Science: Bill & the Little Beast

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No one could tell them how to make a supersonic airplane fly safely at slow speeds, i.e., below 650 m.p.h. At Mach 2, very small wings will give sufficient lift. If they are made bigger, to give lift at low speed, they stir up too much drag. So the tiny wings of the X3, designed for efficiency and minimum drag at very high speed, make the ship unstable and cranky when it is flying below the speed of sound. This is one reason why Bill Bridgeman quietly denounced the X-3 as a "nasty little beast." When he does, one of the Douglas designers retorts: "What do you expect? The X-3 wasn't built to hover."

Heat Barrier. Beyond the problems of design and control lies an even more serious obstacle. Some experts believe that heat will defeat all attempts of men to fly for long at twice the speed of sound. Rocket planes like the Skyrocket do not encounter the "heat barrier"; they do not fly long enough to heat up seriously. But the X3, expected to fly at high speed for a considerable period, is another matter. Its designers had to build into it resistance to the floods of heat caused by its own motion,

The problems involved were staggering. Aluminum alloys lose much of their strength at 300° F., so large parts of the X-3's skin, especially parts that get heat from the engines as well as from outside, are made of titanium. The cabin, which must be kept at a temperature where a man can sit, is cooled by a refrigerator powerful enough to air-condition an average movie theater. The refrigerator accounts for 10% of the empty weight of the X3, and absorbs 2,600 horsepower from its engines. Despite all this cooling, the windows of the cockpit (which must be glass, not plastic) are expected to get hot enough to burn Bridgeman's hands.

Airman Bridgeman views the "heat barrier" calmly. He does not seem alarmed by the prospect of flying an airplane whose windows are too hot to touch. He is not optimistic, either, about the ultimate outcome. "The sound barrier," he says from experience, "wasn't too bad. It was sort of like jumping over a fence. But the heat barrier is like fighting your way into a thicket of thorns. The farther you get into it, the more thorns stick into you."

Problematic Plan. Not all airplane designers believe that the X-3 has a chance of reaching the speed for which it was designed. It is underpowered, they say, and, without complete redesign, it cannot use the bigger engines that are coming along. Bill is noncommittal. Neither liking nor trusting his little beast, he still intends to fly it with high professional competence, however tricky its character. The plan for Bill Bridgeman and the X-3 is many more flights, perhaps 40 of them, gradually increasing the speed to the maximum. Some of the flights are sure to be unpleasant, but Bill does not worry much. The flights will not come very close together; after almost every flight the X-3 is torn apart to remove some of its hazards. Between flights, Bill can enjoy his considerable salary, hunt for abalone on the surf-foaming rocks, and enjoy the guest of the evening in his beach house. If he worried overmuch, he would not be a test pilot.