THREAD 🧵AIM-120 AMRAAM
In this thread I will go over how the most ubiquitous Air to Air missiles was developed , its early testing phases and its many many upgrades and variants (1/n)
In this thread I will go over how the most ubiquitous Air to Air missiles was developed , its early testing phases and its many many upgrades and variants (1/n)
Cold War Genesis & Strategic Imperative
The AIM-120 AMRAAM story begins in the late 1970s during the height of Cold War tensions. Soviet advances in beyond-visual-range (BVR) technology, particularly the R-23 Goa (AA-7 Apex) and developmental R-27 Alamo (AA-10) threatened USAF air superiority .
The 1979 Iranian revolution and subsequent intelligence revelations about Soviet missile capabilities created an urgent Pentagon requirement develop a "fire-and-forget" air-to-air missile that could restore US technological dominance and tactical flexibility in BVR combat.(2/n)
The AIM-120 AMRAAM story begins in the late 1970s during the height of Cold War tensions. Soviet advances in beyond-visual-range (BVR) technology, particularly the R-23 Goa (AA-7 Apex) and developmental R-27 Alamo (AA-10) threatened USAF air superiority .
The 1979 Iranian revolution and subsequent intelligence revelations about Soviet missile capabilities created an urgent Pentagon requirement develop a "fire-and-forget" air-to-air missile that could restore US technological dominance and tactical flexibility in BVR combat.(2/n)
Technical & Tactical Limitations of Aim-7 Sparrow
The AIM‑7 Sparrow, introduced in the 1950s, dominated U.S. BVR capabilities for decades. Yet it demanded continuous target illumination, suffered from limited ECCM (electronic counter‑countermeasures), and offered ranges under 40 km against maneuvering targets. Combat data showed Sparrow's kill probability was very very low in Vietnam ( approx 10%), which to be fair were caused by other issues such poor training and maintenance . Nevertheless by the 1970's Sparrow was old, having come into service in the late 1950's.(3/n)
The AIM‑7 Sparrow, introduced in the 1950s, dominated U.S. BVR capabilities for decades. Yet it demanded continuous target illumination, suffered from limited ECCM (electronic counter‑countermeasures), and offered ranges under 40 km against maneuvering targets. Combat data showed Sparrow's kill probability was very very low in Vietnam ( approx 10%), which to be fair were caused by other issues such poor training and maintenance . Nevertheless by the 1970's Sparrow was old, having come into service in the late 1950's.(3/n)
Program Start and Competition
The program was started in 1975 , with the competition narrowing down to Raytheon and Hughes by 1979 .That said the industrial base for AMRAAM was already in the making with DARPA's Lightweight Radar Missile (LWRM) project in the early 1970's. Requirements for the AMRAAM were ( I couldn't find a proper doc so this is me stitching statements )
1) Similar form factor but lighter /smaller to the Sparrow so all aircraft can use it .
2) Active radar, so no need for illumination like the Aim-7
3) Greater Range range vs Aim-7
Image of competitors in the AMRAAM competition ( small note : Raytheon and Northrop Submissions do kinda look like JATM ) (4/n)
The program was started in 1975 , with the competition narrowing down to Raytheon and Hughes by 1979 .That said the industrial base for AMRAAM was already in the making with DARPA's Lightweight Radar Missile (LWRM) project in the early 1970's. Requirements for the AMRAAM were ( I couldn't find a proper doc so this is me stitching statements )
1) Similar form factor but lighter /smaller to the Sparrow so all aircraft can use it .
2) Active radar, so no need for illumination like the Aim-7
3) Greater Range range vs Aim-7
Image of competitors in the AMRAAM competition ( small note : Raytheon and Northrop Submissions do kinda look like JATM ) (4/n)
Development Phase
Hughes won the competition in 1982 , it was same year there was joint NATO MoU that shifted BVR production to US and WVR production that would lead to ASRAAM to Europe .
Coming back to the Aim-120 . AMRAAM's early development faced catastrophic technical challenges that nearly killed the program. The miniaturized X-band radar seeker required breakthrough advances in gallium arsenide (GaAs) semiconductors and digital signal processors technologies that barely existed in 1982.
