U.S. Helicopter Armament Subsystems

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The helicopter itself has added much to the modern battlefield, changing land warfare tactics across the board. Transportation, with the ability to rapidly deploy or evacuate forces or casualties has changed huge aspects of post-modern warfare. The helicopter as an armed weapon has also added a whole new dimension to the battlefield.

Although one of the first Armies to experiment with helicopters, the United States Army was slow to fully explore the possibilities of armed helicopters. Experiments between the Korean War and US involvement in South East Asia were small and fairly simple. Learning much from the these involments the US decided to look further into the idea of air mobile tactics, and subsequently armed helicopters, though an armed helicopter had been proposed and rejected in the early 1940s. By the time the UTTHCO (Utility Tactical Transport Helicopter Company) was deployed to Vietnam in 1962 the US had started experimenting more with the idea of arming helicopters, both for defensive and offensive purposes.^[1] UTTHCO was a sort of expeditionary unit, deployed to Vietnam to assist the South Vietnamese Army and to provide on the ground testing for new air mobile theory. Weapon systems used by UTTHCO were often crude and made from field expedient parts and weapons.

By 1965, the United States had deployed a truly Air Mobile unit, the 1/7th Cavalry, which began to use more standardized armament systems. Throughout US involvement in Vietnam the US Army, US Marine Corp, and US Air Force would develop and utilize a number of armament systems designed for a variety of helicopters, and would pave the way for more dedicated attack helicopters.

With the arrival of dedicated gunship helicopters, such as the AH-1 Cobra and later the AH-64 Apache, armament subsystems for non-specific types would begin to drop off, with mostly defensive armament packages remaining. Such armament packages, giving decidedly heavy armament to small or primarily transport helicopters have become popular among second and third world countries who lack the funds for dedicated attack helicopters. Most of the systems bear some resemblance to the plethora of US systems that follow in this entry.

Contents 1 Armament Sub-Systems For Non-Dedicated Gunships 1.1 OH-13 Sioux and OH-23 Raven 1.2 CH-21 Shawnee 1.3 UH-34/CH-34 Chocktaw/Seahorse 1.4 CH-47 Chinook and ACH-47A "Guns-a-GoGo" 1.5 OH-6 Cayuse and OH-58 Kiowa 1.6 UH-1 Iroquois 1.7 UH-60 Black Hawk 2 Armament Sub-Systems For Dedicated Gunships 2.1 AH-1 Cobra 2.2 AH-56 Cheyenne 3 Citations 4 References

[edit] Armament Sub-Systems For Non-Dedicated Gunships

[edit] OH-13 Sioux and OH-23 Raven

• XM1/XM1E1

In service between 1960 and 1972, the XM1 consisted of two M37C .30-06 machine guns mounted on the landing skids of either the OH-13 or OH-23 helicopter. These weapons were fixed forward, but flexible in elevation, with their ammunition (500 rounds per gun) stored externally. The XM1E1 was the product engineering design.^[2]

NOTE: What would appear to have been a variant of the XM1 system was used by UTTHCO on their HU-1A's (later UH-1A) for a short period.^[3]

• M2

The M2 system was a variation on the XM1, replacing the M37C machine guns with 7.62x51mm NATO M60C machine guns. The mounts were similar to the XM1, also providing flexible elevation, with 650 rounds per gun stored externally.

[edit] CH-21 Shawnee

• Offensive Armament

Experiments were done using CH-21s with both fixed forward M2HB .50 caliber machine guns and forward firing rocket launchers. Neither system was standardized, but both paved the way for similar systems on later helicopter types.

• Defensive Armament

UTTHCO deployed with a number of CH-21's, and experimented with field expidient bars mated to the cargo doors, fitted with M37C .30-06 machine guns and feed from boxes mounted on top of the weapon.^[4]

NOTE: It would appear that similar mounts were fabricated for use with early UH-1s as well.

[edit] UH-34/CH-34 Chocktaw/Seahorse

• TK-1

A USMC weapon system to provide H-34 helicopters with offensive armament, the TK-1 (Temporary Kit-1) featured two M60C 7.62x51mm machine guns on each side, fixed forward, with ammunition fed out from boxes inside the aircraft. Helicopters equipped with the TK-1 were sometimes referred to as "Stingers."

• Defensive Armament

Both the US Army and the USMC developed pintle mounts for use in the main cargo door, mounting a single infantry type M60 7.62x51mm machine gun (sometimes referred to as "M60A"), allowing the crew chief to fire the weapon while seated on the opposite side.

