SUBROC
The SUBROC (Submarine Rocket), operational from 1964.6 This
weapon provided a means of attacking targets detected by sonar at distances
beyond the range of Mk 37 and Mk 45 ASTOR (nuclear) torpedoes. After being
launched from a standard torpedo tube, SUBROC streaked to the surface, left the
water, and traveled on a ballistic trajectory for a predetermined distance out
to about 25 n. miles (46.3 km). At that point the expended rocket booster fell
away and the W55 nuclear warhead re-entered the water, to detonate at a preset
depth. The warhead could be selected to detonate with an explosive force of
from one to five kilotons. Before launching a SUBROC the submarine had to
transmit an active acoustic "ping" to determine the range to the
target, initially detected by passive sonar. This use of active sonar-however
brief-was eschewed by U. S. submarine captains, who throughout the Cold War
embraced passive acoustic tactics.
ASROC
First deployed in 1960, the ASROC (antisubmarine rocket) is
still the most important ship-launched antisubmarine weapon in the U.S. Navy’s
arsenal. It also arms many antisubmarine warships of allies of the United
States.
The ASROC developed from two earlier programs, Grebe and RAT
(rocket assisted torpedo), which were intended to attack submarines at long
range. Grebe was to be a ship-launched, remote-piloted vehicle that could
transport a heavy, deep-diving Mark 41 torpedo up to 20 miles. As this was well
beyond contemporary sonar range, the project was cancelled. RAT was a much
simpler concept, a ballistic rocket carrying a lightweight homing torpedo and
launched from rails on gunhouse sides or from a basic freestanding launcher.
Its range was 1,500–5,000 yards and its performance matched that of the new
SQS-4 sonar that entered service in the mid-1950s.
RAT proved too short-ranged and too inaccurate even for a
homing torpedo. Its successor, the ASROC, had a range of 900 to 10,000 yards
and was more accurate. Accuracy, however, required increasing the rocket’s fin
area, which, in turn, reduced the box launcher’s capacity from 12 rounds, as
initially conceived, to only 8 missiles. Nevertheless, the ASROC, when matched
with an even longer-ranged SQS-23 sonar, proved a valuable weapon, particularly
since it could carry a variety of payloads, including a nuclear depth charge.
In 1990 a new vertical launch version of the ASROC entered
service. It offers still greater range (1,000 to 15,000 yards) and, since it uses
the standard Mark 41 Vertical Launch System, it allows much greater flexibility
in its deployment.