![SO4 Hoe open Web](https://upload.wikimedia.org/wikipedia/commons/5/5d/SO4_Hoe_open_Web.jpg)
A kinetic energy weapon (also known as kinetic weapon, kinetic energy warhead, kinetic warhead, kinetic projectile, kinetic kill vehicle) is a
weapon
A weapon, arm or armament is any implement or device that can be used to deter, threaten, inflict physical damage, harm, or kill. Weapons are used to increase the efficacy and efficiency of activities such as hunting, crime, law enforcement, s ...
based solely on a
projectile
A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found in ...
's
kinetic energy
In physics, the kinetic energy of an object is the energy that 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 stated velocity. Having gained this energy during its accele ...
instead of an
explosive or any other kind of
payload
Payload is the object or the entity which is being carried by an aircraft or launch vehicle. Sometimes payload also refers to the carrying capacity of an aircraft or launch vehicle, usually measured in terms of weight. Depending on the nature of ...
.
The term Hit-to-kill, or kinetic kill, is also used in the military
aerospace
Aerospace is a term used to collectively refer to the atmosphere and outer space. Aerospace activity is very diverse, with a multitude of commercial, industrial and military applications. Aerospace engineering consists of aeronautics and astrona ...
field to describe kinetic energy weapons. It has been used primarily in the
anti-ballistic missiles
An anti-ballistic missile (ABM) is a surface-to-air missile designed to counter ballistic missiles (missile defense). Ballistic missiles are used to deliver nuclear, chemical, biological, or conventional warheads in a ballistic flight trajec ...
(ABM) and
anti-satellite weapons (ASAT) area, but some modern
anti-aircraft missiles are also hit-to-kill. Hit-to-kill systems are part of the wider class of kinetic projectiles, a class that has widespread use in the
anti-tank field.
Typical kinetic energy weapons are blunt projectiles such as
rocks
In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's ...
and
round shot
A round shot (also called solid shot or simply ball) is a solid spherical projectile without explosive charge, launched from a gun. Its diameter is slightly less than the bore of the barrel from which it is shot. A round shot fired from a la ...
s, pointed ones such as
arrow
An arrow is a fin-stabilized projectile launched by a bow. A typical arrow usually consists of a long, stiff, straight shaft with a weighty (and usually sharp and pointed) arrowhead attached to the front end, multiple fin-like stabilizers c ...
s, and somewhat pointed ones such as
bullet
A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. Bullets are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax. Bullets are made in various shapes and co ...
s. Among projectiles that do not contain explosives are those launched from
railgun
A railgun or rail gun is a linear motor device, typically designed as a weapon, that uses electromagnetic force to launch high velocity projectiles. The projectile normally does not contain explosives, instead relying on the projectile's high ...
s,
coilgun
A coilgun, also known as a Gauss rifle, is a type of mass driver consisting of one or more coils used as electromagnets in the configuration of a linear motor that accelerate a ferromagnetic or conducting projectile to high velocity. In almos ...
s, and
mass driver
A mass driver or electromagnetic catapult is a proposed method of non-rocket spacelaunch which would use a linear motor to accelerate and catapult payloads up to high speeds. Existing and contemplated mass drivers use coils of wire energized by e ...
s, as well as
kinetic energy penetrators. All of these weapons work by attaining a high
muzzle velocity, or initial velocity, generally up to
hypervelocity
Hypervelocity is very high velocity, approximately over 3,000 meters per second (6,700 mph, 11,000 km/h, 10,000 ft/s, or Mach 8.8). In particular, hypervelocity is velocity so high that the strength of materials upon impact is v ...
, and
collide with their targets, converting the
kinetic energy
In physics, the kinetic energy of an object is the energy that 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 stated velocity. Having gained this energy during its accele ...
associated with the relative velocity between the two objects into destructive shock waves and heat. Other types of kinetic weapons are accelerated over time by a rocket engine, or by gravity. In either case, it is this kinetic energy that destroys its target.
Basic concept
Kinetic energy
In physics, the kinetic energy of an object is the energy that 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 stated velocity. Having gained this energy during its accele ...
is a function of mass and the velocity of an object. For a kinetic energy weapon in the aerospace field, both objects are moving and it is the
relative velocity
The relative velocity \vec_ (also \vec_ or \vec_) is the velocity of an object or observer B in the rest frame of another object or observer A.
Classical mechanics
In one dimension (non-relativistic)
We begin with relative motion in the classi ...
that is important. In the case of the interception of a
reentry vehicle (RV) from an
intercontinental ballistic missile
An intercontinental ballistic missile (ICBM) is a ballistic missile with a range greater than , primarily designed for nuclear weapons delivery (delivering one or more thermonuclear warheads). Conventional, chemical, and biological weapons c ...
(ICBM) during the terminal phase of the approach, the RV will be traveling at approximately while the interceptor will be on the order of . Because the interceptor may not be approaching head-on, a lower bound on the relative velocity on the order of can be assumed, or converting to SI units, approximately 7150 meters per second.
