The
Small Arms Protective Insert (
SAPI) is a
ceramic plateCeramic plates are commonly used as inserts in soft ballistic vests. Most ceramic plates used in body armor provide National Institute of Justice Type III protection, allowing them to stop rifle bullets. Ceramic plates are a form of composite armor...
fielded by the
US militaryThe United States armed forces are the overall unified military forces of the United States.The history of the United States armed forces dates to 1775, even before the Declaration of Independence marked the establishment of the United States...
. It was first used in the
Interceptor body armorInterceptor is a type of body armor formerly fielded by the U.S. military. It is more effective than traditional bulletproof vests and is the successor to Personnel Armor System for Ground Troops . Materials for Interceptor were developed by DARPA in the 1990s and a contract for production was...
, a bullet resistant vest. It is now also used in the
Improved Outer Tactical VestThe Improved Outer Tactical Vest, or IOTV, is a replacement to the older Interceptor body armor fielded by the United States Army. It is compatible with the Deltoid Axillary protection system, E-SAPI and Side SAPI plates, as well as the interceptor body armor's groin protector...
as well as the
Modular Tactical VestThe Modular Tactical Vest is a new American body armor, originally adopted by the United States Marine Corps in 2006. The MTV was designed as a solution to shortcomings in the current, decade-old Interceptor body armor and was selected after a rigorous proposal and examination process by the...
, in addition to commercially available "plate carriers". The
kevlarKevlar is the registered trademark for a light, strong para-aramid synthetic fiber, related to other aramids such as Nomex and Technora.Developed at DuPont in 1965 by Stephanie Kwolek it was first commercially used in the early 1970s as a replacement for steel in racing tires...
Interceptor vest itself is designed to stop projectiles up to and including 9x19mm Parabellum
submachine gunA submachine gun is a firearm that combines the automatic fire of a machine gun with the cartridge of a pistol, and is usually between the two in weight and size...
rounds, in addition to fragmentation. To protect against higher velocity
rifleA rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...
rounds, SAPI plates are needed.
In May 2005, the
US militaryThe United States armed forces are the overall unified military forces of the United States.The history of the United States armed forces dates to 1775, even before the Declaration of Independence marked the establishment of the United States...
began replacing the standard Small Arms Protective Insert plates with the Enhanced Small Arms Protective Insert (ESAPI).
An ESAPI provides protection from armor piercing bullets, but costs about $600 per plate, 50% more than SAPI plates.
The
Small Arms Protective Insert (
SAPI) is a
ceramic plateCeramic plates are commonly used as inserts in soft ballistic vests. Most ceramic plates used in body armor provide National Institute of Justice Type III protection, allowing them to stop rifle bullets. Ceramic plates are a form of composite armor...
fielded by the
US militaryThe United States armed forces are the overall unified military forces of the United States.The history of the United States armed forces dates to 1775, even before the Declaration of Independence marked the establishment of the United States...
. It was first used in the
Interceptor body armorInterceptor is a type of body armor formerly fielded by the U.S. military. It is more effective than traditional bulletproof vests and is the successor to Personnel Armor System for Ground Troops . Materials for Interceptor were developed by DARPA in the 1990s and a contract for production was...
, a bullet resistant vest. It is now also used in the
Improved Outer Tactical VestThe Improved Outer Tactical Vest, or IOTV, is a replacement to the older Interceptor body armor fielded by the United States Army. It is compatible with the Deltoid Axillary protection system, E-SAPI and Side SAPI plates, as well as the interceptor body armor's groin protector...
as well as the
Modular Tactical VestThe Modular Tactical Vest is a new American body armor, originally adopted by the United States Marine Corps in 2006. The MTV was designed as a solution to shortcomings in the current, decade-old Interceptor body armor and was selected after a rigorous proposal and examination process by the...
, in addition to commercially available "plate carriers". The
kevlarKevlar is the registered trademark for a light, strong para-aramid synthetic fiber, related to other aramids such as Nomex and Technora.Developed at DuPont in 1965 by Stephanie Kwolek it was first commercially used in the early 1970s as a replacement for steel in racing tires...
Interceptor vest itself is designed to stop projectiles up to and including 9x19mm Parabellum
submachine gunA submachine gun is a firearm that combines the automatic fire of a machine gun with the cartridge of a pistol, and is usually between the two in weight and size...
rounds, in addition to fragmentation. To protect against higher velocity
rifleA rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...
rounds, SAPI plates are needed.
ESAPI
In May 2005, the
US militaryThe United States armed forces are the overall unified military forces of the United States.The history of the United States armed forces dates to 1775, even before the Declaration of Independence marked the establishment of the United States...
began replacing the standard Small Arms Protective Insert plates with the Enhanced Small Arms Protective Insert (ESAPI).
