Air-to-Surface Missiles
ALARM
ALARM, or Air-Launched Anti-Radiation Missile was designed to meet British Air Staff Target 1228. ALARM is much lighter than the American HARM, & as a result three rounds can be carried on a single Tornado pylon. The ALARM's advantages over the HARM don't stop there; ALARM can deploy a parachute, which allows the missile to glide slowly in the air. While the parachute is deployed, ALARM searches the area for hostile emitters. Because of the time ALARM spends in the air, the chances are that the enemy will have turned their radars back on after the delivery aircraft has passed over them. This means that the ALARM can detect almost all of the hostile emitters in the area, & prioritise them. When ALARM has selected the most important target it has detected, it jettisons its parachute, its fins flick out, & it homes at high speed onto its target. This advanced feature places ALARM ahead of any other radar-homing missile in the world, & ensures that the missile hits the highest value target in the area.
Exocet
Exocet is probably the most famous ASM in the world, thanks to its success in the Falklands. The AM.39 Exocet is fed with target data before launch, & provided with mid-course guidance. Exocet flies at a speed of Mach 0.93, at a height of only 2.5m (8ft). When the missile gets within range of its target, which can be up to 70km (43.5 miles) away, it turns on its EMD Adac X-band monopulse active radar seeker, & homes in to the target, piercing armour at contact angles of up to 70°.
The Argentine strike on HMS Sheffield shocked the British government into initiating several covert operations to block Argentina's supply of Exocets, including Operation Denial, where a team headed by ex. MI6 agent Anthony Divall posed as arms dealers, leading the Argentines to believe they could be supplied with Exocets by the team. The team managed to stop a delivery of newly-built Exocets from France, & also got Peru to embargo the missile.
Unfortunately for the Royal Navy, the Exocet claimed several kills, including the Atlantic Conveyor. The Atlantic Conveyor was carrying the task-force's Chinook helicopters, only one of which survived. The Exocet's sea-skimming ability proved lethal to the Royal Navy's ships, which had no defence against such a threat. The success of Exocet in the Falklands won the missile large export orders, & prompted several Western nations to provide their ships with defences against sea-skimming threats.
HARM (AGM-88A)
Development of the HARM began in 1972 at the Naval Weapons Center of the US Navy. HARM (High-speed Anti-Radiation Missile) was designed to replace Shrike & Standard ARM (AGM-78). HARM would have to be able to lock-on & be fired before its target could switch-off its emitter, launch countermeasures or take any other sort of action, combine the versatility & low cost of Shrike & the sensitivity & large launch envelope of AGM-78 with a new passive homing system, & also have a much higher flight speed than its two predecessors. In 1974, Texas Instruments was selected as the system integration contractor, assisted by Dalmo-Victor, Hughes, Itek & the Stanford Research Institute (SRI).
A simple Texas Instruments fixed antenna provides HARM with broadband coverage, a low cost autopilot is fitted & a Motorola optical target detector is integrated into the fuzing system for the advanced-design warhead. The HARM can operate in three different modes: Self-protect mode (where the Itek ALR-45 radar detects threats & the launch computer prioritises the threats & uploads the data to the missile, which is then ready to be fired), Pre-briefed mode (where the missile is fired without a lock-on, & acquires a target during flight. If a target cannot be acquired, the missile self-destructs) & Target of Opportunity mode (where the sensitive seeker of the HARM locks-on to an emitter broadcasting on certain frequencies only).
Martel
The Martel (Missile Anti-Radar Television) project was initiated as a result of studies by Hawker-Siddeley Dynamics in the UK, & Nord-Aviation & Matra in France between 1960 & 1963. In September 1964, the British & French governments signed an agreement to develop the missile jointly, & development was split into two types of Martel: Hawker-Siddeley Dynamics developed the the AJ.168 TV guided Martel, & Engins Matra developed the AS.37 anti-radar Martel.
The operator of the AJ.168 Martel acquires a target via the control screen in his cockpit, which is linked to the Marconi Vidicon camera in the nose of the missile. After he has found the target, the operator then locks-on to the target by manually steering a small box over the target on his display. The missile is then fired, & a small under-wing pod on the aircraft receives video signals from the missile & displays it on the screen in the cockpit. The missile's operator steers the missile to the target with a control stick in the cockpit.
The AS.37 has an EMD AD.37 passive radiation seeker with a steerable inverse-Cassegrain aerial. If the rough location of a hostile radar is known, then the AD.37 seeker will search a preset band of frequencies. If it detects enemy radiation during this search, the aerial sweeps through 90° in azimuth to find the hostile emitter's location. When the emitter's location is found, the missile locks-on, launches & homes automatically to the target. If the hostile radar's operating frequency is known, however, a matched aerial & receiver can be fitted to the missile to pinpoint the hostile emitter's position. The missile will then lock-on, launch & home in on its target. The AS.37 will remain locked-on to its target even if the hostile emitter changes frequency (providing that the new frequency remains in the missile's preset band).
