Sonic Cruiser returns, quietly

You thought the Sonic Cruiser was dead -- sacrificed more than nine years ago for the 787-yielding Super Efficient.

Maybe you also thought Boeing was never really serious about the Sonic Cruiser anyway, unveiling the M0.98 speedster in 2001 only to distract the industry from its decision to drop the 747-X Stretch.

You're probably still right.

And, yet, the Sonic Cruiser is not entirely dead.

Somewhere deep inside Boeing, a team of engineers is even now continuing to fiddle with the last decade's most high-profile conceptual aerospace flop. A new Boeing patent application, which was posted online on 19 April, reveals a new and improved Sonic Cruiser. Filing a patent application, mind you, should not be construed as a confession of even long-term corporate strategy. It's most likely just a project some engineers are fiddling around with. Still, it reveals an interesting new approach to an old and fascinating concept.

The new Sonic Cruiser appears to be just as fast as the original design unveiled by a beaming Alan Mullaly at the 2001 Paris Air Show. Improvements are focused on reducing the nearly supersonic aircraft's noise and heat signatures. Rather than embedding the engines under the wing, high bypass turbofans are installed on top of the fuselage. Vertical stabilizers mounted outboard of each engine shields noise generated by the exhaust, while the long aft deck blocks sound waves aimed at the ground. In addition, Boeing's engineers have proposed variable geometry chevrons on the exhaust nozzles of each engine, which soften the noisy mixing of very hot exhaust air with much cooler ambient air.

Besides the new engine locations, Boeing has also made several aerodynamic changes. The differences are clear by comparing the drawing above with the image shown below, which first appeared in a 2003 Boeing patent filing for the original Sonic Cruiser concept. Notice the differences in shaping in the fuselage, nose and wings.