Protection Systems For Armoured Fighting Vehicles
An active protection system or APS, protects a tank or other armoured fighting vehicle from incoming fire before it hits the vehicle’s armour. There are two general categories:
Soft kill systems –
These use jamming or decoys to confuse a missile’s guidance system
hard kill systems –
these which attempt to detect and destroy incoming projectiles.
Hard-kill systems are activated when a millimetre-wavelength radar or other sensor detects an incoming projectile. In considerably less than a second, they launch a counter-projectile in an attempt to physically damage or destroy the incoming round. Examples include the TROPHY and Iron Fist from Israel, the Quick Kill system from the United States, and the Russian Drozd and Arena.
NBC Protection Systems
Most MBT’s have a principal NBC protection system and a backup system to allow the crew to continue fighting should they be attacked by Nuclear, Biological or Chemical weapons. The principal NBC protection system provides dry, temperature-controlled, filtered air to the crew compartment and individual crew member air outlets. For the principal NBC system to operate, the crew must have the tank’s engine running. The principal NBC system automatically turns on after starting the engine, and is controlled from the commanders control panel. With the engine running at idle and the gun breech open, the principal NBC system provides roughly a total of 200 cubic feet per minute of filtered air at 35 pounds per square inch (psi).
The four crew outlets receive approximately 18 cfm (AKA cubic feet per minute) of filtered air for their protective masks and air cooled vests. The crew compartment bulk dump receives approximately 128 cfm of filtered air to create a positive pressure in the crew compartment. The positive pressure keeps contaminated air out and forces the smoke produced from firing the main or coax guns out.
The backup system does not produce as much air as the principal NBC system but it does produce enough air to protect the crew when they wear their protective masks, drawing air from outside the tank.