[edit] CH-47 Chinook and ACH-47A "Guns-a-GoGo"

• M24

A defensive armament subsystem, the M24 provides a pintle mount for an M60D 7.62x51mm machine gun at either left or right front cargo doors on the CH-47. The system feeds from standard 200-round ammunition boxes attached to the weapon.^[5]

NOTE: The US Army has recently begun to phase out the M60D in favor of the new M240H, but it is unknown whether the necessity of a new cradle for the weapon will result in the system being redesignated. The mount is otherwise the same.

• XM32

A defensive armament subsystem, the XM32 provides pintle mounts for either M60D 7.62x51mm machine guns or M2HB .50 caliber machine guns at both cargo door positions and at both rear emergency hatches of the CH-47 helicopter, with weapons feeding from standard ammunition boxes. This system was developed specifically for the ACH-47 helicopter.^[6]

• XM33

A defensive armament subsystem, the XM33 provides a mount for either an M60D 7.62x51mm or an M2HB .50-caliber machine gun on the rear cargo ramp of the CH-47 helicopter. This system was developed specifically for the ACH-47 helicopter, with the weapon feeding from standard ammunition boxes.^[7]

• XM34

An offensive armament subsystem developed for the ACH-47 helicopter, the XM34 provides two M24A1 20mm cannons with ammunition boxes on sponsons at the front of the aircraft fixed forward.^[8]

NOTE: These sponsons were also fitted with aircraft-style hardpoints that allowed the mounting of XM159B/XM159C 19-tube 2.75"-rocket launchers or M18/M18A1 7.62x51mm gun pods.

• XM41/M41

A defensive armament subsystem, the M41 provides a mount for an M60D 7.62x51mm machine gun on the rear cargo ramp of the CH-47 helicopter. The system feeds from standard 200-round ammunition boxes attached to the weapon.^[9]

NOTE: The US Army has recently begun to phase out the M60D in favor of the new M240H, but it is unknown whether the necessity of a new cradle for the weapon will result in the system being redesignated. The mount is otherwise the same.

[edit] OH-6 Cayuse and OH-58 Kiowa

• XM8

The XM8 system provides a mount for one M129 40mm grenade launcher for either the OH-6 or OH-58 light observation helicopters. The system is provided with an XM70/E1 sight and 150 rounds of ammunition. The XM8's mount is interchangeable with the M27 system.^[10] See XM8 armament subsystem for more.

• M27/M27E1

The M27 system provides a mount for one M134 7.62x51mm machine gun (Minigun) for either the OH-6 or OH-58 light observation helicopters. The system is provided with an XM70/E1 sight and a MAU-56/A delinking feeder with 2000 rounds of ammunition. The original M27 featured a bulky aerodynamic fairing covering the gun and mount, which was disposed of because of the increased weight on the M27E1. The M27's mount is interchangeable with the XM8 system.

[edit] UH-1 Iroquois

• XM156/M156

Not technically an armament subsystem, the XM156/M156 universal mount provided mounting supports and racks for a number of systems used on the UH-1 series of helicopters.

• XM3/M3

The M3, sometimes referred to as "Aerial Rocket Artillery" or ARA, consisted of two 2.75" 24-Tube rocket launchers, one on either side of the aircraft, along with a Mk 8 sight. The launchers fired in pairs, one from each side to prevent the aircraft from becoming off balance. The original XM3s used system specific mounts, but later M3 systems were attached using the XM156/M156 universal mount.

NOTE: The XM3 was also tested on the CH-34/UH-34 helicopter, but with the switch to the UH-1, this was dropped.

• XM5/M5

The XM5/M5 system consists of a nose turret for a single M75 40mm grenade launcher. The mount was fully flexible and controlled by the pilot via a hand controlled sight electronically linked to the turret. The system either provided 150 or 302 rounds of ammunition.^[11]

• XM6/M6

The XM6/M6 system was one of the first systems to make use of the XM156/M156 universal mount, providing two M60C 7.62x51mm machine guns on either side of the helicopter.^[12] This system would later be expanded upon, but initially gave the UH-1 increased firepower and an improved offensive system over the skid mounts originally used.

Some M6 systems were coupled the four guns with four MA-2/A 2.75" 2-Tube rocket launchers on each side of the aircraft, giving an even greater punch. This arrangement was later supplanted by the XM16/M16 system.

