Before making the 787, Boeing launched a project for a high-speed delta-wing jet capable of Mach 0.98. Key Aero reveals the story of the Sonic Cruiser, which ended up being dropped in favour of the Dreamliner
As the world entered a new millennium, ambition was high in the aviation industry as companies began launching bold and impressive projects.
In Europe, Airbus went big and unveiled its A380 to much fanfare from the industry. Shortly after its rival’s launch, across the pond Boeing revealed its Sonic Cruiser on March 29, 2001.
The company had recently withdrawn its proposed 747X variant from competition with the A380 because there was little interest from airlines, and instead proposed the Sonic Cruiser as a completely different answer.
With capacity for between 200 and 250 passengers, the jet was designed for rapid point-to-point flying instead of the hub and spoke model of the A380. American Airlines and Virgin Atlantic were reported to have been openly enthusiastic about the potential design. The UK carrier’s boss, Richard Branson expected to make a tentative order for three to six aircraft in May 2001.
A 1/40-scale model was unveiled at the Paris Air Show in June that year to much fanfare from the onlookers. Popular Science magazine named the type on its list of the “the best of what’s new” for 2001.
Design
A 2001 patent filing showed the baseline aircraft’s dimensions to be approximately 250ft (76m) in length, with a wingspan of around 165ft (50m). The design featured a distinctive delta wing and canards arrangement and could fly just short of the speed of sound at Mach 0.95-0.98 (approximately 650mph).
Boeing intended to use composite and titanium materials to reduce weight and further improve fuel efficiency. The jet was promised to be 15-20% faster than conventional airliners without the noise pollution caused by the sonic boom from supersonic travel.
The type – which was expected to fly at altitudes more than 40,000ft to avoid existing air traffic – was projected to have a range between 6,000 and 10,000nm. It was estimated that the jet would have similar fuel efficiency to the twin-engine widebodies of 2002 on a per-passenger basis.
The design team finalised the Sonic Cruiser’s configuration throughout 2002 and used wind tunnel testing and computational fluid dynamics analysis to refine the concept.
Cancellation
In the end, the Sonic Cruiser concept didn’t attract enough interest from potential airline customers. Most operators favoured lower utilisation costs over a marginal speed increase. Logistical problems arose to do with integrating the faster aircraft into existing air traffic networks. Concerns were also raised about the jet arriving at airports before the morning noise curfews.
Following the September 11th attacks in 2001, demand for air travel fell dramatically and as a result, Boeing began marketing Project Yellowstone to potential customers for the first time in February and March 2002.
The more efficient Project Yellowstone/7E7 – later renamed Boeing 787 Dreamliner – was favoured by potential airline customers who were mostly looking for improved operating efficiencies.
In December that year, the Sonic Cruiser was finally abandoned in favour of the Dreamliner but much of the work and research was later applied to the 787, including carbon fibre reinforced plastic for the fuselage and wings, bleedless engines, cockpit and avionics.
