Missile launcher

BGM-71 TOW, a tripod-mounted infantry ATGM system.

A missile launcher is a weapon which fires a self-powered guided projectile. It is distinct from a rocket launcher, which fires a self-powered unguided projectile, though in less formal use the terms are often treated as interchangeable. Infantry guided missiles are typically either launched rested on top of the gunner's shoulder, or from a tripod or similar mounting.

History

Nord Aviation SS.10, the first widely-produced man-portable missile system.

The fundamentals of guided missile research date back to the first experiments in radio control in the last decade of the 19th century. By the 1930s, radio control was a sufficiently mature technology that the Soviet military had already fielded remote controlled "teletanks" in combat, while the British Royal Navy employed full-sized remote-controlled Tiger Moth biplanes as gunnery targets. The first weapons to be radio-controlled were naval torpedoes, with the first examples demonstrated in 1909.

Research in applying this technology to the control of missiles and bombs began in the 1930s with the first prototype systems developed during the closing years of the Second World War. However, missile systems were restricted to vehicle use until the late 1950s due to the challenge of miniaturizing a guidance system to the point infantry could reasonably carry it. The advent of the transistor was a great step forward in this regard. The first infantry missile systems still used missiles too large for an enclosed gun-like launcher, instead being launched from a portable firing rail or their own carrying box.

The first such system to be issued in quantity was the French Nord Aviation SS.10 (Sol-Sol, "Surface to Surface"), a box-launched system. This was based on WW2 German work on a rail-launched wire-guided MCLOS ATGM for aircraft called the Ruhrstahl X-7. This system entered service with the French military in 1955, with the improved SS.11 entering service a year later: however, an infantry version of the latter as not produced until 1962.

Another French box-launched system, ENTAC (ENgin Téléguidé Anti-Char, "Remote controlled engine, anti-tank"), entered service in 1957. The US military adopted both the SS.10 (on a limited basis) and ENTAC, under the designations MGM-21A and MGM-32A.

9M14 Malyutka (AT-3 Sagger) missile assembled on 9P111 carrying case and launch unit, with firing cable.

The Soviet Union acquired examples of these systems, along with the Swiss Cobra ATGM that had entered service in 1957. The Kolomna Machine Design Bureau, who had already built the 3M6 Shmel (Шмель, "Bumblebee," NATO reporting name AT-1 Snapper) vehicle-mounted ATGM, were directed to produce a similar man-portable MCLOS system. In 1963 they produced the first variant of the 9M14 Malyutka (Малютка, "Little One" NATO reporting name AT-3 Sagger) anti-tank missile, one of the most widely-produced ATGMs of all time.

The US military began studies of a second-generation guidance system at Redstone Arsenal starting in January 1957, quickly settling on the idea of a tube-launched, optically tracked, wire guided missile, a concept described by the acronym TOW. Three roles were identified for new ATGM systems, heavy antitank weapon (HAW), a crew-served support weapon to replace SS.10, ENTAC and the M40 recoilless rifle, medium antitank weapon (MAW), a more portable infantry system to replace the M67 recoilless rifle, and combat vehicle weapon system (CVWS), a missile that could be fired from either a tube launcher or a closed-breech gun launcher.

Types

Launching of an FIM-92 Stinger MANPADS.

While there are many types of guided missile system, infantry systems typically fall into the following two categories:

ATGM

An Anti-Tank Guided Missile system is designed to engage ground-based armored vehicles. Infantry ATGM systems usually subdivide into "portable" and "heavy," the latter being somewhat analogous to heavy machine guns in their employment and limitations. Due to the requirement to carry a powerful hollow-charge or explosively formed penetrator warhead, they are not manoeuvrable enough to attack fixed-wing aircraft, though they are often suitable for attacking helicopters.

MANPADS

A MAN Portable Air Defense System is an infantry missile launcher designed to engage aircraft. They are typically not suited to engaging vehicles due to their use of fragmentation warheads, though a few examples have a limited dual-purpose functionality due to using kinetic penetrators or hollow charge warheads.

Launch modes and backblast

Example of a backblast danger area diagram: this one is for the FGM-148 Javelin.

As with rocket systems, missiles are described as having one of two launch modes, either hot/hard launch, where the main booster fires immediately, or a cold/soft launch where a smaller launch motor fires to eject the missile from its casing, with the main booster firing after a short delay allows the missile to clear its launch site. The "cold" term is usually applied to silo and VLS launched missiles rather than infantry systems. Modern infantry missile systems use soft launch exclusively.

