Dictionary and translator for handheld
New : sensagent is now available on your handheld
A windows (pop-into) of information (full-content of Sensagent) triggered by double-clicking any word on your webpage. Give contextual explanation and translation from your sites !
With a SensagentBox, visitors to your site can access reliable information on over 5 million pages provided by Sensagent.com. Choose the design that fits your site.
Improve your site content
Add new content to your site from Sensagent by XML.
Crawl products or adds
Get XML access to reach the best products.
Index images and define metadata
Get XML access to fix the meaning of your metadata.
Please, email us to describe your idea.
Lettris is a curious tetris-clone game where all the bricks have the same square shape but different content. Each square carries a letter. To make squares disappear and save space for other squares you have to assemble English words (left, right, up, down) from the falling squares.
Boggle gives you 3 minutes to find as many words (3 letters or more) as you can in a grid of 16 letters. You can also try the grid of 16 letters. Letters must be adjacent and longer words score better. See if you can get into the grid Hall of Fame !
Change the target language to find translations.
Tips: browse the semantic fields (see From ideas to words) in two languages to learn more.
||This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2007)|
Armoured fighting vehicles are classified according to their intended role on the battlefield and characteristics. This classification is not absolute; at different times different countries will classify the same vehicle in different roles. For example, armoured personnel carriers were generally replaced by infantry fighting vehicles in a very similar role, but the latter has some capabilities lacking in the former.
Successful general-purpose armoured fighting vehicles often also serve as the base of a whole family of specialised vehicles, for example, the M113 and MT-LB tracked carriers, and the MOWAG Piranha wheeled AFV.
The first AFVs were armoured cars, dating back virtually to the invention of the motor car. Such vehicles were largely used as scouting vehicles, and were armoured to protect the crew. The development of the AFV continued into World War I, when the tracked tank was introduced on the Western Front - a machine that was armoured because it was specifically designed to be fired upon. The tank proved highly successful, and as technology improved the tank became a weapon that could cross large distances at much higher speeds than supporting infantry and artillery. The need to provide the units that would fight alongside the tank led to the development of the wide range of AFVs that exist today, with most armies having vehicles to carry infantry, artillery and anti-aircraft weaponry by the end of World War II. Most modern AFVs are superficially similar in design to their World War II counterparts, with significantly better armour, weapons, engines and suspension - however with an increase in the capacity of transport aircraft allowing AFVs to be practically transported by air, many armies are replacing some or all of their traditional heavy vehicles with lighter airmobile versions, often with wheels instead of tracks.
|This section requires expansion.|
The level of armour protection between AFVs varies greatly - a main battle tank will normally be designed to take hits from other tank guns and anti-tank missiles, whilst light reconnaissance vehicles are often only armoured "just in case". Whilst heavier armour provides better protection, it makes vehicles less mobile (for a given engine power), limits its air-transportability, increases cost, uses more fuel and may limit the places it can go - for example, many bridges may be unable to support the weight of a main battle tank. A trend toward composite armour is taking place in place of steel - composites are stronger for a given weight, allowing the tank to be lighter for the same protection as steel armour, or better protected for the same weight. Armour is being supplemented with active protection systems on a number of vehicles, allowing the AFV to protect itself from incoming projectiles.
The level of protection also usually varies considerably throughout the individual vehicle too, depending on the role of the vehicle and the likely direction of attack. For example, a main battle tank will usually have the heaviest armour on the hull front and the turret, lighter armour on the sides of the hull and the thinnest armour on the top and bottom of the tank. Other vehicles - such as the MRAP family - may be primarily armoured against the threat from IEDs and so will have heavy, sloped armour on the bottom of the hull.
Weaponry varies by a very wide degree between AFVs - lighter vehicles for infantry carrying, reconnaissance or specialist roles may have only a machine gun for self-defence (or no armament at all), whereas heavy self propelled artillery will carry large guns, mortars or rocket launchers. These weapons may be mounted on a pintle, affixed directly to the vehicle or placed in a turret or cupola.
The greater the recoil a weapon on an AFV is, the larger the turret ring needs to be. A larger turret ring necessitates a larger vehicle. To avoid listing to the side, turrets are usually located at the centre of the vehicle on vehicles that are capable of amphibious operations.
Turret stabilization is an important capability because it enables firing on the move and prevents crew fatigue.
The tank is an all terrain AFV designed primarily to engage enemy forces by the use of direct fire in the frontal assault role. Though several configurations have been tried, particularly in the early experimental days of tank development, a standard, mature design configuration has since emerged to a generally accepted pattern. This features a main artillery gun, mounted in a fully rotating turret atop a tracked automotive hull, with various additional machine guns throughout.
