The Royal Navy during the Second World War A24895

The Type 281 radar was a British naval

early-warning radar An early-warning radar is any radar system used primarily for the long-range detection of its targets, i.e., allowing defences to be alerted as ''early'' as possible before the intruder reaches its target, giving the air defences the maximum t ...

developed during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

. It replaced the Type 79 as the

Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by Kingdom of England, English and Kingdom of Scotland, Scottish kings from the early medieval period, the first major maritime engagements were foug ...

's main early-warning radar during the war. The prototype system was mounted on the

light cruiser A light cruiser is a type of small or medium-sized warship. The term is a shortening of the phrase "light armored cruiser", describing a small ship that carried armor in the same way as an armored cruiser: a protective belt and deck. Prior to thi ...

in October 1940. This radar used a

frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from '' angular frequency''. Frequency is measured in hertz (Hz) which is ...

of 90 MHz, a

beamwidth The beam diameter or beam width of an electromagnetic beam is the diameter along any specified line that is perpendicular to the beam axis and intersects it. Since beams typically do not have sharp edges, the diameter can be defined in many differ ...

of 35°, and a

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tr ...

of . It required separate transmitting and receiving antennas that were rotated by hand. For long-range warning the radar used a 15 microsecond pulse at a power level of 350 kW that gave a detection range up to for aircraft. For tracking surface targets it used a 2–3 microsecond pulse at 1 MW that gave a range up to . A second set was installed in January 1941 aboard the battleship and production began of another 57 sets with the first deliveries occurring the following month. This set also had a secondary aerial and surface gunnery capability and used a Precision Ranging Panel. The Type 281 ranging system allowed the user to select either a to or a to range display with range accuracies of or RMS, respectively. Aerial target ranges were passed directly to the

HACS High Angle Control System (HACS) was a British anti-aircraft fire-control system employed by the Royal Navy from 1931 and used widely during World War II. HACS calculated the necessary deflection required to place an explosive shell in the loca ...

table (fire control computer). Type 281B consolidated the transmission and receiving antennas while the Type 281BP radar had the short-pulse feature removed. It was fitted with improved receivers that increased the maximum detection range for an aircraft at to . At lower altitudes, ranges declined to at and at . The Type 281BQ was a Type 281BP fitted with power rotation, at 2 or 4 rpm, and equipped with a plan position indicator. After the end of the war, the Type 281 was replaced by the Type 960 radar.Friedman, p. 194

Notes

Bibliography

* * * * * *{{cite book, last=Watson, first=Raymond C. Jr., title=Radar Origins Worldwide: History of Its Evolution in 13 Nations Through World War II, publisher=Trafford, year=2009, isbn=978-1-4269-2111-7

External links

The RN Radar and Communications Museum

Type 279 radar The Type 279 radar was a British naval early-warning radar developed during World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World ...

Naval radars World War II radars Royal Navy Radar