Target For Track-and-Destroy Anti-Aircraft Gun -- An "R-Cat" 300-mile-per-hour, radio-controlled target airplane is prepared for take-off at demonstration at Weybourne, England, during test of new U.S. 75mm skysweeper Anti-Aircraft gun. The new gun, demonstrated for senior British officers and reporters by the 32nd Anti-Aircraft Artillery Bridge, has built-in radar and an electronic brain that works cut speeds, heights and angles. It can fire 22 12-pounder shells in 30 seconds at aircraft flying