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Lettris is a curious tetris-clone game where all the bricks have the same square shape but different content. Each square carries a letter. To make squares disappear and save space for other squares you have to assemble English words (left, right, up, down) from the falling squares.
Boggle gives you 3 minutes to find as many words (3 letters or more) as you can in a grid of 16 letters. You can also try the grid of 16 letters. Letters must be adjacent and longer words score better. See if you can get into the grid Hall of Fame !
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The Hedgehog (also known as an Anti-Submarine Projector) 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. The weapon worked by firing a number of small spigot mortar bombs from spiked fittings. 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.
The Hedgehog received its name because when unloaded, the rows of empty spigots resembled the spines of a hedgehog.
Hedgehog was replaced in new construction for the Royal Navy by the Squid mortar in 1943. Squid was in turn replaced by the three-barreled Limbo. The United States produced a rocket version of Hedgehog called Mousetrap. The United States developed Weapon Alpha as a replacement for Hedgehog and Mousetrap. Hedgehog remained in service with the United States Navy into the cold war until both Hedgehog and the less satisfactory Weapon Alpha were replaced by ASROC.
The Hedgehog was adapted into a 7 shot launcher form for use on the back of the Matilda tank serving with Australian forces.
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.
Technically the weapon was a multiple 'spigot mortar' or spigot discharger, a type of weapon developed in the interwar period by Lt-Col Blacker, RA. The spigot mortar was based on early infantry trench mortars. By using a spigot, the warhead and barrel size were no longer dependent in the design. 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 and the later PIAT anti-tank weapon.
The adaptation of the bombard for naval use was made in partnership with MIR(c) under Major Millis Jefferis who had taken Blacker's design and brought it into use with Army. 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. The mounting initially was fixed but was later replaced by a gyro-stabilised one to allow for the rolling and pitching of the attacking ship.
The launcher had 4 "cradles", each with 6 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, and the weapon could easily be retrofitted to any convenient place on a ship. Reloading took about 3 minutes.
The Hedgehog had four key advantages over the depth charge:
The Hedgehog became much more successful than depth-charge attacks (the best kill rate was about 25% of attacks whereas depth charges never achieved more than 7%). It initially had a very poor record, although many of the factors had nothing to do with the design of the weapon. USS England sank six Japanese submarines in a matter of days with Hedgehog in May 1944.
For a single bomb
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