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Base Bleed
Base bleed is a system used on some artillery shells to increase range, typically by about 20–35%. It expels gas into the low pressure area behind the shell to reduce base drag (it does not produce thrust). Since base bleed extends the range by a percentage, it is more useful on longer range artillery where an increase of approximately can be achieved. Until the late 1980s the small gains in range were not considered worthwhile for field artillery. Base bleed shells are becoming more common in units equipped with modern artillery with far greater range than older guns, but are usually only used when the longer range is required, due to their higher cost. Function Most (50–60%) of the drag on an artillery shell comes from the nose of the shell, as it pushes the air out of its way at supersonic speeds. Shaping the shell properly can reduce this drag. However, another powerful source of drag is the low-pressure area left behind the shell due to its blunt base. Base blee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Artillery
Artillery is a class of heavy military ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during sieges, and led to heavy, fairly immobile siege engines. As technology improved, lighter, more mobile field artillery cannons developed for battlefield use. This development continues today; modern self-propelled artillery vehicles are highly mobile weapons of great versatility generally providing the largest share of an army's total firepower. Originally, the word "artillery" referred to any group of soldiers primarily armed with some form of manufactured weapon or armor. Since the introduction of gunpowder and cannon, "artillery" has largely meant cannons, and in contemporary usage, usually refers to shell-firing guns, howitzers, and mortars (collectively called ''barrel artillery'', ''cannon artillery'', ''gun artillery'', or - a layman t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drag (physics)
In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers (or surfaces) or between a fluid and a solid surface. Unlike other resistive forces, such as dry friction, which are nearly independent of velocity, the drag force depends on velocity. Drag force is proportional to the velocity for low-speed flow and the squared velocity for high speed flow, where the distinction between low and high speed is measured by the Reynolds number. Even though the ultimate cause of drag is viscous friction, turbulent drag is independent of viscosity. Drag forces always tend to decrease fluid velocity relative to the solid object in the fluid's path. Examples Examples of drag include the component of the net aerodynamic or hydrodynamic force acting opposite to the di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drag (physics)
In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers (or surfaces) or between a fluid and a solid surface. Unlike other resistive forces, such as dry friction, which are nearly independent of velocity, the drag force depends on velocity. Drag force is proportional to the velocity for low-speed flow and the squared velocity for high speed flow, where the distinction between low and high speed is measured by the Reynolds number. Even though the ultimate cause of drag is viscous friction, turbulent drag is independent of viscosity. Drag forces always tend to decrease fluid velocity relative to the solid object in the fluid's path. Examples Examples of drag include the component of the net aerodynamic or hydrodynamic force acting opposite to the di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Generator
A gas generator is a device for generating gas. A gas generator may create gas by a chemical reaction or from a solid or liquid source, when storing a pressurized gas is undesirable or impractical. The term often refers to a device that uses a rocket propellant to generate large quantities of gas. The gas is typically used to drive a turbine rather than to provide thrust as in a rocket engine. Gas generators of this type are used to power turbopumps in rocket engines, in a gas-generator cycle. It is also used by some auxiliary power units to power electric generators and hydraulic pumps. Another common use of the term is in the industrial gases industry, where gas generators are used to produce gaseous chemicals for sale. For example, the chemical oxygen generator, which delivers breathable oxygen at a controlled rate over a prolonged period. During World War II, portable gas generators that converted coke to producer gas were used to power vehicles as a way of alleviat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrust
Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that system. The force applied on a surface in a direction perpendicular or normal to the surface is also called thrust. Force, and thus thrust, is measured using the International System of Units (SI) in newtons (symbol: N), and represents the amount needed to accelerate 1 kilogram of mass at the rate of 1 meter per second per second. In mechanical engineering, force orthogonal to the main load (such as in parallel helical gears) is referred to as static thrust. Examples A fixed-wing aircraft propulsion system generates forward thrust when air is pushed in the direction opposite to flight. This can be done by different means such as the spinning blades of a propeller, the propelling jet of a jet engine, or by ejecting hot gases from a rocket ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swedish National Defence Research Institute
