Numerous classes of conventionally-armed air-to-ground munitions (AGMs) are in service. Many are currently being upgraded. New, even higher-performance tactical AGMs are being developed.
Bomb Guidance Kits
Despite the plethora of missiles in modern inventories, aerial bombs remain a major tool of warfare. Unguided gravity bombs have largely been replaced by precision bombs, whereby legacy gravity ordnance is frequently endowed with precision attributes through add-on kits. These kits consist of a sensor and guidance system affixed to the head of the so-called ‘dumb bomb’, and a set of aerodynamic control surfaces attached to the rear.
The Armement Air-Sol Modulaire (AASM; ENG: Modular Air-to-Ground Ordnance) produced by Safran Electronics and Defense is one of the newest bomb guidance kits available. Internationally it is also known as the Highly Agile Modular Munition Extended Range or HAMMER. Introduced in 2007, the all-weather capable AASM is available in various bomb-weight classes (125 kg to 1,000 kg). The modular system can be fitted with a choice of guidance suites including Inertial Navigation System (INS)/ Global Positioning System (GPS), INS/GPS/Infra-Red (IR), or INS/GPS/Semi-Active Laser (SAL). These varied guidance system options make the HAMMER resistant to electronic jamming and Global Navigation Satellite System (GNSS) denial, and (with SAL targeting) permit destruction of moving targets. According to Safran, ongoing technology upgrades continue to enhance performance, versatility and reliability for collaborative and high-intensity operations.
The kit’s integrated propulsion system enables a stand-off range in excess of 70 km. This can be achieved from any deployment altitude, from high to very low. The system’s fire-and-forget capability enables the pilot to program and release up to six bombs simultaneously. Each bomb can be set for either airburst, impact or penetration (impact delay) detonation. Tactical capabilities cover the complete AGM-mission spectrum, including suppression or destruction of enemy air defences (SEAD/DEAD), close-air support (CAS), and engagement of stationary and moving targets. AASM is fully integrated with the Dassault Rafale fighter aircraft, but Safran has developed the Hammer Stand Alone System (HASAS) to permit integration on other aircraft models. The firm also offers integration on light attack fighters as well as transport aircraft. According to Safran, the HAMMER has achieved a 99% success rate in combat.
Ultra-High-Yield Bombs
Very large ‘bunker buster’ and area-effects bombs constitute a small portion of bomb inventories, but stand out due to their size and their dramatic results. The two best known are the GBU-43B Massive Ordnance Air Blast (MOAB) and the GBU-57A/B Massive Ordnance Penetrator (MOP). Operated exclusively by the US Air Force (USAF), they are considered the world’s strongest non-nuclear weapons, and are reserved for exceptional targets.
The GPS-guided MOAB, manufactured by Dynetics, entered service in 2003. A total of 15 were procured. Only one has been used, targeting a tunnel complex in Afghanistan in 2017. The 9 m long weapon weighs 9,800 kg and must be deployed via the cargo ramp of an MC-130 aircraft. It is designed to detonate immediately before impact in order to destroy soft-to-medium surface or near-surface targets. While the blast effect extends some 1,600 m from the point of impact, the weapon’s power also unfolds well in contained environments where the blast energy is channelled, such as a cave or tunnel complex.
In contrast to MOAB, the Boeing-built MOP is configured as a deep-penetration weapon to destroy hardened targets such as underground command and control centres or weapons of mass destruction facilities. The 14,000 kg weapon was declared operational in 2011 and is currently the world’s largest bomb; it is currently only deployable on the B-2 bomber. The warhead weighs 2,500 kg. The AFX-757 plastic-bonded explosive used in the warhead was developed by the Air Force Research Laboratory and offers both higher blast characteristics and greater stability than other military grade high explosives. The major penetration effect is achieved through the kinetic impact of the very dense and hardened structure of the bomb casing. USAF acquired 20 units, none of which has yet been deployed in combat. Since 2010 the Air Force has been pursuing development of the Next Generation Penetrator (NPG). The service hopes to acquire a weapon with comparable performance but circa one-third the weight of the MOP.
