Hedgehog (weapon)
Hedgehog | |
---|---|
Directorate of Miscellaneous Weapons Development | |
Designed | 1941[1] |
Specifications | |
Shell | 65 lb (29 kg)[1] |
Calibre | 7 in (178 mm)[1] |
Barrels | 24[1] |
Effective firing range | 200–259 m (656–850 ft) |
Filling | 30 lb (14 kg) TNT or 35 lb (16 kg) Torpex[1] |
Detonation mechanism | Contact |
The Hedgehog (also known as an Anti-Submarine Projector) was a forward-throwing
As the mortar projectiles employed
Development
The "Hedgehog", so named because the empty rows of its launcher spigots resembled the spines on the back of a
The weapon was a multiple 'spigot mortar' or spigot discharger, a type of weapon developed between the wars by Lieutenant Colonel Stewart Blacker, RA. The spigot mortar was based on early infantry trench mortars. The spigot design allowed a single device to fire warheads of different sizes. The propelling charge was part of the main weapon and worked against a rod (the spigot) set in the baseplate which fitted inside a tubular tail of the 'bomb'. This principle was first used on the Blacker Bombard 29 mm Spigot Mortar and the later PIAT anti-tank weapon.
The adaptation of the bombard for naval use was made in partnership with
The system was developed to solve the problem of the target submarine disappearing from the attacking ship's
History
The Hedgehog entered service in 1942. Carrying a 16 kg (35 lb) Torpex charge, each mortar projectile had a diameter of 18 cm (7.1 in) and weighed about 29.5 kg (65 lb). The spigots were angled so the projectiles would land in a circular pattern with a diameter of 40 m (130 ft), about 180 m (590 ft) ahead of the ship's position. The projectiles would then sink at about 7 m/s (23 ft/s).[1] They would reach a submerged U-boat, for example at 200 ft (61 m) in under 9 seconds. Sympathetic detonation of projectiles near those contacting hard surfaces was a possibility, but the number of explosions counted was usually fewer than the number of projectiles launched.[5]
The prototype launcher was tested aboard HMS Westcott in 1941, but there were no submarine kills until November 1942, after it had been installed aboard one hundred ships.[1] Initial success rates, of about 5%, were only slightly better than depth charges. Swells and spray frequently covered the launcher during heavy North Atlantic weather,[6] and subsequent attempts to launch from the soaked launcher were often hindered by firing circuit problems, launching an incomplete pattern.[7] A depth charge total miss would still produce an explosion, leading crews to think that they might have damaged their target or at least demoralised its personnel; a Hedgehog miss was discouragingly quiet. The Royal Navy launched Hedgehog so seldom in early 1943 that a directive was issued ordering captains of ships equipped with Hedgehog to report why they had not used Hedgehog on an underwater contact.[8] The results were blamed on crew inexperience and low confidence in the weapon. However, after an officer from the DMWD was sent to the base at Londonderry, where the escort vessels were based, with better training and shipwide talks on examples of successful Hedgehog attacks, the kill rate improved considerably.[9] By the end of the war, statistics showed that on average, one in every five attacks made by Hedgehog resulted in a kill (compared with fewer than one in 80 with depth charges).[3]
In response to this new deadly threat to its U-boats, the Kriegsmarine brought forward its programme of acoustic torpedoes in 1943, beginning with the Falke. These new "homing" acoustic torpedoes could be employed effectively without the use of a periscope, providing submarines a better chance to remain undetected and evade counterattack.
In the Pacific Theatre, USS England sank six Japanese submarines in a two-week period with the Hedgehog in May 1944.[5]
In 1946, the destroyer escort USS Solar was destroyed while unloading ammunition when a crewman accidentally dropped a Hedgehog charge near one of her main turret ammunition rooms, triggering three devastating explosions that wrecked the superstructure.
Operational usage
The launcher had four "cradles", each with six launcher spigots. The firing sequence was staggered so all the bombs would land at about the same time. This had the added advantage of minimising the stress on the weapon's mounting so that deck reinforcement was not needed, allowing the weapon to be easily retrofitted at any convenient place on a ship. Reloading took about three minutes.[1]
The Hedgehog had four key advantages over the depth charge:
- An unsuccessful attack does not hide the submarine from sonar.
- When a depth charge explodes, it can take 15 minutes before the disturbance can settle down enough that sonar becomes effective. Many submarines escaped during the time after an unsuccessful depth charge attack. Since Hedgehog charges explode only on contact, sonar tracking of the submarine is less likely to be disrupted by an unsuccessful Hedgehog attack.
- Proximity weapons (such as depth charges) need to be set for the target's correct depth to be effective. Contact-fuzed charges do not have that limitation, and an explosion at the time predicted for the contact-fuzed projectile to reach the target depth may indicate a "hit".[10]
- However, although knowledge of target depth was less important, the Hedgehog was less successful against deep targets. Doctrine based on combat experience discouraged use on targets deeper than 400 feet (120 m).[1]
- There is no "blind period" allowing the submarine to escape undetected.
- Until depth-finding sonar became available (the first was the Royal Navy's Q attachment in 1943), there was a "dead period" during the final moments before a depth-charge attack began when contact with the target would be lost. U-boat commanders became adept at sharp course changes and direction speed at these moments to break contact and escape. Hedgehog remained usable while the submarine was detectable by sonar giving it no time to take evasive actions.