At that speed, every kilogram of the interceptor will have an energy of:
TNT
Trinitrotoluene (), more commonly known as TNT, more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene, is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reagen ...
has an explosive energy of about 4853
joules
The joule ( , ; symbol: J) is the unit of energy in the International System of Units (SI). It is equal to the amount of work done when a force of 1 newton displaces a mass through a distance of 1 metre in the direction of the force applied. ...
per gram, or about 5 MJ per kilogram. That means the impact energy of the mass of the interceptor is over five times that of a detonating warhead of the same mass.
It may seem like this makes a warhead superfluous, but a hit-to-kill system has to actually hit the target, which may be on the order of half a meter wide, while a conventional warhead releases numerous small fragments that increase the possibility of impact over a much larger area, albeit with a much smaller impact mass. This has led to alternative concepts that attempt to spread out the potential impact zone without explosives. The SPAD concept of the 1960s used a metal net with small steel balls that would be released from the interceptor missile, while the
Homing Overlay Experiment
The Strategic Defense Initiative (SDI), derisively nicknamed the "''Star Wars'' program", was a proposed missile defense system intended to protect the United States from attack by ballistic strategic nuclear weapons ( intercontinental ballisti ...
of the 1980s used a fan-like metal disk.
As the accuracy and speed of modern
surface-to-air missile
A surface-to-air missile (SAM), also known as a ground-to-air missile (GTAM) or surface-to-air guided weapon (SAGW), is a missile designed to be launched from the ground to destroy aircraft or other missiles. It is one type of anti-aircraft syst ...
s (SAMs) improved, and their targets began to include
theatre ballistic missile
A theatre ballistic missile (TBM) is any ballistic missile with a range less than , used against targets " in-theatre". Its range is thus between that of tactical and intermediate-range ballistic missiles. The term is a relatively new one, encompa ...
s (TBMs), many existing systems have moved to hit-to-kill attacks as well. This includes the
MIM-104 Patriot
The MIM-104 Patriot is a surface-to-air missile (SAM) system, the primary of its kind used by the United States Army and several allied states. It is manufactured by the U.S. defense contractor Raytheon and derives its name from the radar compon ...
, whose PAC-3 version removed the warhead and upgraded the
solid fuel rocket
A solid-propellant rocket or solid rocket is a rocket with a rocket engine that uses Rocket propellant#Solid chemical propellants, solid propellants (fuel/oxidizer). The earliest rockets were solid-fuel rockets powered by gunpowder; they were u ...
motor to produce an interceptor missile that is much smaller overall, as well as the
RIM-161 Standard Missile 3
The RIM-161 Standard Missile 3 (SM-3) is a ship-based surface-to-air missile system used by the United States Navy to intercept short- and intermediate-range ballistic missiles as a part of Aegis Ballistic Missile Defense System. Although primari ...
, which is dedicated to the anti-missile role.
Delivery
Some kinetic weapons for targeting objects in
spaceflight
Spaceflight (or space flight) is an application of astronautics to fly spacecraft into or through outer space, either with or without humans on board. Most spaceflight is uncrewed and conducted mainly with spacecraft such as satellites in o ...
are
anti-satellite weapon
Anti-satellite weapons (ASAT) are space weapons designed to incapacitate or destroy satellites for strategic or tactical
purposes. Several nations possess operational ASAT systems. Although no ASAT system has been utilised in warfare, a few ...
s and
anti-ballistic missile
An anti-ballistic missile (ABM) is a surface-to-air missile designed to counter ballistic missiles (missile defense). Ballistic missiles are used to deliver nuclear weapon, nuclear, Chemical weapon, chemical, Bioagent, biological, or conventiona ...
s. Since in order to reach an object in orbit it is necessary to attain an extremely high velocity, their released kinetic energy alone is enough to destroy their target; explosives are not necessary. For example: the energy of
TNT
Trinitrotoluene (), more commonly known as TNT, more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene, is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reagen ...
is 4.6 MJ/kg, and the energy of a kinetic kill vehicle with a closing speed of is 50 MJ/kg. For comparison, 50MJ is equivalent to the kinetic energy of a
school bus
A school bus is any type of bus owned, leased, contracted to, or operated by a school or school district. It is regularly used to transport students to and from school or school-related activities, but not including a charter bus or transit bus ...
weighing 5 metric tons, traveling at .
This saves costly weight and there is no
detonation
Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with ...
to be precisely timed. This method, however, requires direct contact with the target, which requires a more accurate
trajectory
A trajectory or flight path is the path that an object with mass in motion follows through space as a function of time. In classical mechanics, a trajectory is defined by Hamiltonian mechanics via canonical coordinates; hence, a complete traj ...
. Some
hit-to-kill
A kinetic energy weapon (also known as kinetic weapon, kinetic energy warhead, kinetic warhead, kinetic projectile, kinetic kill vehicle) is a weapon based solely on a projectile's kinetic energy instead of an explosive or any other kind of payl ...
warheads are additionally equipped with an explosive directional warhead to enhance the kill probability (e.g. Israeli
Arrow
An arrow is a fin-stabilized projectile launched by a bow. A typical arrow usually consists of a long, stiff, straight shaft with a weighty (and usually sharp and pointed) arrowhead attached to the front end, multiple fin-like stabilizers c ...
missile or U.S.
