This is just some basic information to help people understand tanks. Feel free to add to it.
Caliber= The caliber of the main gun is expressed by L for length- for example 125mm L48. The formula is length of the barrel divided by the size of the round.
Bridge weight/ rail weight. This is the total weight of the tank when a single structure or item must bear it. This is where terms like CL50 or CL 70 bridges come from.
Ground pressure- usually expressed in psi or Kg/cm^2. This is the weight the tank exerts on any one piece of ground square inch or square centimeter. The wider the track, then the wider the "footprint' to spread the tanks weight. This is one reason why the heavy western MBT's like the Abrams and Challenger do not bog down in sand. They have a low ground pressure do to the width and length of the tracks which give the tanks a large foot print. Its also why all tracked vehicles generally do better on soft ground than wheels.
Long Rod Penetrators, and sabots (LRP/ sabots). The LRP is the business part of the APFSDS (Armor Piercing Fin Stabilized Discarding Sabot). The sabot is actually the boot that blows away when the round exits the barrel. Most modern sabots are LRP designs. They use a spool style sabot that looks like a thread spool. The spool keeps the round centered in the barrel and provides the surface for the exhaust gasses to push on. By using a spool style the fins can be smaller and less draggy allowing longer ranged shots before too much energy is lost to effect a penetration. LRP are generally in excess of 600mm long and some are in excess of 830mm long. This length often prevents systems using two piece ammunition from using a LRP. This can be a serious handicap espaecially with older bore riding sabots. A bore riding sabot had larger fins that touch the bore of the barrel and kept the round centered. A simple disc sabot caught the exhaust gases. The large fins limited performance past 1500m and the shorter length limited performance as well.
Kinetic Energy- the force imparted to the target by a LRP's impact. The formula is half mass times velocity squared and is usually expressed in joules. Ke=.5mXv^2=j
TIS Thermal Imaging System
CITV Commanders Independent Thermal Viewer
Hunter-Killer Capability- requires that the commander and gunner each have their own sight so that the commander can hunt and input targets for the gunner to then track and kill.
APS Active protection system. There are two main types- counter measures like electrooptical, laser and IR jamming. And systems that have a hard kill ability to defeat incoming rounds. They can be, but are not always combined together.
HEAT- High Explosive Anti-Tank. A shaped charge round that turns a copper cone into a plug of hyper velocity molten metal.
HEAP High Explosive Armor Piercing- A high explosive round with a hard nose or cap designed to defeat light armor before detonating.
HESH/HEP High Explosive Squash Head/ High Explosive Plastic. These shells use a plastic explosive round that deforms to the target before detonating. The detonation causes high velocity spalling. Not used much any more since modern armor is spaced or layered and spall resistant.
Spall- pieces of metal that flake off the inside surface of a target hit an incoming round. If the impact is big enough the pieces act like machine gun bullets and can shred the crew/passengers, start fires and do other damage.
Anti-Spall liner- usually Kevlar or some other synthetic weave applied to the inside of a vehicle designed to keep spall from reaching the crew/passengers.
pack/ power pack- the engine and transmission of a tank or other armored vehicle.
Coax- a machine gun located along side the main gun to serve as an anti-infantry weapon. Also older coax guns could be used to range with if the machine gun and the main gun had a similar ballistics profile. This has recently come in vogue but in reverse with the US Army's M1A2SEPTUSK. A remote 50 cal heavy machine gun is mounted semi-coaxially above the main gun since both weapons (1200mm APFSDS and 50 cal bullet) have a similar flight path. This lets the gunner use the tanks laser and FCS to great effect in controlling the remote 50 cal.
ERA Explosive Reactive Armor- 2 steel plates with explosive sandwiched between them. When hit by a round the compression detonates the explosive and the plates move inducing shear as well. These combine to disrupt the attack. early ERA was only effective vs HEAT rounds. However, new heavy ERA can also greatly reduce the ability of LRP rounds. A recent trend has been researching non-explosive reactive armors (NxRA, NERA). This system proposes to use rubber instead of explosive and rely more on sheer forces on the side of the penetrator (HEAT plug/ APFSDS)to disrupt the attack.
RHA Rolled Homogeneous Armor- military grade steel armor that is face hardened. The old standby. Rounds are judged by what level of RHA they will penetrate.
RHAe Rolled Homogeneous Armor equivalent. Modern armors like ceramics, composites, applique', alloyed weaves etc are rated by how much protection they offer vs how much RHA would have to be used to reach the same level.