- A direct hit by a single Hedgehog bomb was usually sufficient to sink a U Boat.[11]
- Many depth charges were required to inflict enough cumulative damage to sink a U Boat; even then, many survived hundreds of detonations over a period of many hours. For example, U-427 survived 678 depth charges dropped against it in April 1945. The effectiveness of the depth charge was reduced because they detonated at a set depth at a distance away from the submarine, the explosive shock was rapidly dissipated by a cushion of water between it and the target. In contrast the Hedgehog charge exploded in direct contact with the hull.[11] However, misses with the Hedgehog were silent and did not cause any damage unlike the cumulative damage caused by depth charging; nor did it have the same psychological effect as a depth charge attack.
-
USS Moberly makes a Hedgehog attack against U-853 in 1945.
-
A large white upwelling of water from an underwater explosion just ahead of Moberly's bow following Hedgehog launch[12]
-
USS Sarsfield after firing dual Hedgehogs, 1950
Derivatives and successors
In late 1943 the Royal Navy introduced Squid. This was a three-tubed mortar that launched depth charges. Initially it was used as a single weapon, but when this failed to be successful, it was upgraded to the "double squid" that consisted of two launchers placed in parallel. In 1955 this system was upgraded to the three-barrelled Limbo that launched 400 lb (180 kg) Minol charges.
The United States produced a rocket version of Hedgehog called
Three "Hedgerow" flotillas of specialized Landing Craft Assault boats carrying the Hedgehog instead of troops were used during the Normandy landings.[14] An addition of impact fuse extensions in the projectile noses enabled detonating the warheads above ground. The bombs were used to clear 100-yard-wide paths through mines and barbed wire obstacles on the beach.[15][16]
The Australian Army adapted the marine Hedgehog into a land-based seven-shot launcher that could be mounted on the back of Matilda tanks.
In 1949, a copy of Hedgehog was created in the
Weapons derived from the Hedgehog have been largely phased out from Western navies in favor of homing torpedoes, and in Russia and allied states like India by anti-submarine rocket launchers like the RBU-6000.
Former operators
- Royal Navy
- Spanish Navy
- United States Navy
- Royal Canadian Navy
- United States Coast Guard
- Philippine Navy
- Royal Danish Navy
General characteristics
- Ammunition
- Weight: 65 lb (29 kg)
- Shell diameter : 7.2 in (183 mm)
- Shell length: 3 ft 10.5 in (1,181 mm)
- Explosive charge: 30 lb (14 kg) TNT or 35 lb (16 kg) Torpex
- Range: about 250 yd (230 m)
- Sinking speed: 22 to 23.5 ft/s (6.7 to 7.2 m/s)
- Fuze: Contact, high explosive
- Launcher
- Firing order: Ripple in pairs, one every tenth of a second
- Reload time: ~3 minutes
Variants
- Mark 10: elliptical pattern measuring about 140 by 120 feet (43 m × 37 m) to a range of 200 yards (180 m).
- Mark 11: circular pattern measuring 200 feet (61 m) in diameter out to a range of about 188 yards (172 m).
- Mark 15: pattern as for the Mark 11 but mounted on a platform adapted from that of a quadruple 40 mm Bofors gunmount. The Mark 15 could be fired remotely from the ship's plotting room.
References
- ^ ISBN 978-0-87021-459-2.
- ISBN 978-0-670-81416-9.
- ^ a b "Britain ASW Weapons". www.navweaps.com. Retrieved 28 May 2015.
- ^ Fitzsimons, Bernard, ed. (1977). "Illustrated Encyclopedia of 20th Century Weapons & Warfare". 12. London: Phoebus: 1283.
{{cite journal}}
: Cite journal requires|journal=
(help) - ^ a b Lanier, William D., and Williamson, John A., CAPT USN. "The Twelve Days of the England". United States Naval Institute Proceedings, March 1980, pp. 76–83.
- ^ Morison, Samuel Eliot (1975). The Battle of the Atlantic. Vol. I. Boston: Little, Brown and Company. p. 212.
- ^ Middlebrook, Martin (1976). Convoy. New York: William Morrow and Company. p. 165.
- ISBN 978-0-87021-450-9.
- ISBN 978-1848320260.
- ISBN 978-0-87021-925-2.
- ^ a b "The Hedgehog — Meet the Allies' Devastatingly Effective U-Boat Killer". www.militaryhistorynow.com. 29 April 2023.
- ^ USS Moberly, PF-63, U.S. Coast Guard, p. 4
- ^ Albrecht, Gerhard. Weyer's Warship of the World 1969. (Annapolis, MD: United States Naval Institute Press, 1969), pp. 325-328 & 340
- ^ "Major Landing Craft of World War II". The Royal Marines Museum. 6 October 2011. Archived from the original on 9 June 2014. Retrieved 21 December 2016.
- ISBN 978-0-88254-392-5.
- ^ "Royal Marines & Landing Craft" (PDF). Royal Marine Museum. Archived from the original (PDF) on 7 October 2009.
- ISBN 985-13-0183-3.