10 YEARS AGO — 2001
DuPont wins gold:
Sports enthusiasts who watched Olympic gold-medalist Michael Johnson probably didn’t think much about the soles of his shoes. Johnson’s custom-designed Nikes in the Sydney Olympics used a featherlight sole plate molded from DuPont glass-reinforced Zytel nylon resin. At just 30 gm, it weighs less than half that of standard racing shoe soles, says DuPont. Zytel is stiff, which is important for sprinters because it adds extra support and helps them stay on their toes. After combining and testing several materials, Nike engineers found that Zytel let them stiffen the sole without increasing weight. The soles are said to be exceptionally tough, withstanding more than 10,000 flex cycles in tests.

30 YEARS AGO — 1981
Drop testing proves Hornet’s strength: Structural testing on the McDonnell Douglas F/A-18 Hornet strike fighter is proving the aircraft’s strength and resistance to fatigue. The drop-test (pictured) lets F/A-18 engineers simulate landings on aircraft carriers, one of the most-severe tasks a fighter aircraft must handle because it is jolted to a halt by the arresting hook engaging a cable strung across the carrier deck. Full power is applied at the time of anticipated engagement in the event of a miss, or bolter. The resulting strain on the airframe is immense. Structural engineers can simulate the roll, pitch, yaw, and rate of descent or sink speed on the test prototype by varying angle and height at the time of release.

50 YEARS AGO — 1961
This is a computer-tutor
, the first teaching system to use a digital computer. Designed by the System Development Group, Santa Monica, Calif., the “teacher” has a Bendix G-13 computer programmed to respond to answers on multiple-choice questions. Punching the correct key on the electric typewriter brings the next question; punching the wrong one gives the student additional instruction in the form of remedial questions.

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