Enduring lure of the supersonic

Until the Air France Concorde crashed outside Paris on Tuesday, killing 113 people, the supersonic jet that has symbolized the future for two generations of air travelers had managed to resist the spirit of this age.

First conceived nearly 40 years ago in "the white heat of the technological revolution," as then British Industry Minister Tony Benn put it, the sleek, sharpnosed aircraft looks as modern today as it did then. Somehow, until Tuesday, it had managed to defy mankind's deepening mistrust of technology. Attracting admiration everywhere it flew - with a faultless safety record - it was an icon of industrial perfection.

The human tragedy and smoking ashes of flight AF4590 have buried that image. But the dream of supersonic passenger travel, embodied by Concorde since its first flight in 1969, still lives.

In Europe and in the United States, engineers are studying the prospects for a second generation of supersonic passenger jets, undeterred by Concorde's economic failure. "We are close to an economically viable supersonic passenger plane," says Jean Calmon, head of the French National Air and Space Academy. "From the technical and economic points of view, Concorde could have a successor."

Whether it will, however, is doubtful. In an age when capital markets, not national governments, finance such projects, "the bottom line on supersonic is that it is not economically viable," argues R. John Hansman, professor of aeronautics and astronautics at the Massachusetts Institute of Technology in Cambridge, Mass. "There isn't enough of a market of people willing to pay that much extra to go fast."

If Concorde flew triumphantly, it crashed commercially. Until Tuesday, only 13 of the planes were in service, operated by Air France and British Airways - the national carriers of the two countries which built the craft. Deterred by high operating costs and environmental problems, other airlines spurned Concorde.

Nor did any other country attempt to build a rival, after the Soviet prototype supersonic Tupolev 144 crashed in 1978. The US abandoned plans for a supersonic passenger jet in 1971, when President Richard Nixon killed a Boeing project.

In fits and starts, however, scientists and engineers continue to research supersonic issues, driven by the prospect of a plane that could carry passengers from Los Angeles to Tokyo in under five hours - compared with the 12 hours a conventional aircraft takes. Earlier this year the French government funded 19 research projects, designed "to determine whether we and our European partners should launch ourselves into a post-Concorde development project," in the words of the Research Ministry's tender for proposals.

The projects focus on such problems as fuel consumption - extraordinarily high in supersonic flight - materials stress at high temperatures, and noise suppression.

Concorde's thundering roar on takeoff is a signature trademark, but it is not appreciated by people living close to airports where the plane operates. "People are becoming less and less tolerant of aircraft noise," says Jim McKenna, executive director of the Aviation Safety Alliance in Washington. Agrees Mr. Calmon of the Air and Space Academy: "We have to find technical solutions that we do not have today, and they will be essential for any second generation supersonic plane."

But nothing major can be done about the sonic boom that trails behind any aircraft traveling faster than sound - a boom that is outlawed in the US and in many other countries. This essentially limits supersonic flights to routes over water (flying subsonically is extremely expensive for planes designed to fly supersonically), which severely restricts the number of airports a supersonic plane might serve.

It was the noise problem that persuaded Boeing to pull out of NASA-led research into a larger supersonic craft in 1998, says Rodney Ricketts, a NASA engineer who worked on the $1.5 billion project. "The noise requirements were getting more stringent around airports ... so we were chasing a moving target," he explains. Boeing wasn't "sure if we could achieve a quiet enough airplane with the technology that we had." The project was wound up in 1999, but Congress this year granted $15 million over three years to a Defense Department agency studying supersonics, just to keep the idea alive.

French experts have estimated that it would cost upward of $25 billion to develop a 250-seat supersonic passenger plane - twice as much as the European aircraft manufacturer Airbus plans to invest in its new triple-decker airliner, the A3XX. And it is far from clear that a market exists for the hundreds of supersonic planes that would have to be sold to make the enterprise profitable.

However the sums work out, proponents of supersonic research say that it benefits subsonic aircraft development as well. Engineers working on the abandoned US project, for example, envisaged a cockpit without a front window. Instead, pilots would have looked at a screen carrying a computer-generated view based on information from navigation systems, radar, video cameras, and infrared sensors.

Such artificial displays overcome difficulties like darkness or fog, and they could one day be used in conventional aircraft.

Ongoing research could also be put to use in smaller supersonic projects. Gulfstream, the maker of executive jets, for example, has been working on a supersonic business plane for the past two years, with engineers from Lockheed Martin.

"We are still early in the research and development," says Gulfstream spokeswoman Kelly Holland, "but we are encouraged by the results so far and we have decided to continue to explore the possibility of a supersonic business jet."

Still, nowhere in the world is a supersonic successor to Concorde on the drawing board. Boeing has lost interest in the idea, and Airbus, the only other manufacturer capable of building such a plane, is currently consumed with launching its superjumbo A3XX, designed to be the largest passenger plane in the world with up to 656 seats.

Some analysts say there never will be another supersonic jet. "In some sense," says Professor Hansman of MIT, Tuesday's crash "may signal the beginning of the end of an era. There will be no more Concordes made ... as we start to lose them they won't be replaced."

Others have not lost the faith. "I am quite optimistic that supersonic passenger planes will exist in the future," says Calmon. "But I couldn't tell you today what sort of planes they will be."

(c) Copyright 2000. The Christian Science Publishing Society