A linear motor is an electric motor that has had its stator and rotor "unrolled", thus, instead of producing a torque ( rotation ), it produces a linear force along its length. However, linear motors are not necessarily straight. Characteristically, a linear motor's active section has ends, whereas more conventional motors are arranged as a continuous loop.
166-429: A railgun or rail gun , sometimes referred to as a rail cannon , is a linear motor device, typically designed as a weapon, that uses electromagnetic force to launch high- velocity projectiles . The projectile normally does not contain explosives, instead relying on the projectile's high kinetic energy to inflict damage. The railgun uses a pair of parallel rail-shaped conductors (simply called rails), along which
332-609: A United States Air Force Research Laboratory project concerning the development of a coaxial plasma railgun. It is one of several United States Government efforts to develop plasma-based projectiles. The first computer simulations occurred in 1990, and its first published experiment appeared on 1 August 1993. As of 1993 the project appeared to be in the early experimental stages. The weapon was able to produce doughnut-shaped rings of plasma and balls of lightning that exploded with devastating effects when hitting their target. The project's initial success led to it becoming classified, and only
498-556: A ball screw , timing belt , or rack and pinion , is that they provide any combination of high precision, high velocity, high force and long travel. Linear motors are widely used. One of the major uses of linear motors is for propelling the shuttle in looms . A linear motor has been used for sliding doors and various similar actuators. They have been used for baggage handling and even large-scale bulk materials transport. Linear motors are sometimes used to create rotary motion. For example, they have been used at observatories to deal with
664-403: A muzzle velocity of more than ≈2 km/s (Mach 5.9), railguns can readily exceed 3 km/s (Mach 8.8). For a similar projectile, the range of railguns may exceed that of conventional guns. The destructive force of a projectile depends upon its kinetic energy (proportional to its mass and the square of its velocity) at the point of impact. Because of the potentially higher velocity of
830-482: A "shell" as opposed to "shot". By the time of the Second World War, AP shells with a bursting charge were sometimes distinguished by appending the suffix "HE". At the beginning of the war, APHE was common in anti-tank shells of 75 mm caliber and larger due to the similarity with the much larger naval armour piercing shells already in common use. As the war progressed, ordnance design evolved so that
996-536: A 1543 English mortar shell was filled with "wildfire." By the 18th century, it was known that if loaded toward the muzzle instead, the fuse could be lit by the flash through the windage between the shell and the barrel. At about this time, shells began to be employed for horizontal fire from howitzers with a small propelling charge and, in 1779, experiments demonstrated that they could be used from guns with heavier charges. The use of exploding shells from field artillery became relatively commonplace from early in
1162-581: A US patent on 1 April 1919, which was issued in July 1922 as patent no. 1,421,435 "Electric Apparatus for Propelling Projectiles". In his device, two parallel busbars are connected by the wings of a projectile, and the whole apparatus surrounded by a magnetic field . By passing current through busbars and projectile, a force is induced which propels the projectile along the bus-bars and into flight. In 1923, Russian scientist A. L. Korol'kov detailed his criticisms of Fauchon-Villeplee's design, arguing against some of
1328-464: A bastion of the Bavarian city of Ingolstadt , Germany . Many of the grenades contained their original black-powder loads and igniters. Most probably the grenades were intentionally dumped in the moat of the bastion before the year 1723. An early problem was that there was no means of precisely measuring the time to detonation – reliable fuses did not yet exist, and the burning time of
1494-538: A better effect. This guideline was achieved by the 1960s with the 155 mm L15 shell, developed as part of the German-British FH-70 program. The key requirement for increasing the HE content without increasing shell weight was to reduce the thickness of shell walls, which required improvements in high tensile steel. The most common shell type is high explosive , commonly referred to simply as HE. They have
1660-426: A bursting charge in the projectile which unleashes a swarm of smaller projectiles over a large area. Assuming that the many technical challenges facing fieldable railguns are overcome, including issues like railgun projectile guidance, rail endurance, and combat survivability and reliability of the electrical power supply, the increased launch velocities of railguns may provide advantages over more conventional guns for
1826-401: A cartridge case and it achieves obturation through a screw breech instead of a sliding block. Sometimes when reading about artillery the term separate loading ammunition will be used without clarification of whether a cartridge case is used or not, in which case it refers to the type of breech used. Heavy artillery pieces and naval artillery tend to use bagged charges and projectiles because
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#17327919024431992-494: A challenge because there was no way of ensuring that the impact mechanism contacted the target. Therefore, ball shells needed a time fuse that was ignited before or during firing and burned until the shell reached its target. Cast iron shells packed with gunpowder have been used in warfare since at least early 13th century China. Hollow, gunpowder-packed shells made of cast iron used during the Song dynasty (960-1279) are described in
2158-460: A coil or simply a piece of plate metal, that is placed in this field will have eddy currents induced in it thus creating an opposing magnetic field, in accordance with Lenz's law . The two opposing fields will repel each other, thus creating motion as the magnetic field sweeps through the metal. In this design a large current is passed through a metal sabot across sliding contacts that are fed by two rails. The magnetic field this generates causes
2324-464: A concrete demolition 203 mm (8 in) shell 146 kg (322 lbs), a 280 mm (11 in) battleship shell about 300 kg (661 lbs), and a 460 mm (18 in) battleship shell over 1,500 kg (3,307 lbs). The Schwerer Gustav large-calibre gun fired shells that weighed between 4,800 kg (10,582 lbs) and 7,100 kg (15,653 lbs). During the 19th century, the British adopted
2490-423: A few full-power shots before replacement of the rails is required. In current designs massive amounts of heat are created by the electricity flowing through the rails, as well as by the friction of the projectile leaving the device. This causes three main problems: melting of equipment, decreased safety of personnel, and detection by enemy forces owing to increased infrared signature . As briefly discussed above,
2656-432: A few km) would require very strong acceleration forces, higher than humans can tolerate. Other designs include a longer helical (spiral) track, or a large ring design whereby a space vehicle would circle the ring numerous times, gradually gaining speed, before being released into a launch corridor leading skyward. Nevertheless, if technically feasible and cost effective to build, imparting hyper-velocity escape velocity to
2822-402: A few milliseconds, as opposed to a few seconds). Such a development would then convey a further military advantage in that the elimination of explosives from any military weapons platform will decrease its vulnerability to enemy fire. The concept of the railgun was first introduced by French inventor André Louis Octave Fauchon-Villeplée, who created a small working model in 1917 with the help of
2988-644: A few references to MARAUDER appeared after 1993. Full-scale models have been built and fired, including a 90 mm (3.5 in) bore, 9 megajoule kinetic energy gun developed by the US DARPA . Rail and insulator wear problems still need to be solved before railguns can start to replace conventional weapons. Probably the oldest consistently successful system was built by the UK's Defence Research Agency at Dundrennan Range in Kirkcudbright , Scotland . This system
3154-430: A few shots from a single set of rails. The barrel must withstand these conditions for up to several rounds per minute for thousands of shots without failure or significant degradation. These parameters are well beyond the state of the art in materials science. The power supply must be able to deliver large currents, sustained and controlled over a useful amount of time. The most important gauge of power supply effectiveness
3320-412: A fixed round becomes too long or too heavy to load by a gun crew. Another issue is the inability to vary propellant charges to achieve different velocities and ranges. Lastly, there is the issue of resource usage since a fixed round uses a case, which can be an issue in a prolonged war if there are metal shortages. Separate loading cased charge ammunition has three main components: the fuzed projectile,
3486-412: A half-inch. The sabot was also intended to reduce jamming during loading. Despite the use of exploding shells, the use of smoothbore cannons firing spherical projectiles of shot remained the dominant artillery method until the 1850s. The mid–19th century saw a revolution in artillery, with the introduction of the first practical rifled breech loading weapons. The new methods resulted in the reshaping of
