Mk 4 AWHS

History

The Mk 4 AWHS (ASROC Weapon Handling System) was the reloading system for the Mk 112 launcher on the Spruance class destroyers. Unlike other automated reloading systems for the Mk 112 launcher, the reloads were transferred from below the launcher. The likely reason for this is the ability to modernise ships that used the Mk 4 AWHS with the new multi-purpose launcher then in development. This launcher ended up being the Mk 26 GMLS.

The Mk 4 AWHS was only used on the Spruance class. It was in use from the first ships commissioning in 1975 and was kept in use on the Spruance class ships that were not VLS converted until 1994, when the Mk 112 launchers were removed from the ships still retaining them. While the Mk 4 AWHS was meant to be replaced 1 on 1 by an Mk 26 Mod 0 GMLS, the Mk 26 was never refitted on any Spruance class ships. Instead, the Mk 41 VLS was fitted on 24 ships of the class.

As far as is known, the Mk 4 AWHS could reload any weapon compatible with the Mk 112 launcher. As far as is known, only ASROC was carried operationally. The Mk 4 AWHS offered storage for 16 weapons, giving the Spruance class a total load of 24 (ASW) weapons: 8 in the launcher, 16 in the magazine.

Inside the magazine, 2 vertical rings each held 8 weapon reloads. a single reload rammer could transfer a weapon from the rings to the box launcher trough deck hatches. The weapons on the service rings sat on top of an plenum connected to a blowout door that was on the starboard side in the hull. If a booster happened to ignite in the magazine, the service ring would restrain the weapon and the flame would be channeled out this door to avoid cooking off the other rounds.

Until 1989 Spruances sometimes carried ASROC nuclear depth charges. A typical loadout was 4 of these, all held in the magazine, 2 on each ring. Another slot in each ring would have to be kept empty, as the launcher would have to unload an regular ASROC before the nuclear depth charge could be loaded. One more slot held a training round for the crew to practice handling nuclear weapons. This meant that when ASROC nuclear depth charges were carried, the effective amount of reloads was reduced to only 9 regular ASROC (plus of course 8 in the launcher). In 1989, all remaining nuclear depth charge ASROC were retired and scrapped.

On the spruance class, the Mk 4 AWHS is fitted on the bow with the launcher behind it. No other arrangements seem to have been proposed.

Used on

• Spruance class ( until 1994)

Affiliated systems

• RUR-5 ASROC
• Mk 112 launcher
• W44 nuclear depth charge
• RIM-24 Tartar
• RGM-84 Harpoon
• Mk 26 GMLS

Part description

The component has 3 versions drawn in 3 views each. The versions are without the launcher fitted, in normal (standby) position and as an example, during reloading of one of the 4 modules. The views are a side, front and top view. The top view is drawn twice to show it's relation to the side and front views.