 SM (No. 10) aboardUSS Lexington | |
| Country of origin | United States |
|---|---|
| Manufacturer | General Electric |
| Introduced | 1943 |
| No. built | 23 |
| Type | Fighter-direction radar |
| Frequency | A/G-band |
| PRF | 775–825Hz |
| Pulsewidth | 1μs |
| Range | 35mi (30.4nmi) |
| Precision | 200yd (0.1nmi), 3 ° |
| Power | 45–65kW |
SM was an American made fighter-directionradar used for theship ground-controlled interception (GCI) duringWorld War II by theUnited States Navy. Variation included the SM-1.[1]
Microwave set with threeaxis stabilizedantenna, installed onaircraft carriers to search for enemy planes, particularly low-flying and shadow planes, and tosupply height, speed and course data so that a Fighter Director Officer can direct fighters to an interception. It can also be used to search for ships and periscopes. SM is correlated with search sets, such asSK, and withradio communication to planes. There are provisions forA andG-bandIFF, and a built-in BO antenna. For night interception,AI is required in planes.[2]
SM has a reliable detection range of 35miles (56 km) on amedium bomber 500 ft (150 m) above optical horizon as surfacedsubmarines can be followed to horizon.Periscopes can be seen 6 miles (9.7 km) or more, andbuoys can be seen up to the horizon. Range can be determined to ±200 yd (180 m), or 1/4%, whichever is greater. Bearing can be determined to ±1/2°. Elevation can be determined to ±1/3° if an airplane is 2 1/2° or more above optical horizon. If the plane is lower, data is less reliable. Accuracy of range difference between two targets is ±50 yd (46 m) for separation of 500–10,000 yd (460–9,140 m). Elevation limit is 90°.[2]
Spares, testing equipment and separate generator supplied. SM has 23 components weighing a total of about 9tons. The largest unit is the antenna mount, at 131 in (3.3 m) high, with a diameter of 67 in (1.7 m) at base, and weighing about 4,600 lb (2,100 kg). The antenna is 6 ft (1.8 m) in diameter; 8-foot (2.4 m) antennas will be installed on later sets. The console, 76 ft × 65 ft × 24 ft (23.2 m × 19.8 m × 7.3 m) in dimensions and 1,800–2,000 lb (820–910 kg) in weight, splits into 3 parts for installation. Minimum operators per shift required are two, plus one assistant radar officer. Recommended personnel: 15 per day. Power required is 45-65kW, 440V, 3-phase, 60Hz, supplied bymotor–generator set, or, in emergencies, from ship's supply.[2]
USSLexington (CV-16) was equipped with the first prototype of SM radar in March 1943, whileUSSEnterprise (CV-6) andUSSBunker Hill (CV-17) were equipped with the first two production models in October of the same year. 26 SM-1 variants were all produced andleased to theRoyal Navy. SM was developed from theSCR-584 radar.[3]
United States
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SP or CXDT was the lightweight version of the SM radar. It replaced the SK radar in the later stages of the war.[4]
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United States
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This article incorporates text from this source, which is in thepublic domain.