Boeing's Supersonic Dreams

DALLAS - During the 1950s, the dream of building a commercial "Supersonic Transport" (SST) became a race between the aviation giants of the United States, Europe, and the Soviet Union.

In January 1958, Boeing set up a supersonic project office to study the construction of an SST. But the plane maker quickly realized that the financial requirements needed to create such an aircraft would be far beyond its capabilities.

Across the pond, the French and British were progressing well with their own SST, Concorde, and in 1963, Pan American (PA) placed an order for six of the type. President John F. Kennedy was enraged and called for tenders from US manufacturers to create an SST that would be bigger, better, and faster than its European rival. He promised that the government would fund 75% of the program as an incentive.

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US Enters The Race

Rivals Lockheed came up with the L-2000, and McDonnell Douglas (McD) submitted a design for an aircraft capable of flying at Mach 3, or three times the speed of sound.

Boeing, meanwhile, led by Chief Designer Maynard Pennell, unveiled its bold design dubbed the 2707. Claiming the aircraft would have seat mile costs well below the 707, it would be capable of carrying almost 300 passengers in a two-class configuration.

Powered by four General Electric GE4/J5P turbojets, the 2707 would fly at Mach 2.7 (1,800mph or 2,898km/h), with a range of around 3,500 miles (6,400 km). Boeing would construct the jet entirely of stainless steel and titanium materials.

But it was the radical 'swing-wing' design that caught everyone's attention. The wing would be straight at low speeds, providing additional lift and improving handling at low speeds. They would then swing back to the fuselage when the jet accelerated.

On New Year's Eve 1966, the US government announced that it would choose Boeing's design to become the United States' first SST.

Design Flaws

However, as development progressed, it became clear that the mechanics required to operate the swing-wing would be weighty. Thus, the 2707 would be able to carry virtually no payload.

Boeing was forced back to the drawing board, and in October 1968, the swing-wing was dropped in favor of a more standard delta-shaped design. The redesigned airframe would also be smaller, capable of carrying 234 passengers.

Costs continued to spiral, and so did the public unrest regarding the environmental and noise impacts of the jet. This issue would later impact Concorde's entry-in-to-service on routes to the United States.

Despite 26 airlines taking up delivery options, including PA, TWA (TW), Qantas (QF), and Alitalia (AZ), in March 1971, the US Senate and House of Representatives pulled the plug on the project.

Boeing turned its attention to the 747, utilizing many of the design features from the 2707 in its iconic Jumbo Jet.

A Second Attempt

In 1990, Boeing resurrected the idea of building an SST. Teaming up with McD and European manufacturers British Aerospace (BAe) and Aerospatiale of France, the group began to study the possibility of developing the "Son of Concorde."

But the European aviation industry was undergoing significant changes, and the English and French manufacturers soon stepped away from the project. Enter NASA, which was developing its own 'High-Speed Research program.' The space agency provided US$1.3 billion to Boeing, McD, Rockwell-Collins, Pratt & Whitney, and General Electric to develop a new High-Speed Civil Transport (HSCT).

The HSCT would be capable of crossing the Atlantic or Pacific in half the time of conventional sub-sonic aircraft and carry 290 passengers.

To assist in the research program, a Tupolev Tu-144 was restored as part of a six-month joint US/Russian flight-test program. The Tu-144 was Russia's answer to Concorde, which first flew on December 31, 1968, some two months before its European rival.

Despite being an old airframe, the Russian jet had been in storage for some ten years and had just over 100 flying hours on the clock. The aircraft was dismantled entirely, with all systems and instruments checked. Its engines were removed and replaced with new Kuznetsov NK-321 turbofans.

Various modifications were made to the airframe, including installing numerous computers to record readings from the 1,800 sensors fitted to carry out the different experiments. These included structure and cabin noise, engine operation, surface/structure temperature variations and handling quality assessments.

Twenty-seven research flights were conducted by the aircraft over two years. These were hailed a success by all parties, with NASA later stating that the tests 'greatly enhanced the supersonic flight databases available to US and Russian aeronautical engineers.'

Despite these successes, in 1998, NASA announced an indefinite delay to the program. The blame was again placed on environmental and noise concerns, with NASA stating that its noise targets were unattainable with the technology available at the time. A year later, the project had been shelved.

The 'Sonic Cruiser'

But Boeing wasn't ready to give up its supersonic ambitions. While Airbus was busy launching the A380 'Superjumbo' to take on the hub-and-spoke market, Boeing decided to improve point-to-point services with a near-sonic/supersonic airliner known as the 'Sonic Cruiser.'

The project was officially launched on March 29, 2001, just three months after Airbus unveiled the A380. Many believed the Sonic Cruiser was a knee-jerk reaction to the European rival's announcement. However, Boeing stated that the jet would "change the way the world flies" by offering passengers shorter flight times and increased comfort.

The Sonic Cruiser was a significant departure from conventional aircraft design at the time. It featured a constant cross-section cabin with a twin-aisle layout. Its large delta-style wing had raked wingtips, and two large canards were located on the forward fuselage.

Twin engines were placed on either side of the 'gloved' fuselage at the rear, and near vertical tail surfaces were mounted atop the engine nacelles.

Around 60% of the airframe would be constructed using composite and titanium materials. This would allow the aircraft to be lighter, burn less fuel and have a greater range.

Early discussions were held with Rolls-Royce, Pratt & Whitney, and General Electric about providing engines for the Sonic Cruiser. However, only the latter would offer a proposal. The 'Gen-X' was an 80% scaled-down version of the GE90-115B used to power the manufacturer's 777s.

Supersonic Buzz

There was much enthusiasm for the jet by American Airlines (AA) and Virgin Atlantic (VS) bosses, with the latter's founder, Sir Richard Branson, planning on making a tentative order for between three and six aircraft in 2001. Despite the buzz, Boeing canceled the ambitious project in December 2002.

They claimed that this was down to rising fuel costs and the downturn in the global economy and aviation industry following the 9/11 terrorist attacks.

However, Boeing utilized much of the research into its Project Yellowstone/7E7, which would later become the 787 'Dreamliner'.

Today, Boeing has seemingly passed the baton in the SST race to Boom Supersonic and its 'Overture' jet, due to enter service in 2029.

Featured image: Building a supersonic airliner was Boeing's priority during the 1960s. Photo: Boeing.