Both versions of the Martel have the same warhead, & the AS.37 has a Thompson-CSF proximity fuze. The AS.37 was carried by the SEPECAT Jaguar, Mirage III, Atlantic & Buccaneer; the AJ.168 was only carried by RAF Buccaneers, but Phantoms, Tornadoes & two-seat Jaguars & Harriers could have been converted to carry the missile.
Sea Eagle
Originally designated P3T, the Sea Eagle was developed from the Anglo-French Martel to provide the RAF & Fleet Air Arm with an over-the-horizon fire-&-forget Anti-Ship Missile with active radar, air-breathing propulsion & sea-skimming capability to meet Air staff Requirement 1226. Launch trials began in November 1980, & the Sea Eagle made its first full-range sea-skimming flight in April 1981. In early 1982, a fixed £200 million contract for the production of the missile for the RAF & RN was announced.
Sea Eagle has a virtually identical airframe to that of the Martel, except for the ventral air inlet to feed the Microturbo TRI 60-1 Model 067 turbojet. The missile is guided by what is essentially an autopilot, with an on-board micro-processor storing the targets last known position & velocity. A steady altitude is maintained by the Plessey radar altimeter, which follows a pre-programmed altitude profile.
The Sea Eagle is guided by an advanced active radar seeker made by Marconi, allowing the missile to operate at night & in severe weather conditions, as well as against some of the most powerful & electronically sophisticated targets in the world. Lithium batteries power all of the Sea Eagle's electronics. The Sea Eagle can be carried by most NATO tactical aircraft, & is especially well suited to the Sea Harrier & AV-8B.
Sea Skua
Originally known as project number CL-834 by the Ministry of Defence, the Sea Skua was developed as a replacement to the French-built AS.12, & is considerably more advanced than its predecessor. The Sea Skua is SARH (Semi-Active Radar Homing) guided, & is usually launched by a helicopter, such as the Lynx. The Lynx can carry up to four missiles, which are guided by its Ferranti Seaspray over-water radar. The Lynx's Decca Tans navigation system can combine with ESM cross-bearings to identify & fix the target, backing up the position on the Seaspray display. When the target is locked, a simple GO/ NO GO check is performed, & the missile is then fired. The Sea Skua drops down to one of four pre-selected sea skimming heights (depending on wave state), using a BAe-manufactured TRT radio altimeter to regulate its altitude. When the missile nears the target, a pre-programmed instruction lifts the missile to target acquisition altitude for the Marconi homing head to lock on. The Sea Skua can also be launched from fixed-wing aircraft.
The Sea Skua, even though it is only a tenth as heavy as the Exocet, can destroy ships with up to a 1,000 tonne displacement with one shot, & is capable of crippling the radars & weapons launchers of all known targets. This was proved in the Falklands on the 2nd of May 1982, when two Lynx helicopters ripple-fired a pair of Sea Skuas, Sinking an 800-ton warship & crippling another, despite bad weather & rough seas.
TOW (BGM-71)
TOW (Tube-launched, Optically tracked, Wire-guided) is in widespread use throughout the world, & can be launched from the surface & the air alike. The Army Air Corps is the UK's main user of the missile, the Lynx being used as the launch platform. Hughes Aircraft began development of the missile in 1965 to replace the 106mm recoilless rifle used by the US Army. The first versions of the missile were in infantry form, fired from launchers carried by troops. TOW entered service in 1970, & was used in Vietnam. The missile proved extremely successful, & TOW production was increased greatly. TOW production switched to ER (Extended Range) TOW in 1976, with extended guidance wires.
Next came the M65 air-launched TOW, which equips the US Army & USMC's AH-1 Cobras, & the attack helicopters of several other countries, including the BO 105, A109, A129, 500MD & the UK's own Westland Lynx. All TOW-equipped helicopters can carry two quad-launchers of the missile, & AH-1 Cobras also have TSUs (Telescopic Sight Units). Hughes later developed an MMU (Mast Mounted Sight), which uses the BAe TOW roof sight, but with a TV down-tube from the unit which is mounted on a mast above the main rotor hub of the 500MD attack helicopter.
Production of Improved TOW (I-TOW) began in 1981, which has a long probe to give the missile a 381mm (15in) stand-off distance for improved armour penetration & a new LX14-filled shaped-charge warhead. After I-TOW came TOW 2, which is similar to I-TOW except for a longer probe, a refined warhead & a 30% greater total motor impulse. Both I-TOW & TOW 2 are air-launched.
TOW has been produced in greater numbers than any missile ever. Production of the missile had passed the 300,000 by 1983, the majority of the missiles being sold to US forces, although a significant amount has also been exported to countries such as Canada, Germany, Norway, Pakistan, the UK & even Vietnam.