Bofors 40 mm gun
The Bofors 40 mm gun referred to as the Bofors gun, is an anti-aircraft autocannon designed in the 1930s by the Swedish arms manufacturer AB Bofors. It was one of the most popular medium-weight anti-aircraft systems during World War II, used by most of the western Allies as well some captured systems being used by the Axis powers. A small number of these weapons remain in service to this day, saw action as late as the Persian Gulf War. In the post-war era, the original design was not suitable for action against jet-powered aircraft, so Bofors introduced a new model of more power, the 40 mm L/70. In spite of sharing nothing with the original design other than the calibre and the distinctive conical flash hider, this weapon is widely known as "the Bofors". Although not as popular as the original L/60 model, the L/70 remains in service as a multi-purpose weapon for light armoured vehicles, as on the CV 90. Bofors has been part of BAE Systems AB since March 2005; the Swedish Navy purchased a number of 2-pounder Pom-Poms from Vickers as anti-aircraft guns in 1922.
The Navy approached Bofors about the development of a more capable replacement. Bofors signed a contract in late 1928. Bofors produced a gun, a smaller version of a 57 mm semi-automatic gun developed as an anti-torpedo boat weapon in the late 19th century by Finspång, their first test gun was a re-barreled Nordenfelt version of the Finspong gun, to, added a semi-automatic loading mechanism. Testing of this gun in 1929 demonstrated that a problem existed feeding the weapon in order to maintain a reasonable rate of fire. A mechanism, strong enough to handle the stresses of moving the large round was too heavy to move enough to fire rapidly. One attempt to solve this problem used zinc shell cases; this proved to leave heavy zinc deposits in the barrel, had to be abandoned. In the summer of 1930 experiments were made with a new test gun that did away with controlled feed and instead flicked the spent casing out the rear whereafter a second mechanism reloaded the gun by "throwing" a fresh round from the magazine into the open breech.
This seemed to be the solution they needed, improving firing rates to an acceptable level, the work on a prototype commenced soon after. During this period Krupp purchased a one-third share of Bofors. Krupp engineers started the process of updating the Bofors factories to use modern equipment and metallurgy, but the 40 mm project was kept secret; the prototype was completed and fired in November 1931, by the middle of the month it was firing strings of two and three rounds. Changes to the feed mechanism were all that remained, by the end of the year it was operating at 130 rounds per minute. Continued development was needed to turn it into a weapon suitable for production, completed in October 1933. Since acceptance trials had been passed the year before, this became known as the "40 mm akan M/32". Most forces referred to it as the "Bofors 40 mm L/60", although the barrel was 56.25 calibres in length, not the 60 calibres that the name implies. The gun fired a 900 g high explosive 40 × 311R shell at 2,960 ft/s.
The rate of fire was about 120 rounds per minute, which improved when the barrels were closer to the horizontal as gravity assisted the feeding from the top-mounted magazine. In practice firing rates were closer to 80–100 rpm, as the rounds were fed into the breech from four round clips which had to be replaced by hand; the maximum attainable ceiling was 7,200 m. The gun was provided with an advanced sighting system; the trainer and layer were both provided with reflector sights for aiming, while a third crew-member standing behind them "adjusted" for lead using a simple mechanical computer. Power for the sights was supplied from a 6V battery. In spite of the successful development, the Swedish Navy changed its mind and decided it needed a smaller hand-traversed weapon of 13 mm-25 mm size, tested various designs from foreign suppliers. With the 40 mm well along in development, Bofors offered a 25 mm version in 1932, selected as the Bofors 25 mm M/32; the first version of the 40 mm the Navy ordered was intended for use on submarines, where the larger calibre allowed the gun to be used for both AA and against smaller ships.
