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Guns were the main armament of c“e world’s principal warships from about 1350 until 1942, when the U- S. and Japanese navies demonstrated that aircraft were the main striking weapons of surface fleets. Guns certainly remained important naval weapons after 1942, especially for air defense and shore bombard- tnent. Both gun requirements appear t0 remain despite missiles having Joined aircraft as primary naval Weapons. *
For the past one hundred years, the U- S. Navy has been in the forefront °f gun development and, by virtue of being the largest oceangoing Navy from about 1940 until the 1970s, had the largest number of guns at sea. But this situation has now ended. The U. S. Navy’s last “gun cruiser,” the Oklahoma City (CG-5, ex-CL-9l), will be stricken next December. The “OK City,” with her three 6-inch (152- torn.) guns, is the only U. S. warship ln commission with guns larger than 5-inch (127-mm.).
The number of 5-inch guns in the fleet has declined steadily as the numerous four-gun FRAM destroyers tvere shifted from the active fleet to the Naval Reserve Force. But even that backup force is being reduced; only eight FRAM' destroyers with 30 5-inch guns will remain in the reserve force by 1980, plus the slightly newer Edson (DD-946) with three 5-inch weapons. (See Figure 1 for an overview of the U. S. Navy’s gun power.)
Replacements for the FRAMs are, in part, the 30 Spruance (DD-963)-class destroyers. While highly capable ASW ships, their firepower includes only two lightweight, Mk-45 guns. These guns are elevation limited and their fire-control systems cannot handle aircraft targets.
Beyond the Spruances, the only surface combatants being built in the United States are the final missile cruiser, the Arkansas (CGN-41), the
lead Aegis destroyer (DDG-47), and a large number of Oliver Hazard Perry (FFG-7)-class frigates. The cruiser and destroyer each have two Mk-45 guns, but the frigates have only a single 76-mm. OTO Melara Mk-75 gun. Although the 76-mm. has a much higher rate of fire than the 5-inch gun (75 to 85 compared to 16 to 20 rounds per minute), the smaller gun has about 5,000 yards less range, fires a smaller projectile (14 pounds compared to 70 pounds), and cannot handle advanced munitions.
The situation will be further exacerbated in the future as, for example, the remaining Forrest Sherman (DD-933)-class destroyers are retired in the mid-1980s. There are reports of only one 5-inch gun being fitted in later Aegis DDGs and that the next generation of surface combatants— now designated as DDX—could have only 76-mm. guns or no guns larger than the 20-mm. Phalanx close-in weapon system.
Guns still appear to be important for modern warships. Small-caliber, rapid-fire weapons are useful for close-in defense (the subject of a future column), while guns of 127-mm. and larger offer the capabilities of (1) shore bombardment, (2) close-in firepower in a “D-day shootout” between U. S. and Soviet forces, (3) countering small patrol/torpedo craft, which are abundant in the Third World, and (4) political presence—by impressing people in a way that missile launchers and submarines cannot, and for firing the sometimes needed shot across a ship’s bow. You cannot fire a Harpoon missile across a ship’s bow!
Several developments enhance gun effectiveness in these roles, among them are laser-guided and infrared- guided projectiles, and improved- conventional munitions (ICM). These provide increased accuracy, range, and effectiveness. For example, a 5-inch LGP round could probably hit a one-
square meter target at a range of 15 miles. An ICM—with submunitions in a canister shell—hitting a warship’s superstructure could shred missile launchers and radars. Guns have certain other attributes: they can be kept hot manned and ready to fire— for sustained periods while missiles are limited in how long they can be kept ready to launch; guns can fire at a more rapid rate than missiles; a larger number of relatively inexpensive “bullets can be carried compared to the limited magazine capabilities for missiles; and antimissile decoys and chaff cannot stop a bullet.
Current U. S. gun requirements are considered in two categories, shore bombardment and antiship/antiair. Shore bombardment is generally addressed in the context of direct support for amphibious assaults. Marine Corps doctrine shows the requirements listed in Figure 2.
Clearly, a single older destroyer or two Spruances can support a Marine Corps battalion-size landing. Naval gunfire support for a larger size landing, however, is inadequate. But just as clearly, large-size (e.g., division) assaults against serious opposition are unlikely in the foreseeable future. There is ample historical evidence, however, that conventional forces have a deterrent effect, and a forward- deployed battalion or two of marines could have significant value in this regard. That value is, obviously, enhanced by a few big-gun barrels offshore when the marines arrive on the scene.
