Projectile

A projectile is any object propelled into space (empty or not) by the exertion of a force. Although a thrown baseball is technically a projectile too, the term more often refers to a weapon..

For details of the mathematics surrounding projectile trajectory, see equations of motion.

Motive force

See also: Projectile motion

Arrows, darts, spears, and similar weapons are fired using pure mechanical force applied by another object; apart from throwing without tools, mechanisms include the catapult, slingshot, and bow.

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 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" (weapon and engine): an ICBM is a missile with rocket engines.

Delivery projectiles

Many projectiles, e.g. shells, may carry an explosive charge or another chemical or biological substance. Aside from explosive payload, a projectile can be designed to cause special damage, e.g. fire (see also early thermal weapons), or poisoning (see also arrow poison).

Kinetic projectiles

See also: Kinetic energy penetrator

A projectile which does not contain an explosive charge nor any other kind of charge is termed kinetic projectile, kinetic energy weapon, kinetic energy warhead, kinetic warhead or kinetic penetrator. Typical kinetic energy weapons are blunt projectiles such as rocks and round shots, pointed ones such as arrows, and somewhat pointed ones such as bullets. Among projectiles which do not contain explosives are those launched from railguns, coilguns, and mass drivers, as well as kinetic energy penetrators. All of these weapons work by attaining a high muzzle velocity (hypervelocity), and collide with their objective, converting their kinetic energy into destructive shock waves and heat.

Some kinetic weapons for targeting objects in spaceflight are anti-satellite weapons and anti-ballistic missiles. 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 is 4.6 MJ/kg, and the energy of a kinetic kill vehicle with a closing speed of 10 km/s is of 50 MJ/kg. This saves costly weight and there is no detonation to be precisely timed. This method, however, requires direct contact with the target, which requires a more accurate trajectory.

With regard to anti-missile weapons, the Arrow missile and MIM-104 Patriot have explosives, while the Kinetic Energy Interceptor (KEI), Lightweight Exo-Atmospheric Projectile (LEAP, see RIM-161 Standard Missile 3), and THAAD do not (see Missile Defense Agency).

See also Hypervelocity terminal ballistics, Exoatmospheric Kill Vehicle (EKV).

A kinetic projectile can also 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 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] This method has been used in Operation Iraqi Freedom and the subsequent military operations in Iraq by mating concrete-filled training bombs with JDAM GPS guidance kits, to attack vehicles and other relatively "soft" targets located too close to civilian structures for the use of conventional high explosive bombs.

A Prompt Global Strike may use a kinetic weapon. A kinetic bombardment may involve a projectile dropped from Earth orbit.

A hypothetical kinetic weapon that travels at a significant fraction of the speed of light, usually found in science fiction, is termed a relativistic kill vehicle (RKV).

Wired projectiles

Some projectiles stay connected by a cable to the launch equipment after launching it:

• for guidance: wire-guided missile (range up to 4000 meters)
• to administer an electric shock, as in the case of a Taser (range up to 10.6 meters); two projectiles are shot simultaneously, each with a cable.
• to make a connection with the target, either to tow it towards the launcher, as with a whaling harpoon, or to draw the launcher to the target, as a grappling hook does.

Typical projectile speeds

See also: Orders of magnitude (speed) and Muzzle velocity

Projectile	Speed (m/s),(km/h)	(ft/s)	(mph)	Kinetic energy = (Mass * Speed^2) / 2
object falling 1 m	4.43 m/s, 15.948 km/h	14.5 ft/s	9.9 mph	9.8 J/kg
object falling 10 m	14 m/s, 50.4 km/h	46 ft/s	31 mph	98 J/kg
thrown club (weapon) (expert thrower)	40 m/s, 144 km/h	130 ft/s	90 mph	800 J/kg
object falling 100 m	45 m/s, 162 km/h	150 ft/s	100 mph	980 J/kg
refined (= flexible) atlatl dart (expert thrower)	45 m/s, 162 km/h	150 ft/s	100 mph	1000 J/kg
80-lb-draw pistol crossbow bolt	58 m/s, 208.8 km/h	190 ft/s	130 mph	1.7 kJ/kg
paintball fired from marker	91 m/s, 327.6 km/h	300 ft/s	204 mph	4.1 kJ/kg
175-lb-draw crossbow bolt	97 m/s, 349.2 km/h	320 ft/s	217 mph	4.7 kJ/kg
air gun pellet 6 mm BB	100 m/s, 360 km/h	328 ft/s	224 mph	5 kJ/kg
rifle bullet 4.5 mm	150 m/s, 540 km/h	492 ft/s	336 mph	11 kJ/kg
air gun pellet (conventional maximum)	244 m/s, 878.4 km/h	800 ft/s	545 mph	29.8 kJ/kg
9x19 mm (bullet of a pistol)	340 m/s, 1224 km/h	1116 ft/s	761 mph	58 kJ/kg
12.7x99 mm (bullet of a heavy machine gun)	800 m/s, 2880 km/h	2625 ft/s	1790 mph	320 kJ/kg
5.56x45 mm (standard bullet used in many assault rifles)	920 m/s, 3312 km/h	3018 ft/s	2058 mph	470 kJ/kg
125x1400 mm (shell of a tank)	1700 m/s, 6120 km/h	5577 ft/s	3803 mph	1.4 MJ/kg
2kg Tungsten Slug (from Experimental Railgun)	3000 m/s, 10800 km/h	9843 ft/s	6711 mph	4.5 MJ/kg
ICBM reentry vehicle	up to 4 km/s	up to 13000 ft/s	up to 9000 mph	up to 8 MJ/kg
projectile of a light gas gun	up to 7 km/s	up to 23000 ft/s	up to 16000 mph	up to 24 MJ/kg
satellite in low earth orbit	8 km/s	26000 ft/s	19000 mph	32 MJ/kg
Exoatmospheric Kill Vehicle	closing speed roughly 10 km/s	~33000 ft/s	~22000 mph	~ 50 MJ/kg
projectile (e.g. space debris) and target both in low earth orbit	closing speed 0 - 16 km/s	~53000 ft/s	~36000 mph	~ 130 MJ/kg

Miscellaneous

Ballistics analyze 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.

Projectile is also the name of an annual anarchist film festival based in Newcastle UK * [2]

See also

• Category:Projectiles
  • Arrow
  • Dart
  • Spear
  • Torpedo
  • Missile
• Atlatl
• Gunpowder
• Impact depth
• Trajectory of a projectile
• Range of a projectile
• Space debris
• Ballistics
• Kinetic bombardment
• Projectile use by living systems

External links

• Projectile Motion Applet