Boeing is pitching its ‘super
efficient airplane’ concept to airlines as a long-range 200-250-seater that
would be capable of matching the seat-mile operating costs of the larger 777
The US manufacturer is studying the
conventionally configured “reference aircraft” alongside three versions of the
Sonic Cruiser and could make a decision on which aircraft to launch in 2003 if
there is sufficient airline interest, Sonic Cruiser vice president and
programme manager Walt Gillette said in a conference call with journalists in
Asia today. Entry into service is tentatively targeted for 2008.
The super efficient aircraft would
fly at approximately the same speed as today’s 777 but incorporate the advanced
“enabling technologies” under study as part of the Sonic Cruiser project.
Boeing is currently trying to
understand whether airlines want a 250-seater that could cruise at speeds of up
to Mach 0.98 – saving approximately 1hr per 3,000nm (5,500km) flown – at
approximately the same seat-mile cost as today’s 767, or the efficiency optimised
aircraft that would be 17-20% cheaper to operate, says Gillette.
“We need to discuss the value of
speed,” says Gillette. “What we are doing now is having a dialogue with the
airlines about which way we should do this.”
The four key enabling technologies
identified by Gillette are advanced computational fluid dynamics (CFD),
composite and aluminium materials, systems and engines.
Contemporary CFD technology enables
designers to predict aerodynamic performance with an accuracy in excess of 99%,
he says. Meanwhile “very great competition” is developing between producers of
aerospace composites and advanced aluminium alloys, offering much lighter
materials than those available when the 767 was designed.
Thirdly it is now possible in
principle to eliminate an aircraft’s engine-driven bleed air system altogether
and rely solely on electrical and high-pressure (5,000psi) hydraulic power
transmission. Electrical power would come from an engine shaft-mounted
generator rather than via a step-aside gear box.
Finally all-new engines should
provide further efficiency gains, says Gillette. The 767’s current powerplants
are “one-and-a-half generations old”, with each generation typically yielding a
“5-6%” improvement in efficiency, he believes.
three Sonic Cruiser configurations under study include the now familiar
canard-equipped configuration, and two “mid-wing” alternatives with no canard
and conventional empennages that can cruise at the same high Mach 0.98 speed
mid-wing design has aft-mounted engines similar to the original Sonic Cruiser
design, while the alternative has forward-mounted engines on nacelle struts and
significantly more area-ruling of the fuselage.
three of these will do the Sonic Cruiser mission,” says Gillette, which he
defines as operating at Mach 0.95-0.98 over a range of 7,500nm.
The super efficient aircraft would
meanwhile offer the same speed, range and passenger comfort as the 777, but at
a 17-20% lower seat-mile operating cost compared with the 767 and comparable to
that of the larger 777. “Obviously we would be looking at further enhancements
over that design,” he says.
It is currently optimised for long-range
missions but “would also do very well at the short ranges”, says Gillette.
However it would not necessarily replace the existing 757 and 767 families.
Boeing last month hosted potential
customer airlines in Seattle. “We are all thinking about what would be the best
way to move forward,” he says. “All of the carriers expressed interest in both
choices. I don’t believe anyone has made a firm decision.”