Guided Glide Bombs
SDB
At the opposite end of the size spectrum lies the GBU-39B Small Diameter Bomb (SDB). The Boeing-produced munition entered service in 2006, with 24,000 units now in the USAF inventory. At only 114 kg weight and 1.8 m length, SDB permits fighter aircraft and bombers to carry significantly more ordnance per sortie (up to 28 bombs on an F-15E), speeding suppression of enemy forces while reducing exposure of the aircraft and crew. The upgraded GBU-53B SDB II Stormbreaker is produced by Raytheon. The 93 kg Stormbreaker incorporates a multi-mode target seeker that utilises an IR channel, millimetre wave (MMW) radar and SAL seeker in addition to the original GPS/INS guidance system; this permits precise engagement of moving targets even under severely degraded visibility. The bomb has a standoff range of circa 110 km against stationary targets and 72 km against moving targets, with a circular error probable (CEP) of 1 m. The 48 kg warhead is lethal against armoured and soft targets.
SmartGlider
Reflecting the need for ever-greater standoff-range capability, MBDA is developing the SmartGlider family of PGMs, described by the firm as “a new generation of air-to-ground tactical strike weapons for the decades to come.” SmartGlider comes in a light and a heavy variant in order to maximise the operational profile which includes air interdiction, offensive counter air (destruction of enemy air assets on the ground), CAS and SEAD/DEAD. Fixed and stationary targets including networked short and medium-range surface-to-air systems can be engaged. The light variant is nearly 2 m long and weighs 120 kg. It is armed with an 80 kg multi-effect unitary charge warhead. MBDA’s Hexabomb Smart Launcher (HSL) permits fighter aircraft to carry 12-18 small SmartGliders per mission in support of stand-off saturation attacks against enemy air defences, convoys or force concentrations. The heavy variant is 4 m long and weighs 1,300 kg. This includes a 1,000 kg warhead capable of delivering combined high penetration and blast effects against large and hardened targets.
The ‘fire and forget’ SmartGlider family combines INS/GNSS navigation with a multi-mode terminal guidance suite which includes low-light television (TV), IR, and a SAL seeker. Radiofrequency sensors, particularly useful against air defence networks, are optional. The aircrew can implement in-flight targeting updates via data link. Available payload effects include airburst, impact and delayed detonation.
Credit: MBDA
According to MBDA, both versions achieve a range “much greater than” than 100 km when launched from circa 12 km altitude. As a glide bomb, SmartGlider does not utilise a propulsion motor. Once launched, the weapon unfolds two glide wings which offer a high lift-to-drag ratio. Pitch and flight control are regulated by the triform tail. The manoeuvrable glider can evade obstacles and threats and assume variable angles of attack to facilitate precision strike. MBDA unveiled the SmartGlider concept at the 2017 Paris Air Show. The light version is expected to be available by 2025, followed by the heavy variant.
Air Launched Cruise Missiles
Conventional air launched cruise missiles (ALCM) combine the high payload potential of aerial bombs with much greater range as well as the ability to change course and altitude throughout their flight. Their very high standoff range permits bomber and fighter aircraft to stay well beyond enemy air defence zones while delivering precision strikes on high value targets.
JASSM
The AGM-158 Joint Air-to-Surface Standoff Missile (JASSM) was originally developed by Lockheed Martin for USAF and the US Navy, with initial production beginning in 2001. Armed with a 450 kg penetrator warhead, the air force variant cruise missile is designed to attack fixed and relocatable targets including moderately hardened or buried targets. Low-observability technology is applied in order to reduce the detection range by air-defence systems, permitting JASSM to fly at higher altitudes than many cruise missiles.
