2.75" (70mm) Air-to-Surface Rocket
Using Service (US):
Air Force, Army, Navy and Marine Corps
General Dynamics Corp. (GD-OTS)
The General Dynamics
Hydra-70 Family of 2.75-inch (70 mm) air-to-surface, unguided rockets are used by U.S. Army, U.S. Air Force, U.S. Navy,
Marine Corps, and Special Operations Forces fixed and rotary-wing aircraft to perform a number of roles
including anti-materiel, anti-personnel, air-to-ground suppression and illumination.
The Hydra-70 rocket system has three main components: the Mk 66 MOD 4 rocket motor; one of nine different warheads; and a point-detonating, omni-directional, remote-set fuze. Hydra-70 rockets are fired from the M260 7-tube, M261 19-tube, LAU-61 19-tube, LAU-68 7-tube, and LAU-131/A 7-tube rocket launchers. The system can be installed on most rotary and fixed-wing aircraft, including the AH-64 Apache/Apache Guardian attack helicopter, the UH-60 Black Hawk utility helicopter, the OH-58 Kiowa Warrior armed reconnaissance helicopter, the AV-8B Harrier II, the AH-1Z Viper and UH-1Y Venom, the A-10 Thunderbolt II ground attack aircraft, and F-16 Fighting Falcon.
Since 1996, General Dynamics Ordnance and Tactical Systems (GD-OTS) has produced more than four million Hydra-70 rockets in support of the Army's Joint Attack Munition Systems (JAMS) Project Office at Redstone Arsenal in Alabama.
The Hydra-70 was developed in the late 1940s and has become the standard ground-attack rocket for U.S. military aircraft. It was used extensively in the Korean War, Vietnam, and Operation Desert Storm.
In the following, the nine main variants of the Hydra-70 rocket are presented:
The M151 HEPD is a unitary fragmenting 10-pound anti-personnel, anti-material warhead with the M423 Point Detonating Fuze. Upon detonation, the warhead fragments into thousands of small high velocity fragments. The fuzed warhead is 16.2" long and weighs 9.3 pounds.
The M156 white phosphorus (smoke) is primarily used for target marking. The M156 has the same ballistic characteristics as the M151 warhead and is of similar construction. Filler for the M156 is 2.2 pounds of white phosphorus with a 0.12 pound bursting charge of composition B. The fuzed warhead is 16.2" long and weighs 9.65 pounds.
The M229 High Explosive warhead is a heavier version of the M151. The U.S. Army is currently not buying this variant. The fuzed warhead is 26" long and weighs 17 pounds.
The M255A1 Flechette warhead consists of a nose cone assembly, a warhead case, an integral fuze, 1,179 60-grain flechettes and an expulsion charge assembly. The primary fuze (M439) is remotely set with the Aerial Rocket Control System (ARCS) Multifunctional Display (MFD) or Rocket Management System (RMS) to provide a range from 500 meters to 7,200 meters. At expulsion, the 1,179 60-grain, hardened-steel flechettes separate and form a disk-like mass which breaks up with each flechette assuming an independent trajectory. The flechette uses kinetic energy derived from the velocity of the rocket to produce the desired impact and penetration of the target. The fuzed warhead is 26.9" long and weighs 14 pounds.
The M257 Illuminating warhead is designed to provide battlefield illumination and does not require the use of Infrared (IR) goggles. The M257 flare rocket can be launched by from either fixed wing or rotary-wing aircraft. The M442 motor burnout fuze functions after a 9-second delay. The fuzed warhead is 29.1" long and weighs 11 pounds.
The MPSM warhead (weight is 13.9 pounds) provides improved lethal effectiveness against area targets such as light armor, wheeled vehicles, materiel, and personnel. The M73 Submunitions are deployed over the target and descend almost vertically. The M261 Warhead is a cargo warhead consisting of a nose cone assembly, a case, integral fuze, nine submunitions, and an expulsion charge assembly. The primary M439 warhead fuze is remotely set with the Aerial Rocket Control System (ARCS), Multifunctional Display (MFD) or Rocket Management System (RMS) to provide a range from 500 meters to 7,200 meters.
The M264 RP (red phosphorous) Smoke is used as a red phosphorous filled smoke rocket propelled by the Mk 66 motor and the smoke is deployed at a range set remotely from within the aircraft cockpit. The M264 warhead is used for smoke obscuration in the visible light spectrum. The fuzed warhead is 26.9" long and weighs 8.6 pounds.
The M274 warhead is a smoke/flash signature practice warhead used for pilot/gunner training missions and consists of a cast iron warhead modified with vent holes, an aluminum nose cap with firing pin, a M423 fuze safe and arming device, and a smoke/flash cartridge. The fuzed warhead is 16.2" long and weighs 9.3 pounds.
The M278 Infrared Flare warhead is designed for battlefield illumination for use with Infrared (IR) goggles. The flare rockets can be launched from either fixed wing or rotary-wing aircraft. The 442 motor burnout fuze functions after a 9-second delay. The fuzed warhead is 29.1" long and weighs 11 pounds.
The fuzed warhead is 16.2" long and weighs 9.3 pounds.
In FY 2014, the unit cost of a Hydra-70 M255A1 Flechette rocket is approximately $1,548, while the unit cost of the Hydra-70 M151 HEPD rocket is $1,273.
Anti-materiel, antipersonnel, air-to-ground suppression, and illumination.
Procurement funds in the amount of $165.5 million will purchase approximately 99,922 rockets.
FY 2015 Base procurement funds in the amount of $27.3 million will purchase 741 Hydra 70 rockets.
FY 2015 OCO procurement funds in the amount of $66.9 million will purchase 45,336 Hydra 70 rockets.
In total (Base + OCO), funds in the amount of $94.2 million will purchase 46,077 rockets.
For more information, click to see the Complete FY 2015 Army Hydra-70 Budget.
Sources: U.S. Department of Defense (DoD) and General Dynamics Corp.
Last Update: August 14, 2014.
By Joakim Kasper Oestergaard /// (firstname.lastname@example.org)
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