Active Protection System

From Growing Horizons

The Active Protection Systems are the further development of several old ideas to improve the survivability of a combat vehicle, be it ground or aerospace, adding its protective abilities to those of armor and electromagnetic shielding.

An active protection system is a system designed to prevent line-of-sight guided anti-tank missiles/projectiles from acquiring and/or destroying a target.

Electronic countermeasures that alter the electromagnetic, acoustic or other signature(s) of a target thereby altering the tracking and sensing behavior of an incoming threat (e.g., guided missile) are designated soft-kill measures.

Measures that physically counterattack an incoming threat thereby destroying/altering its payload/warhead in such a way that the intended effect on the target is severely impeded are designated hard-kill measures.

Soft Kill measures

Soft-kill measures are applied when it is expected that a sensor-based weapon system can be successfully interfered with. The threat sensor can be either an artificial one, e.g., a solid-state infrared detector, or the human sensory system (eye and/or ear).

Soft-kill measures generally interfere with the signature of the target to be protected. In the following the term signature refers to the electromagnetic or acoustic signature of an object in either the ultraviolet (wavelength: 0.3–0.4 μm), visual (0.4–0.8 μm), or infrared (0.8 - 14 μm) spectral range as well as cm-radar range (frequency: 2–18 GHz), mmw-radar (35, 94, 144 GHz) and finally sonar range (either 50 Hz – 3 kHz and/or 3–15 kHz).

One or more of the following actions may be taken to provide soft-kill:

  • Reduction of signature
  • Augmentation of signature

Soft-kill countermeasures can be divided into on-board and expendable countermeasures. Whereas on-board measures are fixed on the platform to be protected, expendable measures are ejected from the platform.

Preemptive action of countermeasures is directed to generally prevent lock-on of a threat sensor to a certain target. It is based on altering the signature of the target by either concealing the platform signature or enhancing the signature of the background, thus minimizing the contrast between the two.

Reactive action of countermeasures is directed toward break-lock of a threat already homing in on a certain target. It is based on the tactics of signature imitation, augmentation, or reduction.

Hard Kill Measures

Hard Kill Measures are generally measures taken to actively destroy an incoming projectile this can either be achieved by Reactive Armor or by Anti-Aircraft Weaponry used in an anti-projectile role.

Reactive Armor

Reactive armor is a type of vehicle armor that reacts in some way to the impact of a weapon to reduce the damage done to the vehicle being protected. It is most effective in protecting against shaped charges and specially hardened kinetic energy penetrators. The most common type is explosive reactive armor (ERA), but variants include self-limiting explosive reactive armor (SLERA), non-energetic reactive armor (NERA), non-explosive reactive armor (NxRA), and electric reactive armor. NERA and NxRA modules can withstand multiple hits, unlike ERA and SLERA, but a second hit in exactly the same location may potentially penetrate any of those.

Essentially all anti-armor munitions work by piercing the armor and killing the crew inside, disabling vital mechanical systems, or both. Reactive armor can be defeated with multiple hits in the same place, as by tandem-charge weapons, which fire two or more shaped charges in rapid succession. Without tandem charges, hitting the same spot twice is much more difficult.

Anti-Aircraft/Missile Weaponry

Generally any anti-aircraft/missile can be used to intercept missiles, guided projectiles and dumb projectiles by causing it to detonate by direct kinetic impact, shrapnel or laser impulse.

General Point Defense Platform

While only a single system, such as anti-aircraft kinetic or laser weapons, have been prevalent before the 2190s, the development of large spacecraft classes and the need for a more standardized anti-aircraft/projectile weapon system led to the development of a combined weapon system, the General Point Defense Platform, which can be utilized in ground and aerospace vehicles.

The GPDP is made up of a pair of 35mm Helical Railguns with an internal magazine of up to 2000 35mm fragmentation rounds and a single 5MW solid state 300mn free electron laser with a 30cm aperture. Both weapon systems are combined into the same motive mount,so that they are pointed at the same direction. Additionally, the GPGP contains a compact phased array radar, a low powered lidar and an IR sensor. The latter two make use of the same 30mm aperture as the 5MW laser. Combined with a mostly autonomous control program that can communicate with other GPDP systems via internal or external network links, a series of GPDPs can actively protect most vehicles independently from the main fire control systems.

Being a standardized system, the GPDP integrates with MIL-STD-102343.