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#17327919024433652-707: A huge cloud of smoke and concealed shooters were given away by a cloud of smoke over the firing position. Guncotton , a nitrocellulose-based material, was discovered by Swiss chemist Christian Friedrich Schönbein in 1846. He promoted its use as a blasting explosive and sold manufacturing rights to the Austrian Empire . Guncotton was more powerful than gunpowder, but at the same time was somewhat more unstable. John Taylor obtained an English patent for guncotton; and John Hall & Sons began manufacture in Faversham . British interest waned after an explosion destroyed
3818-402: A large mass driver that can accelerate cargo up to escape velocity , though RLV launch assist like StarTram to low Earth orbit has also been investigated. High-acceleration linear motors are difficult to design for a number of reasons. They require large amounts of energy in very short periods of time. One rocket launcher design calls for 300 GJ for each launch in the space of less than
3984-585: A limited number of large interceptors can be carried. A railgun projectile can reach several times the speed of sound faster than a missile; because of this, it can hit a target, such as a cruise missile, much faster and farther away from the ship. Projectiles are also typically much cheaper and smaller, allowing for many more to be carried (they have no guidance systems, and rely on the railgun to supply their kinetic energy, rather than providing it themselves). The speed, cost, and numerical advantages of railgun systems may allow them to replace several different systems in
4150-594: A long-term program of theoretical and experimental research on railguns. The work was conducted predominantly at the Aberdeen Proving Ground , and much of the early research drew inspiration from the railgun experiments performed by the Australian National University . Topics of research included plasma dynamics, electromagnetic fields, telemetry, and current and heat transport. While military research into railgun technology in
4316-405: A magnet stator and a moving coil. A Hall effect sensor is attached to the rotor to track the magnetic flux of the stator. The electric current is typically provided from a stationary servo drive to the moving coil by a moving cable inside a cable carrier . In this design, the force is produced by a moving linear magnetic field acting on conductors in the field. Any conductor, be it a loop,
4482-501: A muzzle speed of 930 m/s (3,050 ft/s), and the 16-inch/50-caliber Mark 7 gun that armed World War II American battleships has a muzzle speed of 760 m/s (2,490 ft/s), which because of its much greater projectile mass (up to 2,700 pounds) generated a muzzle energy of 360 MJ and a downrange kinetic impact of energy of over 160 MJ (see also Project HARP ). By firing smaller projectiles at extremely high velocities, railguns may yield kinetic energy impacts equal or superior to
4648-495: A number of potential practical applications, primarily for the military. However, there are other theoretical applications currently being researched. Electrodynamic assistance to launch rockets has been studied. Space applications of this technology would likely involve specially formed electromagnetic coils and superconducting magnets . Composite materials would likely be used for this application. For space launches from Earth, relatively short acceleration distances (less than
4814-409: A particular form of designating artillery. Field guns were designated by nominal standard projectile weight, while howitzers were designated by barrel caliber. British guns and their ammunition were designated in pounds , e.g., as "two-pounder" shortened to "2-pr" or "2-pdr". Usually, this referred to the actual weight of the standard projectile (shot, shrapnel, or high explosive), but, confusingly, this
4980-450: A plan to turn this idea into a realized technology. Because of strong acceleration, this system would launch only sturdy materials, such as food, water, and—most importantly—fuel. Under ideal circumstances (equator, mountain, heading east) the system would cost $ 528/kg, compared with $ 5,000/kg on the conventional rocket. The McNab railgun could make approximately 2000 launches per year, for a total of maximum 500 tons launched per year. Because
5146-490: A projectile launching at sea level, where the atmosphere is the most dense, may result in much of the launch velocity being lost to aerodynamic drag . In addition, the projectile might still require some form of on-board guidance and control to realize a useful orbital insertion angle that may not be achievable based simply on the launcher's upward elevation angle relative to the surface of the earth, (see practical considerations of escape velocity ). In 2003, Ian McNab outlined
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5312-455: A prototype of a 64 MJ weapon to be deployed aboard Navy warships. The main problem the U.S. Navy has had with implementing a railgun cannon system is that the guns wear out because of the immense pressures, stresses and heat that are generated by the millions of amperes of current necessary to fire projectiles with megajoules of energy. While not nearly as powerful as a cruise missile like a BGM-109 Tomahawk , that will deliver 3,000 MJ of energy to
5478-600: A prototype system for supporting interception tasks is to be ready by 2018, and operational by 2025. This timeframe suggests the weapons are planned to be installed on the Navy's next-generation surface combatants, expected to start construction by 2028. BAE Systems was at one point interested in installing railguns on their Future Fighting Vehicle . India has successfully tested their own railgun. Russia , China , Turkey 's ASELSAN and Yeteknoloji are also developing railguns. Germany, France and Japan will jointly develop
5644-425: A railgun weapon. Helical railguns are multi-turn railguns that reduce rail and brush current by a factor equal to the number of turns. Two rails are surrounded by a helical barrel and the projectile or re-usable carrier is also helical. The projectile is energized continuously by two brushes sliding along the rails, and two or more additional brushes on the projectile serve to energize and commute several windings of
5810-638: A railgun with a 240 kJ, low inductance capacitor bank operating at 5 kV power able to launch projectiles of 3–3.5 g weight to a velocity of more than 2,000 m/s (4,500 mph; 7,200 km/h; 6,600 ft/s). In 1995, the Center for Electromagnetics at the University of Texas at Austin designed and developed a rapid-fire railgun launcher called the Cannon-Caliber Electromagnetic Gun . The launcher prototype
5976-457: A railgun-launched projectile, its force may be much greater than conventionally launched projectiles of the same mass. The absence of explosive propellants or warheads to store and handle, as well as the low cost of projectiles compared to conventional weaponry, are also advantageous. Railguns are still very much at the research stage after decades of R&D , and it remains to be seen whether they will be deployed as practical military weapons in
6142-409: A result, the U.S. military focused on developing small guided projectiles that could withstand the high-G launch from ultra-high velocity plasma armature railguns. But after the publication of an important Defense Science Board study in 1985, the U.S. Army , Marine Corps , and DARPA were assigned to develop anti-armor, electromagnetic launch technologies for mobile ground combat vehicles . In 1990,
6308-426: A second. Normal electrical generators are not designed for this kind of load, but short-term electrical energy storage methods can be used. Capacitors are bulky and expensive but can supply large amounts of energy quickly. Homopolar generators can be used to convert the kinetic energy of a flywheel into electric energy very rapidly. High-acceleration linear motors also require very strong magnetic fields; in fact,
6474-513: A sliding projectile called an armature is accelerated by the electromagnetic effects of a current that flows down one rail, into the armature and then back along the other rail. It is based on principles similar to those of the homopolar motor . As of 2020, railguns have been researched as weapons utilizing electromagnetic forces to impart a very high kinetic energy to a projectile (e.g. APFSDS ) rather than using conventional propellants. While explosive-powered military guns cannot readily achieve
6640-899: A slotted conduit. Outside of public transportation, vertical linear motors have been proposed as lifting mechanisms in deep mines , and the use of linear motors is growing in motion control applications. They are also often used on sliding doors, such as those of low floor trams such as the Alstom Citadis and the Socimi Eurotram . Dual axis linear motors also exist. These specialized devices have been used to provide direct X - Y motion for precision laser cutting of cloth and sheet metal, automated drafting , and cable forming. Most linear motors in use are LIM (linear induction motor), or LSM (linear synchronous motor). Linear DC motors are not used due to their higher cost and linear SRM suffers from poor thrust. So for long runs in traction LIM
6806-419: A small rocket motor built into its base to provide additional thrust. The second has a pyrotechnic device in its base that bleeds gas to fill the partial vacuum created behind the shell and hence reduce base-drag. These shell designs usually have reduced high-explosive filling to remain within the permitted mass for the projectile, and hence less lethality. The caliber of a shell is its diameter . Depending on
