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Modified W-class Destroyer, HMS Whitehall (I94) (1941)
Development and service history:
The Admiralty W class of destroyers comprised of 21 vessels ordered in december of 1916 under the 10th War Programme. These ships were found to be successful and to admiralty specifications, so two additional orders were placed in 1918 under the name of the Modified Admiralty W-class, which had improvements over the preceding class, with the introduction of the new BL 4.7 inch Mark I gun, as well as providing triple torpedo tubes as standard. These ships were ordered under the 13th War Programme in january of 1918 With HMS Whitehall being laid down in June of1918 by Swan Hunter at Wallsend, Newcastle upon Tyne, with the ship being ultimately complete in July of 1924 when she entered commission on july 9th. Like most aging destroyers she was assigned to convoy duty during the start of the second world war, though this changed in june of 1941, when she was selected to trial a new anti submarine weapon system, known as the “Five Wide Virgins”. This was a heavy mortar system designed by John I. Thornycroft & Company to fire full sized depth charges ahead of a ship attacking an enemy submarine. Whitehall conducted these trials in july of 1941, though the system was proven unsatisfactory, and lost out to the admiralty designed hedgehog system, which would become the standard antisubmarine weapon for the allies during the second world war.
Thornycroft five-barreled long-range depth charge projector:
Soon after the start of the Fairlie Mortar project which would ultimately become the hedgehog launcher, an alternative proposal appeared from the competing firm Thornycroft. The private firm attempting to develop their own anti-submarine bomb launcher for existing ammunition, to allow more rapid adoption by the royal navy during war time conditions. This called for the development of a long range depth charge thrower/launcher, which lead to the creation of what would be aptly named the five wide virgins. The name of course was unofficial, but the project came from the idea that Thornycroft experts suggested that one launcher with five trunks would be the most viable solution to the task at hand. This launcher was intended to be mounted on the deck of a ship on a reinforced rectangular platform, on which the bombthrowers were themselves installed. This choice would allow the system to be installed without special requirements to strengthen the ship at the cost of stabalization.
The system would therefore be permently fixed to an elevation of 50 degrees, providing the maximum possible range for the shot fired. Because the proposed ammunition for the thrower was the Mark VII standard depthcharge, which carried 132kg of tnt, this gave the launcher a range of around 330 yards (300m). along with the launchers cranes and other equiptment was also added to suppliment the loading of the heavy weapons system and quickly a prototype was developed and offered for testing with the navy in the span of only a few months in early 1941. unfortunately it was soon found that in the short term testing that the new weapon system was grossly unsuitable for practical operation, as it proved equally dangerous for enemy submarines as its own carrier. The first issue being how it was extremely inconveniant from the point of view of preperation for firing, as a full reload required 8 people to work together and around 10 minutes to complete. This meant the destroyer effectivly lost its ability to preform a second attack, leaving a massive window in which it was vulnerable to the submarines it was engaging. the bigger issue though was that due to the low muzzle velocity of the charge, the ship rished moving over the exploding depth charges, if it was travelling at only a medium speed, which could result in damage.
The obvious solution would be to increase the propellant charge, but with the design as it this proved impossible, as the recoil would be untennable for destroyers to bear. An attempt to circumnavigate the issue involved adding tail stabilizers to the depth charge increasing its length to 1.4m but this too proved unsuccessful. All in all it was an abject failure, as it took up more space, took too long to reload due to the compese procedure and infact made the bombs fall even shorter, increasing the risk of damage to the vessel launching them. Because of this the Thornycroft mortar did not pass test trials, and was rejected, leaving it just a forgotten competitio to the Fairlie mortar, which would go on to become the now legendary Hedgehog.
Vehicle specification:
Displacement: 1,140 tons standard, 1,550 tons full
Length: 300 ft (91 m) o/a, 312 ft (95 m) p/p
Beam: 29 ft 6 in (8.99 m)
Draught: 9 ft (2.7 m), 11 ft 3 in (3.43 m) under full load
Propulsion: Yarrow type Water-tube boilers, Brown-Curtis geared steam turbines, 2 shafts, 27,000 shp
Speed: 34 kn (63 km/h)
Range: 320–370 tons oil, 3,500 nmi (6,500 km) at 15 kn (28 km/h), 900 nmi (1,700 km) at 32 kn (59 km/h)
Complement: 127
Sensors and processing systems: Type 286M Air Warning Radar fitted 1940
Type 271 Surface Warning Radar fitted 1940
Armament:
2 × BL 4.7 in (120-mm) Mk.I guns, mount P Mk.I
2 × QF 2 pdr Mk.II “pom-pom” (40 mm L/39)
3 × 21-inch (530 mm) torpedo tubes (one triple mount)
1 x Thornycroft five-barreled long-range depth charge projector “Five Wide Virgins”
2 x depth charge racks
2 x stern mounted depth charge throwers
Additional Historical photos of the Mortar trials:
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Sources:
- HMS Whitehall - Wikipedia (Wiki page for the ship)
- Fairlie Mortar - Wikipedia (wiki page for the mortar system)
- HMS Whitehall, destroyer (Ships service history)
- HMS Whitehall (D 94) of the Royal Navy - British Destroyer of the Admiralty Modified W class - Allied Warships of WWII - uboat.net (Additional service history)
- Anti-submarine bombers Fairlie Mortar and Thornycroft Mortar (Additonal info on the mortar system)