Word: rotors
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Dates: during 1960-1969
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...aboard, and their Vietnamese crewman, never had a chance. As the battle blazed, the desperate Viet Cong poured murderous fire into the other whirlybirds. Fourteen more were hit but limped back to Saigon. On the second day another Huey, zeroing in on a Communist beach emplacement, lost its rear rotor to an enemy bullet, fell like a stone into...
When U.S. oil crews used helicopters to fly to remote drilling sites in Pakistan eight years ago, the Pakistanis were so intrigued by the strange machines that the pilots had to keep their rotor blades turning while on the ground to hold back the curious crowds. Last week Pakistanis were not only staring at helicopters, but flying in them too. Pakistan International Airlines has started a helicopter service that will eventually link 20 east-Pakistan towns in the world's most extensive helicopter network. In a land where travel is made slow and difficult by hundreds of marshes...
Developed by Minneapolis-Honeywell on theories worked out at the University of Illinois, the bottled star is officially named ESG (Electrically Suspended Gyro). Like all the gyroscopic equipment that guides modern missiles, ships, aircraft and spacecraft, ESG's performance depends on the fact that a rapidly spinning rotor tends to maintain an unchanging attitude in space; it sticks to its stance regardless of the movement of the vessel on which it is mounted. Gyros that can do this job accurately for short periods are not too hard to build. But when a gyro is used steadily for days...
Electrical Support. For all practical purposes Honeywell's ESG has no friction at all. The beryllium sphere that is its rotor is enclosed in a ceramic case lined with copper electrodes that do not quite touch the sphere's surface. The electrodes carry powerful electric charges so that each of them tugs at the sphere. Whenever the tug gets uneven, a quick and intricate electronic circuit adjusts the charges so that the beryllium ball remains precisely in the center of the cavity, supported by nothing but electrical force...
Before the suspended sphere can work as a gyroscope, almost every trace of air must be pumped out of the cavity. Then a set of coils creates a rotating magnetic field that spins the sphere like an electric motor. When the rotor reaches a speed of 30,000 r.p.m., the power is shut off and the sphere spins on for weeks or months without appreciable slowing...