XAF RADAR
Encyclopedia
The XAF Radar was an experiment radar constructed in 1938, survived World War II as a historical artifact, and is now placed on exhibit at the Historical Electronics Museum, located in Linthicum, Maryland
that resulted from several years' technical progress by the Naval Research Laboratory (NRL)—was constructed in 1938, following a late February decision to install a radar set on a major warship. Operating at 200 megacycles
(1.5 meter wavelength) at a power of 15 kilowatts, the XAF featured a "bedspring"-like antenna about 17 feet square. This was mounted in a rotating yoke that allowed it to scan around the horizon, and to elevate for what was hoped would be improved aircraft detection. This large antenna and yoke had to be strong enough for sea service, while remaining as light as possible to avoid excessive topside weight. Accordingly, the Brewster Aeronautical Corporation
(then also building the Navy's first monoplane shipboard fighter, the F2A "Buffalo"
), was given the job of fabricating a suitable duralumin
structure. The XAF's transmitter, receiver and other equipment were made by NRL.
. This work, with the antenna mounted atop the pilothouse (where it displaced a large rangefinder—moved to the top of the ship's Number Two 14-inch gun turret) was completed in December 1938. During nearly three months of constant operation, averaging almost twenty hours daily as New York participated in winter maneuvers and battle practice in the Caribbean
, the XAF's performance and reliability exceeded expectations. It detected aircraft up to 100 nautical miles
(nm) away and ships out to 15 nm. The radar was also employed for navigation and in gunnery practice
, spotting the fall of shot and even tracking projectiles in flight.
(RCA). Designated CXAM
, six of these production models were delivered in 1940 and installed on an aircraft carrier, a battleship and four cruisers. An improved version, CXAM-1, with a simplified antenna, was produced in greater numbers. By the time the United States entered World War II in December 1941, the use of radar in the U.S. Navy
was rapidly expanding.
's waterfront. However, the outdoor environment contributed to serious deterioration in the antenna's condition, and it was placed in storage in the mid-1990s. In May 2008 it was loaned to the Historical Electronics Museum, located in Linthicum, Maryland
, where it is to be restored and again placed on public exhibit.
Linthicum, Maryland
Linthicum is a census-designated place and an unincorporated community in Anne Arundel County, Maryland, United States. The population was 7,539 at the 2000 census. It is the approximate location of Baltimore-Washington International Thurgood Marshall Airport...
Creation and development
The XAF—an experimental radarRadar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
that resulted from several years' technical progress by the Naval Research Laboratory (NRL)—was constructed in 1938, following a late February decision to install a radar set on a major warship. Operating at 200 megacycles
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
(1.5 meter wavelength) at a power of 15 kilowatts, the XAF featured a "bedspring"-like antenna about 17 feet square. This was mounted in a rotating yoke that allowed it to scan around the horizon, and to elevate for what was hoped would be improved aircraft detection. This large antenna and yoke had to be strong enough for sea service, while remaining as light as possible to avoid excessive topside weight. Accordingly, the Brewster Aeronautical Corporation
Brewster Aeronautical Corporation
The Brewster Aeronautical Corporation was a North American defense contractor that operated from the 1930s until the end of World War II.It started existence as an aircraft division of Brewster & Co., a company that originally sold carriages and had branched into automobile bodies and airplane parts...
(then also building the Navy's first monoplane shipboard fighter, the F2A "Buffalo"
Brewster Buffalo
The Brewster F2A Buffalo was an American fighter aircraft which saw limited service early in World War II. Though the Buffalo won a competition against the Grumman F4F Wildcat in 1939 to become the US Navy's first monoplane fighter aircraft, it turned out to be a big disappointment...
), was given the job of fabricating a suitable duralumin
Duralumin
Duralumin is the trade name of one of the earliest types of age-hardenable aluminium alloys. The main alloying constituents are copper, manganese, and magnesium. A commonly used modern equivalent of this alloy type is AA2024, which contains 4.4% copper, 1.5% magnesium, 0.6% manganese and 93.5%...
structure. The XAF's transmitter, receiver and other equipment were made by NRL.
Testing
When development and construction were complete, the XAF was installed on the battleship New YorkUSS New York (BB-34)
USS New York was a United States Navy battleship, the lead ship of her class of two . She was the fifth ship to carry her name....
. This work, with the antenna mounted atop the pilothouse (where it displaced a large rangefinder—moved to the top of the ship's Number Two 14-inch gun turret) was completed in December 1938. During nearly three months of constant operation, averaging almost twenty hours daily as New York participated in winter maneuvers and battle practice in the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
, the XAF's performance and reliability exceeded expectations. It detected aircraft up to 100 nautical miles
Nautical mile
The nautical mile is a unit of length that is about one minute of arc of latitude along any meridian, but is approximately one minute of arc of longitude only at the equator...
(nm) away and ships out to 15 nm. The radar was also employed for navigation and in gunnery practice
Gun
A gun is a muzzle or breech-loaded projectile-firing weapon. There are various definitions depending on the nation and branch of service. A "gun" may be distinguished from other firearms in being a crew-served weapon such as a howitzer or mortar, as opposed to a small arm like a rifle or pistol,...
, spotting the fall of shot and even tracking projectiles in flight.
Use and evolution
At the conclusion of these tests, New York's Commanding Officer recommended installation of radar in all aircraft carriers (whose vulnerability to surprise air attack was very well-understood), while the Commander of the Atlantic Squadron commented "The XAF equipment is one of the most important military developments since the advent of radio ...". Later in 1939, the XAF was reengineered and placed in production by the Radio Corporation of AmericaRCA
RCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. The RCA trademark is currently owned by the French conglomerate Technicolor SA through RCA Trademark Management S.A., a company owned by Technicolor...
(RCA). Designated CXAM
CXAM radar
The CXAM radar system was the first production radar system deployed on United States Navy ships. It followed several earlier prototype systems, such as the NRL radar installed in April 1937 on the destroyer ; its successor, the XAF, installed in December 1938 on the battleship ; and the first...
, six of these production models were delivered in 1940 and installed on an aircraft carrier, a battleship and four cruisers. An improved version, CXAM-1, with a simplified antenna, was produced in greater numbers. By the time the United States entered World War II in December 1941, the use of radar in the U.S. Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
was rapidly expanding.
On exhibit
The XAF radar's antenna survived World War II as a historic artifact. For several decades in the middle and later Twentieth Century it was exhibited in Willard Park, close to the Washington Navy YardWashington Navy Yard
The Washington Navy Yard is the former shipyard and ordnance plant of the United States Navy in Southeast Washington, D.C. It is the oldest shore establishment of the U.S. Navy...
's waterfront. However, the outdoor environment contributed to serious deterioration in the antenna's condition, and it was placed in storage in the mid-1990s. In May 2008 it was loaned to the Historical Electronics Museum, located in Linthicum, Maryland
Linthicum, Maryland
Linthicum is a census-designated place and an unincorporated community in Anne Arundel County, Maryland, United States. The population was 7,539 at the 2000 census. It is the approximate location of Baltimore-Washington International Thurgood Marshall Airport...
, where it is to be restored and again placed on public exhibit.