Swedish National Defence Research Institute ( sv, Försvarets forskningsanstalt, FOA) was a Swedish government agency in defense research existing from 1945 to 31 December 2000. It was amalgamated with the National Aeronautical Research Institute (FFA) into the Swedish Defence Research Agency (FOI) which was established on 1 January 2001. History The National Defence Research Institute (FOA) was established in 1945 (Instruction TS C:II No. 24), and took over operations at the Swedish Armed Forces Chemical Institute (''Försvarsväsendets kemiska anstalt'', FKA), the Military Physics Institute and the Telecommunications Technical Working Group of the Swedish Board of Inventions (''Statens uppfinnarnämnds teletekniska arbetsgrupp'', SUN), that is, essentially all technical and scientific research outside the industry. FOA was organized in three research departments, FOA 1 chemistry/medicine, FOA 2 general physics and FOA 3 telecommunications and an office. In 1959 FOA 4 (nuclear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Defence Materiel Administration (Sweden)
The Swedish Defence Materiel Administration ( sv, Försvarets materielverk, FMV) is a Swedish government agency that reports to the Ministry of Defence. The agency is responsible for the supply of materiel to the Swedish defence organisation. It is located in Stockholm. Director Generals since 1968 *1968–1975: Sten Wåhlin *1974–1982: Ove Ljung *1982–1988: Carl-Olof Ternryd *1988–1995: Per Borg *1995–2005: Birgitta Böhlin *2005–2012: Gunnar Holmgren *2012–2015: Lena Erixon *2015–2016: Dan Ohlsson (acting) *2016–present: Göran Mårtensson Lieutenant General Carl Göran Mårtensson (born 26 May 1960) is a Swedish Army officer. He is currently the Director General of the Swedish Defence Materiel Administration. Career Mårtensson was born in Kristianstad, Sweden. He became a lieute ... See also * Government agencies in Sweden References External links * 1968 establishments in Sweden Defence agencies of Sweden Government agencies established in 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rocket Assisted Projectile
A rocket-assisted projectile (RAP) is a cannon, howitzer, mortar, or recoilless rifle round incorporating a rocket motor for independent propulsion. This gives the projectile greater speed and range than a non-assisted ballistic shell, which is propelled only by the gun's exploding charge. Some forms of rocket-assisted projectiles can be outfitted with a laser-guide for greater accuracy. The German Sturmtiger (1944) used a 380 mm Rocket Propelled Round as its main projectile. These rounds were high explosive shells or shaped charges with a maximum range of 6,000 m. The gun first accelerated the projectile to 45 m/s (150 ft/s), the 40 kg (88 lb) rocket charge then boosted this to about 250 m/s (820 ft/s). Also the German Krupp K5 railway gun of World War 2 used rocket assisted projectiles in the later stages of the war, although it also used conventional artillery projectiles. The North Korean M-1978 / M1989 (KOKSAN) 170mm self-propelled gun can use rocket assisted projecti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerodynamic Drag
In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers (or surfaces) or between a fluid and a solid surface. Unlike other resistive forces, such as dry friction, which are nearly independent of velocity, the drag force depends on velocity. Drag force is proportional to the velocity for low-speed flow and the squared velocity for high speed flow, where the distinction between low and high speed is measured by the Reynolds number. Even though the ultimate cause of drag is viscous friction, turbulent drag is independent of viscosity. Drag forces always tend to decrease fluid velocity relative to the solid object in the fluid's path. Examples Examples of drag include the component of the net aerodynamic or hydrodynamic force acting opposite to the di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
12 Cm Tornautomatpjäs M/70
The 12 cm tornautomatpjäs m/70 ("12 cm automatic turret gun model 1970"), also known as ERSTA (''Ersättning Tungt Artilleri'' or "Replacement Heavy Artillery") was developed to defend vital points like seaports from enemy landing ships, as well as area denial and fire support, even on a nuclear battlefield. Due to political cost-cutting requirements, the number of 12/70 batteries built in Sweden was limited to six. For the same reason, some protection aspects were abandoned. History In the 1960s, the Swedish Coastal Artillery sought to replace several older heavy artillery systems. A study called ERSTA (''Ersättning Tungt Artilleri'' – "Replacement Heavy Artillery") was initiated to ascertain which alternative (conventional artillery, rocket artillery or missiles) would be best for heavy coastal defense. The ERSTA study The ERSTA study was a 1960s Swedish coastal defense study aimed at determining what would become the next heavy coastal defense system. A 120 m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