(Credit: USAF)
JASSM continues to be upgraded and enhanced. The subsonic cruise missile uses GPS/INS navigation and an Imaging Infrared (IIR) terminal seeker. An anti-jam GPS receiver is currently being pursued. The AGM-158A baseline version has a range of circa 370 km. The AGM-158B JASSM-ER was introduced in 2014, utilising a more efficient engine and extending range to over 900 km. Production of the AGM-158A ceased in 2016 in favour of the JASSM-ER variant. Development of the ‘extreme range’ AGM-158B-2 or JASSM-XR began in 2018, with low-rate initial production (LRIP) beginning in 2021; deliveries are to commence in early 2024. The XR variant more than doubles the effective range to circa 1,900 km.
The next iteration is the proposed JASSM New Variant (JASSM-NV) which is intended to improve survivability and lethality when operating in contested environments against sophisticated defences. USAF awarded Lockheed Martin a non-competitive development contract in October 2022. The NV variant will have “added capabilities” over the current ER, but most details remain classified.
TAURUS KEPD 350
The Target Adaptive Unitary & Dispenser Robotic Ubiquity System / Kinetic Energy Penetration Destroyer (TAURUS KEPD 350) is produced by Taurus Systems GmbH, a joint venture of MBDA Deutschland GmbH and SAAB Dynamics. The KEPD 350 flies at high-subsonic speeds (Mach 0.6-0.95) and achieves a 500 km range. The ALCM features stealth attributes including a radar absorbent coating and curved air intakes which, together with terrain-hugging flight tactics and electronic countermeasures, enabling high penetration potential against dense air defence networks. The Tri-Tec multi-mode navigation system utilises INS supported by GPS, image-based navigation (IBN) and terrain-reference navigation (TRN) to achieve high strike accuracy. The on-board sensors are integrated with and reference databases to constantly monitor the missile’s location and trajectory as it approaches pre-programmed waypoints en route to target, making it independent of GPS access.
(Credit: TAURUS)
The terminal attack phase is guided by image recognition of the target, referencing an on-board visual database. The 1,400 kg missile carries the 480 kg MEPHISTO tandem warhead equipped with an initial precursor shaped charge warhead (understood to be a High Explosive Anti-Tank (HEAT) type) capable of breaching hard and deeply buried targets, and secondary warhead consisting of a delayed-fuze penetrating main charge packaged inside a kinetic penetrator casing. According to SAAB, the KEPD 350 is the only AGM which can be programmed to detonate the main charge on a pre-selected floor of the target; this is achieved through layer counting and void sensing technology. Alternately the KEPD 350 can be set to detonate in air-burst mode to destroy high value surface and area targets including major radar installations, bridges, and runways. The ALCM entered service with the German Air Force in 2005, followed by Spain and South Korea. The modular architecture of the KEPD 350 enables regular upgrading of key components.
Storm Shadow/SCALP
The British-French Storm Shadow ALCM (designated the ‘Système de Croisière Autonome à Longue Portée – Emploi Général or SCALP-EG in Frech service) entered service in 2003, and has been deployed in nine different conflicts, including the ongoing war in Ukraine. It has demonstrated a high success rate against various targets including airfields, bridges, bunkers and moored naval vessels. The combination of stealthy design and terrain-hugging flight reduces the risk of intercept. According to manufacturer MBDA, Storm Shadow flies at Mach 0.8 and has a range exceeding 250 km. The navigation system utilises INS, GPS and TRN. Near the pre-programmed coordinates the missile pops up to acquire the target utilising an IR sensor in conjunction with an onboard image database. A final steep dive achieves precision strike with minimised collateral damage. Detonation options for the circa 450 kg tandem warhead include air-burst, impact, or penetration (delayed) modes.
In 2017 the UK and France contracted with MBDA for mid-life refurbishment of the Storm Shadow, adapting the system to counter evolving threats and extending the missile’s service life to 2032. In addition to this refit, the missile also received a software upgrade which permits attacking targets located up to 4,000 m above sea level.
