Whilst commercial jet
transports began to enter service after World War 2, aiming for a
supersonic airliner was a remote dream, until Convair developed their
Mach 2 B-58 bomber. The dreams revived. Some studies proposed a
B-28-like aircraft with a detachable passenger pod slung below it.
Britain set up the Supersonic Transport Aircraft Committee in 1956, and
in 1959 they favoured two main types of SST (supersonic transport). One
was a radical Mach 1.2 transport with a double-kinked M-shaped wing
plan, and the other was a longer range, larger Mach 1.8 aircraft, a
slender delta design.
These designs were considered to be about as far as such an aircraft
could go with a traditional aluminium-alloy airframe. In the USA, steel
sandwich structures were already being used. The XB-70 Valkyrie
would use stainless steel, and the A-12 Blackbird used titanium.
When it became clear, from 1962, that the Anglo-French SST, to be named
Concorde, would actually go ahead, other nations began to work
on designs of their own. In the USSR, the Tupolev design bureau began
working on their Tu-144. America could hardly stand by, and in 1962
NASA began the SCAT (Supersonic Commercial Air Transport) program.
The SST program gained impetus when, in a speech delivered on 5th June,
1963, President John F. Kennedy announced that such a program was
authorised. The Federal Aviation Authority issued a Request for
Proposals for an SST design to three airframe and three engine
manufacturers - Boeing, Lockheed, North American, Curtiss Wright,
General Electric and Pratt & Whitney. The designs were submitted to the
FAA on January 15th, 1964.
Unlike everyone else, the Americans would aim for a Mach 3 (2,000 mph)
airframe of steel or titanium.
Boeing had quietly worked on a concept for an SST aircraft since 1952,
as part of the project work which goes with corporate forward-thinking.
In 1958 they had set up a small group to concentrate entirely on
developing an SST design, and by 1960 were spending over $1m annually
on it. Using Boeing Model no. 733, they came up with a few alternative
Most of their options involved delta-wing designs. The work of another
Boeing team on a design for a TFX tactical fighter with variable sweep
wings (later to be shelved in favour of the the General Dynamics F-111)
drew their attention to the benefits of a variable geometry.
During 1960 a "competition" was held within the Boeing SST group
between the delta and variable-sweep configurations, looking to a
150-seat aircraft capable of non-stop flight between Western Europe and
the Eastern US. The variable sweep option emerged substantially ahead.
the design which Boeing submitted to the FAA for evaluation against the
delta design of Lockheed's L-2000. A tentative Model 2707 was used to
designate the design, but mostly Boeing simply called it their "1966
model". It was submitted to the FAA in early 1964 as the Model 733-197.
The FAA initiated further studies of proposals submitted by Boeing,
Lockheed, GE and P&W, the results of which were submitted that
November. By now Boeing's design had become the Model 733-290, with 250
Final design submissions were next sought by the FAA, and Boeing
produced the 733-390, with a capacity for up to 300 passengers. By the
final phase, in September 1966, Boeing was working with an even larger
design, for up to 300 passengers. They had built a mock-up of the
aircraft by now. It was the last day of 1966 when the final design was
chosen. It was the Boeing design.
The mock-up of the variable-geometry aircraft was 306 feet long (91.8
m.). It showed both Pratt & Whitney JTF17A and General Electric GE4/J5
engine pods, with the latter being selected by the FAA for development
along with the Boeing SST.
The wings on the mock-up could be moved, manually from fully aft, with
a 72° ;eading edge sweep, to fully extended, with a 30° sweep. A design
modification brought the forward sweep forward to 20° for better
take-off and landing performance. A benefit of variable geometry was,
of course, the ability to take off and land at lower speeds and in less
distance than would a comparable fixed wing aircraft.
Seating was to be seven abreast, two seats each side with three in the
centre, and two aisles. The mock-up was fitted with 277 seats (30
first-class and 247 tourist). The impression on entering the cabin was
that the so-called "narrow" part of the fuselage was noticably wider
(about 4 ft or 1.22 m) than any contemporary jet transport. The cabin
length was interrupted by two galley/toilet areas. Wardrobe racks,
galley tray containers and bar units could be removed from stowed
positions and wheeled up and down aisles. Overhead luggage racks
included restrainers, and were capable of housing items which usually
had to be stowed under passengers' feet.
Boeing mocked up two possible forms of inflight entertainment;
retractable TV screens in the overhead luggage racks at every sixth
row, or small permanent screens in consoles between the paired
first-class seats. Windows had an external diameter of only 6 inches,
but the 12 inch internal diameter gave an illusion of size. Rather than
sun blinds, Boeing proposed a rotatable inner panel of polarised glass.
Seats were the company's own design, and claimed to adjust to adults up
to 6 ft. 7 in. (2.0 m) tall. In addition to underfloor holds, there was
a large baggage compartment to the rear of each cabin.
Like the Concorde the SST had a variable nose geometry to
improve flight deck forward views on approach. Boeing used a
double-hinge, with the section forward of the cockpit angling down but
the nose cone maintaining a similar axis to that of the fuselage. With
the nose raised, minimum ground clearance was 8 ft. 9 in (2.67 m),
reducing to only 4 feet (1.22 m) with it lowered.
Boeing predicted that if design and construction of prototypes began in
early 1967, the first flight could be made in early 1970. Design and
fabrication of production aircraft could begin in early 1969 with the
flight testing in late 1972. The first aircraft could then be certified
and introduced to airline service in mid-1974. By 1980 the company
estimated there would be a market for a larger Model 390-475 SST, with
between 700 and 1,000 aircraft being required.
The Boeing variable-geometry SST dream was never realised. The
variable-sweep idea was abandoned in October 1968, and the 2707-300 was
cut to 234 seats, with a fixed gull wing mounted ahead of a horizontal
tail. It used essentially the same fuselage and engines as the
Two prototypes were begun in September 1969 but, amid a general US
protest against Concorde, the US Senate closed down the SST
program completely on 24th March, 1971, possibly the first time the US
had backed away from a potentially huge market.
The Russian Tu-144 entered cargo service in 1975, despite the crash of
the second pre-production aircraft in Paris in 1973. After another
accident production ceased in June 1978. The Concorde first flew
on 2nd March, 1969. It entered service between London, Paris, Bahrain,
and Rio/Dakar. The obvious destination, New York, refused to admit the
foreign SST until 24th May, 1976.
Boeing SST data:
Four General Electric GE4/J5P turbojets, each of 63,200 lb. st
(28677 kgp) each, with augmentation.
EMPTY OPERATING WEIGHT
287,500 lb (130308 kg)
MAX. RAMP WEIGHT:
675,000 lb (306175 kg)
MAX. LANDING WEIGHT:
430,000 lb (195045 kg)
75,000 lb (34020 kg)
NORMAL CRUISING SPEED:
Mach 2.7 1,800 mph (2900 km/h)
at 64,000 ft / 21000m
4,250 mls (6840 km)
with 277 passengers
5,700 ft (1870 m)
6,500 ft (2133 m)
180 ft 4 in (54.97 m) spread,
105 ft 9 in (32.23 m) swept.
306 ft 0 in (93.27 m)
46 ft 3 in (14.1 m)
FUSELAGE MAX. EXTERNAL DIMENSIONS:
Width 16 ft 8 in (5.08 m),