In a military context, an unguided rocket is a self-contained unit of ammunition which, when fired at a point or area target, flies to its destination primarily by the energy provided by a rocket motor until the motor exhausts its fuel; see rocket science for the formal analysis of its performance. During its flight, the rocket stays on the preset course using aerodynamic methods, either fin stabilization or spin stabilization. Aerodynamic surfaces, such as the fins (or, in some cases, the overall rocket body) only stabilize; they do not adjust the course to increase the probability of hitting the target.
Rockets are fired from rocket launchers. These fall into two general categories, individual rocket launchers and multiple rocket launchers. The rockets carry a variety of payloads, including high explosive (i.e., blast), blast-fragmentation, various types of armor-piercing, incendiary, chemical, cluster submunition, smoke, electronic jammers, etc. The payload triggers by any of a variety of fuzing methods, using contact fuzes, time fuzes, proximity fuzes, etc.
While they may have a large, visible, and locally dangerous backblast emanating from their engines, rockets are recoilless, and thus rocket launchers can be constructed far more lightly than would be a cannon of equivalent payload, which has to absorb the recoil of the explosion that propels an artillery shell through the barrel and into the open. All modern unguided rockets use solid fuel.
Multiple rocket launchers for artillery missions
Early multiple rocket launchers (MRL) were area-effect weapons; the relative inaccuracy of each rocket was desirable, as it allowed tens of rockets fired from the compact launcher to spread out to blanket an area. The Soviet Katyusha, an advanced version of the German Nebelwerfer were widely deployed in WWII; GRAD rockets began to replace the Kayusha around 1949.
Individual rocket launchers
Launchers for individual rockets fall into two general categories: man-portable for infantry support, and artillery rockets that may come close in accuracy to that of unguided cannon shells. Infantry support rockets are usually direct fire, and most commonly are used against fortifications, buildings, and armored vehicles.
Individual rockets from MRL systems, while inaccurate, could be easily transported and fired from improvised ramps; these are popular with guerrillas. Locally made Qassam rockets, less powerful than a GRAD, are common on the Palestinian border.
Aircraft pod launchers
Toward the end of the Second World War and early Cold War, while there was significant interest in using heavy individual rockets with diameter from 5" to 11" or more, before guided missiles of comparable power was available, there was also significant interest in airborne multiple rocket launchers intended to cover area targets.
Early among these was the 2.75"/70mm U.S. Folding Fin Aircraft Rocket (FFAR), intended both for "shotgun" use against ground and air targets. Due to the lack of recoil, these are especially attractive on helicopters. Canada's CRV-7 series is an evolution of the FFAR, with greater velocity giving greater range and accuracy. Greater velocity also makes gives the weapon kinetic kill useful against harder targets, such as tanks and bunkers. The new propellant is lower-smoke, which makes it more difficult for ground troops to recognize and target the the launcher; while the initial deployment is on CF-18 Hornet and RAF Harrier aircraft, but the low smoke lets the CF fit some of its CH-146 Griffon utility helicopters with CRV-7s. This is now feasible because of the development of low-smoke rocket motors.
Advanced Multiple Rocket Launchers
Advanced multiple rocket launchers, using heavy rockets to blanket an area, are exemplified by the U.S. M270 Multiple Launch Rocket System, which have greater range than 155mm howitzers. They are especially useful in counterbattery fire. While the Gulf War vintage M26 rocket for the M270 is unguided, there has been a strong tendency to introduce guidance for these large rockets; the ATACMS guided missile could always be fired from the M270. M26 and guided M30, and ATACMS missiles used cluster submunitions, tactically effective but with political consequences. An evolution, for example, is the XM31, with a large unitary high explosive payload.
- "Background — CF-18 Ground Attack – CRV-7 Unguided Rocket", Canadian American Strategic Review