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6972-867: A smooth surface finish. All of the following applications are in rapid transit and have the active part of the motor in the cars. Originally developed in the late 1970s by UTDC in Canada as the Intermediate Capacity Transit System (ICTS). A test track was constructed in Millhaven, Ontario , for extensive testing of prototype cars, after which three lines were constructed: ICTS was sold to Bombardier Transportation in 1991 and later known as Advanced Rapid Transit (ART) before adopting its current branding in 2011. Since then, several more installations have been made: All Innovia Metro systems use third rail electrification. One of
7138-759: A solid, non-conducting payload in a similar manner to the propellant gas pressure in a conventional gun. A hybrid armature uses a pair of plasma contacts to interface a metallic armature to the gun rails. Solid armatures may also 'transition' into hybrid armatures, typically after a particular velocity threshold is exceeded. The high current required to power a railgun can be provided by various power supply technologies, such as capacitors, pulse generators and disc generators. For potential military applications, railguns are usually of interest because they can achieve much greater muzzle velocities than guns powered by conventional chemical propellants. Increased muzzle velocities with better aerodynamically streamlined projectiles can convey
7304-548: A speed of many kilometers per second (km/s). Although these speeds are possible, the heat generated from the propulsion of the object is enough to erode the rails rapidly. Under high-use conditions, current railguns would require frequent replacement of the rails, or to use a heat-resistant material that would be conductive enough to produce the same effect. At this time it is generally acknowledged that it will take major breakthroughs in materials science and related disciplines to produce high-powered railguns capable of firing more than
7470-482: A strong steel case, a bursting charge, and a fuse . The fuse detonates the bursting charge which shatters the case and scatters hot, sharp case pieces ( fragments , splinters ) at high velocity. Most of the damage to soft targets, such as unprotected personnel, is caused by shell pieces rather than by the blast. The term "shrapnel" is sometimes used to describe the shell pieces, but shrapnel shells functioned very differently and are long obsolete. The speed of fragments
7636-472: A target, such weapons would, in theory, allow the Navy to deliver more granular firepower at a fraction of the cost of a missile, and will be much harder to shoot down versus future defensive systems. For context, another relevant comparison is the Rheinmetall 120mm gun used on main battle tanks, which generates 9 MJ of muzzle energy. In 2007, BAE Systems delivered a 32 MJ prototype (muzzle energy) to
7802-476: A thickness about 1/15th of the total diameter and filled with powder, saltpeter, pitch, coal and tallow. They were used to 'suffocate or expel the enemy in casemates, mines or between decks; for concealing operations; and as signals. During the First World War , shrapnel shells and explosive shells inflicted terrible casualties on infantry, accounting for nearly 70% of all war casualties and leading to
7968-406: A traditional electric motor in that no use is made of additional field windings (or permanent magnets). This basic configuration is formed by a single loop of current and thus requires high currents (on the order of one million amperes ) to produce sufficient accelerations (and muzzle velocities). A relatively common variant of this configuration is the augmented railgun in which the driving current
8134-619: A variety of offensive and defensive scenarios. Railguns have limited potential to be used against both surface and airborne targets. The first weaponized railgun planned for production, the General Atomics Blitzer system, began full system testing in September 2010. The weapon launches a streamlined discarding sabot round designed by Boeing's Phantom Works at 1,600 m/s (5,200 ft/s) (approximately Mach 5) with accelerations exceeding 60,000 g n . During one of
8300-447: A very high speed; for example, see the coilgun . High-acceleration linear motors are typically used in studies of hypervelocity collisions, as weapons , or as mass drivers for spacecraft propulsion . They are usually of the AC linear induction motor (LIM) design with an active three-phase winding on one side of the air-gap and a passive conductor plate on the other side. However,
8466-926: A world record by conducting a 33 MJ shot from the railgun, which was built by BAE Systems. Linear motor A typical mode of operation is as a Lorentz -type actuator, in which the applied force is linearly proportional to the current and the magnetic field ( F → = I L → × B → ) {\displaystyle ({\vec {F}}=I{\vec {L}}\times {\vec {B}})} . Linear motors are most commonly found in high accuracy engineering applications. Many designs have been put forward for linear motors, falling into two major categories, low-acceleration and high-acceleration linear motors. Low-acceleration linear motors are suitable for maglev trains and other ground-based transportation applications. High-acceleration linear motors are normally rather short, and are designed to accelerate an object to
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#17327919024438632-455: Is semi-fixed ammunition. With semi-fixed ammunition the round comes as a complete package but the projectile and its case can be separated. The case holds a set number of bagged charges and the gun crew can add or subtract propellant to change range and velocity. The round is then reassembled, loaded, and fired. Advantages include easier handling for larger caliber rounds, while range and velocity can easily be varied by increasing or decreasing
8798-423: Is a projectile whose payload contains an explosive , incendiary , or other chemical filling. Originally it was called a bombshell , contrasting with solid shells used for early rifled artillery, but "shell" has come to be unambiguous in a military context. A shell can hold a tracer . All explosive- and incendiary-filled projectiles, particularly for mortars , were originally called grenades , derived from
8964-426: Is channeled through additional pairs of parallel conductors, arranged to increase ('augment') the magnetic field experienced by the moving armature. These arrangements reduce the current required for a given acceleration. In electric motor terminology, augmented railguns are usually series-wound configurations. Some railguns also use strong neodymium magnets with the field perpendicular to the current flow to increase
9130-399: Is controlled, usually electronically, to track the motion of the rotor. For cost reasons synchronous linear motors rarely use commutators , so the rotor often contains permanent magnets, or soft iron . Examples include coilguns and the motors used on some maglev systems, as well as many other linear motors. In high precision industrial automation linear motors are typically configured with
9296-470: Is described in U.S. patent 782,312 (1905 - inventor Alfred Zehden of Frankfurt-am-Main), for driving trains or lifts. The German engineer Hermann Kemper built a working model in 1935. In the late 1940s, Dr. Eric Laithwaite of Manchester University , later Professor of Heavy Electrical Engineering at Imperial College in London developed the first full-size working model. In a single sided version
9462-472: Is enough energy to deliver 2 kg (4.4 lb) of projectile at 3 km/s (1.9 mi/s)—at that velocity, a sufficiently long rod of tungsten or another dense metal could easily penetrate a tank , and potentially pass through it, (see APFSDS ). The United States Naval Surface Warfare Center Dahlgren Division demonstrated an 8 MJ railgun firing 3.2 kg (7.1 lb) projectiles in October 2006 as
9628-605: Is equivalent to the kinetic energy of a school bus weighing 5 metric tons, traveling at 509 km/h (316 mph; 141 m/s). For single loop railguns, these mission requirements require launch currents of a few million amperes , so a typical railgun power supply might be designed to deliver a launch current of 5 MA for a few milliseconds. As the magnetic field strengths required for such launches will typically be approximately 10 tesla (100 kilogauss ), most contemporary railgun designs are effectively air-cored, i.e., they do not use ferromagnetic materials such as iron to enhance
9794-404: Is generally most suitable but cupronickel or gilding metal were also used. Although an early percussion fuze appeared in 1650 that used a flint to create sparks to ignite the powder, the shell had to fall in a particular way for this to work and this did not work with spherical projectiles. An additional problem was finding a suitably stable "percussion powder". Progress was not possible until
9960-426: Is mostly preferred and for short runs LSM is mostly preferred. High-acceleration linear motors have been suggested for a number of uses. They have been considered for use as weapons , since current armour-piercing ammunition tends to consist of small rounds with very high kinetic energy , for which just such motors are suitable. Many amusement park launched roller coasters now use linear induction motors to propel
10126-443: Is obsolete. Typically, the thickness of the metal body was about a sixth of their diameter, and they were about two-thirds the weight of solid shot of the same caliber. To ensure that shells were loaded with their fuses toward the muzzle, they were attached to wooden bottoms called sabots . In 1819, a committee of British artillery officers recognized that they were essential stores and in 1830 Britain standardized sabot thickness as
