Science: Bill & the Little Beast

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Brute Force v. Guile. Bill Bridgeman does not love the X3: "It's a nasty little beast," he says, "and the Skyrocket was a queen." But the Douglas engineers who designed X-3 come fiercely to its defense. The X3, they explain with indignant passion, is designed to do something that has never been done before. It is intended to reach high supersonic speed, probably Mach 2 (1,320 m.p.h.), and still show some of the essential characteristics of a real airplane.

The rocket planes (the Bell X-1 and the Douglas Skyrocket) that really "broke the sound barrier" sacrificed everything to speed. They used rocket motors, which burn something like a ton of fuel a minute. To hang up their speed and altitude records, they had to be carried off the airfield by bombers and dropped off in thin air at 35,000 ft. The longest supersonic flight so far (by Bridgeman in the Skyrocket) lasted only 100 seconds. This impractical "brute force" method, say the X-3's engineers, was all right for the first tests in supersonic flight, but it is not enough.

The X-3's objective is much more ambitious. Instead of smashing the sound barrier by brute rocket force, it will attempt to sneak through it with aerodynamic guile. It takes off from the ground, as a proper airplane should, and its comparatively economical jet engines are counted on to give it considerable time at high speed. If successful, it may father a line of true and useful supersonic airplanes.

The objective, easy to state, is fantastically hard to attain. The air behaves strangely and stubbornly at Mach 2. Inconspicuous projections or badly designed curves can eat up thousands of horse power. Shock waves must be outwitted or they will beat on the airplane like hammers or hold it back like a wall. Every part that faces forward must be sharp-pointed or knife-edged. Blunt shapes can be forced through the stubborn air at Mach 2, but only at enormous cost in power and fuel.

Menacing Beauty. Starting in 1944, the Douglas engineers, financed chiefly by the Air Force, and advised by the N.A.C.A.

(National Advisory Committee for Aeronautics), explored dozens of possible designs, including unlikely patterns with the tail in front or no tail at all. They studied 700 wing sections. They called in physicists and mathematicians. According to one Douglas man, 32½ man-lifetimes were poured into the design of the X3.

Slowly the plane took shape, progressing from tables of figures to blueprints, to mockups, to a thing of menacing beauty in metal and shining white lacquer. But for eight years the X-3 did not fly. Some flaw or unforeseen difficulty was forever showing up. Until a few months ago, the X-3 was not considered ready to be risked in flight.

Some of the faults were designed away; others were removed by improvements in engines, materials or manufacturing methods. New aerodynamic knowledge, much of it flowing from the wind tunnels of the N.A.C.A., told Douglas engineers how to improve their design.