Science: Here to There, Accurately

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In a Closet. The Instrumentation Laboratory's most important technological advance in building the jam-proof navigational system was the development of the Hermetic Integrating Gyro (HIG), a 3-in. long package containing a gyroscope spinning at 12,000 r.p.m. in an inner cylinder pivoted on virtually friction-free bearings and floated in a heavy liquid. Three HIGs —one to "memorize" each coordinate of a point'on an imaginary star line at take-off —and three accelerometers (to measure change of speed in each direction) are fixed to a gimbals-mounted, free-swinging platform unaffected by changes in the plane's movements.

From the angle made by the platform and the Schuler-pendulum, corrected by a chronometer which allows for the earth's rotation, exact readings of a plane's (or missile's) latitude and longitude are made, then translated into instructions for the servomechanisms that operate the controls. (A variant of this layout, not described by Draper, uses similar gyros to fix position, radios continuously back to home base for flight instructions.) Throughout the flight, the control system also operates like a normal automatic pilot, making necessary minor corrections for pitch, yaw and roll.

The Inertial Guidance system that guided the 1953 flight with nearly pinpoint accuracy weighed a hefty 2,700 Ibs., got the tag "navigation in a closet." To be effective in a missile where each pound of excessive weight exacts a heavy toll in lost speed and distance, the mass of wires, tubes and gyros would have to be slimmed down from closet to pocket size. Advances in accuracy and miniaturization since the first flight are classified, but the M.I.T. scientists, who have been working on Inertial Guidance since 1939, serve as consultants to the Air Force and Navy on such systems, and are known to be designing the Inertial Guidance system of the Navy's 1,500-mile Polaris missile. These scientists say carefully that "efficiency of the equipment is known to have become even greater than in 1953." When the U.S.'s first rocket-powered, space-tunneling ICBM rises on its maiden test flight some time this spring, the chances are that a tiny, precocious descendant of M.I.T.'s 1953 navigator may be at the throttle.