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The Soviets' first atomic bomb test in 1949, in background, prompted tense aerial duels between (top to bottom) Soviet Tu-95 bombers, F-101s, and F-102s. Bottom: The blast effects of a one megaton bomb exploding over Pittsburgh. (David Peters; Sources: NASM (SI Neg. #85-16420); NASM (SI Neg. #1B44791); SOVFOTO)

The Thin Aluminum Line

Supersonic airplanes and a screen of radar stood ready during the cold war to avert the end of the world.

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On another floor, Air Force personnel sat in the soft blue light of communications and display consoles, watching for signs of war.

New radar picket lines were going up in the north. Begun in 1951, the Pinetree Radar Line by 1954 had 30 manned stations along the U.S.-Canada border at 49 degrees north latitude. A Mid-Canada Line, built in the late 1950s, provided a fence of eight main and 90 unmanned Doppler stations along the 55th parallel.

The most daunting feat, however, was raising the northernmost radar fence: the Distant Early Warning (DEW) Line, draped along the 70th parallel from western Alaska and the Aleutian chain eastward across Canada to Greenland. When President Dwight Eisenhower approved construction in February 1954, virtually the only structures north of the continent’s tree line were Inuit villages.

Just three years later, 58 stations were operational; the number would eventually grow to 70. Each main station had big AN/FPS-19 L-band search radar (or, in the two Greenland stations, a more powerful AN/FPS-20). Unattended AN/FPS-124 Doppler radars filled in the gaps, looking for low-flying targets.

Perched precariously atop rocky promontories or along the pebbly, ice-bound shores of the Arctic seas, most DEW Line stations existed in almost total isolation, broken only by occasional airlifts of people and supplies.

The missing piece of this new air defense scheme was an all-weather fighter that could catch anything the other side deployed.

When the Air Force started what it called the “Ultimate Interceptor Program,” it began by looking at a design that had been shelved years before.

In September 1948, just weeks after the F-89’s maiden flight, the Consolidated Vultee XF-92 had made its first flight, at Edwards Air Force Base in California. Clean and arrow-like, it was the first military jet to incorporate the delta wing, pioneered by German designer Alexander Lippisch. At the time, however, airplanes built for long-range escort and penetration missions were eclipsing interceptors, and the XF-92 program was shut down.

In 1951, the Air Force asked Convair to take another look. The result was the YF-102, similar to the earlier delta prototype but larger.

Engineers applied the then-novel area rule to sand away transonic drag, making a determinedly subsonic airplane supersonic. (Even if an airplane is flying at subsonic speed, localized areas of airflow can be supersonic, and the resulting shock waves cause considerable drag. The effect can be reduced by presenting a smaller area to the oncoming flow.)

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