Monday, December 15, 2014

Fleet’s First Radar Celebrates a Birthday

By Claire Peachey, Technical Information Services, Naval Research Laboratory


View of USS New York (BB-34)’s forward superstructure, with the antenna of the XAF radar atop her pilot house, circa late 1938 or early 1939. A cropped version of this image, emphasizing the radar antenna, is Photo # NH 77350-A Note the battleship’s foremast, with its gunfire control facilities; her armored conning tower; and the rangefinder atop her Number Two gun turret. Official U.S. Navy Photograph, from the collections of the Naval History and Heritage Command.

The Naval Research Laboratory’s (NRL) XAF radar, fondly known as the “flying bedspring,” was the prototype that showed the Navy what this new radio detecting and ranging system – not yet called radar – was capable of doing.
On Dec. 15, 1938, the XAF radar was installed aboard USS New York (BB 34) in preparation for Fleet exercises in the Caribbean in early 1939. During the at-sea exercises, the 200 MHz XAF system successfully spotted aircraft at distances up to 48 miles, and ships at 10 miles. It could even follow 14-inch shells in flight and detect and pinpoint destroyers making nighttime simulated torpedo attacks.

Robert M. Page, Naval Research Laboratory physicist, was one of the developers of the XAF radar system. NRL photo

NRL physicist Robert M. Page, one of the developers of the XAF system and inventor of many other radar technologies, was aboard New York and later described the reaction after the mock attacks: “These performances were at night, with no possibility of seeing the destroyers. Their lights were out. That really impressed the officers. From then on they were sold on the stuff and they would give us anything we wanted.”
Adm. A.W. Johnson, Commander, Atlantic Squadron, reported after witnessing the demonstrations: “The equipment is one of the most important military developments since the advent of radio itself. Its value as a defensive instrument of war and as an instrument for avoidance of collisions at sea justifies the Navy’s unlimited development of the equipment.”
XAF’s capabilities resulted in the recommendation for immediate procurement of “10 to 20 of the devices in their present form” for installation on Fleet vessels.

XAF Radar (Transmitter and Receiver) which was installed on USS New York (BB-34) by the U.S. Naval Research Laboratory in late 1938. While mounted on that ship, this experimental 200 megacycle radar was tested at sea during the first months of 1939. Official U.S. Navy Photograph, from the collections of the Naval History and Heritage Command.

The NRL system went rapidly to production by RCA as the CXAM and CXAM-1 models, and by the time the United States entered World War II, these radar units were installed on 20 Navy vessels, mainly heavy cruisers, carriers, and battleships.
Radar surged in importance, and NRL, which had a wide-ranging program of radio research, developed prototypes of air and submarine radars that were also used during the war. Radar of this type contributed to the victories of at Coral Sea, Midway, and Guadalcanal.
NRL continues to be a leading center for research and development of radar systems. Today, NRL’s Radar Division conducts research on basic physical phenomena of importance to radar and related sensors, investigates new engineering techniques applicable to radar, demonstrates the feasibility of new radar concepts and systems, performs related systems analyses and evaluation of radar, and provides special consultative services. The emphasis is on new and advanced concepts and technology in radar and related sensors that are applicable to enhancing the Navy’s ability to fulfill its mission.

The National Museum of the U.S. Navy, located at the Washington Navy Yard has the original XAF radar on display in the Atlantic section of its World War II exhibit. U.S. Navy Photo by Shejal Pulivarti.
The National Museum of the U.S. Navy, located at the Washington Navy Yard has the original XAF radar on display in the Atlantic section of its World War II exhibit. Devoted to the display of naval artifacts, models, documents and fine art, the museum chronicles the history of the United States Navy from the American Revolution to the present. Interactive exhibits commemorate the Navy’s wartime heroes and battles as well as peacetime contributions in exploration, diplomacy, navigation and humanitarian service.

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