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#173279190244310292-546: Is over 400 kg. There would be a peak operating magnetic field of 5 T—half of this coming from the rails, and the other half from augmenting magnets. This halves the required current through the rails, which reduces the power fourfold. NASA has proposed to use a railgun to launch "wedge-shaped aircraft with scramjets " to high altitude at Mach 10, where it would then launch a small payload into orbit using conventional rocket propulsion. The extreme g-forces involved with direct railgun ground-launch to space may restrict
10458-427: Is the energy it can deliver. As of December 2010, the greatest known energy used to propel a projectile from a railgun was 33 megajoules. The most common forms of power supplies used in railguns are capacitors and compulsators which are slowly charged from other continuous energy sources. The rails need to withstand enormous repulsive forces during shooting, and these forces will tend to push them apart and away from
10624-555: Is usually a cylinder topped by an ogive -tipped nose cone for good aerodynamic performance , and possibly with a tapered boat tail ; but some specialized types differ widely. Gunpowder is a low explosive , meaning it will not create a concussive, brisant explosion unless it is contained, as in a modern-day pipe bomb or pressure cooker bomb . Early grenades were hollow cast-iron balls filled with gunpowder, and "shells" were similar devices designed to be shot from artillery in place of solid cannonballs ("shot"). Metonymically ,
10790-575: The Combustion Light Gas Gun in a 155 mm prototype form was projected to achieve 2500 m/s with a 70 caliber barrel. In some hypervelocity research projects, projectiles are 'pre-injected' into railguns, to avoid the need for a standing start, and both two-stage light-gas guns and conventional powder guns have been used for this role. In principle, if railgun power supply technology can be developed to provide safe, compact, reliable, combat survivable, and lightweight units, then
10956-520: The French word for pomegranate , so called because of the similarity of shape and that the multi-seeded fruit resembles the powder-filled, fragmentizing bomb. Words cognate with grenade are still used for an artillery or mortar projectile in some European languages. Shells are usually large-caliber projectiles fired by artillery, armoured fighting vehicles (e.g. tanks , assault guns , and mortar carriers ), warships , and autocannons . The shape
11122-769: The Industrial Revolution that Armstrong was able to construct a viable solution. Another innovative feature was what Armstrong called its "grip", which was essentially a squeeze bore ; the 6 inches of the bore at the muzzle end was of slightly smaller diameter, which centered the shell before it left the barrel and at the same time slightly swaged down its lead coating, reducing its diameter and slightly improving its ballistic qualities. Rifled guns were also developed elsewhere – by Major Giovanni Cavalli and Baron Martin von Wahrendorff in Sweden, Krupp in Germany and
11288-594: The Republic of Venice at Jadra in 1376. Shells with fuses were used at the 1421 siege of St Boniface in Corsica . These were two hollowed hemispheres of stone or bronze held together by an iron hoop. At least since the 16th century grenades made of ceramics or glass were in use in Central Europe. A hoard of several hundred ceramic grenades dated to the 17th century was discovered during building works in front of
11454-584: The Research School of Physical Sciences at the new Australian National University , initiated the design and construction of the world's largest (500 megajoule) homopolar generator . This machine was operational from 1962 and was later used to power a large-scale railgun that was used as a scientific experiment. In 1980, the Ballistic Research Laboratory (later consolidated to form the U.S. Army Research Laboratory ) began
11620-462: The Royal Arsenal at Woolwich . The piece was rifled , which allowed for a much more accurate and powerful action. Although rifling had been tried on small arms since the 15th century, the necessary machinery to accurately rifle artillery only became available in the mid-19th century. Martin von Wahrendorff and Joseph Whitworth independently produced rifled cannons in the 1840s, but it
11786-624: The Shanghai maglev train , for instance, is an LSM. Brushless linear motors are members of the Synchronous motor family. They are typically used in standard linear stages or integrated into custom, high performance positioning systems . Invented in the late 1980s by Anwar Chitayat at Anorad Corporation, now Rockwell Automation , and helped improve the throughput and quality of industrial manufacturing processes. Brushed linear motors were used in industrial automation applications prior to
11952-731: The Société anonyme des accumulateurs Tudor (now Tudor Batteries ). During World War I, the French Director of Inventions at the Ministry of Armaments , Jules-Louis Brenton , commissioned Fauchon-Villeplee to develop a 30-mm to 50-mm electric cannon on 25 July 1918, after delegates from the Commission des Inventions witnessed test trials of the working model in 1917. However, the project was abandoned once World War I ended later that year on 11 November 1918. Fauchon-Villeplee filed for
12118-585: The Wiard gun in the United States. However, rifled barrels required some means of engaging the shell with the rifling. Lead coated shells were used with the Armstrong gun , but were not satisfactory so studded projectiles were adopted. However, these did not seal the gap between shell and barrel. Wads at the shell base were also tried without success. In 1878, the British adopted a copper " gas-check " at
12284-604: The fuzed projectile, the casing to hold the propellants and primer , and the single propellant charge. Everything is included in a ready-to-use package and in British ordnance terms is called fixed quick firing . Often guns which use fixed ammunition use sliding-block or sliding-wedge breeches and the case provides obturation which seals the breech of the gun and prevents propellant gasses from escaping. Sliding block breeches can be horizontal or vertical. Advantages of fixed ammunition are simplicity, safety, moisture resistance and speed of loading. Disadvantages are eventually
12450-490: The 17th century onwards. The British adopted parachute lightballs in 1866 for 10-, 8- and 5 1 ⁄ 2 -inch calibers. The 10-inch was not officially declared obsolete until 1920. Smoke balls also date back to the 17th century, British ones contained a mix of saltpetre, coal, pitch, tar, resin, sawdust, crude antimony and sulphur. They produced a "noisome smoke in abundance that is impossible to bear". In 19th-century British service, they were made of concentric paper with
12616-436: The 19th century. Until the mid 19th century, shells remained as simple exploding spheres that used gunpowder, set off by a slow burning fuse. They were usually made of cast iron , but bronze , lead , brass and even glass shell casings were experimented with. The word bomb encompassed them at the time, as heard in the lyrics of The Star-Spangled Banner ("the bombs bursting in air"), although today that sense of bomb
12782-549: The Austrian factories blew up in 1862, Thomas Prentice & Company began manufacturing guncotton in Stowmarket in 1863; and British War Office chemist Sir Frederick Abel began thorough research at Waltham Abbey Royal Gunpowder Mills leading to a manufacturing process that eliminated the impurities in nitrocellulose making it safer to produce and a stable product safer to handle. Abel patented this process in 1865, when
12948-419: The Faversham factory in 1847. Austrian Baron Wilhelm Lenk von Wolfsberg built two guncotton plants producing artillery propellant, but it was dangerous under field conditions, and guns that could fire thousands of rounds using gunpowder would reach their service life after only a few hundred shots with the more powerful guncotton. Small arms could not withstand the pressures generated by guncotton. After one of
13114-577: The First World War (such as the BL 60-pounder gun , RML 2.5 inch Mountain Gun , 4 inch gun, 4.5 inch howitzer) through to the end of World War II (5.5 inch medium gun, 25-pounder gun-howitzer , 17-pounder tank gun), but the majority of naval guns were by caliber. After the end of World War II, field guns were designated by caliber. There are many different types of shells. The principal ones include: With
13280-520: The Galaxy : Cosmic Rewind at Epcot both use LSM to launch their ride vehicles into their indoor ride enclosures. In 2023 a hydraulic launch roller coaster, Top Thrill Dragster at Cedar Point in Ohio, USA, was renovated and the hydraulic launch replaced with a weaker multi-launch system using LSM, that creates less g-force . Explosive shell A shell , in a modern military context,
13446-758: The German super- railway guns , Gustav and Dora , which were 800 mm (31.5 in) in caliber. Very large shells have been replaced by rockets , missiles , and bombs . Today the largest shells in common use are 155 mm (6.1 in). Gun calibers have standardized around a few common sizes, especially in the larger range, mainly due to the uniformity required for efficient military logistics. Shells of 105 and 155 mm for artillery with 105 and 120 mm for tank guns are common in NATO allied countries. Shells of 122, 130, and 152 mm for artillery with 100, 115, and 125 mm for tank guns, remain in common usage among