The barrel was shorter at 42 calibers long, with the effect of reducing the muzzle velocity to about 700 m/s. When not in use, the gun retracted into a watertight cylinder; the only known submarines that used this arrangement was the Sjölejonet-class boats. The guns were removed as the subs were modified with streamlined conning towers; the first order for the "real" L/60 was made by the Dutch Navy, who ordered five twin-gun mounts for the cruiser De Ruyter in August 1934. These guns were stabilized using the Hazemeyer mount, in which one set of layers aimed the gun, while a second manually stabilized the platform the gun sat on. All five mounts were operated by one fire control system. Bofors developed a towable carriage which they displayed in April 1935 at a show in Belgium; this mount allowed the gun to be fired from the carriage with no setup required, although with limited accuracy. If time was available for setup, the gunners used the tow-bar and muzzle lock as levers, raising the wheels off the ground and thereby lowering the gun onto supporting pads.
Two additional legs folded out to the sides, the platform was leveled with hand cranks. The entire setup process could be completed in under a minute. Orders for the land based versions were immediate, starting with
Pearl Harbor is a lagoon harbor on the island of Oahu, west of Honolulu. It has been long visited by the Naval fleet of the United States, before it was acquired from the Hawaiian Kingdom by the U. S. with the signing of the Reciprocity Treaty of 1875. Much of the harbor and surrounding lands is now a United States Navy deep-water naval base, it is the headquarters of the United States Pacific Fleet. The U. S. government first obtained exclusive use of the inlet and the right to maintain a repair and coaling station for ships here in 1887. The attack on Pearl Harbor by the Empire of Japan on December 7, 1941, was the immediate cause of the United States' entry into World War II. Pearl Harbor was an extensive shallow embayment called Wai Momi or Puʻuloa by the Hawaiians. Puʻuloa was regarded as the home of the shark goddess, Kaʻahupahau, her brother, Kahiʻuka, in Hawaiian legends. According to tradition, the head of the powerful Ewa chiefs, is credited with cutting a navigable channel near the present Puʻuloa saltworks, by which he made the estuary, known as "Pearl River," accessible to navigation.
Making due allowance for legendary amplification, the estuary had an outlet for its waters where the present gap is. During the early 19th century, Pearl Harbor was not used for large ships due to its shallow entrance; the interest of United States in the Hawaiian Islands grew as a result of its whaling and trading activity in the Pacific. As early as 1820, an "Agent of the United States for Commerce and Seamen" was appointed to look after American business in the Port of Honolulu; these commercial ties to the American continent were accompanied by the work of the American Board of Commissioners for Foreign Missions. American missionaries and their families became an integral part of the Hawaiian political body. Throughout the 1820s and 1830s, many American warships visited Honolulu. In most cases, the commanding officers carried letters from the U. S. Government giving advice on governmental affairs and of the relations of the island nation with foreign powers. In 1841, the newspaper Polynesian, printed in Honolulu, advocated that the U.
S. establish a naval base in Hawaii for protection of American citizens engaged in the whaling industry. The British Hawaiian Minister of Foreign Affairs Robert Crichton Wyllie, remarked in 1840 that "... my opinion is that the tide of events rushes on to annexation to the United States." From the conclusion of the Civil War, to the purchase of Alaska, to the increased importance of the Pacific states, the projected trade with countries in Asia and the desire for a duty-free market for Hawaiian staples, Hawaiian trade expanded. In 1865, the North Pacific Squadron was formed to embrace Hawaii. Lackawanna in the following year was assigned to cruise among the islands, "a locality of great and increasing interest and importance." This vessel surveyed the Northwestern Hawaiian Islands toward Japan. As a result, the United States claimed Midway Island; the Secretary of the Navy was able to write in his annual report of 1868, that in November 1867, 42 American flags flew over whaleships and merchant vessels in Honolulu to only six of other nations.