By 1984 the program was two years behind schedule and costs per missile had grown from $182,000 to nearly $438,000 (in 1987 dollars).
Hughes' first seeker prototypes failed 60% of ground tests due to thermal cycling problems, electromagnetic interference, and power supply instabilities. By 1985, AMRAAM was in serious trouble: huge cost overruns and delays meant that not a single test round was fired in a hostile ECM-environment until October 1986.(5/n)
Hughes won the competition in 1982 , it was same year there was joint NATO MoU that shifted BVR production to US and WVR production that would lead to ASRAAM to Europe .
Coming back to the Aim-120 . AMRAAM's early development faced catastrophic technical challenges that nearly killed the program. The miniaturized X-band radar seeker required breakthrough advances in gallium arsenide (GaAs) semiconductors and digital signal processors technologies that barely existed in 1982.
By 1984 the program was two years behind schedule and costs per missile had grown from $182,000 to nearly $438,000 (in 1987 dollars).
Hughes' first seeker prototypes failed 60% of ground tests due to thermal cycling problems, electromagnetic interference, and power supply instabilities. By 1985, AMRAAM was in serious trouble: huge cost overruns and delays meant that not a single test round was fired in a hostile ECM-environment until October 1986.(5/n)
All the above caused delays in the IOC of the missile , which originally supposed to IOC in 1987, instead 1987 saw the approval of the LRIP of the missile between two contractors, Hughes and Raytheon. Of the initial 180 missile, USD $537.4 million (four times higher than estimated) order, Raytheon produced 75 and Hughes 105 rounds. The subsequent FY 1988 order for 630 missiles was split 55/45 with the biggest share for Hughes. Continued LRIP was approved in May 1991.
In September 1991, IOC (Initial Operational Capability) was achieved for the AMRAAM on USAF F-15 aircraft. The F-16 followed in January 1992, and the Navy in October 1993. Full-rate production of the missile was approved in April 1992. (6/n)
In September 1991, IOC (Initial Operational Capability) was achieved for the AMRAAM on USAF F-15 aircraft. The F-16 followed in January 1992, and the Navy in October 1993. Full-rate production of the missile was approved in April 1992. (6/n)
Technical Details and Evolution
With program developmental (initial) history done lets focus on what made the Aim-120A itself .
The AMRAAM is housed in a light-weight structure of steel and titanium. The airframe is divided into four major sections: guidance, warhead, propulsion and control. The four wings and fins are detachable. The guidance section features an active X-band radar terminal seeker using a highpower solid-state transmitter with a low-sidelobe, wide-gimbal antenna, and a built-in radio-frequency processor. Navigation, autopilot, radar, datalink, fuzing, sequencing, and self-test functions are allhandled by a single 30MHz microprocessor. The propulsion section consists of an advanced solid-fuel rocket motor to achieve a speed of Mach 4 and a range in excess of 30 miles.
In long-range engagements AMRAAM heads for the target using inertial guidance and receives updated target information via data link from the launch aircraft. It transitions to a self-guiding terminal mode when the target is within range of its own monopulse radar set, operating in high-PRF mode. Since this seeker uses its own active radar (unlike the Sparrow), it does not require the launch aircraft to illuminate the target or to track the target. In case the target tries to protect itself with active jamming, AMRAAMs seeker switches to a medium-PRF "home-on-jam" mode. With its sophisticated avionics, high closing speed, and excellent end-game maneuverability, chances of escape from AMRAAM are minimal. Upon intercept an active-radar proximity fuze detonates the 40-pound high-explosive warhead to destroy the target. At closer ranges AMRAAM guides itself all the way using its own radar, freeing the launch aircraft to engage other targets. The lethal range of the 40lbs. blast fragmentation warhead has not been disclosed. (7/n)
With program developmental (initial) history done lets focus on what made the Aim-120A itself .