Caliber= The caliber of the main gun is expressed by L for length- for example 125mm L48. The formula is length of the barrel divided by the size of the round.
Bridge weight/ rail weight. This is the total weight of the tank when a single structure or item must bear it. This is where terms like CL50 or CL 70 bridges come from.
Ground pressure- usually expressed in psi or Kg/cm^2. This is the weight the tank exerts on any one piece of ground square inch or square centimeter. The wider the track, then the wider the "footprint' to spread the tanks weight. This is one reason why the heavy western MBT's like the Abrams and Challenger do not bog down in sand. They have a low ground pressure do to the width and length of the tracks which give the tanks a large foot print. Its also why all tracked vehicles generally do better on soft ground than wheels.
Long Rod Penetrators, and sabots (LRP/ sabots). The LRP is the business part of the APFSDS (Armor Piercing Fin Stabilized Discarding Sabot). The sabot is actually the boot that blows away when the round exits the barrel. Most modern sabots are LRP designs. They use a spool style sabot that looks like a thread spool. The spool keeps the round centered in the barrel and provides the surface for the exhaust gasses to push on. By using a spool style the fins can be smaller and less draggy allowing longer ranged shots before too much energy is lost to effect a penetration. LRP are generally in excess of 600mm long and some are in excess of 830mm long. This length often prevents systems using two piece ammunition from using a LRP. This can be a serious handicap espaecially with older bore riding sabots. A bore riding sabot had larger fins that touch the bore of the barrel and kept the round centered. A simple disc sabot caught the exhaust gases. The large fins limited performance past 1500m and the shorter length limited performance as well.
Kinetic Energy- the force imparted to the target by a LRP's impact. The formula is half mass times velocity squared and is usually expressed in joules. Ke=.5mXv^2=j
TIS Thermal Imaging System
CITV Commanders Independent Thermal Viewer
Hunter-Killer Capability- requires that the commander and gunner each have their own sight so that the commander can hunt and input targets for the gunner to then track and kill.
APS Active protection system. There are two main types- counter measures like electrooptical, laser and IR jamming. And systems that have a hard kill ability to defeat incoming rounds. They can be, but are not always combined together.
HEAT- High Explosive Anti-Tank. A shaped charge round that turns a copper cone into a plug of hyper velocity molten metal.
HEAP High Explosive Armor Piercing- A high explosive round with a hard nose or cap designed to defeat light armor before detonating.
HESH/HEP High Explosive Squash Head/ High Explosive Plastic. These shells use a plastic explosive round that deforms to the target before detonating. The detonation causes high velocity spalling. Not used much any more since modern armor is spaced or layered and spall resistant.
Spall- pieces of metal that flake off the inside surface of a target hit an incoming round. If the impact is big enough the pieces act like machine gun bullets and can shred the crew/passengers, start fires and do other damage.
Anti-Spall liner- usually Kevlar or some other synthetic weave applied to the inside of a vehicle designed to keep spall from reaching the crew/passengers.
pack/ power pack- the engine and transmission of a tank or other armored vehicle.
Coax- a machine gun located along side the main gun to serve as an anti-infantry weapon. Also older coax guns could be used to range with if the machine gun and the main gun had a similar ballistics profile. This has recently come in vogue but in reverse with the US Army's M1A2SEPTUSK. A remote 50 cal heavy machine gun is mounted semi-coaxially above the main gun since both weapons (1200mm APFSDS and 50 cal bullet) have a similar flight path. This lets the gunner use the tanks laser and FCS to great effect in controlling the remote 50 cal.
ERA Explosive Reactive Armor- 2 steel plates with explosive sandwiched between them. When hit by a round the compression detonates the explosive and the plates move inducing shear as well. These combine to disrupt the attack. early ERA was only effective vs HEAT rounds. However, new heavy ERA can also greatly reduce the ability of LRP rounds. A recent trend has been researching non-explosive reactive armors (NxRA, NERA). This system proposes to use rubber instead of explosive and rely more on sheer forces on the side of the penetrator (HEAT plug/ APFSDS)to disrupt the attack.
RHA Rolled Homogeneous Armor- military grade steel armor that is face hardened. The old standby. Rounds are judged by what level of RHA they will penetrate.
RHAe Rolled Homogeneous Armor equivalent. Modern armors like ceramics, composites, applique', alloyed weaves etc are rated by how much protection they offer vs how much RHA would have to be used to reach the same level.
