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Hydra 70 Folding-Fin Aerial Rocket

The Hydra 70 rocket system is a family of unguided air-to-surface rockets. Basically, Hydra 70 refers to the MK 66 rocket motor with any warhead / fuze combination. The rocket motor was designed to provide a common rocket for helicopters and high-performance aircraft. These rockets are used to perform various roles, including anti-materiel, anti-personnel, air-to-ground suppression and illumination.

Status

In active service

Contractors

Original MK 66 rocket motor manufacturer: BEI Defense
Manufacturer: Lockheed Martin Ordnance Systems (until being sold to General Dynamics)
Manufacturer: General Dynamics Armament and Technical Products

MK 66 rocket motor versions

  • MK 66 MOD 0: the original version, which was not mass-produced.
  • MK 66 MOD 1: the first production version for the U.S. Army.
  • MK 66 MOD 2: the first production version for the U.S. Air Force and Navy. The MOD 2 development made the motor HERO (Hazards of Electromagnetic Radiation to Ordnance) safe. HERO safety prevents accidental ignition of the motor by stray electromagnetic fields like those emitted by a radar.
  • MK 66 MOD 3: the HERO safe version of the MOD 1 for the U.S. Army.
  • MK 66 MOD 4: this version has internal changes, including new initiator and igniter, for further enhanced HERO safety. It is used by all armed service branches.

Warhead types

  • M151: anti-personnel fragmentation warhead.
  • M156: white phosphorus smoke warhead.
  • M229: anti-personnel fragmentation warhead (elongated version of M151).
  • M247: shaped-charge anti-armor warhead.
  • M255: flechette warhead; contains about 2500 28-grain (1.8 g) flechettes.
  • M255E1: flechette warhead; contains about 1180 60-grain (3.8 g) flechettes.
  • M257: parachute-retarded battlefield illumination flare.
  • M259: white Phosphorus smoke warhead.
  • M261: high-explosive MPSM (Multipurpose Submunition) warhead; contains nine M73 anti-personnel/anti-materiel bomblets, which are released in mid-air, and drag-retarded to fall vertically to the ground.
  • M264: red phosphorus smoke warhead.
  • M267: practice warhead for M261 (contains three M75 practice submunitions).
  • M274: practice warhead for M151 (contains a smoke signature charge).
  • M278: parachute-retarded infrared illumination flare.
  • MK 67 MOD 0: white phosphorus smoke warhead.
  • MK 67 MOD 1: red phosphorus smoke warhead.
  • WDU-4A/A: flechette warhead; contains about 2200 20-grain (1.3 g) flechettes.
  • WTU-1/B: inert practice warhead.

Characteristics

Dimensions
Length: 140 - 178 centimeters 55 - 70 inches
Warhead length:
- M151: 41.2 centimeters 16.2 inches
- M229: 66 centimeters 26 inches
- M264: 68.3 centimeters 26.9 inches
- M255A1: 68.3 centimeters 26.9 inches
- M257/M278: 73.9 centimeters 29.1 inches
- M278: 73.9 centimeters 29.1 inches
- M156: 41.2 centimeters 16.2 inches
- WTU-1B: 41.2 centimeters 16.2 inches
- M274: 41.2 centimeters 16.2 inches
Diameter: 7 centimeters 2.75 inches
Weight
Weight: 10.4 - 12.25 kilograms 23 - 27 pounds
Warhead weight:
- M151: 4.22 kilograms 9.3 pounds
- M229: 7.7 kilograms 17 pounds
- M264: 3.9 kilograms 8.6 pounds
- M255A1: 6.35 kilograms 14 pounds
- M257/M278: 5 kilograms 11 pounds
- M278: 5 kilograms 11 pounds
- M156: 4.38 kilograms 9.65 pounds
- WTU-1B: 4.22 kilograms 9.3 pounds
- M274: 4.22 kilograms 9.3 pounds
Features
Range: 10 500 meters 11 500 yards
Maximum speed: 739 meters per second 2 425 feet per second
Rocket motor thrust: 6.7 kilonewtons (for 1.1 seconds) 1 500 pounds (for 1.1 seconds)
Miscellaneous
Propulsion: MK 66 solid-fieled rocket

Timeline

1972 - Field date for the MK 66 Mod 0
1981 - MK 66 Mod 2 full-rate production began for the U.S. Air Force
January 1986 - MK 66 Mod 2 full-rate production began for the U.S. Navy
1991 - Development began on the MK 66 Mod 4
December 1999 - MK 66 Mod 4 full-rate production began