AGM-129 Advanced Cruise Missile [ACM]
A decision was made in 2007 to retire the fleet. At the time of the decision there were approximately 460 in the inventory located at Minot Air Force Base in North Dakota and Barksdale Air Force Base, La. In February 2008, the final destruction decision was received, and the ACM was directed to be demilitarized, within 66 months. As April 2012, almost 17 months before the required deadline, all operational missiles had been completely destroyed.
The ACM's external shape was optimized for low observables characteristics and includes forward swept wings and control surfaces, a flush air intake and a flat exhaust. These, combined with radar-absorbing material and several other features, resulted in a missile that was virtually impossible to detect on radar.
The ACM was capable of carrying a nuclear warhead and was highly accurate with a range of more than 2,000 miles. It was nearly 21 feet long, with a wingspan of 10 ½ feet. It was 2 ½ feet in diameter and when militarized, weighed in at 3,500 pounds, according to the Air Force fact sheet. The weapons system was delivered exclusively by the B-52H Stratofortress bombers. B-52H bombers could carry up to six AGM-129A missiles on each of two external pylons for a total of 12 per aircraft.
The AGM-129A was a subsonic, turbofan-powered, air-launched cruise missile. The ACM was a low-observable, air- launched, strategic missile with significant improvements over the ALCM-B in range, accuracy, and survivability. Armed with a W80 warhead, it was designed to evade air and ground-based defenses in order to strike heavily defended, hardened targets at any location within any potential enemy's territory.
When the threat was deep and heavily defended, the AGM-129 delivers the proven effectiveness of a cruise missile enhanced by stealth technology. Launched in quantities against enemy targets, the ACM's difficulty to detect, flight characteristics and range result in high probability that enemy targets will be eliminated. It was harder to detect, and has greater range and accuracy than the AGM-86 air-launched cruise missile. The ACM achieves maximum range through its highly efficient engine, aerodynamics and fuel loading.
The AGM-129A's external shape was optimized for low observables characteristics and includes forward swept wings and control surfaces, a flush air intake and a flat exhaust. These, combined with radar-absorbing material and several other features, result in a missile that was virtually impossible to detect on radar.
The AGM-129's Stealth features are immediatly apparent when viewing the missile. The nose was sharply pointed with sharp edges or chines, reminiscent of the chines used on the SR-71 Blackbird. The missile's wings are swept forward at 26 degrees, again to reduce reflections back to a radar transmitter/reciever forward of the missile. The ACM's turbofan engine exhaust consists of a 2D nozzle. It was in a 2D shape to allow the hot exhaust to rapidly mix with the cool surrounding air to reduce the overall IR signature. The Inlet was mounted flush with the fuselage to reduce it's RCS, and the missile was constructed with radar-absorbing materials and radar-absorbing structures.
The AGM-129A offers improved flexibility in target selection over other cruise missiles. Missiles are guided using a combination of inertial navigation and terrain contour matching enhanced with highly accurate speed updates provided by a laser Doppler velocimeter. These, combined with small size, low-altitude flight capability and a highly efficient fuel control system, give the United States a lethal deterrent capability well into the 21st century. The AGM-129A Advanced Cruise Missile uses light detection and ranging (LADAR) for terminal guidance. Although LADAR had not been commonly used missile guidance, the basic laser technology was not new and has been used extensively in applications ranging from medical instruments and bar-code scanners.
The ACM was designed for B-52H external carriage. B-52H bombers can carry up to six AGM-129A missiles on each of two external pylons for a total of 12 per aircraft. After a missile was released from the bomber, the missile's engine ignites and its avionics equipment guides it to the target.
ACMs are protected from the worst of the elements through storage in secured, structurally reinforced igloos. The majority of the stockpile was stored mounted on pylons, and generally referred to as "packages." Periodically, packages are pulled from storage for maintenance, testing and exercises. Results of the maintenance checks and tests are recorded by munitions personnel.
A MIT [Missile Interface Test] was a communication test between the aircraft and the missile and was normally performed after package upload onto the aircraft. The aircraft offensive avionics system (OAS) sends a command word to the missile and tells it to perform an internal built-in test (BIT) test on any components it has and report the results back to the aircraft. SITs [System Interface Test] are more involved and must be performed (per technical order) if a single missile swap occurs on the flight line. In addition to all the tests the MIT performs, a SIT commands the missile inertial navigation element (INE) to go into a Fine Align/Coarse Align. This test ensures that the inertial platform was able to align to an earth reference and can take 1-second updates from the aircraft.
A Loaded Launcher Test / Loaded Pylon Test (LLT/LPT) Type A was run after building the package and to certify operational capability of the package. It was primarily a communication test and verifies that the aircraft will be able to communicate through the pylon/launcher and down to the missile. A LLT/LPT Type B was a retest of previous SIT or MIT failure. The test was identical to a LLT/LPT Type A and serves a similar purpose as a Level 1 except at the package level (as opposed to the individual missile level).
