Into Space with the X-15

One approach to manned space flight is to put a man in a rocket and depend on a parachute or other drag-making device to ease him back to earth. Another approach is to fit a piloted airplane with rocket motors powerful enough to toss it out of the atmosphere. It will have wings of a sort for gliding, and the pilot will land it like a conventional but extra-hot airplane.

The X-15 rocket-plane built by North American Aviation, Inc. is the second approach. It will probably make its first flight to the edge of space in less than a year. Made of stainless steel to resist heat, it is a stubby-winged airplane only 50 ft. long, weighing about 33,000 Ibs. when fully fueled. Its single rocket engine has 60,000 Ibs. of thrust and is capable of lifting it off the ground like a ballistic missile.

Ballistic Trajectory. But the X-15 will not fly into space in this crude way. With a pilot in its cramped cockpit, it will be carried 35,000 ft. above Wendover Air Force Base, Utah by a specially adapted B-52. As soon as it cuts loose with its rocket engine roaring, the pilot will head it on a steep trajectory like a ballistic missile. In 30 to 40 seconds, if all goes well, it will approach Mach 3 (three times the speed of sound) at an altitude of 100,000 ft. From this point it will be, as the airplane people say, "beyond the envelope of knowledge," flying higher and faster than a manned aircraft has ever flown.

The rocket engine will have fuel for only six minutes of powered flight, but after its fuel is gone, the X-15 is expected to climb on momentum at least 100 miles above the earth, probably a good deal higher. This altitude is not strictly space; there is still a little air, but it is much too thin for an airplane to steer by. So for controls the X-15 will use six small jets of hydrogen peroxide gases shooting out of its tail and wings. When the X-15 is above the effective atmosphere, its pilot will feel zero gravity and float off his seat to the limit of his belts. Loose objects in the cockpit, if any, will drift around like smoke. This condition will last for something like five minutes, ending only when the X-15 meets denser air on the way down.

Tricky Return. Return to earth will be the most ticklish part of the flight. The pilot will have the help of special flight instruments, and his object will be to meet the atmosphere at a very low angle to minimize speed and heating. The temperature of some parts of the structure is expected to reach 1,000DEG F. If the temperature rises too high, the pilot may point the nose upward to get into thinner air and let the ship cool off. Gradually the X-15 will lose both speed and altitude. When it has lost enough of both, the pilot will ease it down to a skid landing at Edwards Air Force Base, Calif., 485 miles from Wendover.

Counting on the success of the X-15, North American has proposed a beefed-up version with a booster rocket that will push it up to orbiting speed (18,000 m.p.h.). It will climb into genuine space, well above 150 miles. There will be no human pilot on the first flights. Automatic instruments will ride the winged satellite around the earth for awhile. Then, perhaps on electronic command from below, they will glide it to earth. Later, as the art develops, the first human pilot may take the same ride.

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