In 2017, France and the UK jointly launched the Future Cruise/Anti-Ship Weapon (FC/ASW) program aimed at replacing the Storm Shadow/SCALP ALCM as well as the Harpoon and Exocet anti-ship missiles; and in June 2023 Italy joined the project. Following conclusion of the concept phase, preparatory works were initiated in February 2022. According to MBDA, two complementary missile concepts are being assessed, namely “a subsonic low observable concept and a supersonic, highly manoeuvrable concept.” It is currently unclear whether MBDA will ultimately present a single, dual-role weapon or two specialised missiles. FC/ASW is expected to be operational in the early 2030s.
Precision-Guided Missiles
Conventionally propelled precision guided missiles (PGMs) mostly rely on solid-fuel motors, as opposed to the air-breathing engines of ALCMs. They are smaller and cheaper than ALCMs, and are produced in considerably greater numbers. Most have a short to medium operating range, although longer range configurations are being introduced. Unlike ALCMs, they can be deployed by helicopters and UAVs as well as by fixed-wing manned aircraft.
AGM-114 Hellfire/JAGM
One of the most ubiquitous PGMs is the AGM-114 Hellfire, which has been acquired by some 30 countries. Produced by Lockheed Martin, the supersonic Hellfire missile has undergone several enhancements since initial introduction in 1982. Depending on variant, the 1.6 metre long weapon weighs 45-49 kg and achieves a maximum range of 8 km when ground launched, or out to 12+ km when air-launched. The two most important variants in the current arsenal are the AGM-114L Longbow (produced 1995-2005) and the AGM-114R ‘Hellfire Romeo’ (in production since 2012). The Longbow is a beyond-line-of-sight (BLOS) ‘fire and forget’ weapon which utilises a MMW radar seeker to acquire its target, preserving operational proficiency in the face of adverse weather and battlefield obscurants; the tandem-HEAT warhead can engage heavy tanks. The Romeo uses a Semi-Active Laser (SAL) targeting system which requires the target to be illuminated by the host aircraft or a third party; the AGM-114R replaced several previous variants and carries a multipurpose tandem-HEAT warhead with a fragmentation sleeve, capable of defeating different target classes – including hard, soft and enclosed objectives – with the same warhead. A major enhancement found on the AGM-114R is the three–axis inertial measurement unit (IMU) which enables the missile to manoeuvre and attack the side or rear of targets without requiring the firing aircraft to position itself behind the target.
(Credit: US Army)
A special variant designated the AGM-114R9X was developed for targeted anti-terrorist strikes. To significantly minimise the risk of collateral casualties, the ‘R9X’ does not carry an explosive warhead. On impact, it deploys six long blades which dismember any targets who survive the kinetic energy of the missile’s impact; these blades have given rise to the unofficial nickname ‘Ninja missile’. The weapon’s existence was first reported by the Wall Street Journal which described initial deployment against targets in Syria in 2017.
The planned successor to the Hellfire family is the AGM-179 Joint Air-to-Ground Missile or JAGM. Based on the AGM-114R missile body, it features a new seeker head with a multi-mode guidance system which combines MMW and SAL capabilities, and retains the Romeo’s warhead. The enhanced all-weather, fire-and-forget guidance capabilities promise greater versatility and combat effectiveness against stationary or moving targets in all operational environments, as well as enhancing the missile’s ability to overcome countermeasures.
LRIP began in 2018, advancing to full-rate production in 2022. The new weapon is being fielded incrementally, with the US Marine Corps’AH-1Z and the Army’s AH-64E Apache to be equipped first. In November 2022 Lockheed Martin tested the advanced JAGM-MR (Medium Range) variant. It would double the JAGM’s effective range from 8 km to 16 km, and expands the guidance system through addition of an IIR sensor.