"Soft" launch is only in relative terms, and such missiles still have significant areas behind them where potentially lethal blast and overpressure are generated by the firing of the launch motor. All such missiles will also have a "caution zone" extending further than the danger area where the primary backblast may still cause injury by hurling debris. Firing from indoor enclosures usually requires some efforts to be made to sweep up debris, open doors and in some cases even smash holes in walls to prevent harm to the crew or structural damage to the building from overpressure, though some modern launchers are designed to be simpler to fire from confined spaces.

The effects are not confined to physical injury: the use of hearing protection is vital when employing a missile system to avoid permanent deafness.

Guidance

All missile guidance techniques fit into two super-categories, called GOLIS (go onto location in space) and GOT (go onto target). GOLIS guidance, such as inertial and satellite, manoeuvres the missile to a fixed location. It is not typically used on infantry systems, normally being restricted to weapons such as ICBMs and cruise missiles, though some overfly top attack (OTA) missiles like FGM-172A SRAW and MBT LAW use a GOLIS method, namely pre-programming an autopilot using the measured motion of the target as detected by the launcher. The missile in this system does not use sensor data to steer itself after launch: rather, the target detection system is only used to detonate the warhead, having no role in guidance.

GOT, on the other hand, tracks a specific target, and so GOT guidance methods are far more commonly used for attacking mobile targets. There are many subtypes of GOT guidance.

Command line-of-sight guidance

Command Line-of-sight (CLOS) guidance is where the sight (called a "tracker" in most such systems) designates a target within its own field of view, remotely directing the missile to the system's sightline. The missile is "commanded" in that it is relayed signals from the tracker, either through trailing command wires (wire-guided missiles) or through a transmission method such as radio. It is the most common guidance mode for anti-tank missiles, and also used on some anti-aircraft missiles.

• MCLOS - Manual command line of sight. No element of the system is automated: the operator must directly steer the missile using a device such as a joystick, while keeping track of both it and the target. This was the first system of missile guidance developed, used with early guided weapons such as the German Wasserfall SAM and Fritz-X glide bomb, and the American AZON guided bomb.
  • TV guidance - Television guidance. Subtype of MCLOS where the operator steers the missile using a camera in its nose rather than by tracking it from their own position.

• SMCLOS - Semi-manual command line of sight. Missile is steered directly, but either missile tracking or target tracking is automated.
• SACLOS - Semi active command line of sight or semi automatic command line of sight. One element of the system is an active beacon or designator and the other is a passive detector that tracks it.
  • IR SACLOS - A thermal detector in the launcher tracks a beacon on the missile's tail, generating course corrections to steer it to the tracker's point of aim.
  • LOSBR - Line of sight beam riding. The launcher aims a conical radar, radio or laser beam at the target created by rapid scanning, with the missile using a sensor in its tail to detect the scanning of the beam, using this information to steer itself into the middle of the cone.

• ACLOS - Automatic command line of sight. Target tracking, missile tracking and guidance are all automated.

Homing systems

Homing guidance systems have the missile generate its own guidance commands, removing the need for a direct connection between launcher and missile. They subdivide into active homing, in which the missile emits energy of some kind and tracks its reflection from the target, semi-active homing in which the missile tracks energy from an active emitter on either its launch platform or a third-party source, and passive homing, where the missile detects energy emitted by the target only.

Active homing requires the missile contain an active emitter, detector, a power supply for both and all the equipment needed to process their signals. The weight and cost restricts active homing to use on air-to-air and anti-ship missiles, and it has yet to be used in any portable system.

In a semi-active homing system, the target is illuminated with a designator, either a radar beam (semi-active radar homing, SARH) or a laser (semi-active laser homing, SALH). A passive detector in the missile's nose detects the reflected energy and generates course corrections to intercept the source. The designator can either originate from the launching platform, or from a third-party designator: in some systems like the SALH Hellfire missile, this allows the weapon to be launched "blind" and acquire a target not within the launching platform's line of sight. This functionality is called lock-on after launch (LOAL).

The most common method of passive homing is contrast detection, where a detector, either visual-range or more often UV or thermal, looks for areas within its field of view that are significantly brighter or darker than their surroundings, generating course corrections to steer towards an anomaly and intercept it. Modern MANPADS often compare the output of IR and UV sensors so as to defeat countermeasures.

Modern tracking systems may assist the contrast detector using some type of tracking gate system, which allows the operator to manually narrow the initial search area: for example, FGM-148 Javelin has the operator draw a box around the desired search area by adjusting track gate markers at its four corners, while designating the target's center of mass with a crosshair.