13612-621: The Japanese Linimo magnetic levitation train line near Nagoya . However, linear motors have been used independently of magnetic levitation, as in the Bombardier Innovia Metro systems worldwide and a number of modern Japanese subways, including Tokyo 's Toei Ōedo Line . Similar technology is also used in some roller coasters with modifications but, at present, is still impractical on street running trams , although this, in theory, could be done by burying it in
13778-594: The Medium Caliber Launcher. Since 1993 the British and American governments have collaborated on a railgun project at the Dundrennan Weapons Testing Centre that culminated in the 2010 test where BAE Systems fired a 3.2 kg (7 pound) projectile at 18.4-megajoules [3,390 m/s (7,600 mph; 12,200 km/h; 11,100 ft/s)]. In 1994, India's DRDO 's Armament Research and Development Establishment developed
13944-509: The Mummy at Universal Studios Singapore opened in 2010. They both use LIMs to accelerate from certain point in the rides. Revenge of the Mummy also located at Universal Studios Hollywood and Universal Studios Florida . The Incredible Hulk Coaster and VelociCoaster at Universal Islands of Adventure also use linear motors. At Walt Disney World , Rock 'n' Roller Coaster Starring Aerosmith at Disney's Hollywood Studios and Guardians of
14110-551: The Royal Artillery was adopted by the army. It was a wooden fuze about 6 inches long and used shear wire to hold blocks between the fuze magazine and a burning match. The match was ignited by propellant flash and the shear wire broke on impact. A British naval percussion fuze made of metal did not appear until 1861. Gunpowder was used as the only form of explosive up until the end of the 19th century. Guns using black powder ammunition would have their view obscured by
14276-577: The U.S. Army collaborated with the University of Texas at Austin to establish the Institute for Advanced Technology (IAT), which focused on research involving solid and hybrid armatures, rail-armature interactions, and electromagnetic launcher materials. The facility became the Army's first Federally Funded Research and Development Center and housed a few of the Army's electromagnetic launchers, such as
14442-568: The U.S. Navy ( Naval Research Laboratory ), the Institute for Advanced Technology at the University of Texas at Austin , and BAE Systems. The rails and projectiles must be built from strong conductive materials; the rails need to survive the violence of an accelerating projectile, and heating because of the large currents and friction involved. Some erroneous work has suggested that the recoil force in railguns can be redirected or eliminated; careful theoretical and experimental analysis reveals that
14608-451: The U.S. Navy. The same amount of energy is released by the detonation of 4.8 kg (11 lb) of C4 . On 31 January 2008, the U.S. Navy tested a railgun that fired a projectile at 10.64 MJ with a muzzle velocity of 2,520 m/s (8,270 ft/s). The power was provided by a new 9-megajoule prototype capacitor bank using solid-state switches and high-energy-density capacitors delivered in 2007 and an older 32-MJ pulse power system from
14774-632: The US Army's Green Farm Electric Gun Research and Development Facility developed in the late 1980s that was previously refurbished by General Atomics Electromagnetic Systems (EMS) Division. It is expected to be ready between 2020 and 2025. A test of a railgun took place on 10 December 2010, by the U.S. Navy at the Naval Surface Warfare Center Dahlgren Division. During the test, the Office of Naval Research set
14940-515: The United States ensued continuously in the following decades, the direction and focus that it took shifted dramatically with major changes in funding levels and the needs of different government agencies. In 1984, the formation of the Strategic Defense Initiative Organization caused research goals to shift toward establishing a constellation of satellites to intercept intercontinental ballistic missiles . As
15106-458: The adoption of steel combat helmets on both sides. Frequent problems with shells led to many military disasters with dud shells, most notably during the 1916 Battle of the Somme . Shells filled with poison gas were used from 1917 onwards. Artillery shells are differentiated by how the shell is loaded and propelled, and the type of breech mechanism. Fixed ammunition has three main components:
15272-459: The armature is proportional to B {\displaystyle \mathbf {B} } , so the increased field increases the force on the projectile. Railgun velocities generally fall within the range of those achievable by two-stage light-gas guns ; however, the latter are generally only considered to be suitable for laboratory use, while railguns are judged to offer some potential prospects for development as military weapons. A light gas gun,
15438-499: The base of their studded projectiles and in 1879 tried a rotating gas check to replace the studs, leading to the 1881 automatic gas-check. This was soon followed by the Vavaseur copper driving band as part of the projectile. The driving band rotated the projectile, centered it in the bore and prevented gas escaping forwards. A driving band has to be soft but tough enough to prevent stripping by rotational and engraving stresses. Copper
15604-454: The benefits of increased firing ranges while, in terms of target effects, increased terminal velocities can allow the use of kinetic energy rounds incorporating hit-to-kill guidance, as replacements for explosive shells . Therefore, typical military railgun designs aim for muzzle velocities in the range of 2,000–3,500 m/s (4,500–7,800 mph; 7,200–12,600 km/h) with muzzle energies of 5–50 megajoules (MJ). For comparison, 50 MJ
15770-591: The biggest challenges faced by Japanese railway engineers in the 1970s to the 1980s was the ever increasing construction costs of subways. In response, the Japan Subway Association began studying on the feasibility of the "mini-metro" for meeting urban traffic demand in 1979. In 1981, the Japan Railway Engineering Association studied on the use of linear induction motors for such small-profile subways and by 1984
15936-542: The bursting charges in APHE became ever smaller to non-existent, especially in smaller caliber shells, e.g. Panzergranate 39 with only 0.2% HE filling. Although smokeless powders were used as a propellant, they could not be used as the substance for the explosive warhead, because shock sensitivity sometimes caused detonation in the artillery barrel at the time of firing. Picric acid was the first high-explosive nitrated organic compound widely considered suitable to withstand
16102-559: The casing to hold the propellants and primer, and the bagged propellant charges. The components are usually separated into two or more parts. In British ordnance terms, this type of ammunition is called separate quick firing . Often guns which use separate loading cased charge ammunition use sliding-block or sliding-wedge breeches and during World War I and World War II Germany predominantly used fixed or separate loading cased charges and sliding block breeches even for their largest guns. A variant of separate loading cased charge ammunition
16268-410: The central axes of the rails and the armature. In combination to all with the current ( I ) in the armature, this produces a Lorentz force which accelerates the projectile along the rails, always out of the loop (regardless of supply polarity) and away from the power supply, toward the muzzle end of the rails. There are also Lorentz forces acting on the rails and attempting to push them apart, but since
16434-490: The claims that Fauchon-Villeplee made about the advantages of his invention. Korol'kov eventually concluded that while the construction of a long-range electric gun was within the realm of possibility, the practical application of Fauchon-Villeplee's railgun was hindered by its enormous electric energy consumption and its need for a special electric generator of considerable capacity to power it. In 1944, during World War II , Joachim Hänsler of Germany's Ordnance Office proposed
16600-532: The combustion temperature and hence erosion and barrel wear. Cordite could be made to burn more slowly which reduced maximum pressure in the chamber (hence lighter breeches, etc.), but longer high pressure – significant improvements over gunpowder. Cordite could be made in any desired shape or size. The creation of cordite led to a lengthy court battle between Nobel, Maxim, and another inventor over alleged British patent infringement. A variety of fillings have been used in shells throughout history. An incendiary shell
16766-640: The current layered defense approach. A railgun projectile without the ability to change course can hit fast-moving missiles at a maximum range of 30 nmi (35 mi; 56 km). As is the case with the Phalanx CIWS, unguided railgun rounds will require multiple/many shots to bring down maneuvering supersonic anti-ship missiles, with the odds of hitting the missile improving dramatically the closer it gets. The Navy plans for railguns to be able to intercept endoatmospheric ballistic missiles, stealthy air threats, supersonic missiles, and swarming surface threats;
16932-434: The curve was a segment of a circle having a radius of twice the shell caliber. After that war, ogive shapes became more complex and elongated. From the 1960s, higher quality steels were introduced by some countries for their HE shells, this enabled thinner shell walls with less weight of metal and hence a greater weight of explosive. Ogives were further elongated to improve their ballistic performance. Advances in metallurgy in