The AMRAAM is housed in a light-weight structure of steel and titanium. The airframe is divided into four major sections: guidance, warhead, propulsion and control. The four wings and fins are detachable. The guidance section features an active X-band radar terminal seeker using a highpower solid-state transmitter with a low-sidelobe, wide-gimbal antenna, and a built-in radio-frequency processor. Navigation, autopilot, radar, datalink, fuzing, sequencing, and self-test functions are allhandled by a single 30MHz microprocessor. The propulsion section consists of an advanced solid-fuel rocket motor to achieve a speed of Mach 4 and a range in excess of 30 miles.
In long-range engagements AMRAAM heads for the target using inertial guidance and receives updated target information via data link from the launch aircraft. It transitions to a self-guiding terminal mode when the target is within range of its own monopulse radar set, operating in high-PRF mode. Since this seeker uses its own active radar (unlike the Sparrow), it does not require the launch aircraft to illuminate the target or to track the target. In case the target tries to protect itself with active jamming, AMRAAMs seeker switches to a medium-PRF "home-on-jam" mode. With its sophisticated avionics, high closing speed, and excellent end-game maneuverability, chances of escape from AMRAAM are minimal. Upon intercept an active-radar proximity fuze detonates the 40-pound high-explosive warhead to destroy the target. At closer ranges AMRAAM guides itself all the way using its own radar, freeing the launch aircraft to engage other targets. The lethal range of the 40lbs. blast fragmentation warhead has not been disclosed. (7/n)
Now Coming to Aim-120B
AIM-120B deliveries began in 1994. The B-model incorporates a new digital processor, erasable programmable read only memory, and five major electronic unit hardware chassis upgrades..Most of all this was reprogrammable , this was very important and allowed for rapid iteration and improvement . ( P.S all the Meteor comparisons are relative to this version as it was made to replace this )
Aim-120C Series
C-3: On this variant the fin size was reduced to allow F-22 to carry 6 AAM vs only 4 being possible for the older AMRAAM models . This was first phase of Pre-Planned Product Improvement (P3I) program.
C-4: The warhead was replaced by the new, lighter and stronger WDU-41/B model.
C-5: This shrank the control actuator section allowing the motor to be extended by five inches to the aft, which was accompanied by a switch from the baseline boost-sustain grain design to an all-boost motor
C-6: Implements improved fuzing via new Quadrant Target Detection Device (QTDD)
C-7: There were updates to antenna, receiver, and signal processing parts, installing miniaturized electronic parts, rebuilding some software parts based on C++, modifying the overall software, and applying a new induction algorithm. This was the last phase of the P3I program. ( allegedly c-7 repackaged the guidance electronics to save six inches, which was earmarked for the propulsion upgrade planned as part of AIM-120D. That upgrade never happened however, so modern AIM-120 variants have six inches of empty space instead. Basically they were able to extend the length of the missile by almost eight percent without actually changing the outer mold lin)
C-8: Under F3R (Form, Fit, Function Refresh) the there were upgrades to multiple circuit cards and advanced processors in the guidance section of the missile and to re-host legacy software. (8/n)
AIM-120B deliveries began in 1994. The B-model incorporates a new digital processor, erasable programmable read only memory, and five major electronic unit hardware chassis upgrades..Most of all this was reprogrammable , this was very important and allowed for rapid iteration and improvement . ( P.S all the Meteor comparisons are relative to this version as it was made to replace this )
Aim-120C Series
C-3: On this variant the fin size was reduced to allow F-22 to carry 6 AAM vs only 4 being possible for the older AMRAAM models . This was first phase of Pre-Planned Product Improvement (P3I) program.
C-4: The warhead was replaced by the new, lighter and stronger WDU-41/B model.