Cruise Missile Functional Ground Testing (FGT) was required to provide the capability to non-destructively accomplish functional flight simulation of a full-up missile flight profile on the ground to obtain additional reliability data. This capability will provide critical reliability data without the cost of flight test mission and will also retain the missiles in the inventory. This effort will develop the software and hardware for an existing test facility for accomplishment of the ground tests.
The W-80 SLEP was to replace warhead components to extend its service life. The National Nuclear Security Administration (NNSA) was responsible for most of the refurbishment costs associated with the W-80 Warhead. The Air force was responsible for funding ACM/W-80 integration. Integration included evaluation of interface control changes as part of the Initial Concept Design, missile testing and logistics requirements necessary to support a First Production Unit (FPU) delivery.
Advanced Cruise Missile History
A DARPA program, TEAL DAWN, developed key technologies and a design later incorporated into the Air Force Advanced Cruise Missile (ACM). The TEAL DAWN Program involved a series of studies and developments related to the development of a long-range stealthy strategic cruise missile. DARPA experience in low observables was incorporated into the design of the low-signature engine inlet and nozzle. Other technologies included the unique aerosurface sweep angles that provided a benefit to the aerodynamic performance. Clearly recognized performance goals (signature, range, flight profile) were successfully demonstrated during the DARPA phase of the program. Wind tunnel and radar ranges testing also were accomplished by the Air Force under DARPA sponsorship.
In 1982 the Air Force began studies for a new cruise missile with stealth characteristics after it became clear that the AGM-86B ALCM would soon be too easy to detect by future air defense systems. The Air Force assumed responsibility for the ACM Program and successfully managed the system through concept demonstration; engineering and manufacturing development; production; and development. The follow-on Air Force program focused on operational test and evaluations (OT&E) and manufacturing objectives with a high degree of confidence that program objectives would be realized.
In 1983 General Dynamics was awarded a contract to develop the new AGM-129A ACM. The first test missile flew in 1985; the first missiles were delivered to the Air Force in mid-1990.
Plans called for an initial production of approximately nuclear tipped AGM-129A 1,500 missiles. The end of the Cold War and subsequent budget cuts led the Air Force to cease production after 460 missiles, with the final delivery in 1993. Missile procurement was complete. Procurement of the AGM-129 was halted at 460 missiles in lieu of the originally planned 1,460. FY96, FY97 and FY98 funds were required to complete the last 15% of mission support development work. Several corporate changes during production resulted in Raytheon Missile Systems as the final production firm.
A projected AGM-129B version of the ACM was an AGM-129A "modified with structural and software changes and an alternate nuclear warhead for accomplishing a classified cruise missile mission." [from "DOD 4120.15-L: Model Designation of Military Aerospace Vehicles", Department of Defense, 1990 ] No additional information has been forthcoming, and it seems probable that no ACMs were completed to the AGM-129B configuration.
An Advanced Cruise Missile with a conventional non-nuclear warhead was proposed by [then] prime contractor General Dynamics to the USAF. This configuration, which was unofficially designated as the AGM-129C, was not funded. Reports which attribute the AGM-129B designation to an unfunded, non-nuclear variant of the ACM appear to be erroneous.
The DARPA Smart Weapons Program of 1985 was a concept that would put almost all the brains in the missile bus, the Autonomous Air Vehicle (AAV), and make the submunitions as dumb (hence cheap) as possible. Thirsty Saber, the second phase of the SWP, sought to define a transition path for the SWP payload. Because of its endurance and low observability, the Advanced Cruise Missile (ACM) was picked as the probable first transition for the sensor, brain, and munitions suite. To avoid the cost of actually integrating the payload into the ACM, the program made extensive use of surrogate platforms for the major proof-of-principle demos. The concept of Thirsty Saber was to put sensors and weapons in the target area at the same time, to attack time-critical (fleeting) targets such as missile launchers as they appeared.
In 1991, an accelerated, fully packaged version of Thirsty Saber was proposed in response to Desert Storm. Dubbed Thirsty Warrior (TW), the effort would have bypassed the normal DARPA hesitation in fully integrating a flyaway version of this complex system. There was substantial, high-level support in the initial few months, in spite of significant funding needed to fully integrate the TS capabilities into a cruise missile. Impetus for this program concept waned rapidly upon the sudden end of the war.
The Air Force stated in February 2006 that it expected to keep the missile active until 2030. And in July 2006 senior Air Force officials said they planned to maintain the ACM inventory and possibly work with the Energy Department to update the missile's warhead. An Air Force factsheet dated August 2007 stated that "The ACM is anticipated to remain in service until 2030."
Budget documents released in Feburary 2007 stated that "The ACM fleet design service life expires between the years 2003 and 2008. .... FY08-13 funding was zeroed out for higher Air Force priorities." On 07 March 2007 the Air Force announced that it will retire the more than 400 Advanced Cruise Missiles carried by the B-52 bomber. Air Force public affairs officials were unable to provide additional details, including the rationale for the decision.
On 30 August 2007, a B-52H bomber armed with six [some accounts report five] nuclear-tipped Advanced Cruise missiles travelled from Minot Air Force base, ND, to Barksdale AFB, LA, with the missiles mounted onto pylons on the bomber's wings.
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