This is a model of the Gulfstream SBJ that was shown at 1998's NBAA. Maybe yes; maybe no.

Dassault earlier this year announced the only boom that held its attention was not the supersonic kind, but the one for its existing Falcons. The French company claimed there is no suitable powerplant for such a jet -- at least, not for its three-engined proposal.

If Dassault hasn't found it, Gulfstream thinks it must be because it didn't look hard enough. While executives in Savannah wonder if Dassault has really stopped its research or just wants to continue its program more secretively, they are themselves convinced that studies so far show that further studies are worthwhile. They believe an engine will not be a problem.

"All three engine companies are working with us, and are looking at derivatives of existing powerplants, materials and cycles," Gulfstream senior VP in charge of programs Pres Henne told Show News.

Now that the F-22 fighter has shown it can reach and sustain speeds of up to Mach 1.6 (not confirmed, but widely whispered in the industry) without use of an afterburner, it is evident that supercruise is achievable and sustainable in terms of technology and materials. This is the first requirement for an engine for the Supersonic Business Jet. In addition, NASA's High Speed Research program into a supersonic airliner has developed materials which can tolerate high temperatures for thousands of hours of operation, unlike fighter engines that see peak temperatures for only minutes at a time.

A Gulfstream SBJ is expected to be about the size of a G-V, and with two engines could feasibly be powered by engines in the class of Pratt's F119 or GE's F120 that will also propel the Joint Strike Fighter into supercruise territory.

"Engines are the key element," Henne said. Once a potential powerplant has been identified, then the issues of noise and emissions can be addressed.

But the next obstacle to the SBJ is the sonic boom. Today, civilian aircraft are prohibited from flying supersonically over the United States -- and many other parts of the world--because of the damage their shock wave causes on the ground. However, the Skunk Works has found that stealth technology developed to reduce radar signatures can also be applied to reducing the sonic boom aerodynamically.

At this point Gulfstream claims its lips are sealed. The model of the SBJ unveiled last year is no longer accurate, and while it still has two engines beneath its wings, the configuration has "changed" considerably. Just how, Gulfstream says, "is classified." Indeed, NASA said earlier it would restrict the release of data from its High Speed Research program to prevent non-U.S. companies (i.e. competitors in Europe) from using it.

But as Gulfstream President Bill Boisture told Show News, there is no point in building an SBJ just to prove it can be done. The key is the market.

Henne said Gulfstream typically builds airplanes on a business plan of 200 units. He added that is not an unrealistic number for an SBJ given that the Concord will probably be retired within the next 20 years and there is no replacement on the horizon to whisk executives from one side of the Atlantic to the other.

The Skunk Works has also enlisted the support of Executive Jet Aviation fractional ownership billionaire Warren Buffett to help lobby the U.S. government to endow NASA with funds to build a supersonic research vehicle which would, coincidentally, be just about the size of a GV. That effort has met with little success to date.

As Boisture pointed out, the SBJ will be very expensive, and its success could depend on the support of fractional ownership programs. These have already shown they can achieve the utilization rates necessary to achieve an adequate return on expensive assets, and that there is fractional demand for intercontinental travel as with the GIV-SP and the G-V.

Would an engine manufacturer develop an engine just for a 200-plane SBJ market? That could well depend on what else is going on at the Skunk Works as the military deepens its interest in stealthy Unmanned Combat Aerial Vehicles, and what level of importance the air force and navy place on supercruise.

"This really is way in the future--probably an end-of-next-decade airplane," said Henne. "We want to make sure we don't miss an opportunity."