• XM9

A variant of the XM6/M6 system, the XM9 substitutes the four M60C 7.62x51mm machine guns with two M75 grenade launchers, one on either side of the aircraft

• XM11, XM22/M22, and the Maxwell System

Both of these armament systems were designed to allow the UH-1 to fire the AGM-22 missile. The XM11 provided an XM70 sight and support racks for 6 missiles, three on each side of the aircraft. The support racks were similar to those used on the original XM3/M3 rocket launchers. The M22 was an improvement providing a more specific sight, the XM58, and using the XM156 universal mount. The M22 also provided for a total of 6 missiles, three on each side of the aircraft. It is important to note as well that that the XM11 was designed to fire standard SS.11 missiles, while the XM22/M22 system was designed around the US upgraded AGM-22.^[13]

The Maxwell System was a hybrid system designed by Warrant Office Robert Maxwell as a field modification. Maxwell's unit had been sent both the M3 and XM11 systems, and he noticed that often aircraft with the M3 system only firing half or less of their total rocket load. By removing one or two banks of rockets (and reducing the total carried to 12 or 18 total rockets versus 24) and adding a single launching mount for an AGM-22 missile he effectively gave the aircraft both suppression and point attack capabilities.^[14]

• XM16/M16

The XM16/M16 system mated the previous M6 with either two M157 or two M158 2.75" 7-Tube rocket launchers utilizing the M156 Universal Mount. The combined weight and aircraft limitations meant that only seven-tube launchers could be used.^[15]

• XM21/M21

A further variation on what had essentially become a basic system, the XM21/M21 subsystem replaced the XM16/M16's four M60Cs with two M134 7.62x51mm Miniguns.

• XM23/M23

The M23 system provides a pintle mount at both main cabin doors for an M60D 7.62x51mm machine gun, with the weapon feeding from either a standard ammunition box or a larger purpose built box connected the mount.^[16] The M23 is specifically designed for long fuselage UH-1s (UH-1D/H/N).

• XM26

With the development of the BGM-71 TOW missile Hughes had been given the contract to develop a launching system for the UH-1. By 1968 development had shifted over to development of a system for the AH-56 helicopter which was eventually canceled. The XM26 provided two 3-Tube launchers on either side of the aircraft, as well as, the necessary sighting equipment. While the XM26 was more of a test platform, the two prototypes were deployed operationally as an emergency measure in South Vietnam to counter the Easter Invasion in 1972.^[17]

• XM29 and the Sagami Mount

The XM29 was an experimental door pintle for the main cabin doors of short fuselage UH-1s (at the time the UH-1B/C), for an M60D 7.62x51mm machine gun.

Far more common on such helicopters, including the later UH-1F/P/M specifically, was the Sagami Mount, a skeleton frame mount that swung out from a fixed position at the rear of the cabin. This mount was designed for the M60D, but in certain instances, primarily by the US Navy Seawolves, dual M60s, M2HB machine guns or M134 Miniguns were fitted.

Sources debate the origin of the "Sagami" name, with it being attributed to the soldier responsible for its creation^[18], as well as, to the name of the US facility on Okinawa where it was developed.

• XM30

An experimental system, the XM30 provided fully flexible mounts using the XM156/M156 universal mounts for two XM140 30mm cannons, with 600 rounds of ammunition per gun.^[19]

• XM31

Another attempt to up the firepower from existing systems, the XM31 provided two M24A1 20mm cannons in pods fitted to XM156/M156 universal mounts each with 600 rounds of ammunition, and flexible in elevation only.^[20]

• XM50

XM50 is a designation for the combination of the XM5/M5 and the XM21/M21 armament subsystems, a common configuration used by US forces in South East Asia.

• XM59/M59

A variation on the M23, the XM59/M59 was modified to accept either an XM213/M213 .50 caliber machine gun or an XM175 40mm grenade launcher in addition to being able to mount the M60.

• XM93/XM93E1

This armament subsystem provides door mounts for long fuselage UH-1s (UH-1D/H/N) for two M134 7.62x51mm Miniguns. The USAF also used this system on their short fuselage UH-1F/P helicopters. These weapons are equipped with chutes connected to their ejection ports that directs spent cases and links away from the aircraft.^[21]

The XM93E1 is a variation on the system that allows both guns to be trained forward and remotely fired by the pilot via an electronically linked sight.

