SBJ Patent Has Unusual Features

A newly published Lockheed Martin patent shows a new possible configuration for the supersonic business jet which the company is studying in collaboration with Gulfstream Aerospace. As a "design" patent, it reveals no SBJ technical details, but the concept includes some very unusual features.

The newly unveiled design is a slender double-delta canard with a gull wing. Under the wing are two engine installations, apparently comprising a narrow, turbojet-like core engine with a square two-dimensional nozzle surrounded by a larger circular-section duct, suggesting some type of variable-bypass engine. The slender forward fuselage is blended into the wing and the canard is located at the extreme nose.

Late last year, another Lockheed Martin patent showed an SBJ configuration with an inverted-V tail and a long, conical-tipped nose. Both designs are aimed at reducing the effects of the aircraft's sonic boom to the point where the SBJ can operate overland without restrictions. Lockheed Martin disclosed at last year's Paris Air Show that Skunk Works engineers had made significant progress in low-boom technology, and Gulfstream leaders have stated that the SBJ must be a low-boom design if it's to sell in numbers that make economic sense.

Prodded by the aerospace industry, with support from investor and NetJets owner Warren Buffett, the U.S. government has allocated some funds to support low-boom research. The Defense Advanced Research Projects Agency (DARPA) has issued a request for information covering a Quiet Supersonic Platform (QSP) project, with the aim of flying a low-boom, high-efficiency supersonic cruiser by the mid-2000s. Such an aircraft could have military applications as well as filling commercial needs. In particular, DARPA is interested in "highly integrated configurations with innovative propulsion systems" -- a category that could well cover the Lockheed design's unusual engine installations. DARPA is also interested in the potential of plasmas to reduce drag and sonic boom.

NASA, meanwhile, has included the design of an advanced supersonic inlet among its latest batch of Revolutionary Concept, or RevCon programs.

By Bill Sweetman