design into a 250-seat model, the Model 733-290. Due to concerns about jet blast, the four engines were moved to a position underneath an enlarged tailplane. When the wings were in their swept-back position, they merged with the tailplane to give a delta-wing platform.

Both companies were now asked for considerably more detailed proposals, to be presented for final selection in 1966. When this occurred, Boeing's design was now the 300-seat Model 733-390. Both the Boeing and Lockheed L-2000 designs were presented in September 1966 along with full-scale mock-ups. A lengthy review followed, and on December 31, 1966, Boeing was announced as the winner. The design would be powered by the General Electric GE4/J5 engines. Lockheed's L-2000 was judged simpler to produce and less risky, but its performance was slightly lower and its noise levels slightly higher.

Refining the design

The -390 would have been an advanced aircraft even if it had been only subsonic. It was one of the earliest wide-body designs, using a 2-3-2 row seating arrangement in a fuselage that was considerably wider than aircraft then in service. The SST mock-up included both overhead storage for smaller items with restraining nets, as well as large drop-in bins between sections of the aircraft. In the main 247-seat tourist-class cabin, the entertainment system consisted of retractable televisions placed between every sixth row in the overhead storage. In the 30-seat first-class area, every pair of seats included smaller televisions in a console between the seats. Windows were only 6" due to the high altitudes the aircraft flew at maximizing the pressure on them, but the internal pane was 12" to give an illusion of size.

Boeing predicted that if the go-ahead were given, construction of the SST prototypes would begin in early 1967 and the first flight could be made in early 1970. Production aircraft could start being built in early 1969, with the flight testing in late 1972 and certification by mid-1974.


A major change in the design came when Boeing added canards behind the nose—which added weight. Boeing also faced insurmountable weight problems due to the swing-wing mechanism. In October 1968, the company was finally forced to abandon the variable geometry wing. The Boeing team fell back on a tailed delta wing—somewhat in irony given that the rejected Lockheed design had a fixed wing. The new design was also smaller, seating 234, and known as the Model 2707-300. Work began on a full-sized mock-up and two prototypes in September 1969, now two years behind schedule.

A promotional film claimed that airlines would soon pay back the federal investment in the project, and it was projected that SSTs would dominate the skies with subsonic jumbo jets (such as Boeing's own 747) being only a passing intermediate fad.

Government funding cut

In March 1971, despite the project's strong support by the administration of President Richard Nixon, the U.S. Senate rejected further funding. Afterward, letters of support from aviation buffs, containing nearly $1 million worth of contributions, poured in. But the SST project was canceled on May 20, 1971. At the time, there were 115 unfilled orders by 25 airlines; at the same time, Concorde had 74 orders from 16 customers. The two prototypes were never completed. The SST became known as "the airplane that almost ate Seattle." Due to the loss of several government contracts and a downturn in the civilian aviation market, Boeing reduced its number of employees by more than 60,000. A billboard was erected in 1971 that read, "Will the last person leaving Seattle - turn out the lights"

Legacy

North American Rockwell's B-1 would successfully use a similar layout as the model 733-197. The B-1B is the only swing-wing aircraft still in service with US forces.

Seattle's NBA basketball team formed in 1968 was dubbed the Seattle SuperSonics or just "Sonics", a name inspired by the newly won SST contract. The team kept that name until its 2008 move to Oklahoma City, and Seattle holds the right to apply the name to any future NBA franchise there.

The Museum of Flight in Seattle parks its Concorde a few blocks from the building where the original mockup was housed in Seattle. While the Soviet Tu-144 had a short service life, Concorde was successful enough to fly as a small luxury fleet from 1976 into the 21st century. As the most advanced supersonic transports became some of the oldest airframes in the fleet, they also fell to the economics of new efficient subsonic jets and upgrade costs.

Though many designs have been studied since, it is unlikely similar aircraft will be economically feasible in the foreseeable future. Concorde's model of cooperation paved the way for Airbus, Boeing's most formidable competitor. Seattle's economy is now more diverse, and 2007 made Boeing a leader in sales again. Boeing's Future of Flight museum has the story and models of all of its production jetliners and Concorde, but not the SST project.

One of the wooden mockups was displayed at the SST Aviation Exhibit Center in Kissimmee, Florida from 1973 to 1981. It is now on display at the Hiller Aviation Museum of San Carlos, California.

Airline commitments

Specifications

Model Boeing 2707-200 SST
Wingspan 180 feet 4 inches (55.0 m) spread, 105 feet 9 inches (32.2 m) swept.
Length 306 feet 0 inches (93.3 m)
Height 46 feet 3 inches (14.1 m)
Takeoff length 5,700 feet (1,700 m)
Landing length 6,500 feet (2,000 m)
Fuselage max. external dimensions Width 16 feet 8 inches (5.1 m), depth 15 feet 7 inches (4.7 m)
Engines (4x) General Electric GE4/J5P turbojets, 63,200 lbf (281 kN) each, with augmentation.
Empty operating weight International model: 287,500 pounds (130,400 kg)
Max. ramp weight 675,000 pounds (306,000 kg)
Max. landing weight 430,000 pounds (200,000 kg)
Max. payload: 75,000 pounds (34,000 kg)
Normal cruising speed Mach 2.7: 1,800 miles per hour (2,900 km/h) at 64,000 feet (20,000 m)
Range 4,250 miles (6,840 km) with 277 passengers

See also

Comparable aircraft

External links




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Published - July 2009














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