NOTE: The USAF was the primary user of this system and often combined it with two 7-Tube 2.75" rocket launchers of varying types on two independent support rack and pylon assemblies.^[22]

• XM94

A variant of the XM93, the XM94 substitutes the M129 40mm grenade launcher for one or both of the door mounted M134 7.62x51mm Miniguns.^[23]

• TK-2

A variant of the TK-1 for the CH-34/UH-34 helicopter, the TK-2 (Temporary Kit-2) was developed by the USMC for their UH-1E helicopter. The system provides the same four M60C 7.62x51mm machine guns as the TK-1, but adds two independent support rack and pylon assemblies to the system, for mounting an acceptable aircraft style armament. Typically these mounts were used for 7-Tube 2.75" rocket launchers of varying types, but were also seen tested with XM18/M18 Minigun pods (USAF SUU-11/A).^[24]

• Emerson TAT-101

Unqiue to USMC UH-1E helicopters between April 1967 and 1972 was the use of the Emerson Electric TAT-101 nose turret. The turret housed two M60 machine guns with 1000 rounds total, and had 100 degrees in azimuth left or right, plus 15 degrees of elevation and 45 degrees of depression.^[25] The slew-rate on the turret was 45 degrees per second.^[26] Jamming and the need for maintainence led to the turret's front fairing to be left off to assist ground crews in quickly dealing with any problems, and these reasons combined in the USMC decsision to drop the turrets from inventory entirely at the end of 1972.^[27]

[edit] UH-60 Black Hawk

• M144

The M144 is a defensive subsystem that provides mounts and cradles at the two windows between the pilot doors and the main cabin doors on the UH-60 series of helicopters, each mounting a single M60D 7.62x51mm machine gun.

NOTE: The US Army has recently begun to phase out the M60D in favor of the new M240H, but it is unknown whether the necessity of a new cradle for the weapon will result in the system being redesignated. The mount is otherwise the same.

[edit] Armament Sub-Systems For Dedicated Gunships

[edit] AH-1 Cobra

• XM35/M35

An armament subsystem providing a single M195 20mm cannon on the port inboard pylon of the AH-1G. 950 rounds of ammunition were stored in boxes faired to the side of the aircraft. The system was primarily pilot controlled, but featured dual controls to be either pilot or gunner controlled. For this purpose the pilot was provided with a M73 sight.^[28][29][30]

• XM65/M65

The Cobra Missile System is a functional development of the XM26 and the TOW missile system developed for the failed AH-56 helicopter. Originally designed for the AH-1Q and AH-1S Cobras, the AH-1F Modernized Cobra was also rebuilt to use the system. The original iteration of the system comprises launchers allowing for four BGM-71 TOW missiles per aircraft pylon to be carried, and a TSU or Telescopic Sight Unit, to allow for targeting and guidance of the missile. The TSU has been upgraded with the LAAT (Laser-Augmented Airborne TOW), a day/night range finder, and C-NITE (Cobra-Night Imaging Thermal Equipment), a thermal imagine/FLIR system specifically for the AH-1S and AH-1F Cobra helicopters.

[edit] AH-56 Cheyenne

• XM51

A nose turret with one M129 40mm grenade launcher with 300 rounds. In light of the failure of the AH-56 was proposed as a replacement for the M5 system on the UH-1 helicopoter.^[31]

• XM52

Belly turret with a single XM140 30mm cannon. Use on other helicopters was also debated.^[32]

• XM53

A nose turret with one M134 7.62x51mm Minigun. Also said to be suitable for the UH-1 series of helicopters.^[33]

[edit] Citations

[edit] References

• Drendel, Lou. Gunslingers in Action. Carrollton, TX: Squadron/Signal Publications, Inc, 1974. ISBN 0-89747-013-3.
• Gervasi, Tom. Arsenal of Democracy III: America's War Machine, the Pursuit of Global Dominance. New York, NY: Grove Press, Inc, 1984. ISBN 0-394-54102-2.
• Gunston, Bill. The Illustrated Encyclopedia of Aircraft Armament. New York, NY: Orion Books, 1988. ISBN 0-517-56607-9.
• Mesko, Jim. Airmobile: The Helicopter War in Vietnam. Carrollton, TX: Squadron/Signal Publications, Inc, 1984. ISBN 0-89747-159-8.
• Mutza, Wayne. Walk Aroud: UH-1 Huey Gunships. Carrollton, TX: Squadron/Signal Publications, Inc, 2004. ISBN 0-89747-479-1.
• Mutza, Wayne. H-13 Sioux Mini In Action. Carrollton, TX: Squadron/Signal Publications, Inc, 1995. ISBN 0-89747-329-0.