Although it now seems unlikely that U. S. forces would launch an amphibious assault in the Third World,
U. S. experience in Vietnam, the Mayaguez affair, and Israeli operations in war and counter-guerilla operations demonstrate a continued value of guns for shore bombardment independent of troop landings.
The antiship/antiair role appears
Proceeding’s / August 1979
8-inch active fleet 6-inch active fleet 5-inch active fleet 5-inch Naval Reserve Force
1970
18 (2 ships)
12 (4 ships) 657 (211 ships) 164 (29 ships)
1975
0
6 (2 ships) 267 (151 ships) 132 (34 ships)
1980
0
0
212 (150 ships) 35 (9 ships)
1985 0*
0
210 (136 ships)
Division Assault | 12 | 37 | 56 |
Brigade Assault | 3 | 10 | 15 |
Battalion Assault | 0 | 1-2 | 2-3 |
'Major Caliber Lightweight Gun (Mk-7 1) "Lightweight Gun (Mk-45)
Figure 2 Naval Gunfire Support Requirements
5-inch/54 cal.
Force 8-inch MCLWG' conventional 5-inch LWG1
•Assumes no deployment of advanced 8-inch guns.
more significant. The Harpoon antiship missile is proposed for a large number of surface combatants. However, the number of rounds per ship will be limited, generally eight in two quadruple canisters. Against small, high-speed surface targets or larger ships with electronic/gun/missile defenses, a U. S. captain will need to fire two and perhaps three or even four missiles to achieve a high probability of kill against an enemy warship. This means that he can engage perhaps two or three targets before having to rearm.
While the gun has a smaller warhead and less range than a Harpoon, the gun can pump out many rounds per minute. And, the U. S. ship can carry several hundred rounds of 5-inch or 8-inch ammunition per barrel. Also, underway or vertical replenishment of ammunition is relatively simple compared to missiles. Guided shells would give 5-inch armed ships an effective antiship/anti- small craft capability at minimum cost.
The use of 5-inch guns for air and missile defense is more complicated. Some ships with 5-inch guns do not have fire control systems that can handle air targets and the rate of fire is limited. However, under development is a 5-inch projectile with infrared guidance. This weapon is expected to
have significant effectiveness against short-range missiles, such as low-level sea skimmers launched by surface craft and possibly the “pop-up” SS-N-7 fired by the Soviet "Charlie”-class submarines.
The costs of guided projectiles and rocket-assisted projectiles are more expensive than conventional rounds. But they cost far less than missiles and, as noted above, can be carried in relatively large quantities and can be easily replenished in comparison with missiles. Most important, the 5-inch guns exist in the fleet, and much of the research and development needed for advanced munitions has already been undertaken.
The 8-inch gun situation is more complex and less clear. Despite successful tests of a prototype Mk-71 major caliber lightweight gun (MCLWG) in the destroyer Hull (DD- 945) and plans to replace the forward 5-inch gun in the Spruances with the Mk-71 during the 1980s, the 8-inch gun program appears dead at this writing. Several factors contributed to this situation, including, surprisingly, a lack of strong Marine Corps support for the program during the current budget cycle as is apparent from FY 79-80 budget testimony.
The 8-inch gun was planned for new ships, the Spruances, and the never-built “strike cruiser.” The
DDG-47S cannot accommodate the gun because of the size of their forward missile magazines. However, historical analyses indicate that older ships are generally used for gunfire support- In future operations, the newer and high-capability ships, such as the Spruances, will operate with carrier battle groups and other strike forces. Operational commanders would be reluctant to let them sit off the beach for several days to support an amphibious landing, especially if the carriers were operating elsewhere.
An alternative consideration could be arming older destroyers, such as the Charles F. Adams (DDG-2) class or Forrest Sherman class with the 8-inch gun. Alternatively, the proposed LSD-41 class could be a logical gun platform. Unfortunately, the question of candidate ships for the 8-inch gun is complicated by the fact that we can expect to have a small fleet in the 1980s and 1990s. The already accomplished research and development and at-sea trials, comparatively large gun magazines, now available advanced technology, and other factors demand a more objective study of this question than it appears to have been given to date. Arming the Spruances, as well as older ships, with 5-inch long-range guided projectiles would provide a viable gunfire support system as well as other capabilities without major ship modifications and at minimum cost.
The U. S. Navy will continue to operate surface combatants, at least for the next two decades. Objective analyses of the probable types of crises and conflicts that the United States will become involved in during the next two decades, and the location of those situations and the probable antagonists, should be undertaken to determine U. S. naval gun requirements.
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Proceedings / August 1979