C-5: This shrank the control actuator section allowing the motor to be extended by five inches to the aft, which was accompanied by a switch from the baseline boost-sustain grain design to an all-boost motor
C-6: Implements improved fuzing via new Quadrant Target Detection Device (QTDD)
C-7: There were updates to antenna, receiver, and signal processing parts, installing miniaturized electronic parts, rebuilding some software parts based on C++, modifying the overall software, and applying a new induction algorithm. This was the last phase of the P3I program. ( allegedly c-7 repackaged the guidance electronics to save six inches, which was earmarked for the propulsion upgrade planned as part of AIM-120D. That upgrade never happened however, so modern AIM-120 variants have six inches of empty space instead. Basically they were able to extend the length of the missile by almost eight percent without actually changing the outer mold lin)
C-8: Under F3R (Form, Fit, Function Refresh) the there were upgrades to multiple circuit cards and advanced processors in the guidance section of the missile and to re-host legacy software. (8/n)
Aim-120D
The missile features improved guidance via a "tightly coupled" GPS/inertial measurement unit (IMU) that reduces on-aircraft and in-flight alignment errors.
The new datalink will replace the missile's existing receive-only link and enable the missile to report back after launch its status downrange to the launch aircraft, he said. Among the benefits, this will expand the AMRAAM's capacity for 'high-off-boresight' (HOB) engagements, he noted. HOB engagements are where the missile goes after a threat in its launch aircraft's rear hemisphere. The range was further extended too , reaching approximately 160 to 180 km.
Aim-120.D-3: The latest model with the application of the F3R (Form, Fit, Function Refresh) program and the SIP (System Improvement Program)-3F update, replacing some discontinued parts of the induction part with modernized parts and enabling future software updates.
(9/n)
The missile features improved guidance via a "tightly coupled" GPS/inertial measurement unit (IMU) that reduces on-aircraft and in-flight alignment errors.
The new datalink will replace the missile's existing receive-only link and enable the missile to report back after launch its status downrange to the launch aircraft, he said. Among the benefits, this will expand the AMRAAM's capacity for 'high-off-boresight' (HOB) engagements, he noted. HOB engagements are where the missile goes after a threat in its launch aircraft's rear hemisphere. The range was further extended too , reaching approximately 160 to 180 km.
Aim-120.D-3: The latest model with the application of the F3R (Form, Fit, Function Refresh) program and the SIP (System Improvement Program)-3F update, replacing some discontinued parts of the induction part with modernized parts and enabling future software updates.
(9/n)
Proposed Versions
The AIM-120 has gone through quite a lot of upgrades as can be seen however , there are even more variants and derivatives that weren't realized . FVRAAM/VDFR AMRAAM which competed with the Meteor( but lost ) . Can't find any info but there was also the Hughes Asam-1, an AMRAAM derivative that was offered for the UK's cancelled MSAM requirement.
The AIM-120 has gone through quite a lot of upgrades as can be seen however , there are even more variants and derivatives that weren't realized . FVRAAM/VDFR AMRAAM which competed with the Meteor( but lost ) . Can't find any info but there was also the Hughes Asam-1, an AMRAAM derivative that was offered for the UK's cancelled MSAM requirement.
Then there was DARPA's NCADE Network Centric Airborne Defense Element
.It is an AMRAMM-based ballistic missile interceptor that began development in 2008.
It was aimed at intercepting ballistic missiles in the ascending stage, and was an improved version of AIM-9X instead of radar
. It is equipped with an infrared thermal imaging seeker and adopts the Hit-to-Kill method for reliable target destruction. In addition, the goal was to have a range of over 160 km by installing a two-stage liquid fuel rocket in the place where AMRAAM's warhead originally went.
(10/n)
.It is an AMRAMM-based ballistic missile interceptor that began development in 2008.
It was aimed at intercepting ballistic missiles in the ascending stage, and was an improved version of AIM-9X instead of radar
. It is equipped with an infrared thermal imaging seeker and adopts the Hit-to-Kill method for reliable target destruction. In addition, the goal was to have a range of over 160 km by installing a two-stage liquid fuel rocket in the place where AMRAAM's warhead originally went.
