The SCR-268 was the U.S. Army's first standardized medium-range mobile radar, which came into service with antiaircraft units as early as 1941. Its original primary roles were assisting searchlight crews in locating approaching aircraft and providing aircraft position information to the local Antiaircraft Artillery Intelligence Service (AAAIS). The SCR-268 remained a staple of the Antiaircraft Artillery and underwent several refinements and improvements throughout the war. Although the long-wave SCR-268 may be considered rudimentary and cumbersome when compared to later radar models that were to follow fast on its heels, the unit ushered in a new era for the Antiaircraft Artillery. The radar soon plunged older methods of target location, such as sound locators, over the precipice of obsolescence. Due to the success of the SCR-268 and other later radar systems, the searchlights it initially assisted were often able to be released to missions other than aerial target location and illumination.
The SCR-268 was not originally envisioned as a gun-laying device; its purpose was searchlight control. However, the M4 and M7 fire control directors were capable of accepting data from remote spotting scopes through means of cables and selsyn motors. This remote data system permitted the director to be placed safely in a bomb or splinter-proof shelter while it received tracking data from the distant optical elements. A method was developed to use these existing connectors to supply the director with information from the radar in a manner similar to how the director received data from optical height finders. When such a link was established between properly oriented equipment, the director could train its spotting scopes toward targets while they were still out of visual range, permitting faster pickup on aircraft when they became visible. This was an important advantage in a business where seconds mattered and accuracy of the first shot was critical. When the target appeared within sight, the SCR-268 was used to supply height information only, or was switched out altogether in favor of an optical height finder. Visual tracking was still preferred early in the war.
As the fledgling radar underwent refinements, attempts were made to use the improved versions of the SCR-268 in combination with directors to lay continuous antiaircraft gun fire on unseen targets. However, the SCR-268 struggled to supply the directors, especially the finicky M7 units, with the smooth tracking data necessary for accurate position prediction. Hits were indeed obtained on unseen aircraft using the updated SCR-268, but success was dependent on the skill of the gun and radar crews, along with the proper orientation, synchronization and maintenance of the radar, director and guns. A much more accurate gun-laying method became available with the advent of the SCR-545 and SCR-584 radar sets.
The SCR-268 could be fitted with an IFF system (Identification Friend or Foe) designed to receive radio signals from friendly aircraft properly equipped, thereby giving radar operators positive identification of non-hostile radar echoes. IFF continued to be improved throughout the war and proved useful, but always seemed to be plagued by deficiencies that prevented the technology from operating at optimum reliability.
© Copyright 2009-2010 Brian L. Brooks