Brimstone
The Brimstone AGM family developed by MDBA UK entered service with the RAF in 2005. The Brimstone 2 entered service in 2016, although it is not clear if this version remains in production given that the follow-on Brimstone 3A (previously known as Brimstone 2 Capability Sustainment Programme (CSP), to extend the service life beyond 2030) was contracted in March 2018 and was reported to be in the “Manufacture/Migration” phase in a UK MoD report titled ‘Setting the context: current capability plans to enable Integrated Force 30’ from July 2022. According to the MoD’s ‘The Defence Equipment Plan 2021 – 2031’ report published in February 2022, Brimstone 3A is due to enter service in Spring 2024, following manufacturer delays.
The Brimstone 2 is a 1.8 metre long, 50 kg missile equipped with a solid fuel engine; it flies at Mach 1.3 and has an operating range of 60 km when launched from a fixed-wing aircraft (triple the range of the original Brimstone launched from a fixed-wing platform). The weapon is optimised for armoured and hardened objectives; the target profile includes fast and manoeuvring tanks and armoured vehicles as well as bunkers. Up to three missiles can be carried per underwing or winglet weapons mount; depending on aircraft type, this permits deployment of up to 18 units during one mission. The Brimstone 2 can operate in three guidance modes: SAL only (against static targets with limited radar cross section), SAL plus MMW (for fast-moving targets and to distinguish targets in cluttered environments), and fully autonomous MMW (for simultaneous engagement of multiple targets in fire-and-forget mode). The Brimstone 2 features a ‘man-in-the-loop’ option, enabling last-minute mission abort or redirection, and has an insensitive munition (IM) compliant rocket motor and warhead. The 6.3 kg tandem-HEAT warhead can be initiated using a choice of impact, delayed, air-burst, or proximity fuzing modes. According to the UK MoD, the Brimstone has demonstrated “well over 90 percent” accuracy and reliability during combat operations, including over 98% during the 2011 intervention in Libya.
Credit: Crown (Copyright 2018)
The upgraded Brimstone 3A, which successfully conducted a first test launch in March 2019. It incorporates the latest dual-mode SAL/MMW seeker, microelectromechanical system (MEMS) based IMU, an enhanced autopilot, improved battery. According to MBDA, the Brimstone 3 also includes a significant memory and processing update to “future-proof the missile.” The cockpit crew will be able to pre-determine flight trajectory, angle of attack and impact angle to guarantee precision engagement of targets moving at up to 110 km/h.
Going beyond the Brimstone 3A, in 2021 MBDA announced the integration of a major software upgrade for the 3A variant, to result in the Brimstone 3B variant. The 3B variant was listed as being in the “Assessment & Demonstration” phase in the July 2022 MoD report, and according to the February 2022 report, integration of this variant with the UK’s Apache helicopters has been cancelled, but it will be integrated on the Typhoon FGR4 fighter aircraft and Protector RG Mk 1 Unmanned Aerial Vehicle (UAV), with the former selected as the lead platform to host Brimstone 3B. This missile variant has also been offered to the MoD under the UK’s Battle Group Organic Anti-Armour (BGOAA) programme which aims to replace some of the UK’s legacy ground-based anti-armour guided weapons.
Air Launched Effects
Air Launched Effects (ALE) are a new concept intended to outfit manned helicopters and unmanned aircraft with flexible air-to-ground weapons. ALEs are being primarily pursued by the US armed forces, especially the Army. They will ultimately be fielded in various sizes and models, with larger types having greater payload and performance profiles including an operational range of several hundred kilometres. These multi-mission effectors can deploy as reconnaissance assets (including beyond-line-of-sight targeting aids for long-range artillery), loitering attack munitions, communications nodes, or as signals intelligence or electronic warfare (EW) assets. ALEs can be deployed singly or in swarms, permitting coordinated saturation of airspace sectors. Tactical benefits include extending the aircraft’s sensor range and engaging targets while the aircraft remains beyond detection or engagement range of enemy anti-aircraft systems. They are conceived as comparably low cost, making them procurable in large numbers, and expendable. While of interest for use on current operational aircraft, the US Army is particularly focussed on ALE as a force multiplier element of the Future Vertical Lift ‘ecosystem’ which will consist of the Future Long Range Assault Aircraft (FLRAA), Future Attack Reconnaissance Aircraft (FARA), and the Future Tactical Unmanned Aerial System (FTUAS) programme.
