Projectile
A
projectile is any object sent through space by the application of a force. In a general sense, even a
football or
baseball may be considered a projectile, but in practice most projectiles are designed as
weapons.
Arrows,
darts,
spears, and similar weapons are fired using pure mechanical force applied by another solid object; conversely, other weapons use the compression or expansion of gases as their motive force.
Blowguns and
pneumatic rifles use compressed gases, while most other
guns and
firearms utilize expanding gases liberated by sudden chemical reactions.
Light gas guns use a combination of these mechanisms.
Railguns utilize electromagnetic fields to provide a constant acceleration along the entire length of the device, greatly increasing the
muzzle velocity.
Some projectiles provide propulsion during (part of) the flight by means of a
rocket engine or
jet engine. In military terminology, a
rocket is unguided, while a
missile is
guided. Note the two meanings of "rocket": an
ICBM is a missile with rocket engines.
Although blowguns use small darts, most types of guns and firearms hurl
bullets, pellets, or
shot made of a
metal, usually
lead, that are designed to deform and fragment inside a target, causing significant damage. Items like arrows, hand darts, and spears are generally tipped with sharp metallic or lithic artifacts called
projectile points that allow them to more easily penetrate a target, although some types of arrows used for hunting are designed to stun or kill through shock rather than to penetrate.
Projectiles designed to be non-lethal, for example for use against
riots, include
rubber bullets and
flexible baton rounds.
Some projectiles do
not contain an explosive charge (as opposed to projectiles with explosive charge, such as
shells). They are termed
kinetic projectile,
kinetic energy weapon or
kinetic penetrator. The classic kinetic energy weapon is the
bullet. Among projectiles which do not contain explosives are
railguns,
mass drivers, and
kinetic energy penetrators, in addition to smaller weapons such as bullets. All of these weapons work by attaining a high
muzzle velocity (
hypervelocity), and
collide with their objective, releasing
kinetic energy.
Some kinetic weapons for targeting objects in
spaceflight are
anti-satellite weapons and
anti-ballistic missiles. Since they need to attain a high velocity anyway, they can destroy their target with their released kinetic energy alone; explosives are not necessary. Compare the energy of
TNT, 4.6 MJ/kg, to the energy of a kinetic kill vehicle with a closing speed of 10 km/s, which is 50 MJ/kg. This saves costly weight and there is no
detonation to be done at the right time, but on the other hand it requires a more accurate hit.
With regard to anti-missile weapons, the
Arrow missile and
MIM-104 Patriot have explosives, but the KEI, LEAP, and
THAAD being developed do not (see
Missile Defense Agency).
See also
Hypervelocity terminal ballistics,
Exoatmospheric Kill Vehicle (EKV).
A kinetic projectile can be dropped from aircraft. This is applied by replacing the explosives of a regular bomb e.g. by concrete, for a precision hit with less
collateral damage. A typical bomb has e.g. a mass of 900 kg and a speed of impact of 800 km/h (220 m/s). It is also applied for training the act of dropping a bomb with explosives. [
1]
A
kinetic bombardment may involve a projectile dropped from Earth orbit. For a fictional kinetic weapon, see
Relativistic kill vehicle.
See also
Orders of magnitude (speed),
Muzzle velocity.
Ballistics analyses the projectile
trajectory, the forces acting upon the projectile, and the impact that a projectile has on a target. A
guided missile is not called a projectile.
An explosion, whether or not by a weapon, causes the debris to act as multiple high velocity projectiles. An explosive weapon, or device may also be designed to produce many high velocity projectiles by the break-up of its casing, these are correctly termed
fragments.
The term projectile also refers to
weapons or any other objects thrown, shot or otherwise directed to
enemies in video games or computer games.
*
:Category:Projectiles*
Atlatl*
Bow*
Gunpowder*
Impact depth*
Torpedo*
Trajectory of a projectile