(10/n)
Raytheon also proposed the AMRAAM-ER , by mating the body of the ESSM with the guidance section of a C-7/C-8 a long range AAM was created , despite this it didn't grain much traction in that market but instead it became a much needed boost for NASAMS.(11/n)
NASAMS
AMRAAM while being the premier AAM of the west has also become a valuable SAM recently ( relatively speaking of course ) . It has been deployed and adopted by 13 different countries . The system design is modular allowing for integration of other missile ( AMRAAM ER , Aim-9X) (12/n)
AMRAAM while being the premier AAM of the west has also become a valuable SAM recently ( relatively speaking of course ) . It has been deployed and adopted by 13 different countries . The system design is modular allowing for integration of other missile ( AMRAAM ER , Aim-9X) (12/n)
Operational History
I was thinking about making this section bigger but given how much data is not available due to being recent ( Ukraine , Israel-Iran etc I have chosen to write on few notable moments )
The AMRAAM has seen extensive combat usage from the 90's . The AMRAAM was used operationally for the first time on December 27, 1992, when a USAF General Dynamics F-16D Fighting Falcon shot down an Iraqi MiG-25 that violated the southern no-fly-zone.
On 24 November 2015 a Turkish Air Force F-16 shot down a Russian Su-24M strike aircraft with an AIM-120 missile over northern Syria after it crossed into Turkish airspace.
On 18 June 2017, a US Boeing F/A-18E Super Hornet engaged and shot down a Sukhoi Su-22 of the Syrian Air Force over northern Syria,[16] using an AIM-120. An AIM-9X Sidewinder had failed to bring down the Syrian jet. (13/n)
I was thinking about making this section bigger but given how much data is not available due to being recent ( Ukraine , Israel-Iran etc I have chosen to write on few notable moments )
The AMRAAM has seen extensive combat usage from the 90's . The AMRAAM was used operationally for the first time on December 27, 1992, when a USAF General Dynamics F-16D Fighting Falcon shot down an Iraqi MiG-25 that violated the southern no-fly-zone.
On 24 November 2015 a Turkish Air Force F-16 shot down a Russian Su-24M strike aircraft with an AIM-120 missile over northern Syria after it crossed into Turkish airspace.
On 18 June 2017, a US Boeing F/A-18E Super Hornet engaged and shot down a Sukhoi Su-22 of the Syrian Air Force over northern Syria,[16] using an AIM-120. An AIM-9X Sidewinder had failed to bring down the Syrian jet. (13/n)
Conclusion
From its beginning in 1975 to its troubled development and finally deployment in 1991 .AMRAAM has been the premier AAM has become sort of the measuring stick which all other AAM are inevitably compared. That said as with time and like predecessor the Aim-7,the Aim-120 has served and now it's sunset years are starting with its replacement the Aim-260 JATM finally beginning production . It was leap in technology and its effects can be seen in other missiles too , for example Sm-6 ( and by that Sm-2 IIIC) use a AMRAAM derived seekers . USAF and Army want a AMRAAM ranged missile but half the size ( Cuda and IFPCS inc 2) (14/14)
From its beginning in 1975 to its troubled development and finally deployment in 1991 .AMRAAM has been the premier AAM has become sort of the measuring stick which all other AAM are inevitably compared. That said as with time and like predecessor the Aim-7,the Aim-120 has served and now it's sunset years are starting with its replacement the Aim-260 JATM finally beginning production . It was leap in technology and its effects can be seen in other missiles too , for example Sm-6 ( and by that Sm-2 IIIC) use a AMRAAM derived seekers . USAF and Army want a AMRAAM ranged missile but half the size ( Cuda and IFPCS inc 2) (14/14)
Lastly Sources
1) designation-systems.net/dusrm/m-120.ht…
2)researchgate.net/publication/39…
3)defensefeeds.com/military-tech/…
4)globalmilitary.net/missiles/aim-1…
5)secretprojects.co.uk/threads/aim-12…
6)f-16.net/f-16_armament_…
7)vnfa2.tripod.com/VNFA-AIM-120.h…
8)apps.dtic.mil/sti/pdfs/ADA52…
1) designation-systems.net/dusrm/m-120.ht…
2)researchgate.net/publication/39…
3)defensefeeds.com/military-tech/…
4)globalmilitary.net/missiles/aim-1…
5)secretprojects.co.uk/threads/aim-12…
6)f-16.net/f-16_armament_…
7)vnfa2.tripod.com/VNFA-AIM-120.h…
8)apps.dtic.mil/sti/pdfs/ADA52…
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