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The mechanical voice of the loudspeaker cracked across the clear, dry air of New Mexico's Tularosa Valley: "Ten, nine, eight . . ."
Safe in a concrete bunker, tense men at a periscope window kept their eyes on Sonic Wind No. 2, a squat, steel sled with the menacing look of a robot spider. Beneath its red-and-white-striped cab, a string-straight rail track ran across the shimmering heat of Holloman Air Force Base. A patch of blue water dammed up between the rails stretched toward the end of the line, 3,500 ft. away.
"Seven, six, five, four . . ."
Overhead an F-94C jet fighter slanted down to make a run with the sled.
"Three, two, one, FIRE!"
From the sled's tail end, nine rockets exploded; the Sonic Wind whipped down the track, shot forward by 70,200 lbs. of thrust. Trailing a 35-ft. tail of fire, it roared out from under the speeding observer plane. After 1.8 seconds, the rockets sputtered out. Metal scoops below the sled plowed into the dammed-up water. Spray exploded into a brief fountain as the Sonic Wind slammed to a stop.
In the dead silence, a fire crew inched toward the still monster to douse its blackened rocket chambers with a blanket of foam. The sled's tail flared into a puff of flame, like a last gesture of defiance, and the test run was over. A quick check of the chronographs showed that Sonic Wind No. 2 had hit 995 m.p.h.
No man has yet moved that fast on the surface of the earth. But if all goes well, one man will. Lieut. Colonel John Paul Stapp, a 45-year-old Air Force surgeon with the deceptive paunch of a country doctor, the ramrod posture of a professional soldier and the relentless curiosity of a dedicated scientist, plans to ride the Sonic Wind even faster. Space Surgeon Stapp intends to ride at more than 1,000 m.p.h.
At that speed, the sled's metal wind screen will be blown clear, and air blast will wallop Stapp with the same destructive force that would hit a pilot bailing out at 40,000 ft. and 2,000 m.p.h.
Man Among the Rivets. To Colonel Stapp, that hair-raising sleigh ride will be another day of body-jarring work in a career that has made him the No. 1 hero of Air Force men. Last year, riding an earlier version of the Sonic Wind, he reached a speed of 632 m.p.h., faster than the flight of a .45-cal. bullet, far faster than any earthbound man had ever traveled before. At the end of the run the sled went down from 632 m.p.h. to a dead stop in 1.4 seconds. As the sled decelerated, Colonel Stapp was subjected to more than 40 times the pull of gravity (40 gs); his normal weight of 168 ½ lbs. momentarily shot up to 6,740 lbs. The driver of an ordinary automobile colliding with a brick wall at 50 m.p.h. would be taking much the same jolt—yet Stapp survived it with negligible injuries.
Such rides along the brink of death are much more than a demonstration of daredevil courage; the data they produce are urgently needed in an age when man is opening up dreamlike new frontiers of space and speed.