Boom Times Demand a Supersonic Bizjet, Gulfstream and Lockheed Martin Believe

It will be at least three years before Gulfstream and Lockheed Martin decide whether to offer a supersonic business jet, under the teaming agreement that the two companies announced at Farnborough.

The two companies started to discuss the project only a few months ago, according to Gulfstream Aerospace president and chief operating officer Jim Johnson. However, they have reached agreement on the outline of a four-phase plan.

First, the two companies plan a feasibility study -- Johnson will be "surprised if it takes less than a year" -- to look at what technology is available for the SBJ. The study will look at engines, materials, aerodynamics and environmental and operational issues.

The next stage -- "18 to 24 months, minimum" -- would encompass the design of a specific configuration, wind-tunnel testing and the definition of a product. In the third phase, the partners would assemble an industrial team and define the final stage: the development, certification and production program. This is why the two companies expect that it will be 8-10 years before an SBJ can be delivered.

The numbers discussed at Farnborough -- an eight-passenger aircraft with a 4000 nm range -- are notional, Johnson said, corresponding roughly to a supersonic Gulfstream IV. Likewise, the configuration shown at Farnborough (an arrow-wing, tail-aft design with twin engines under the wings) does not represent a real design, either from Gulfstream or Lockheed Martin.

Unlike Dassault, which is also studying a supersonic business jet, the two U.S. companies will be able to access the data from NASA's High-Speed Research (HSR) program, which has been underway since 1990 and is aimed at building the technology base for a new 300-passenger supersonic airliner. NASA has restricted the release of HSR data to prevent non-U.S. companies from using it.

NASA has decided to pump an extra $2 billion into HSR between now and 2006. Most of this money will pay for the design and construction of a complete ground-test engine, a 70,000 pound thrust monster with an exhaust noise suppressor as big as a motorhome, to address the critical issues of noise and upper-atmosphere pollution. Already, HSR has led to the development of engine materials which can tolerate high temperatures for thousands of hours of operation -- unlike a supersonic fighter engine, which sees peak temperatures for minutes at a time. The NASA program also includes research into heat-resistant, affordable composite materials and the design of a wing which is efficient at Mach 2 and offers high lift at low speeds.

One area of particular interest to Gulfstream and Lockheed is the sonic boom. "An airline can dedicate an aircraft to cross the Atlantic. A corporate operator can't do that, so a greater proportion of its flight will be over land," Johnson said.

The NASA program assumes that the jetliner will fly supersonically only over water or the most sparsely inhabited areas, but Gulfstream and Lockheed Martin will look at technology to reduce the sonic boom energy. "Low-boom" aerodynamic designs have been studied (and the Skunk Works may well have worked on them in the course of stealth research), but early NASA investigations under HSR did not show any conclusive advantages for them. Another approach is to design the aircraft so that it can cruise efficiently at lower supersonic speeds: an aircraft cruising at Mach 1.2 may not cause a boom on the ground, but is still half as fast again as most subsonics.

By Bill Sweetman