An ESAPI provides protection from armor piercing bullets, but costs about $600 per plate, 50% more than SAPI plates. They are produced by
CeradyneCeradyne, Incorporated, is a Costa Mesa, California, USA, manufacturer of ceramics products traded on the NASDAQ Stock Market.
In addition to producing ceramic components for industrial processes such as silicon foundries and ceramic fuel pellets for nuclear reactors, Ceradyne researches and...
,
BAE SystemsBAE Systems plc is a British defence, security and aerospace company headquartered in Farnborough, Hampshire, England, that has global interests, particularly in North America through its subsidiary BAE Systems Inc. BAE is the world's second-largest defence contractor and the largest in Europe...
, and ArmorWorks Enterprises.
XSAPI
A call for a next generation plate, to stop even greater velocity threats that the ESAPI plate has been issued by the
US ArmyThe United States Army is the branch of the United States Military responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military and is one of seven uniformed services...
. They have specifically allowed scalar or flexible systems, and are also calling for greater coverage, with less than a pound of additional weight.
Materials and capabilities
The standard plate for the Interceptor body armor is made of
boron carbideBoron carbide is an extremely hard ceramic material used in tank armor, bulletproof vests, and numerous industrial applications...
or
silicon carbideSilicon carbide , also known as carborundum, is a compound of silicon and carbon with a chemical formula SiC. It occurs in nature as the extremely rare mineral moissanite. Silicon carbide powder has been mass-produced since 1893 for use as an abrasive...
ceramicA ceramic is an inorganic, non-metallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
.New ESAPI plates are also made of
boron carbideBoron carbide is an extremely hard ceramic material used in tank armor, bulletproof vests, and numerous industrial applications...
. A SAPI is able to stop up to three rifle
bulletA bullet is a projectile propelled by a firearm, sling, or air gun. A bullet does not contain explosives, but damages the intended target by its impact or penetration...
s of a
caliberThe term caliber designates the inside diameter of a tube, the diameter of a solid wire or rod, or a measurement of the length of a gun relative to its diameter....
up to
7.62x51mm NATOThe 7.62x51mm NATO is a rifle cartridge developed in the 1950s as a standard for small arms among NATO countries. Specifications for the 7.62x51mm NATO cartridge are not identical to the commercial .308 Winchester though they are safely interchangeable....
M80 ball and of a
muzzle velocityA gun's muzzle velocity is the speed at which the projectile leaves the muzzle of the gun. Muzzle velocities range from subsonic for some pistols to more than 1,800 m/s for tank guns firing kinetic energy penetrator ammunition. The latter velocity is close to the limit achievable with chemical...
up to 838 m/s (2,750 ft/s). The ceramic plate is backed with a shield made of Spectra, a material up to 40% stronger than
KevlarKevlar is the registered trademark for a light, strong para-aramid synthetic fiber, related to other aramids such as Nomex and Technora.Developed at DuPont in 1965 by Stephanie Kwolek it was first commercially used in the early 1970s as a replacement for steel in racing tires...
.
The standard plates are rated as NIJ III when used alone and NIJ IV when backed by the soft armor of the OTV.
Sizes & Weights
SAPI plates meant for body armor come in front and back plates which are identical, and smaller side plates. The front and back plates come in five sizes. Their dimensions are the following:
Front and back SAPI plates:
- Extra Small - 1.27kg (2.8lb) | .184 x .292 m (7.25 x 11.5 in)
- Small - 1.59kg (3.5lb) | .222 x .298 m (8.75 x 11.75 in)
- Medium - 1.82kg (4.0lb) | .241 x .318 m (9.5 x 12.5 in)
- Large - 2.09kg (4.6lb) | .260 x .337 m (10.12 x 13.25 in)
- Extra Large 2.40kg (5.3lb) | .280 x .356 m (11 x 14 in)
ESAPI plates are the same size but slightly greater in weight.
- Extra Small - 1.70 kg (3.75 lb)
- Small - 2.08 kg (4.60 lb)
- Medium - 2.50 kg (5.50 lb)
- Large - 2.85 kg (6.30 lb)
- Extra Large - 3.25 kg (7.20 lb)
Torso side plates are as follows:
- 1 kg (2.3 lb) | .15 x .2 m (6 x 8 in)
Physics
The mechanism of effect lies in absorbing and dissipating the projectile's
kinetic energyThe kinetic energy of an object is the extra energy which it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its current velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its...
in local shattering of the ceramic plate and blunting the bullet material on the hard ceramic. The Spectra backing then spreads the energy of the impact to larger area and stops the fragments, preventing injury to the wearer.
The same principle is used for the ceramic tiles used for the armored cockpits of some military airplanes, and the anti-
spallationIn general, spallation is a process in which fragments of material are ejected from a body due to impact or stress. In nuclear physics, it is the process in which a heavy nucleus emits a large number of nucleons as a result of being hit by a high-energy particle, thus greatly reducing its atomic...
liners used in modern armored personnel carriers.