US Army ALTIUS
The US Army is currently experimenting with the first air-launched prototype of the Agile-Launched, Tactically-Integrated, Unmanned System (ALTIUS). ALTIUS’ production team is led by Anduril’s subsidiary AREA-I, which also provides the air vehicle. Testing of the tube-launched ALE is being conducted from UH-60/ MH-60M helicopters and Gray Eagle UAS, although it can also be deployed from the AC-130J and the unmanned Valkyrie XQ-58. ALTIUS offers greater endurance and a larger payload capacity than most comparably-sized UAVs.
The original ALTIUS is derived from AREA-I’s Altius 600 UAV. The tube-launched drone’s wings unfold after launch, extending to a span of three metres. The body is 15.3 cm in diameter, while the precise length remains classified. Payload capacity is 3.2 kg, with up to four hours endurance and circa 450 km range. A larger ALE variant designated as the ALTIUS-700M was flown by Anduril in 2021. With a 500 km range and a 15.9 kg warhead, this model would expand the target set to include heavily armoured vehicles and artillery systems.
(Credit: US Army)
A single operator can control multiple drones, whereby a high level of autonomy reduces operator workload by facilitating ALE collaborative teaming and coordinated strikes. Major General Wally Rugen, head of the Army’s Aviation Cross Functional Team, stated in May 2023 that the service was favouring a networked “wolf pack” approach with one drone acting as leader and others performing specific tasks to contribute to the swarm’s overarching objective. In April 2022, the Army demonstrated this capacity by launching four sequential swarms of seven ALTIUS-600 drones each to form a networked swarm of 28 units which proceeded to hunt and destroy simulated ground targets. Additionally the drones – which were controlled by a single operator – passed reconnaissance data back to an incoming air assault force, providing updated tactical intelligence before reaching the landing zone.
According to Army budget documents, the service is pursuing an incremental approach that allows rapid prototyping and operational fielding of technology as it becomes viable, while continuing engineering efforts to mature and implement additional capabilities. This is accomplished through parallel and/or sequential development, simulation and physical prototyping activities for the air vehicle, payloads, and mission system architecture. Prototype evaluation is slated to continue through Fiscal Year 2024, while the Army refines its requirements and an initial concept of operations. Budgeting documents show plans to publish a request for proposals in late FY24, with the engineering and manufacturing development contract to be awarded in the third quarter of FY25.
General Atomics Eaglet
Meanwhile, General Atomics Aerial Systems is developing its own ALE, designated Eaglet. It is primarily designed to be launched from larger UAV, a helicopter or a ground vehicle. The Eaglet prototype achieved first launch from an Army-owned General Atomics Gray Eagle UAV in January 2023. Aircraft such as the Gray Eagle could transport the ALE over thousands of kilometres before deploying it, enabling deep penetration missions over hostile territory. Eaglet is being considered primarily as a reconnaissance and EW asset, with additional utility as a deep-penetration command and control node.
(Credit: GA-ASI)
USMC Developments
The US Marine Corps (USMC) is also experimenting with ALEs. As part of the service’s Force 2030 modernisation program, the Corps plans to exchange a portion of its Hellfire arsenal for “a low-cost, air launched family of loitering, swarming munitions.” The main impetus is the significant range advantage offered by some loitering munitions. “That is a capability that brings hundreds of kilometres, and that allows us to be able to use a current platform to be able to do things that we never thought we’d be able to do,” said Brig. Gen. Stephen Lightfoot, director of the USMC’s Capabilities Development Directorate. Lightfoot predicted that ALEs would be operationally fielded “within the next few years.”
Sidney E. Dean