17098-502: The destructive energy of 5"/54 caliber Mark 45 Naval guns , (which achieve up to 10MJ at the muzzle), but with greater range. This decreases ammunition size and weight, allowing more ammunition to be carried and eliminating the hazards of carrying explosives or propellants in a tank or naval weapons platform. Also, by firing more aerodynamically streamlined projectiles at greater velocities, railguns may achieve greater range, less time to target, and at shorter ranges less wind drift, bypassing
17264-402: The direct current homopolar linear motor railgun is another high acceleration linear motor design. The low-acceleration, high speed and high power motors are usually of the linear synchronous motor (LSM) design, with an active winding on one side of the air-gap and an array of alternate-pole magnets on the other side. These magnets can be permanent magnets or electromagnets . The motor for
17430-486: The discovery of mercury fulminate in 1800, leading to priming mixtures for small arms patented by the Rev Alexander Forsyth , and the copper percussion cap in 1818. The percussion fuze was adopted by Britain in 1842. Many designs were jointly examined by the army and navy, but were unsatisfactory, probably because of the safety and arming features. However, in 1846 the design by Quartermaster Freeburn of
17596-401: The distance between the conductors. It also follows that, for railguns with projectile masses of a few kg and barrel lengths of a few m, very large currents will be required to accelerate projectiles to velocities of the order of 1000 m/s. A very large power supply, providing on the order of one million amperes of current, will create a tremendous force on the projectile, accelerating it to
17762-531: The early Ming Dynasty Chinese military manual Huolongjing , written in the mid 14th century. The History of Jin 《金史》 (compiled by 1345) states that in 1232, as the Mongol general Subutai (1176–1248) descended on the Jin stronghold of Kaifeng , the defenders had a " thunder crash bomb " which "consisted of gunpowder put into an iron container ... then when the fuse was lit (and the projectile shot off) there
17928-538: The first being Germany and Austria which introduced new weapons in 1888. Subsequently, Poudre B was modified several times with various compounds being added and removed. Krupp began adding diphenylamine as a stabilizer in 1888. Britain conducted trials on all the various types of propellant brought to their attention, but were dissatisfied with them all and sought something superior to all existing types. In 1889, Sir Frederick Abel , James Dewar and W. Kellner patented (No. 5614 and No. 11,664 in
18094-515: The first theoretically viable railgun. By late 1944, the theory behind his electric anti-aircraft gun had been worked out sufficiently to allow the Luftwaffe 's Flak Command to issue a specification, which demanded a muzzle velocity of 2,000 m/s (4,500 mph; 7,200 km/h; 6,600 ft/s) and a projectile containing 0.5 kg (1.1 lb) of explosive. The guns were to be mounted in batteries of six firing twelve rounds per minute, and it
18260-830: The following subway lines in Japan use linear motors and use overhead lines for power collection: In addition, Kawasaki Heavy Industries has also exported the Linear Metro to the Guangzhou Metro in China; all of the Linear Metro lines in Guangzhou use third rail electrification: There are many roller coasters throughout the world that use LIMs to accelerate the ride vehicles. The first being Flight of Fear at Kings Island and Kings Dominion , both opening in 1996. Battlestar Galactica: Human VS Cylon & Revenge of
18426-405: The force on the projectile. The armature may be an integral part of the projectile, but it may also be configured to accelerate a separate, electrically isolated or non-conducting projectile. Solid, metallic sliding conductors are often the preferred form of railgun armature but plasma or 'hybrid' armatures can also be used. A plasma armature is formed by an arc of ionised gas that is used to push
18592-409: The foreseeable future. Any trade-off analysis between electromagnetic (EM) propulsion systems and chemical propellants for weapons applications must also factor in its durability, availability and economics, as well as the novelty, bulkiness, high energy demand, and complexity of the pulsed power supplies that are needed for electromagnetic launcher systems. The railgun in its simplest form differs from
18758-474: The gun could be ready for production in "two to three years". Railguns are being examined for use as anti-aircraft weapons to intercept air threats, particularly anti-ship cruise missiles , in addition to land bombardment. A supersonic sea-skimming anti-ship missile can appear over the horizon 20 miles from a warship, leaving a very short reaction time for a ship to intercept it. Even if conventional defense systems react fast enough, they are expensive and only
18924-428: The gun to achieve greater range and accuracy than existing smooth-bore muzzle-loaders with a smaller powder charge. The gun was also a breech-loader. Although attempts at breech-loading mechanisms had been made since medieval times, the essential engineering problem was that the mechanism could not withstand the explosive charge. It was only with the advances in metallurgy and precision engineering capabilities during
19090-445: The helical barrel direction in front of and/or behind the projectile. The helical railgun is a cross between a railgun and a coilgun . They do not currently exist in a practical, usable form. A helical railgun was built at MIT in 1980 and was powered by several banks of, for the time, large capacitors (approximately 4 farads ). It was about 3 meters long, consisting of 2 meters of accelerating coil and 1 meter of decelerating coil. It
19256-436: The historical period and national preferences, this may be specified in millimeters , centimeters , or inches . The length of gun barrels for large cartridges and shells (naval) is frequently quoted in terms of the ratio of the barrel length to the bore size, also called caliber . For example, the 16"/50 caliber Mark 7 gun is 50 calibers long, that is, 16"×50=800"=66.7 feet long. Some guns, mainly British, were specified by
19422-627: The industrial era allowed for the construction of rifled breech-loading guns that could fire at a much greater muzzle velocity . After the British artillery was shown up in the Crimean War as having barely changed since the Napoleonic Wars , the industrialist William Armstrong was awarded a contract by the government to design a new piece of artillery. Production started in 1855 at the Elswick Ordnance Company and
19588-410: The introduction of the first ironclads in the 1850s and 1860s, it became clear that shells had to be designed to effectively pierce the ship armour. A series of British tests in 1863 demonstrated that the way forward lay with high-velocity lighter shells. The first pointed armour-piercing shell was introduced by Major Palliser in 1863. Approved in 1867, Palliser shot and shell was an improvement over
19754-401: The invention of Brushless linear motors. Compared with three phase brushless motors, which are typically being used today, brush motors operate on a single phase. Brush linear motors have a lower cost since they do not need moving cables or three phase servo drives. However, they require higher maintenance since their brushes wear out. In this design the rate of movement of the magnetic field
19920-1053: The large radius of curvature. Linear motors may also be used as an alternative to conventional chain-run lift hills for roller coasters. The coaster Maverick at Cedar Point uses one such linear motor in place of a chain lift. A linear motor has been used to accelerate cars for crash tests . The combination of high precision, high velocity, high force, and long travel makes brushless linear motors attractive for driving industrial automations equipment. They serve industries and applications such as semiconductor steppers , electronics surface-mount technology , automotive cartesian coordinate robots , aerospace chemical milling , optics electron microscope , healthcare laboratory automation , food and beverage pick and place . Synchronous linear motor actuators , used in machine tools, provide high force, high velocity, high precision and high dynamic stiffness, resulting in high smoothness of motion and low settling time. They may reach velocities of 2 m/s and micron-level accuracies, with short cycle times and
20086-407: The late 20th century, since electromagnetic guns do not require propellants to fire a shot as conventional gun systems do, significantly increasing crew safety and reducing logistics costs, as well as provide a greater range. In addition, railgun systems have shown to potentially provide higher velocity of projectiles, which would increase accuracy for anti-tank, artillery, and air defense by decreasing
20252-460: The launch track would be 1.6 km long, power will be supplied by a distributed network of 100 rotating machines (compulsator) spread along the track. Each machine would have a 3.3-ton carbon fibre rotor spinning at high speeds. A machine can recharge in a matter of hours using 10 MW power. This machine could be supplied by a dedicated generator. The total launch package would weigh almost 1.4 tons. Payload per launch in these conditions
20418-422: The magnetic fields are often too strong to permit the use of superconductors . However, with careful design, this need not be a major problem. Two different basic designs have been invented for high-acceleration linear motors: railguns and coilguns . Linear motors are commonly used for actuating high performance industrial automation equipment. Their advantage, unlike any other commonly used actuator, such as
