The Supersonic Centuries

Out from the U.S. Air Force recently went a brief announcement: the U.S. was sending the first North American F-100 Super Sabrejet fighters to units in Europe; three demonstration planes were already overseas, with full squadrons to follow soon. The news caused little splash, yet it was one of the most significant announcements of the jet age. It meant that the whole new breed of radically advanced "century" series jets was coming into service.

Though Californians have watched growing formations of the new planes howling overhead or sitting on airfield ramps, Air Force security is still so tight that comparatively few details have been given out about the new supersonic planes. North American's F-100 is only one of the new jet breed. To date, the U.S. has earmarked some $6 billion for a complete arsenal of century-series jets which Air Forcemen like to call the "city-savers."

Under Wraps. As the first of the centuries, North American's F-100 is as great a leap over its F-86 Sabrejet of Korean war fame as the Sabre itself was over World War II's P-51 Mustang. Long and lethal-looking with 45DEG swept-back wings, the F-100 is the first operational fighter--and fighter bomber--to crack the sound barrier in level flight, broke the official world's record by flying 822 m.p.h. last year. Even then it was under wraps; estimates are that it can top 1,000 m.p.h. with its Pratt & Whitney J57 engine and afterburner going full blast. The F-100 can fly and fight effectively at 50,000 ft. (10,000 ft. higher than the F-86), and packs an array of 2.75-in. rockets and radar-sighted 20-mm. cannon which fire so fast a burst sounds like the high toot of a diesel locomotive. Cost of an F-100: $640,000, nearly three times more than an F-86.

Supersonic stable mates in the century series:

P: Convair's delta-winged F-102 interceptor (the "Iron Dart"), slated for squadron service soon. Powered by a J-57, the rocket-carrying F-102 weighs as much as a DC-3 transport (25,200 lbs.), can climb to 40,000 ft. in less than five minutes, hit something like 1,000 m.p.h. in level flight at combat altitude.

P: McDonnell Aircraft's F101 Voodoo, a big, 45,000-lb., long-range (estimated at 1,500 mi.) bomber-escort which can also be used as an interceptor or fighter-bomber. Scheduled for operational service this year, it is powered by two J-57s, has a ceiling of 50,000 ft. plus. Speed: around 1,100 m.p.h.

P: Lockheed's F-104, the fastest of the new planes. Pilots call it "a saddle strapped on an engine with a 20-mm. cannon." Pencil-slim, with straight, stubby eight-foot wings, it combines relatively light weight (17,000 lbs.) with a big General Electric J-79 engine. The F-104 will do an estimated Mach 2 (1,320 m.p.h. at 30,000 ft.) in level flight.

P: Chance Vought's F8U Crusader and Grumman's F11F Tiger, the Navy's newest jets. Both are relatively light, have sharply swept wings and needle-nosed fuselages. The F8U is powered by a Pratt & Whitney J-57, the F11F by a Curtiss-Wright J-65. Speed of the F11F: supersonic in level flight. Speed of the F8U: about 1,050 m.p.h.

Razors & Boosts. To design the new planes, said one planemaker, "we had to use all the skills and sciences developed during the past 2,000 years." Where designers once spent thousands of hours, each century fighter needed millions. North American ticked off 2,000,000 man-hours perfecting its first F-100.

Supersonic flight called for entirely new wings and new controls, developed by working with electronic computers and countless wind-tunnel models. Fuselage design was an even tougher problem. When Convair's F-102 was first designed, the fuselage swept straight back from nose to tail. In the air, the F-102 was beset by mysterious buffeting as it approached the sound barrier. Only after extensive tests did engineers discover the trouble: shock waves were piling up where the wings joined the fuselage.

To eliminate the trouble, the engineers applied the new "area rule" theory of Engineer Richard T. Whitcomb of the Government's National Advisory Committee for Aeronautics. In 1951, Engineer Whitcomb discovered in wind-tunnel experiments that the total drag on a plane is not merely the sum of the drag on each of its parts, but varies according to where the parts are located. Convair's F-102 was redesigned with a punched-in "coke bottle" fuselage to smooth the air flow over the critical wing junction. Result: on its first flight, Convair's new F-102 not only eased through the sound barrier, but flew 100 m.p.h. faster than anyone expected. The area rule, applied to Grumman's F11F and Chance Vought's F8U, helped them both to supersonic speeds.

The Jeweler's Touch. On the century series production lines, workers need a jeweler's touch to fit parts within supersonic tolerances. A single, one-in. hole in a wing can slow a modern jet by as much as 100 m.p.h. And such skilled manpower is hard to find. Though McDonnell has 14,000 workers at its St. Louis plants, it is still desperately short of skilled manpower. Last week, with new F101 orders coming in, McDonnell sent out calls for another 1,000 engineers.

In addition, the planes also needed new methods to test them, since they fly in a world where things happen so fast that human reactions are woefully slow. At Edwards Air Force Base in California, all structural parts are first checked out on a Mach 3 (2,280 m.p.h.) rocket sled to make sure that they will stand up under supersonic stresses. When North American's first F-100s developed tail flutter at speeds above Mach 1, engineers grounded all planes, experimented with a tail attached to a rocket sled. They drove the sled until the tail disintegrated, found where it needed improvement. In the old days, it would have taken many test flights--and perhaps some pilots' lives--to lick the problem.

The extraordinary speed and combat capabilities that U.S. planemakers have built into the new century fighters were well summed up by Lockheed's Chief Engineer C. L. Johnson: "Give us a 16-in. shell up there, and we'll outrace it--or shoot it down. Not at all impossible. After all, the velocity of this shell at 35,000 ft. is 300 ft. per second. We can sure go that fast."

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