This increased activity caused the permanent assignment of at least one warship to Hawaiian waters. It praised Midway Island as possessing a harbor surpassing Honolulu's. In the following year, Congress approved an appropriation of $50,000 on March 1, 1869, to deepen the approaches to this harbor. After 1868, when the Commander of the Pacific Fleet visited the islands to look after American interests, naval officers played an important role in internal affairs, they served as arbitrators in business disputes, negotiators of trade agreements and defenders of law and order. Periodic voyages among the islands and to the mainland aboard U. S. warships were arranged for members of the Hawaiian royal family and important island government officials. When King Lunalilo died in 1873, negotiations were underway for the cession of Pearl Harbor as a port for the duty-free export of sugar to the U. S. With the election of King Kalākaua in March 1874, riots prompted landing of sailors from USS Tuscarora and Portsmouth.
The British warship, HMS Tenedos landed a token force. During the reign of King Kalākaua the United States was granted exclusive rights to enter Pearl Harbor and to establish "a coaling and repair station." Although this treaty continued in force until August 1898, the U. S. did not fortify Pearl Harbor as a naval base. As it had for 60 years, the shallow entrance constituted a formidable barrier against the use of the deep protected waters of the inner harbor; the United States and the Hawaiian Kingdom signed the Reciprocity Treaty of 1875 as supplemented by Convention on December 6, 1884, the Reciprocity Treaty was made by James Carter and ratified it in 1887. On January 20, 1887, the United States Senate allowed the Navy to exclusive right to maintain a coaling and repair station at Pearl Harbor.. The Spanish–American War of 1898 and the desire for the United States to have a permanent presence in the Pacific both contributed to the decision. Following the overthrow of the Hawaiian Kingdom, the United States Navy established a base on the island in 1899.
On December 7, 1941, the base was attacked by the Imperial Japanese Navy airplanes and midget submarines, causing the American entry into World War II. One of the main reasons that Pearl Harbor happened was because the United States had major communication breakdowns among several branches of the U. S. armed services and departments of the U. S. government. This led to the surprise Japanese attack at the Hawai
Hokkaido known as Ezo, Yeso, or Yesso, is the second largest island of Japan, the largest and northernmost prefecture. The Tsugaru Strait separates Hokkaido from Honshu; the two islands are connected by the undersea railway Seikan Tunnel. The largest city on Hokkaido is its capital, its only ordinance-designated city. About 43 km north of Hokkaido lies Russia. To its east and north-east are the disputed Kuril Islands; the Nihon Shoki, finished in 720 AD, is said to be the first mention of Hokkaido in recorded history. According to the text, Abe no Hirafu led a large navy and army to northern areas from 658 to 660 and came into contact with the Mishihase and Emishi. One of the places Hirafu went to was called Watarishima, believed to be present-day Hokkaido. However, many theories exist in relation to the details of this event, including the location of Watarishima and the common belief that the Emishi in Watarishima were the ancestors of the present-day Ainu people. During the Nara and Heian periods, people in Hokkaido conducted trade with Dewa Province, an outpost of the Japanese central government.
From the Middle Ages, the people in Hokkaido began to be called Ezo. Hokkaido subsequently became known as Ezogashima; the Ezo relied upon hunting and fishing and obtained rice and iron through trade with the Japanese. During the Muromachi period, the Japanese created a settlement at the south of the Oshima Peninsula; as more people moved to the settlement to avoid battles, disputes arose between the Japanese and the Ainu. The disputes developed into a war. Takeda Nobuhiro killed the Ainu leader and defeated the opposition in 1457. Nobuhiro's descendants became the rulers of the Matsumae-han, granted exclusive trading rights with the Ainu in the Azuchi-Momoyama and Edo periods; the Matsumae family's economy relied upon trade with the Ainu. They held authority over the south of Ezochi until the end of the Edo period in 1868; the Matsumae clan rule over the Ainu must be understood in the context of the expansion of the Japanese feudal state. Medieval military leaders in northern Honshū maintained only tenuous political and cultural ties to the imperial court and its proxies, the Kamakura Shogunate and Ashikaga Shogunate.
Feudal strongmen sometimes located themselves within medieval institutional order, taking shogunal titles, while in other times they assumed titles that seemed to give them a non-Japanese identity. In fact, many of the feudal strongmen were descended from Emishi military leaders, assimilated into Japanese society; the Matsumae clan were of Yamato descent like other ethnic Japanese people, whereas the Emishi of northern Honshu were a distinctive group related to the Ainu. The Emishi were conquered and integrated into the Japanese state dating back as far as the 8th century, as result began to lose their distinctive culture and ethnicity as they became minorities. By the time the Matsumae clan ruled over the Ainu most of the Emishi were ethnically mixed and physically closer to Japanese than they were to Ainu; this dovetails nicely with the "transformation" theory that native Jōmon peoples changed with the infusion of Yayoi immigrants into the Tōhoku rather than the "replacement" theory which posits that one population was replaced by another.
There were numerous revolts by the Ainu against the feudal rule. The last large-scale resistance was Shakushain's Revolt in 1669–1672. In 1789, a smaller movement, the Menashi–Kunashir rebellion, was crushed. After that rebellion, the terms "Japanese" and "Ainu" referred to distinguished groups, the Matsumae were unequivocally Japanese. In 1799–1821 and 1855–1858, the Edo Shogunate took direct control over Hokkaido in response to a perceived threat from Russia. Leading up to the Meiji Restoration, the Tokugawa Shogunate realized there was a need to prepare northern defenses against a possible Russian invasion and took over control of most of Ezochi; the Shogunate made the plight of the Ainu easier, but did not change the overall form of rule. Hokkaido was known as Ezochi until the Meiji Restoration. Shortly after the Boshin War in 1868, a group of Tokugawa loyalists led by Enomoto Takeaki temporarily occupied the island, but the rebellion was crushed in May 1869. Ezochi was subsequently put under control of Hakodate Prefectural Government.
When establishing the Development Commission, the Meiji Government introduced a new name. After 1869, the northern Japanese island was known as Hokkaido; the primary purpose of the development commission was to secure Hokkaido before the Russians extended their control of the Far East beyond Vladivostok. Kuroda Kiyotaka was put in charge of the venture, his first step was to journey to the United States and recruit Horace Capron, President Grant's Commissioner of Agriculture. From 1871 to 1873 Capron bent his efforts to expounding Western agriculture and mining with mixed results. Capron, frustrated with obstacles to his efforts returned home in 1875. In 1876, William S. Clark arrived to found an agricultural college in Sapporo. Although he only remained a year, Clark left a lasting impression on Hokkaido, inspiring the Japanese with his teachings on agriculture as well as Christianity
5"/38 caliber gun
The Mark 12 5"/38 caliber gun was a United States naval gun. The gun was installed into Single Purpose and Dual Purpose mounts used by the US Navy. On these 5" mounts, Single Purpose means that the mount is limited to 35° elevation with no provision for AA shell fuze setters, is designed to fire at surface targets only. Dual Purpose means that it is designed to be effective against both surface and aircraft targets because it can elevate to 85° and has on mount AA shell fuze setters; the 38 caliber barrel was a mid-length compromise between the previous United States standard 5"/51 low-angle gun and 5"/25 anti-aircraft gun. United States naval gun terminology indicates the gun fired a projectile 5 inches in diameter, the barrel was 38 calibers long, making the 5"/38 dual purpose midway in barrel length between the 5"/51 surface-to-surface and the 5"/25 anti-aircraft guns; the increased barrel length provided improved performance in both anti-aircraft and anti-surface roles compared to the 5"/25 gun.
However, except for the barrel length and the use of semi-fixed ammunition, the 5"/38 gun was derived from the 5"/25 gun. Both weapons had power ramming; the 5"/38 entered service on USS Farragut, commissioned in 1934. The base ring mount, which improved the effective rate of fire, entered service on USS Gridley, commissioned in 1937. Among naval historians, the 5"/38 gun is considered the best intermediate-caliber, dual purpose naval gun of World War II as it was under the control of the advanced Mark 37 Gun Fire Control System which provided accurate and timely firing against surface and air targets; this advanced system required nearly 1000 rounds of ammunition expenditure per aircraft kill. However, the planes were killed by shell fragments and not direct hits; this would result in large walls of shell fragments being put up to take out one or several planes or in anticipation of an unseen plane, this being justifiable as one plane was capable of significant destruction. The comparatively high rate of fire for a gun of its caliber earned it an enviable reputation as an anti-aircraft weapon, in which role it was employed by United States Navy vessels.
Base ring mounts. On pedestal and other mounts lacking integral hoists, 12 to 15 rounds per minute was the rate of fire. Useful life expectancy was 4600 effective full charges per barrel; the 5"/38 cal gun was mounted on a large number of US Navy ships in the World War II era. It was backfitted to many of the World War I-era battleships during their wartime refits replacing 5"/25 guns that were fitted in the 1930s, it has left active US Navy service, but it is still on mothballed ships of the United States Navy reserve fleets. It is used by a number of nations who bought or were given US Navy surplus ships. Millions of rounds of ammunition were produced for these guns, with over 720,000 rounds still remaining in Navy storage depots in the mid-1980s because of the large number of Reserve Fleet ships with 5"/38 cal guns on board; each mount carries one or two Mk 12 5"/38cal Gun Assemblies. The gun assembly shown is used in single mounts, it is the right gun in twin mounts, it is loaded from the left side.
The left gun in twin mounts is the mirror image of the right gun, it is loaded from the right side. The Mk12 gun assembly weighs 3,990 lb; the Mark 12 Gun Assembly was introduced in 1934, where it was first used in single pedestal mounts on the Farragut-class destroyers, but by the time of World War II they had been installed in single and twin mounts on nearly every major warship and auxiliary in the US fleet. The major Mk12 Gun Assembly characteristics are::158 Semi-automatic During recoil, some of the recoil energy is stored in the counter-recoil system; that stored. The firing pin is cocked, the breech is opened, the spent propellant case is ejected, the bore is cleared of debris with an air blast. Hand loaded a powder-man are stationed at each gun assembly, their job is to move the round, consisting of a projectile and a propellant case, from the hoists to the rammer tray projecting from the gun's breech, start the ram cycle. Power rammed This gun used a 7.5 hp electric-hydraulic power rammer, designed to ram a 93 lb, 47.5 in long round into the chamber at any gun elevation in less than one second.:172 The rammer's control box, hydraulic fluid tank and AC motor are bolted to the top of the slide.
The hydraulically driven rammer spade, called the power spade in that picture, is at the back of the rammer tray. If the multiple names of the "spade" are confusing, look at this footnote. Vertical sliding-wedge breech block, it contains the firing pin assembly. Hydraulic recoil Two hydraulic pistons in the housing absorb the major shock of recoil as the housing moves back inside the slide, they buffer the end of counter-recoil for a soft return to battery. Pneumatic counter-recoil At the end of recoil, the counter-recoil system moves the housing forward again until it is back "in battery," and holds it there at any gun elevation. A chamber in the housing is filled with compressed air. At the rear of this chamber is a 3.5 in cylindrical hole with a c
Kamikaze Tokubetsu Kōgekitai, were a part of the Japanese Special Attack Units of military aviators who initiated suicide attacks for the Empire of Japan against Allied naval vessels in the closing stages of the Pacific campaign of World War II, designed to destroy warships more than possible with conventional air attacks. About 3,800 kamikaze pilots died during the war, more than 7,000 naval personnel were killed by kamikaze attacks. Kamikaze aircraft were pilot-guided explosive missiles, purpose-built or converted from conventional aircraft. Pilots would attempt to crash their aircraft into enemy ships in what was called a "body attack" in planes laden with some combination of explosives and torpedoes. Accuracy was much higher than that of conventional attacks, the payload and explosion larger. A kamikaze could sustain damage that would disable a conventional attacker and still achieve its objective; the goal of crippling or destroying large numbers of Allied ships aircraft carriers, was considered by the Empire of Japan to be a just reason for sacrificing pilots and aircraft.
These attacks, which began in October 1944, followed several critical military defeats for the Japanese. They had long since lost aerial dominance as a result of having outdated aircraft and enduring the loss of experienced pilots. Japan suffered from a diminishing capacity for war and a declining industrial capacity relative to that of the Allies. Japan was losing pilots faster than it could train their replacements; these combined factors, along with Japan's unwillingness to surrender, led to the use of kamikaze tactics as Allied forces advanced towards the Japanese home islands. While the term kamikaze refers to the aerial strikes, it has been applied to various other suicide attacks; the Japanese military used or made plans for non-aerial Japanese Special Attack Units, including those involving submarines, human torpedoes and divers. The tradition of death instead of defeat and shame was entrenched in Japanese military culture. One of the primary traditions in the samurai life and the Bushido code: loyalty and honor until death.
The Japanese word kamikaze is translated as "divine wind". The word originated from Makurakotoba of waka poetry modifying "Ise" and has been used since August 1281 to refer to the major typhoons that dispersed Mongol-Koryo fleets who invaded Japan under Kublai Khan in 1274. A Japanese monoplane that made a record-breaking flight from Tokyo to London in 1937 for the Asahi newspaper group was named Kamikaze, she was a prototype for the Mitsubishi Ki-15. In Japanese, the formal term used for units carrying out suicide attacks during 1944–1945 is tokushu kōgekitai, which means "special attack unit"; this is abbreviated to tokkōtai. More air suicide attack units from the Imperial Japanese Navy were called shinpū tokubetsu kōgeki tai. Shinpū is the on-reading of the same characters. During World War II, the pronunciation kamikaze was used only informally in the Japanese press in relation to suicide attacks, but after the war this usage gained acceptance worldwide and was re-imported into Japan; as a result, the special attack units are sometimes known in Japan as kamikaze tokubetsu kōgeki tai.
Before the formation of kamikaze units, pilots had made deliberate crashes as a last resort when their planes had suffered severe damage and they did not want to risk being captured, or wanted to do as much damage to the enemy as possible, since they were crashing anyway. Such situations occurred in both the Allied air forces. Axell and Kase see these suicides as "individual, impromptu decisions by men who were mentally prepared to die". In most cases, little evidence exists that such hits represented more than accidental collisions of the kind that sometimes happen in intense sea or air battles. One example of this occurred on 7 December 1941 during the attack on Pearl Harbor. First Lieutenant Fusata Iida's plane had taken a hit and had started leaking fuel when he used it to make a suicide attack on Naval Air Station Kaneohe. Before taking off, he had told his men that if his plane were to become badly damaged he would crash it into a "worthy enemy target"; the carrier battles in 1942 Midway, inflicted irreparable damage on the Imperial Japanese Navy Air Service, such that they could no longer put together a large number of fleet carriers with well-trained aircrews.
Japanese planners had assumed a quick war and lacked comprehensive programmes to replace the losses of ships and sailors. The following Solomon Islands campaign and the New Guinea campaign, notably the Battles of Eastern Solomons and Santa Cruz, further decimated the IJNAS veteran aircrews, replacing their combat experience proved impossible. During 1943–1944, U. S. forces advanced toward Japan. Newer U. S.-made planes the Grumman F6F Hellcat and Vought F4U Corsair and soon outnumbered Japan's fighter planes. Tropical diseases, as well as shortages of spare parts and fuel, made operations more and more difficult for the IJNAS. By the Battle of the Philippine Sea, the Japanese had to make do with obsolete aircraft and inexperienced aviators in the f