Boeing Facing Sonic Cruiser Realities: New Engines, 100 Percent Composite Frame

Boeing now believes that the Mach 0.98 Sonic Cruiser airliner will need advanced technology -- all-new engines and an all-composite airframe -- to meet its performance, economic and environmental targets, according to product development VP Dan Mooney.

Mooney says that there was "some early optimism" among Boeing leaders who suggested that the radical aircraft could work with simple derivative engines and a conventional structure. "The preliminary design folks were kind of cringing when they heard those statements," he says.

Composites, however, are necessary to meet weight targets given the Sonic Cruiser's large wing area, and the new engines will represent a balance between noise, efficiency and cross-sectional area.

According to Mooney, the first round of wind tunnel tests last year produced positive results in two important respects. "There were two concerns: the drag rise near Mach 1 and what would happen when the aircraft goes through Mach 1." Tests have shown that the drag rise is flat up to Mach 0.98, without an abrupt increase, and that the design is stable above Mach 1.

"What we've done in the last 18 months has told us that we've really got something here," Mooney said here.

Boeing is focusing on capacity of 200 to 250 seats, with a range of 6,500 to 7,500 nautical miles, says Mooney. (In an earlier interview, Boeing preliminary design leader Pete Rumsey said that airlines had sent Boeing "a strong signal that they didn't want the aircraft to be over-designed in range and capacity.") It will have a twin-aisle cabin.

Mooney confirms that Boeing is looking at "different ways of chunking up the airplane." According to some suppliers, the company is looking at engaging a partner to develop and build the entire aft fuselage of the Sonic Cruiser, which will include most of the aircraft's systems, and deliver fully equipped subassemblies to the final assembly site.

By Bill Sweetman