Philosophically, the tank is, by its very nature, an offensive weapon. Being a protective encasement with at least one gun position, it is essentially a pillbox or small fortress (though these are static fortifications of a purely defensive nature) that can move toward the enemy - hence its offensive utility.
Historically, tanks are divided into 3 categories: Light Tanks (small, thinly armoured, weakly gunned, but highly mobile tanks intended for the armoured reconnaissance role), Medium Tanks (mid-sized, adequately armoured, respectably gunned, fairly mobile tanks intended to provide an optimum balance of characteristics for manoeuvre combat, primarily against other tanks), and Heavy Tanks (large, thickly armoured, powerfully gunned, but barely mobile tanks intended for the breakthrough role against fortified lines, particularly in support of infantry formations). Other designations (such as Cavalry Tank, Cruiser Tank, and Infantry Tank) have been used by various countries to denote similar roles.
A modern main battle tank incorporates advances in automotive, artillery, and armour technology to combine the best characteristics of the historic medium and heavy tanks into a single, all around type. It is distinguished by its high level of firepower, mobility and armour protection relative to other vehicles of its era. It can cross comparatively rough terrain at high speeds, but is fuel, maintenance, and ammunition-hungry which makes it logistically demanding. It has the heaviest armour of any vehicle on the battlefield, and carries a powerful weapon that may be able to engage a wide variety of ground targets. It is among the most versatile and fearsome weapons on the battlefield, valued for its shock action against other troops and high survivability, although it can be still be vulnerable to anti-tank weapons.
The military's armoured car is a wheeled armoured vehicle, lighter than other armoured fighting vehicles, primarily being armoured and/or armed for self-defence of the occupants. Other multi-axled wheeled military vehicles can be quite large, and actually be superior to some smaller tracked vehicles in terms of armour and armament. They usually do not have attached weaponry. Armoured cars are often used in military marches and processions, or for the escorting of important figures.
Armoured personnel carriers are intended to carry infantry quickly and relatively safely to point where they are deployed. In 1918, the British Mk V tank was capable of carrying a small number of troops and in 1944, the Canadian general Guy Simonds ordered the conversion of redundant armoured vehicles to carry troops (generically named "Kangaroos"). This proved highly successful, even without training, and the concept was widely used in the 21st Army Group. Post-war, specialised designs were built, culminating in the Soviet BTR-60 and US M113.
An infantry fighting vehicle (IFV) is an armoured personnel carrier which can provide significant fire support. The first IFV was the Soviet BMP-1, which surprised western intelligence analysts when it appeared in a military parade in 1967.
Modern IFVs are well-armed infantry carriers, differencing from earlier APCs by their heavier armament allowing them to give direct-fire support during an assault. Many also have firing ports allowing the infantry to fire personal weapons while mounted and improved armour. They are typically armed with a twenty millimetre or larger autocannon, and possibly with ATGMs. IFVs are usually tracked, but some wheeled vehicles fall into this category, too.
Specially-equipped IFVs have taken on some of the roles of light tanks; they are used by reconnaissance organizations, and light IFVs are used by airborne units which must be able to fight without the heavy firepower of tanks.
Self-propelled artillery vehicles give mobility to artillery. Within the term are covered self-propelled guns (or howitzers) and rocket artillery. They are highly mobile, usually based on caterpillar track carrying either a large howitzer or other field gun or alternatively a mortar or some form of rocket or missile launcher. They are usually used for long-range indirect bombardment support on the battlefield.
In the past, self-propelled artillery has included direct fire vehicles such as assault guns and tank destroyers. These have been heavily armoured vehicles, the former providing close fire-support for infantry and the latter acting as specialized anti-tank vehicles.
Modern self-propelled artillery vehicles may superficially resemble tanks, but they are generally lightly armoured, too lightly to survive in direct-fire combat. However, they protect their crews against shrapnel and small arms and are therefore usually included as armoured fighting vehicles. Many are equipped with machine guns for defence against enemy infantry.
The key advantage of self-propelled over towed artillery is that it can be brought into action much faster. Before the towed artillery can be used, it has to stop, unlimber and set up the guns. To move position, the guns must be limbered up again and brought — usually towed — to the new location. By comparison self-propelled artillery can stop at a chosen location and begin firing almost immediately, then quickly move on to a new position. This ability is very useful in a mobile conflict and particularly on the advance.
Conversely, towed artillery was and remains cheaper to build and maintain. It is also lighter and can be taken to places that self-propelled guns cannot reach, so despite the advantages of the self-propelled artillery, towed guns remain in the arsenals of many modern armies.
|Wikimedia Commons has media related to: Armoured vehicles|
|Wikimedia Commons has media related to: Armored fighting vehicles|