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Hedgehog anti-submarine weapon, British WWII
Hedgehog anti-submarine weapon, British WWII
Hedgehog anti-submarine mortar with full load of practice bombs, circa 2002.
Hedgehog anti-submarine mortar with full load of practice bombs, circa 2002.
For the area denial weapon, see Czech hedgehog. The Czech hedgehog (rozsocháč was a static Tank obstacle defence made of angled Iron (that is lengths with an L- or H- shaped cross section deployed during

The Hedgehog was an anti-submarine weapon developed by the Royal Navy during World War II, that was deployed on convoy escort warships such as destroyers to supplement the depth charge. An anti-submarine weapon is any one of a range of devices that are intended to act against a submarine and its crew to destroy (sink the vessel or to destroy or reduce its capability The Royal Navy of the United Kingdom is the oldest of the British armed services (and is therefore known as the Senior Service) World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including A convoy is a group of Vehicles (of any type but usually motor vehicles or ships traveling together for mutual support A warship is a Ship that is built and primarily intended for Combat. In naval terminology a destroyer is a fast and maneuverable yet long-endurance Warship intended to escort larger vessels in a fleet, Convoy Depth Charge is a character in the Beast Wars: Transformers universe The weapon worked by firing a number of small spigot mortar bombs from spiked fittings. A mortar is a muzzle-loading Indirect fire weapon that fires shells at low velocities short ranges and high-arcing ballistic trajectories A bomb is any of a range of devices that typically rely on the Exothermic Chemical reaction of an Explosive material to produce an extremely Rather than working on a time or depth fuse like depth charges, the bombs exploded on contact and achieved a higher sinking rate against submarines than depth charges did. A submarine is a Watercraft that can operate independently below water as distinct from a Submersible that has only limited underwater capability

Hedgehog received its name because when unloaded, the rows of empty spigots resembled the spines of a hedgehog. A hedgehog is any of the small spiny Mammals of the Subfamily Erinaceinae and the order Erinaceomorpha.

Hedgehog, also known as an Anti-Submarine Projector was developed by the Directorate of Miscellaneous Weapons Development and entered service in 1943. The Directorate of Miscellaneous Weapons Development (DMWD known colloquially as the Wheezers and Dodgers, was a department of the Admiralty responsible for the

Hedgehog was replaced by the more effective Squid mortar in 1943 and this in turn was replaced by the three-barreled Limbo. The Squid was a World War II Ship -mounted anti- Submarine Weapon. Limbo, or Anti Submarine Mortar Mark 10 (A/S Mk10 was the final British development of the anti-submarine ahead-throwing weapon stemming from The United States produced a similar weapon called Mousetrap. The United States of America —commonly referred to as the Mousetrap (ASW Marks 20 and 22 was an anti- Submarine Rocket used mainly during the Second World War by the U

The Hedgehog was adapted into a 7 shot launcher form for use on the back of the Matilda tank serving with Australian forces. The Tank Infantry Mk II Matilda II (A12 (sometimes referred to as Senior Matilda was a British Tank of World War II.

From 1949 a copy of Hedgehog was produced in the USSR as MBU-200, developed in 1956 into MBU-600 with enhanced range of 600 m. The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991

Contents

Description

Technically the weapon was what is called a 'spigot-mortar' or spigot discharger, a type of weapon invented by Lt-Col Blacker, RA. A mortar is a muzzle-loading Indirect fire weapon that fires shells at low velocities short ranges and high-arcing ballistic trajectories The Royal Artillery, is the common name for the Royal Regiment of Artillery, is an Arm of the British Army. That is 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'. The alternative is the common infantry trench-mortar which is basically a tube and the bomb is dropped down inside the tube firing the propelling charge when it hits bottom. The Infantry is the oldest and most numerous of the Combat Arms in the Armed forces, and consists

The weapon fires a salvo of 24 bombs in an arc, aimed to land in a circular or elliptical area about 100 feet (30 m) in diameter at a fixed point about 250 yards (230 m) directly ahead of the attacking ship. Circles are simple Shapes of Euclidean geometry consisting of those points in a plane which are at a constant Distance, called the In Mathematics, an ellipse (from the Greek ἔλλειψις literally absence) is a Conic section, the locus of points in a The mounting initially was fixed but was later replaced by a gyro-stablised one to allow for the rolling and pitching of the attacking ship.

The launcher was 4 "cradles" each of 6 launcher spigots. The firing sequence was staggered so that all the bombs would land at roughly the same time. This had the added advantage of minimising the stress on the weapon's mounting, so that deck re-inforcement was not needed, and the weapon could easily be retro-fitted to any convenient place on a ship. Reloading took about 3 minutes.

The Hedgehog had four key advantages over the depth charge:

  1. An unsuccessful attack does not hide the submarine from sonar. Sonar (which started as an Acronym for sound navigation and ranging) is a technique that uses Sound propagation (usually underwater to navigate
    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 only explode on contact, if they miss, the submarine can still be tracked by sonar.
  2. The depth of the target does not need to be known.
    Proximity weapons (such as depth charges) need to be set for the target's correct depth to be effective. Contact fused charges don't have that limitation. In addition, any explosion indicates a 'hit'.
  3. The weapon gives no warning of the attack.
    Until depth-determining sonar became available (the first was the Royal Navy's 'Q' attachment in 1943) there was a 'dead period' during the final moments of the attack when the attacker had no knowledge of what the target was doing. The Royal Navy of the United Kingdom is the oldest of the British armed services (and is therefore known as the Senior Service) U-boat commanders became adept at sharp changes of direction and speed at these moments, thus making the attack less accurate. Ahead-thrown weapons such as Hedgehog did not give the target the necessary warning of when to dodge.
  4. A direct hit by 1-2 Hedgehog bombs was usually all that was needed to sink a submarine.
    Many depth charges were required in order to inflict accumulating damage sufficient to sink a submarine, even then many U-boats survived hundreds of detonations over a period of many hours; 678 depth charges were dropped onto U 427 in April, 1945. The depth charge, being usually distanced from the submarine had a cushion of water between it and the target which rapidly dissipated the explosive shock. A contact charge, on the other hand, had the cushion on the other side actually increasing the explosive shock.

However the Hedgehog did not have the advantage of any cumulative damage effect of repeated explosions just outside the lethal distance that could make it harder for the target to dodge later attacks or force it to return to base for repairs when it did escape.

The Hedgehog was much more successful than depth-charge attacks eventually (the best kill rate was about 25% of attacks whereas depth-charge attacks never got better than 7%). It initially had a very poor record although many of the factors had nothing to do with the design of the weapon.

General characteristics

For a single bomb

Variants

See also

External links

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