20584-460: The magnetic flux. However, if the barrel is made of a magnetically permeable material, the magnetic field strength increases because of the increase in permeability ( μ = μ 0 * μ r , where μ is the effective permeability, μ 0 is the permeability constant and μ r is the relative permeability of the barrel, and B = μ H {\displaystyle \mathbf {B} =\mu \mathbf {H} } ). The field 'felt' by
20750-431: The magnetic repulsion forces the conductor away from the stator, levitating it, and carrying it along in the direction of the moving magnetic field. He called the later versions of it magnetic river . The technologies would later be applied, in the 1984, Air-Rail Link shuttle, between Birmingham's airport and an adjacent train station. Because of these properties, linear motors are often used in maglev propulsion, as in
20916-445: The metal to be projected along the rails. Efficient and compact design applicable to the replacement of pneumatic cylinders . Piezoelectric drive is often used to drive small linear motors. The history of linear electric motors can be traced back at least as far as the 1840s, to the work of Charles Wheatstone at King's College London , but Wheatstone's model was too inefficient to be practical. A feasible linear induction motor
21082-485: The name Lyddite . Japan followed with an "improved" formula known as shimose powder . In 1889, a similar material, a mixture of ammonium cresylate with trinitrocresol, or an ammonium salt of trinitrocresol, started to be manufactured under the name ecrasite in Austria-Hungary . By 1894, Russia was manufacturing artillery shells filled with picric acid. Ammonium picrate (known as Dunnite or explosive D )
21248-422: The name). At one end, these rails are connected to an electrical power supply, to form the breech end of the gun. Then, if a conductive projectile is inserted between the rails (e.g. by insertion into the breech), it completes the circuit. Electrons flow from the negative terminal of the power supply up the negative rail, across the projectile, and down the positive rail, back to the power supply. This current makes
21414-486: The names of Abel and Dewar) a new formulation that was manufactured at the Royal Gunpowder Factory at Waltham Abbey. It entered British service in 1891 as Cordite Mark 1. Its main composition was 58% nitro-glycerine, 37% guncotton and 3% mineral jelly. A modified version, Cordite MD, entered service in 1901, this increased guncotton to 65% and reduced nitro-glycerine to 30%, this change reduced
21580-421: The need for a pressure-holding casing, so the casing of later shells only needs to contain the munition, and, if desired, to produce shrapnel. The term "shell," however, was sufficiently established that it remained as the term for such munitions. Hollow shells filled with gunpowder needed a fuse that was either impact triggered ( percussion ) or time delayed. Percussion fuses with a spherical projectile presented
21746-470: The number of propellant charges. Disadvantages include more complexity, slower loading, less safety, less moisture resistance, and the metal cases can still be a material resource issue. In separate loading bagged charge ammunition there are three main components: the fuzed projectile, the bagged charges and the primer. Like separate loading cased charge ammunition, the number of propellant charges can be varied. However, this style of ammunition does not use
21912-460: The ordinary elongated shot of the time. Palliser shot was made of cast iron , the head being chilled in casting to harden it, using composite molds with a metal, water cooled portion for the head. Britain also deployed Palliser shells in the 1870s–1880s. In the shell, the cavity was slightly larger than in the shot and was filled with 1.5% gunpowder instead of being empty, to provide a small explosive effect after penetrating armour plating. The shell
22078-477: The physical limitations of conventional firearms: "the limits of gas expansion prohibit launching an unassisted projectile to velocities greater than about 1.5 km/s and ranges of more than 50 miles [80 km] from a practical conventional gun system." Current railgun technologies necessitate a long and heavy barrel, but a railgun's ballistics far outperform conventional cannons of equal barrel lengths. Railguns can also deliver area of effect damage by detonating
22244-402: The powder fuse was subject to considerable trial and error. Early powder-burning fuses had to be loaded fuse down to be ignited by firing or a portfire or slow match put down the barrel to light the fuse. Other shells were wrapped in bitumen cloth, which would ignite during the firing and in turn ignite a powder fuse. Nevertheless, shells came into regular use in the 16th century, for example,
22410-449: The projectile. As rail/projectile clearances increase, arcing develops, which causes rapid vaporization and extensive damage to the rail surfaces and the insulator surfaces. This limited some early research railguns to one shot per service interval. The inductance and resistance of the rails and power supply limit the efficiency of a railgun design. Currently different rail shapes and railgun configurations are being tested, most notably by
22576-410: The railgun behave as an electromagnet , creating a magnetic field inside the loop formed by the length of the rails up to the position of the armature. In accordance with the right-hand rule , the magnetic field circulates around each conductor. Since the current is in the opposite direction along each rail, the net magnetic field between the rails ( B ) is directed at right angles to the plane formed by
22742-432: The rails are mounted firmly, they cannot move. By definition, if a current of one ampere flows in a pair of ideal infinitely long parallel conductors that are separated by a distance of one meter, then the magnitude of the force on each meter of those conductors will be exactly 0.2 micro-newtons. Furthermore, in general, the force will be proportional to the square of the magnitude of the current and inversely proportional to
22908-452: The recoil force acts on the breech closure just as in a chemical firearm. The rails also repel themselves via a sideways force caused by the rails being pushed by the magnetic field, just as the projectile is. The rails need to survive this without bending and must be very securely mounted. Currently published material suggests that major advances in material science must be made before rails can be developed that allow railguns to fire more than
23074-432: The regions of Eastern Europe, Western Asia, Northern Africa, and Eastern Asia. Most common calibers have been in use for many decades, since it is logistically complex to change the caliber of all guns and ammunition stores. The weight of shells increases by and large with caliber. A typical 155 mm (6.1 in) shell weighs about 50 kg (110 lbs), a common 203 mm (8 in) shell about 100 kg (220 lbs),
23240-507: The second Austrian guncotton factory exploded. After the Stowmarket factory exploded in 1871, Waltham Abbey began production of guncotton for torpedo and mine warheads. In 1884, Paul Vieille invented a smokeless powder called Poudre B (short for poudre blanche —white powder, as distinguished from black powder ) made from 68.2% insoluble nitrocellulose , 29.8% soluble nitrocellusose gelatinized with ether and 2% paraffin. This
23406-515: The shock of firing in conventional artillery . In 1885, based on research of Hermann Sprengel, French chemist Eugène Turpin patented the use of pressed and cast picric acid in blasting charges and artillery shells . In 1887, the French government adopted a mixture of picric acid and guncotton under the name Melinite . In 1888, Britain started manufacturing a very similar mixture in Lydd , Kent, under
23572-476: The spherical shell into its modern recognizable cylindro-conoidal form. This shape greatly improved the in-flight stability of the projectile and meant that the primitive time fuzes could be replaced with the percussion fuze situated in the nose of the shell. The new shape also meant that further, armour-piercing designs could be used. During the 20th century, shells became increasingly streamlined. In World War I, ogives were typically two circular radius head (crh) –
23738-432: The stresses involved in firing this sort of device require an extremely heat-resistant material. Otherwise the rails, barrel, and all equipment attached would melt or be irreparably damaged. In practice, the rails used with most railgun designs are subject to erosion from each launch. Additionally, projectiles can be subject to some degree of ablation , and this can limit railgun life, in some cases severely. Railguns have
23904-418: The term "shell", from the casing, came to mean the entire munition . In a gunpowder-based shell, the casing was intrinsic to generating the explosion, and thus had to be strong and thick. Its fragments could do considerable damage, but each shell broke into only a few large pieces. Further developments led to shells which would fragment into smaller pieces. The advent of high explosives such as TNT removed
24070-495: The tests, the projectile was able to travel an additional 7 kilometres (4.3 mi) downrange after penetrating a 1 ⁄ 8 inch (3.2 mm) thick steel plate. The company hopes to have an integrated demo of the system by 2016 followed by production by 2019, pending funding. Thus far, the project is self-funded. In October 2013, General Atomics unveiled a land based version of the Blitzer railgun. A company official claimed
