GREAT IDEAS ARE MYSTERIOUS THINGS. Where do they come from? Do they float down from above, launched like paper gliders by a playful muse? Or do they percolate up out of inner darkness, eventually to erupt into consciousness? Are they born fully formed, or do we construct them out of bits and pieces? Or is an idea not a construction at all but a kind of dissolution, a solvent that breaks apart things we believed to be related and allows them to recombine differently?
From This Story
In 1951, Richard Travis Whitcomb, a slender, sandy-haired man, sits, feet up on his desk, at the Langley Research Center of the National Advisory Committee for Aeronautics in Hampton, Virginia. He wears a dark coat and a tie, and, as always, he is smoking a cigarette. He’s thinking. Suddenly, something else is there, a presence, an annunciating angel: the Idea. It’s not worked up to step by step like the answer to a long-division problem, but just there all at once. “I suddenly realized that the disturbances and shock waves are simply a function of the longitudinal variation of the cross-sectional area.”
Whitcomb’s insight was that at speeds near that of sound, the disturbances in the air produced by a complex object like a streamlined body with protruding wings would be largely equivalent to those produced by a simple streamlined body without wings, but with, in their place, a sort of midriff bulge with a frontal area the same as that of the wings. The idea was so simple that it seemed incredible that no one had had it before.
What Whitcomb’s discovery solved was nothing less than the problem of the famous “sound barrier”—the steep increase in drag and the onset of control problems that beset airplanes as they neared the speed of sound, and that, in 1951, was the principal preoccupation of the U.S. and Russian air forces and the airplane manufacturers who supplied them.
To define the problem in terms of replacing wings with a midriff bulge, as Whitcomb did in the brief secret report in which the NACA revealed the discovery to industry, was a little coy, because nobody was really interested in finding novel ways to produce the same amount of drag. What mattered was what the insight implied. It wasn’t until the last couple of pages of the epoch-making paper that Whitcomb pulled the rabbit out of his hat: If you sucked the fuselage inward in the vicinity of the wings, you could make it look to the air as if the wing wasn’t there. With a single stroke Whitcomb had severed the Gordian knot of transonic aerodynamics and cut the drag rise by half.
Whitcomb’s idea came to be known as the Transonic Area Rule, but when it was declassified and made the front page of the New York Times, the popular press dubbed it the “Cokebottle fuselage.”
At a time when jet engines were less powerful than they are today, the idea was the key to some airplanes’ ability to achieve supersonic speeds. One was the Convair F-102, a delta-wing interceptor, the prototype of which was nearing completion when Whitcomb made his breakthrough. Already committed to a conventional cigar-shaped fuselage, Convair’s management was unwilling to change the design even though Whitcomb’s analysis indicated that it wouldn’t achieve the supersonic speed the Air Force required. Indeed, it didn’t. Management’s first ploy—“It still makes me mad when I think about it,” Whitcomb bristles today—was to pressure the Air Force to accept the airplane as it was. But the Air Force wouldn’t have it; either the airplane had to go supersonic or the contract would be terminated. Finally Convair relented and built a new, arearuled fuselage. The Coke bottle F-102A accelerated through Mach 1 while still climbing.
It happened that the internal layout of the F-102, and also that of its beautiful successor, the F-106 Delta Dagger, permitted deep arearuling of the fuselage. Other designs were more tightly packaged and couldn’t be squeezed. In the case of the Republic F-105, rather than narrowing the fuselage in the vicinity of the wing, Whitcomb proposed fattening it before and after the wing—the goal being, if the total cross-section could not be reduced, at least to make the longitudinal variation of area more continuous. “The [proposed] fuselage looked like a bowling pin,” Whitcomb recalls, and Alexander Kartveli, chief designer at Republic, “wasn’t happy. He liked his airplanes to look sleek.” But when he saw the wind tunnel results, Whitcomb says, Kartveli decided the fuselage didn’t look so bad after all.
“I think that what looks good usually is good,” Whitcomb says, though the example of Kartveli illustrates the circularity of the argument: One’s sense of what looks good is, after all, conditioned by the looks of other things that have already been demonstrated to be good. But in Whitcomb’s case that rule had a deeper meaning, because Whitcomb, unlike his colleagues at Langley and most other workers in the abstruse field of transonic aerodynamics, was in a sense an artistic rather than a theoretical or mathematical thinker. He did not interpret numerically the condition of the flow he was investigating; he felt it. “He was different from anyone else. He had a physical feel for fluid dynamics—and he was very, very good at it,” says Larry Loftin, Whitcomb’s longtime boss at Langley. Anthony Jameson, a mathematical aerodynamicist who worked with him in the 1970s, agrees. “Whitcomb,” he says, “had different thought patterns.”
The difference served him well. The Transonic Area Rule had, in fact, been implicit in earlier work by other researchers, but—perhaps because they were concerned only with the purely mathematical aspects of the problem—they had somehow failed to see its importance for practical aircraft design. Because Whitcomb saw the problem and its solution in physical terms, he was the one who reaped credit for the discovery of the rule.