Antiaircraft Gunfire Director – The Mark 19Waring Hills Nov 19, 2010
With the advent of high-flying and high-speed aircraft, the United States Navy was faced with a new problem, which was ignored until Billy Mitchell’s demonstration of air power in the sinking of the German battleship Ostfriesland in 1921.
In 1925 Ford Instrument built an antiaircraft gun director in response to a navy request and delivered it to the navy the following year as the Mark 19, for the USS Maryland. This device had 55,000 moving parts. It integrated an entire control system into a single unit that sat on the deck, including range-keeper, a stable element, and tracking telescopes. It used the same calculations as the range-keepers did for surface fire control, but added an altitude variable for the target. While it was an impressive solution to a difficult problem…it could neither track a high-speed aircraft or dive bombers and seems to have been intended to guide a barrage of fire to the general area of a target. Forty two Mark 19 gun directors would be installed in the fleet by 07 December 1941, and they served at Midway, Coral Sea and Guadalcanal.
The Mark 19 was used with the 5 inch guns on battleships and cruisers. The initial figures for target speed and altitude, taken from the rangefinder (RF) were fed into the mechanical computer (range-keeper) which predicted the future target position. One set of predictions enabled the pointer and trainer to check the range-keeper output and in effect spot, while a later prediction was used to aim the guns so that they led the target correctly, and there was a later prediction for fuze settings. Gyro and optical stabilization were included (rolling seas).
There would be marked improvement in the years to come and the introduction of the proximity fuse in World War II would aid greatly in the defense of slow-moving ships against high-speed aircraft.