24236-453: The time it takes for the projectile to reach its target destination. During the early 1990s, the U.S. Army dedicated more than $ 150 million into electric gun research. At the University of Texas at Austin Center for Electromechanics, military railguns capable of delivering tungsten armor-piercing bullets with kinetic energies of nine megajoules (9 MJ) have been developed. Nine megajoules
24402-566: The total system volume and mass needed to accommodate such a power supply and its primary fuel can become less than the required total volume and mass for a mission equivalent quantity of conventional propellants and explosive ammunition. Arguably such technology has been matured with the introduction of the Electromagnetic Aircraft Launch System (EMALS) (albeit that railguns require much higher system powers, because roughly similar energies must be delivered in
24568-459: The train at a high speed, as an alternative to using a lift hill . The United States Navy is also using linear induction motors in the Electromagnetic Aircraft Launch System that will replace traditional steam catapults on future aircraft carriers. They have also been suggested for use in spacecraft propulsion . In this context they are usually called mass drivers . The simplest way to use mass drivers for spacecraft propulsion would be to build
24734-450: The usage to only the sturdiest of payloads. Alternatively, very long rail systems may be used to reduce the required launch acceleration. Railguns are being researched as weapons with projectiles that do not contain explosives or propellants, but are given extremely high velocities: 2,500 m/s (8,200 ft/s) (approximately Mach 7 at sea level) or more. For comparison, the M16 rifle has
24900-528: The weight and size of the projectiles and propelling charges can be more than a gun crew can manage. Advantages include easier handling for large rounds, decreased metal usage, while range and velocity can be varied by using more or fewer propellant charges. Disadvantages include more complexity, slower loading, less safety and less moisture resistance. Extended-range shells are sometimes used. These special shell designs may be rocket-assisted projectiles (RAP) or base bleed (BB) to increase range. The first has
25066-462: The weight of their shells (see below). Explosive rounds as small as 12.7 x 82 mm and 13 x 64 mm have been used on aircraft and armoured vehicles, but their small explosive yields have led some nations to limit their explosive rounds to 20mm (.78 in) or larger. International Law precludes the use of explosive ammunition for use against individual persons, but not against vehicles and aircraft. The largest shells ever fired during war were those from
25232-534: Was Armstrong's gun that was first to see widespread use during the Crimean War. The cast iron shell of the Armstrong gun was similar in shape to a Minié ball and had a thin lead coating which made it fractionally larger than the gun's bore and which engaged with the gun's rifling grooves to impart spin to the shell. This spin, together with the elimination of windage as a result of the tight fit, enabled
25398-407: Was a great explosion the noise whereof was like thunder, audible for more than thirty miles, and the vegetation was scorched and blasted by the heat over an area of more than half a mou . When hit, even iron armour was quite pierced through." Archeological examples of these shells from the 13th century Mongol invasions of Japan have been recovered from a shipwreck. Shells were used in combat by
25564-516: Was able to launch a glider or projectile about 500 meters. A plasma railgun is a linear accelerator and a plasma energy weapon which, like a projectile railgun, uses two long parallel electrodes to accelerate a "sliding short" armature. However, in a plasma railgun, the armature and ejected projectile consists of plasma, or hot, ionized, gas-like particles, instead of a solid slug of material. MARAUDER ( Magnetically Accelerated Ring to Achieve Ultra-high Directed Energy and Radiation ) is, or was,
25730-464: Was adopted for the Lebel rifle. Vieille's powder revolutionized the effectiveness of small guns, because it gave off almost no smoke and was three times more powerful than black powder. Higher muzzle velocity meant a flatter trajectory and less wind drift and bullet drop, making 1000 meter shots practicable. Other European countries swiftly followed and started using their own versions of Poudre B,
25896-540: Was correspondingly slightly longer than the shot to compensate for the lighter cavity. The powder filling was ignited by the shock of impact and hence did not require a fuze. However, ship armour rapidly improved during the 1880s and 1890s, and it was realised that explosive shells with steel had advantages including better fragmentation and resistance to the stresses of firing. These were cast and forged steel. AP shells containing an explosive filling were initially distinguished from their non-HE counterparts by being called
26062-608: Was established in 1993 and has been operated for over 10 years. China is now one of the major players in electromagnetic launchers; in 2012 it hosted the 16th International Symposium on Electromagnetic Launch Technology (EML 2012) at Beijing. Satellite imagery in late 2010 suggested that tests were being conducted at an armor and artillery range near Baotou , in the Inner Mongolia Autonomous Region . The United States military have expressed interest in pursuing research in electric gun technology throughout
26228-630: Was filled with molten iron and was intended to break up on impact with an enemy ship, splashing molten iron on the target. It was used by the Royal Navy between 1860 and 1869, replacing heated shot as an anti-ship, incendiary projectile. Two patterns of incendiary shell were used by the British in World War ;I, one designed for use against Zeppelins. Similar to incendiary shells were star shells, designed for illumination rather than arson. Sometimes called lightballs they were in use from
26394-430: Was invented by Valturio in 1460. The carcass shell was first used by the French under Louis XIV in 1672. Initially in the shape of an oblong in an iron frame (with poor ballistic properties) it evolved into a spherical shell. Their use continued well into the 19th century. A modern version of the incendiary shell was developed in 1857 by the British and was known as Martin's shell after its inventor. The shell
26560-723: Was investigating on the practical applications of linear motors for urban rail with the Japanese Ministry of Land, Infrastructure, Transport and Tourism . In 1988, a successful demonstration was made with the Limtrain at Saitama and influenced the eventual adoption of the linear motor for the Nagahori Tsurumi-ryokuchi Line in Osaka and Toei Line 12 (present-day Toei Oedo Line ) in Tokyo . To date,
26726-522: Was later tested at the U.S. Army Research Laboratory , where it demonstrated a breech efficiency over 50 percent. In 2010, the United States Navy tested a BAE Systems-designed compact-sized railgun for ship emplacement that accelerated a 3.2 kg (7 pound) projectile to hypersonic velocities of approximately 3,390 m/s (7,600 mph; 12,200 km/h; 11,100 ft/s), or about Mach 10, with 18.4 MJ of kinetic energy. It
26892-459: Was not always the case. Some were named after the weights of obsolete projectile types of the same caliber, or even obsolete types that were considered to have been functionally equivalent. Also, projectiles fired from the same gun, but of non-standard weight, took their name from the gun. Thus, conversion from "pounds" to an actual barrel diameter requires consulting a historical reference. A mixture of designations were in use for land artillery from
27058-506: Was still in wide use in World War II . The percentage of shell weight taken up by its explosive fill increased steadily throughout the 20th Century. Less than 10% was usual in the first few decades; by World War II , leading designs were around 15%. However, British researchers in that war identified 25% as being the optimal design for anti-personnel purposes, based on the recognition that far smaller fragments than hitherto would give
27224-690: Was the first time in history that such levels of performance were reached. They gave the project the motto "Velocitas Eradico", Latin for "I, [who am] speed, eradicate"—or in the vernacular, "Speed Kills". An earlier railgun of the same design (32-megajoules) resides at the Dundrennan Weapons Testing Centre in the United Kingdom. Low power, small scale railguns have also made popular college and amateur projects. Several amateurs actively carry out research on railguns. A railgun consists of two parallel metal rails (hence
27390-407: Was to fit existing 12.8 cm FlaK 40 mounts. It was never built. When details were discovered after the war it aroused much interest and a more detailed study was done, culminating with a 1947 report which concluded that it was theoretically feasible, but that each gun would need enough power to illuminate half of Chicago. During 1950, Sir Mark Oliphant , an Australian physicist and first director of
27556-650: Was used by the United States beginning in 1906. Germany began filling artillery shells with TNT in 1902. Toluene was less readily available than phenol, and TNT is less powerful than picric acid, but the improved safety of munitions manufacturing and storage caused the replacement of picric acid by TNT for most military purposes between the World Wars. However, pure TNT was expensive to produce and most nations made some use of mixtures using cruder TNT and ammonium nitrate, some with other compounds included. These fills included Ammonal, Schneiderite and Amatol . The latter
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