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Mark 8 Fire Control Radar


Photograph of Mark 8 fire control radar atop a Mark 34 gun director

Naval History and Heritage Command #NH 84813


Specifications:

Wavelength       10 cm
Scan rate
10 scans per second across 30 degree swathe
Power 15-20 kW, later 20-30 kW
Range 40,000 yards or 36,600 meters (BB)
31,000 yards or 28,000 meters (DD)
Antenna
14x3 element MUSA (multi-unit-steerable-antenna) array
Scope
A and B scopes
Accuracy 15 yards/2 mils
14 meters/2 mils
Resolution 400 yards/10 degrees
370 meters/10 degrees
Production
205 by 1943

The Mark 8 (FH) fire control radar was used to direct large-caliber cruiser and battleship guns. Its design dated to 1941, but the previous FC and FD radars were good enough that deployment of FH to the fleet took place at a relatively leisurely pace. It was the first operational radar to make use of the phase array principle, using mechanical switching to alter the phase relationships between different elements to steer the beem without physically moving the antenna. Though it gave no useful altitude information, it had remarkable accuracy in both range and bearing, making it ideal for fire control against surface targets. Its rapid scan of a 30 degree arc simplified acquisition of targets.

One drawback of the Mark 8 was the complexity of its antenna array, which prompted development of the postwar Mark 13 parabolic antenna.

Its combat debut came at Surigao Strait, where the three battleships equipped with the radar (West Virginia, Tennessee, and California) were the first to acquire targets and did almost all of the shooting.

References

Buderi (1998)

Friedman (1981, 1985, 2008)

Goebel (2011; accessed 2012-5-3)
Morison (1958)

NavSource.org (accessed 2012-5-3)


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