The Hydra 70 rocket is a weapon derived from the 2.75 inch (70 mm) "Folding-Fin Aerial Rocket" (Mk 4/Mk 40 Folding-Fin Aerial Rocket) developed by the U.S. Navy for use as a free-flight aerial rocket in the late 1940s.
Overview
The Hydra 70 family of WAFAR (Wrap-Around Fin Aerial Rocket), based around the Mk 66 universal motor was developed from the previous 2.75 inch Mk 40 motor-based FFAR (Folding Fin Aerial Rocket). The Mk 40 was originally used during the Korean and Vietnam wars, beginning a rich history of providing close air support to ground forces from about 20 different firing platforms, both fixed-wing and armed helicopters, by all U.S. armed forces. Today, the OH-58D(R) Kiowa Warrior and AH-64D Apache Longbow carry the Hydra rocket launcher standard on its weapon pylons. To provide some stability the four rocket nozzles were scarfed at an angle to impart a slight spin to the rocket during flight.
Mk 66 rocket motor variants
| Designation
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| Mk 66 Mod 0
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| Mk 66 Mod 1
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| Mk 66 Mod 2
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| Mk 66 Mod 3
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| Mk 66 Mod 4
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| Mk 66 Mod 5
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| Mk 66 Mod 6
| Mk 66 Mod 4/5 variant; designed to reduce the tendency of secondary launch gasses to combust in the parent aircraft’s engine (Primarily with regards to the AH-64 series of helicopters) |
Service
The family of Hydra 70 (70 mm) 2.75 inch rockets perform a variety of functions. The war reserve unitary and cargo warheads are used for anti-
materiel,
anti-personnel, and suppression missions. The Hydra 70 family of Folding-Fin Aerial Rockets (FFAR) also includes smoke screening, illumination, and training
warheads. Hydra 70 rockets are known mainly by either their warhead type or by the
rocket motor designation, Mk 66 in US military service.
USA
In the
U.S. Army, Hydra 70 rockets are fired from the
AH-64A Apache and AH-64D Apache Longbow helicopters using M261 19-tube rocket launchers, and the
OH-58D Kiowa Warrior and the
AH-1F "modernized" Cobra using seven-tube M260 rocket launchers. The M260 and M261 are used with the Mk 66 series of rocket motor, which replaced the Mk 40 series. The Mk 66 has a reduced system weight and provides a remote
fuze setting interface.
The AH-1G Cobra and the UH-1B "Huey" used a variety of launchers including the M158 seven-tube and M200 19-tube rocket launchers. The M158 and M200 were used with the Mk 40 rocket motor. The MK40 rocket motor was replaced by the newer Mk 66 rocket motor. The M158 and M200 rocket launchers are not compatible with the Mk 66 rocket motor. The Hydra 70 rocket system is also used by the U.S. Marine Corps, the U.S. Navy, and the U.S. Air Force.
Germany
The Hydra is used on the
Eurocopter Tiger of the
German Army.
Common U.S. Mk 66 compatible launchers
| Designation
| Description |
| M260
| 7-Tube LWL (LightWeight Launcher) |
| M261
| 19-Tube LWL (LightWeight Launcher) |
| LAU-130/A
| 19-Tube rocket launcher |
| LAU-131/A
| 7-Tube rocket launcher |
| LAU-68D/A
| 7-Tube LAU-68C/A variant; compatible w/ Mk 66 rocket motor; external thermal protection coating; launcher supports single and ripple firing |
| LAU-61C/A
| 19-Tube LAU-61B/A variant; compatible w/ Mk 66 rocket motor; external thermal protection coating; launcher supports single and ripple firing |
Warheads
Hydra 70 warheads fall into three categories:
- Unitary warheads with impact-detonating fuzes or remote-set multi-option fuzes.
- Cargo warheads with airburst-range, with setable fuzes using the "wall-in-space" concept or fixed standoff fuzes.
- Training warheads.
Fuzing options
| #
| Designation
| Description |
| 1
| M423
| Point Detonating |
| 2
| M427
| Point Detonating |
| 3
| XM436
| Airburst, Motor-Burnout Delay |
| 4
| XM438/M438
| Point Detonating |
| 5
| M440
| Point Detonating |
| 6
| Mk 352 Mod 0/1/2
| