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
Okinawa Prefecture is the southernmost prefecture of Japan. It encompasses two thirds of the Ryukyu Islands in a chain over 1,000 kilometres long; the Ryukyu Islands extend southwest from Kagoshima Prefecture in Kyushu to Taiwan. Naha, Okinawa's capital, is located in the southern part of Okinawa Island. Although Okinawa Prefecture comprises just 0.6 percent of Japan's total land mass, about 75 percent of all United States military personnel stationed in Japan are assigned to installations in the prefecture. About 26,000 U. S. troops are based in the prefecture. The oldest evidence of human existence on the Ryukyu islands is from the Stone Age and was discovered in Naha and Yaeyama; some human bone fragments from the Paleolithic era were unearthed from a site in Naha, but the artifact was lost in transportation before it was examined to be Paleolithic or not. Japanese Jōmon influences are dominant on the Okinawa Islands, although clay vessels on the Sakishima Islands have a commonality with those in Taiwan.
The first mention of the word Ryukyu was written in the Book of Sui. Okinawa was the Japanese word identifying the islands, first seen in the biography of Jianzhen, written in 779. Agricultural societies begun in the 8th century developed until the 12th century. Since the islands are located at the eastern perimeter of the East China Sea close to Japan and South-East Asia, the Ryukyu Kingdom became a prosperous trading nation. During this period, many Gusukus, similar to castles, were constructed; the Ryukyu Kingdom entered into the Imperial Chinese tributary system under the Ming dynasty beginning in the 15th century, which established economic relations between the two nations. In 1609, the Shimazu clan, which controlled the region, now Kagoshima Prefecture, invaded the Ryukyu Kingdom; the Ryukyu Kingdom was obliged to agree to form a suzerain-vassal relationship with the Satsuma and the Tokugawa shogunate, while maintaining its previous role within the Chinese tributary system. The Satsuma clan earned considerable profits from trade with China during a period in which foreign trade was restricted by the shogunate.
Although Satsuma maintained strong influence over the islands, the Ryukyu Kingdom maintained a considerable degree of domestic political freedom for over two hundred years. Four years after the 1868 Meiji Restoration, the Japanese government, through military incursions annexed the kingdom and renamed it Ryukyu han. At the time, the Qing Empire asserted a nominal suzerainty over the islands of the Ryukyu Kingdom, since the Ryūkyū Kingdom was a member state of the Chinese tributary system. Ryukyu han became Okinawa Prefecture of Japan in 1879 though all other hans had become prefectures of Japan in 1872. In 1912, Okinawans first obtained the right to vote for representatives to the National Diet, established in 1890. Near the end of World War II, in 1945, the US Army and Marine Corps invaded Okinawa with 185,000 troops. A third of the civilian population died; the dead, of all nationalities, are commemorated at the Cornerstone of Peace. After the end of World War II, the Ryukyu independence movement developed, while Okinawa was under United States Military Government of the Ryukyu Islands administration for 27 years.
During this "trusteeship rule", the United States established numerous military bases on the Ryukyu islands. During the Korean War, B-29 Superfortresses flew bombing missions over Korea from Kadena Air Base on Okinawa; the military buildup on the island during the Cold War increased a division between local inhabitants and the American military. Under the 1952 Treaty of Mutual Cooperation and Security between the United States and Japan, the United States Forces Japan have maintained a large military presence. Since 1960, the U. S. and Japan have maintained an agreement that allows the U. S. to secretly bring nuclear weapons into Japanese ports. The Japanese tended to oppose the introduction of nuclear arms into Japanese territory by the government's assertion of Japan's non-nuclear policy and a statement of the Three Non-Nuclear Principles. Most of the weapons were alleged to be stored in ammunition bunkers at Kadena Air Base. Between 1954 and 1972, 19 different types of nuclear weapons were deployed in Okinawa, but with fewer than around 1,000 warheads at any one time.
Between 1965 and 1972, Okinawa was a key staging point for the United States in its military operations directed towards North Vietnam. Along with Guam, it presented a geographically strategic launch pad for covert bombing missions over Cambodia and Laos. Anti-Vietnam War sentiment became linked politically to the movement for reversion of Okinawa to Japan. In 1965, the US military bases, earlier viewed as paternal post war protection, were seen as aggressive; the Vietnam War highlighted the differences between the United States and Okinawa, but showed a commonality between the islands and mainland Japan. As controversy grew regarding the alleged placement of nuclear weapons on Okinawa, fears intensified over the escalation of the Vietnam War. Okinawa was perceived, by some inside Japan, as a potential target for China, should the communist government feel threatened by the United States. American military secrecy blocked any local reporting on what was occurring at bases such as Kadena Air Base.
As information leaked out, images of air strikes were published, the local population began to fear the potential for retaliation. Political leaders such as Oda Makoto
A depth charge is an anti-submarine warfare weapon. It is intended to destroy a submarine by being dropped into the water nearby and detonating, subjecting the target to a powerful and destructive hydraulic shock. Most depth charges use high explosive charges and a fuze set to detonate the charge at a specific depth. Depth charges can be dropped by ships, patrol aircraft, helicopters. Depth charges were developed during World War I, were one of the first effective methods of attacking a submarine underwater, they were used in World War I and World War II. They remained part of the anti-submarine arsenals of many navies during the Cold War. Depth charges have now been replaced by anti-submarine homing torpedoes. A depth charge fitted with a nuclear warhead is known as a "nuclear depth bomb"; these were designed to be dropped from a patrol plane or deployed by an anti-submarine missile from a surface ship, or another submarine, located a safe distance away. All nuclear anti-submarine weapons were withdrawn from service by the United States, the United Kingdom, France and China in or around 1990.
They were replaced by conventional weapons whose accuracy and range had improved as ASW technology improved. The first attempt to fire charges against submerged targets was with aircraft bombs attached to lanyards which triggered them. A similar idea was a 16 lb guncotton charge in a lanyarded can. Two of these lashed together became known as the "depth charge Type A". Problems with the lanyards tangling and failing to function led to the development of a chemical pellet trigger as the "Type B"; these were effective at a distance of around 20 ft. A 1913 Royal Navy Torpedo School report described a device intended for countermining, a "dropping mine". At Admiral John Jellicoe's request, the standard Mark II mine was fitted with a hydrostatic pistol preset for 45 ft firing, to be launched from a stern platform. Weighing 1,150 lb, effective at 100 ft, the "cruiser mine" was a potential hazard to the dropping ship; the design work was carried out by Herbert Taylor at the RN Torpedo and Mine School, HMS Vernon.
The first effective depth charge, the Type D, became available in January 1916. It was a barrel-like casing containing a high explosive. There were two sizes—Type D, with a 300 lb charge for fast ships, Type D* with a 120 lb charge for ships too slow to leave the danger area before the more powerful charge detonated. A hydrostatic pistol actuated by water pressure at a pre-selected depth detonated the charge. Initial depth settings were 40 or 80 ft; because production could not keep up with demand, anti-submarine vessels carried only two depth charges, to be released from a chute at the stern of the ship. The first success was the sinking of U-68 off Kerry, Ireland, on 22 March 1916, by the Q-ship Farnborough. Germany became aware of the depth charge following unsuccessful attacks on U-67 on 15 April 1916, U-69 on 20 April 1916; the only other submarines sunk by depth charge during 1916 were UC-19 and UB-29. Numbers of depth charges carried per ship increased to four in June 1917, to six in August, 30-50 by 1918.
The weight of charges and racks caused ship instability unless heavy guns and torpedo tubes were removed to compensate. Improved pistols allowed greater depth settings in 50-foot increments, from 50 to 200 ft. Slower ships could safely use the Type D at below 100 ft and at 10 kn or more, so the ineffective Type D* was withdrawn. Monthly use of depth charges increased from 100 to 300 per month during 1917 to an average of 1745 per month during the last six months of World War I; the Type D could be detonated as deep as 300 ft by that date. By the war's end, 74,441 depth charges had been issued by the RN, 16,451 fired, scoring 38 kills in all, aiding in 140 more; the United States requested full working drawings of the device in March 1917. Having received them, Commander Fullinwider of the U. S. Bureau of Naval Ordnance and U. S. Navy engineer Minkler made some modifications and patented it in the U. S, it has been argued. The Royal Navy Type D depth charge was designated the "Mark VII" in 1939. Initial sinking speed was 7 ft/s with a terminal velocity of 9.9 ft/s at a depth of 250 ft if rolled off the stern, or upon water contact from a depth charge thrower.
Cast iron weights of 150 lb were attached to the Mark VII at the end of 1940 to increase sinking velocity to 16.8 ft/s. New hydrostatic pistols increased the maximum detonation depth to 900 ft; the Mark VII's 290 lb amatol charge was estimated to be capable of splitting a 7⁄8 inch submarine pressure hull at a distance of 20 ft, forcing the submarine to surface at twice that. The change of explosive to Torpex at the end of 1942 was estimated to increase those distances to 26 and 52 ft; the British Mark X depth charge weighed 3,000 pounds and was launched from 21-inch torpedo tubes of older destroyers to achieve a sinking velocity of 21 ft/s. The launching ship needed to clear the area at 11 knots to avoid damage, the charge was used. Only 32 were fired, they were known to be troublesome; the teardrop-shaped United States Mark 9 depth charge entered service in the spring of 1943. The charge was 200 lb of Torpex with a sinking speed of 14.4 ft/s and depth settings of up to 600 ft. Versions increased depth to 1,000 ft and sinking
Fukuoka is the capital city of Fukuoka Prefecture, situated on the northern shore of Japanese island Kyushu. It is the most populous city on the island, followed by Kitakyushu, it is the largest city and metropolitan area west of Keihanshin. The city was designated on April 1972, by government ordinance. Greater Fukuoka, with a population of 2.5 million people, is part of the industrialized Fukuoka–Kitakyushu zone. As of 2015, Fukuoka is Japan's sixth largest city. In July 2011, Fukuoka surpassed the population of Kyoto. Since the founding of Kyoto in 794, this marks the first time that a city west of the Kinki region has a larger population than Kyoto. In ancient times, the area near Fukuoka, the Chikushi region, was thought by some historians to have been more influential than the Yamato region. Exchanges from the continent and the Northern Kyushu area date as far back as Old Stone Age, it has been thought. Several Kofun exist. Fukuoka was sometimes called the Port of Dazaifu, 15 km southeast from Fukuoka.
Dazaifu was an administrative capital in 663 A. D. but a historian proposed. Ancient texts, such as the Kojiki and archaeology confirm this was a critical place in the founding of Japan; some scholars claim that it was the first place outsiders and the Imperial Family set foot, but like many early Japan origin theories, it remains contested. Central Fukuoka is sometimes still referred as Hakata, the name of the central ward. In 923, the Hakozaki-gū in Fukuoka was transferred from Daibu-gū in Daibu, 16 km northeast from Dazaifu, the origin of Usa Shrine and established as a branch of the Usa Shrine at Fukuoka. In Ooho, 15 km south from Dazaifu, there are remains of a big ward office with a temple, because in ancient East Asia, an emperor must have three great ministries. In fact, there is a record in Chinese literature that a king of Japan sent a letter in 478 to ask the Chinese emperor's approval for employing three ministries. In addition, remains of the Korokan were found in Fukuoka underneath a part of the ruins of Fukuoka Castle.
Kublai Khan of the Mongol Empire turned his attention towards Japan starting in 1268, exerting a new external pressure on Japan with which it had no experience. Kublai Khan first sent an envoy to Japan to make the Shogunate acknowledge Khan's suzerainty; the Kamakura shogunate refused. Mongolia sent envoys thereafter, each time urging the Shogunate to accept their proposal, but to no avail. In 1274, Kublai Khan mounted an invasion of the northern part of Kyushu with a fleet of 900 ships and 33,000 troops, including troops from Goryeo on the Korean Peninsula; this initial invasion was compromised by a combination of incompetence and severe storms. After the invasion attempt of 1274, Japanese samurai built a stone barrier 20 km in length bordering the coast of Hakata Bay in what is now the city of Fukuoka; the wall, 2–3 metres in height and having a base width of 3 metres, was constructed between 1276 and 1277, was excavated in the 1930s. Kublai sent another envoy to Japan in 1279. At that time, Hōjō Tokimune of the Hōjō clan was the Eighth Regent.
Not only did he decline the offer, but he beheaded the five Mongolian emissaries after summoning them to Kamakura. Infuriated, Kublai organized another attack on Fukuoka Prefecture in 1281, mobilizing 140,000 soldiers and 4,000 ships; the Japanese defenders, numbering around 40,000, were no match for the Mongols and the invasion force made it as far as Dazaifu, 15 km south of the city of Fukuoka. However, the Japanese were again aided by severe weather, this time by a typhoon that struck a crushing blow to the Mongolian troops, thwarting the invasion, it was this typhoon that came to be called the Kamikaze, was the origin of the term Kamikaze used to indicate suicide attacks by military aviators of the Empire of Japan against Allied naval vessels during World War II. Fukuoka was the residence of the powerful daimyō of Chikuzen Province, played an important part in the medieval history of Japan; the renowned temple of Tokugawa Ieyasu in the district was destroyed by fire during the Boshin War of 1868.
The modern city was formed on April 1, 1889, with the merger of the former cities of Hakata and Fukuoka. Hakata was the port and merchant district, was more associated with the area's culture and remains the main commercial area today. On the other hand, the Fukuoka area was home to many samurai, its name has been used since Kuroda Nagamasa, the first daimyō of Chikuzen Province, named it after his birthplace in Okayama Prefecture and the "old Fukuoka" is the main shopping area, now called Tenjin; when Hakata and Fukuoka decided to merge, a meeting was held to decide the name for the new city. Hakata was chosen, but a group of samurai crashed the meeting and forced those present to choose Fukuoka as the name for the merged city. However, Hakata is still used to refer to the Hakata area of the city and, most famously, to refer to the city's train station, Hakata Station, dialect, Hakata-ben. 1903: Fukuoka Medical College, a campus associated with Kyoto Imperial University, is founded. In 1911, the college is established as a separate entity.
1910: Fukuoka streetcar service begins. 1929: Flights commence along the Fukuoka-Osaka-Tokyo route. 1945: Fukuoka was firebombed on 19 June, with the attack destroying 21.5 percent of the city's urban area. 1947: First Fukuoka Marathon. 1951: F
Kure is a port and major shipbuilding city situated on the Seto Inland Sea in Hiroshima Prefecture, Japan. With a strong industrial heritage Kure hosts the second oldest naval dockyard in Japan and remains an important base for the Japan Maritime Self-Defence Force; as of 1 May 2015, the city has an estimated population of 228,030 and a population density of 646 persons per km². The total area is 352.80 km². The Kure Naval District was first established in 1889, leading to the construction of the Kure Naval Arsenal and the rapid growth of steel production and shipbuilding in the city. Kure was formally incorporated on October 1, 1902. From 1889 until the end of World War II, the city served as the headquarters of the Kure Naval District. Kure dockyards recorded a number of significant engineering firsts including the launching of the first major domestically built capital ship, the battlecruiser Tsukuba and the launching of the largest battleship built, the Yamato. During the Pacific War, Kure acted as arsenal.
Most of the city's industry and workforce were employed in the service of the naval installations, munitions factories and associated support functions. In the stages of the conflict Kure came under sustained aerial bombardment culminating in the Bombing of Kure in June and July 1945. From February 1946 until the end of Japan's postwar occupation in 1952, military establishments in Kure served at the operational headquarters for the British Commonwealth Occupation Force. Since 2005 Kure has attracted attention as a tourism center with the Yamato Museum hosting a 1:10 scale model of the IJN Yamato alongside a waterfront JMSDF museum of Japanese naval history; the city continues as a major maritime center hosting both the dockyards of Japan Marine United and numerous shore-based facilities of the JMSDF including training centers and a major hospital. The city serves as the home port of an Escort Flotilla, a Submarine Flotilla and the Training Squadron of the JMSDF Regional Kure District. July 1, 1889 — Kure Naval District established.
1895 — Kure naval shipyard established as a subsidiary of the Onohama Shipyards in Kobe. October 1, 1902 — The towns of Washō and Futagawa and the villages of Miyahara and Sōyamada merge to form the city of Kure. November 10, 1903 — Kure Naval Arsenal established. December 27, 1903 Kure rail line opens providing direct rail access to Hiroshima April 1, 1928 — The towns of Kegoya and Aga merge into Kure. April 21, 1941 — The town of Nigata and the village of Hiro incorporated into Kure. March 19, 1945 — US Navy aircraft attack Japanese warships at Kure May 5, 1945 — Bombing of Hiro Naval Arsenal. June 22, 1945 — Bombing of Kure Naval Arsenal. July 1, 1945 — Kure Air Raid. July 24–28, 1945 — Battle of Kure, American bombers attack the remaining fleet in Kure Naval Base. July 1, 1954 — Japan Maritime Self Defense Forces founded. October 1, 1956 — The town of Tennō and the village of Shōwa in Aki District, the village of Gōhara in Kamo District merge into Kure. November 1, 2000 — Kure becomes a Special City April 1, 2003 — The town of Shimokamagari was merged into Kure.
April 1, 2004 —The town of Kawajiri was merged into Kure. March 20, 2005 — The towns of Ondo and Kamagari, the towns of Yasuura and Yutaka were merged into Kure. Kure faces the Seto Inland Sea. Surrounded by steep hillsides to the north, the two major commercial and industrial centers of the city are bisected by Mount Yasumi 497 m; the city is next to the Setonaikai National Park. As well as densely populated urban and industrial centers, the city incorporates sparsely inhabited outlying islands such as Kurahashi, Shimo-kamagari and Kami-kamagari. Kure has a humid subtropical climate with cool winters. Precipitation is heaviest in summer. Kure is served by the Kure Line, operated by West Japan Railway Company, it leads to Hiroshima, a terminal station. There has been a municipal bus since December 1, 1942; the Kure City Transportation Bureau started using natural gas in 2002. There is a bus route run by Hiroshima Electric Railway, too. In addition, there is Bōyo Kisen, which operates the San'yō Bus and Setouchi Sankō which runs two bus enterprises.
National Route 31 spreads out from Kure to Kaita. National Route 185 is connected from Kure to Mihara; this road has a view of the Inland Sea. National Route 375 is a 165-kilometre-long road to be connected from Kure to Shimane. U. S. forces can use this way for their ammunition transportation. National Route 487 spreads out from Kure to the city of Hiroshima; this road crosses the Ondo Bridge, goes around Etajima. Though they are independent roads, separate from National Routes, there are a series of access roads toward the archipelago of the city; the Akinada Islands series of bridges conclude at Shimokamagari island, Kamikamagari island, Osakishimojima, Nakanoshima at seven bridges. Toyoshima Bridge, concluding at Toyoshima regards traffic of a ship as Kamikamagari island, is 50 m high from the surface of the sea. Japan Marine United IHI Marine United, has a shipyard in the city Nisshin Steel Yodogawa Steel Works Mitsubishi Hitachi Power Systems Sailor Pen Company Disco Corporation has three manufacturing plants in Kure Mitutoyo Oji Paper Company Kure Municipal Museum of Art and Museum Avenue Irifuneyama Memorial Museum Sannose Gohonjin Art and Culture Rantokaku Art Museum Kurahashi-cho Nagato Museum of Shipbu