Boeing 2707 was intended to be the first American supersonic
airliner. It would have been built at the Boeing plant in Seattle, Washington,
but increasing outcry over the environmental effects of the aircraft, notably
sonic boom, led to its cancellation in 1971 before the two prototypes had been
Boeing had been working on a number of small-scale studies on supersonic
transport (SST) designs since 1952, but set up a permanent research committee in
1958 which slowly grew to a $1 million effort by 1960. They proposed a number of
alternative designs, all under the name Model 733. Most of their designs
were built on the basis of 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 proved to be
By the middle of 1962 it was becoming clear that the tentative talks earlier
that year between the Bristol Aeroplane Company and Sud Aviation on a merger of
their SST projects was more serious than originally thought, and it appeared
there was a very real chance they would be offering a design shortly. In
November they annouced that the 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 be off to a massive lead.
On June 5, 1963 President John F. Kennedy committed the government to
subsidizing the development of a commercial airliner to compete with the
Concorde, forming the National Supersonic Transport program, which would
pay for 75% of the development costs. The director of the Federal Aviation
Administration, Najeeb Halaby, decided that the 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 SST was intended to carry 250
passengers (more than twice than the Concorde, or comparable to a modern
wide-body), fly at Mach 2.7–3.0, and have a trans-Atlantic range of 4,000 miles.
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 will cause duralumin
(aircraft aluminium) to go "plastic". Request 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 by 1990 there would be a market for 500 SST's.
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,
known officially as the Model 733-197, but also referred to both as the
1966 Model and the Model 2707. For some unknown reason 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 modern day B-1 Lancer
bomber, with the exception that the engines were mounted in individual nacelles
instead of the box-like system on the Lancer.
A "downselect" of the proposed models resulted in the North American and
Curtiss-Wright efforts being dropped from the program, with both Boeing and
Lockheed asked to offer 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
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, to 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. Given the FAA's mandate to produce a
more advanced design, their decision is perhaps unsurprising.
The -390 would be an advance aircraft even if it was 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
(although not for long). The mock-up included both overhead storage for smaller
items with restraining nets, as well as large drop-in bins between the various
sections of the aircraft. In the main 247-seat tourist-class cabin the
entertainment system consisted of retractable televisions placed between every
6th row in the overhead storage, and 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 was given, construction of the
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. However during the prototype
phase Boeing encounted insurmountable weight problems due to the swing-wing
mechanism. The next major revision was the addition of canards behind the nose,
which added weight. In October 1968 they were finally forced to abandon the
variable geometry wing. The Boeing team fell back to a tailed delta wing,
somewhat in irony given that Lockheed had been rejected because of a fixed wing.
The new design was also smaller, seating 234, and known as the Model 2707-300.
Work began on a full-sized mockup 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 jumbo jets being only a passing intermediate fad.
By this point, the opposition to the project was becoming increasingly vocal.
Environmentalists were the most influential group, voicing concerns about
possible depletion of the ozone layer due to the high altitude flights, and
about noise at airports and from sonic booms. The latter became particularly
significant, the #1 cause to rally around, and supersonic flight over land was
eventually banned. The project suffered political opposition from the left, who
disliked the government subsidizing the development of a commercial aircraft to
be used by private enterprise. The anti-SST campaign was led by Democratic
Senator William Proxmire, who ran the campaign as a crusade against spending by
the federal government.
In March 1971, the U.S. Senate rejected further funding. Afterward, letters
of support containing money, nearly $1 million worth, poured in. But the project
was cancelled May 20, 1971. At the time, there were 120 unfilled orders by 26
airlines. The two prototypes were never completed. The SST became the airplane
that almost ate Seattle as a sign was put up "Will the last person leaving
Seattle please turn out the lights".
The mockup was disassembled and shipped to Florida, where it sat in a
scrapyard for 19 years before it was purchased and partially reassembled for
display at the Hiller Aviation Museum in San Carlos, California. Today, the
Concorde is on display next to the building where the SST was developed, retired
because of the dominance of inexpensive wide and narrow bodied airliners like
the 737 and 747 which remain in production today.