Patriot PAC-3
The MIM-104 Patriot is a surface-to-air missile (SAM) system, the primary of its kind used by the United States Army and several allied states. It is manufactured by the U.S. defense contractor Raytheon and derives its name from the radar compon ...
).
With regard to anti-missile weapons, the
Arrow missile and
MIM-104 Patriot PAC-2
The MIM-104 Patriot is a surface-to-air missile (SAM) system, the primary of its kind used by the United States Army and several allied states. It is manufactured by the U.S. defense contractor Raytheon and derives its name from the radar compon ...
have explosives, while the
Kinetic Energy Interceptor
The Kinetic Energy Interceptor (KEI) was a planned U.S. missile defense program whose goal was to design, develop, and deploy kinetic energy-based, mobile, ground and sea-launched missiles that could intercept and destroy enemy ballistic missiles ...
(KEI),
Lightweight Exo-Atmospheric Projectile
The Lightweight Exo-atmospheric Projectile (LEAP) is a lightweight miniaturized kinetic kill vehicle designed to destroy incoming ballistic missiles both inside or outside the Earth's atmosphere.Paul Baker, Buster Kelley, Anne Avetissian, ''Li ...
(LEAP, used in
Aegis BMDS), and
THAAD
Terminal High Altitude Area Defense (THAAD), formerly Theater High Altitude Area Defense, is an American anti-ballistic missile defense system designed to shoot down short-, medium-, and intermediate-range ballistic missiles in their termina ...
do not (see
Missile Defense Agency
The Missile Defense Agency (MDA) is the section of the United States government's Department of Defense responsible for developing a layered defense against ballistic missiles. It had its origins in the Strategic Defense Initiative (SDI) which w ...
).
A kinetic projectile can also be dropped from aircraft. This is applied by replacing the explosives of a regular bomb with a non-explosive material (e.g. concrete), for a precision hit with less
collateral damage
Collateral damage is any death, injury, or other damage inflicted that is an incidental result of an activity. Originally coined by military operations, it is now also used in non-military contexts.
Since the development of precision guided ...
. A typical bomb has a mass of and a speed of impact of . It is also applied for training the act of dropping a bomb with explosives. This method has been used in
Operation Iraqi Freedom
{{Infobox military conflict
, conflict = Iraq War {{Nobold, {{lang, ar, حرب العراق (Arabic) {{Nobold, {{lang, ku, شەڕی عێراق (Kurdish languages, Kurdish)
, partof = the Iraq conflict (2003–present), I ...
and the subsequent military operations in
Iraq
Iraq,; ku, عێراق, translit=Êraq officially the Republic of Iraq, '; ku, کۆماری عێراق, translit=Komarî Êraq is a country in Western Asia. It is bordered by Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq ...
by mating concrete-filled training bombs with
JDAM
The Joint Direct Attack Munition (JDAM) is a guidance kit that converts unguided bombs, or "dumb bombs", into all-weather precision-guided munitions. JDAM-equipped bombs are guided by an integrated inertial guidance system coupled to a Global Po ...
GPS
The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...
guidance kits, to attack vehicles and other relatively "soft" targets located too close to civilian structures for the use of conventional
high explosive
An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An exp ...
bombs.
Advantages and disadvantages
The primary advantage kinetic energy weapons is that they minimize the launch mass of the weapon, as no weight has to be set aside for a separate warhead. Every part of the weapon, including the airframe, electronics and even the unburned maneuvering fuel contributes to the destruction of the target. Lowering the total mass of the vehicle offers advantages in terms of the required
launch vehicle
A launch vehicle or carrier rocket is a rocket designed to carry a payload (spacecraft or satellites) from the Earth's surface to outer space. Most launch vehicles operate from a launch pad, launch pads, supported by a missile launch contro ...
needed to reach the required performance, and also reduces the mass that needs to be accelerated during maneuvering.
Another advantage of kinetic energy weapons is that any impact will almost certainly guarantee the destruction of the target. In contrast, a weapon using a
blast fragmentation warhead will produce a large cloud of small fragments that will not cause as much destruction on impact. Both will produce effects that can easily be seen at long distance using
radar
Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...
or
infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
detectors, but such a signal will generally indicate complete destruction in the case of a kinetic energy weapons while the fragmentation case does not guarantee a "kill".
The main disadvantage of the kinetic energy weapons is that they require extremely high accuracy in the guidance system, on the order of .
See also
*
Hellfire R9X
*
Terminal ballistics
Terminal ballistics (also known as wound ballistics) is a sub-field of ballistics concerned with the behavior and effects of a projectile when it hits and transfers its energy to a target.
Bullet design (as well as the velocity of impact) larg ...
*
Exoatmospheric Kill Vehicle
The Exoatmospheric Kill Vehicle (EKV) is the Raytheon-manufactured interceptor component with subcontractor Aerojet of the U.S. Ground-Based Midcourse Defense (GMD), part of the larger National Missile Defense system.
The EKV is boosted to an ...
Explanatory notes
References
Bibliography
*
*
External links
*{{Commonscatinline
Anti-ballistic missiles
Projectiles
Collision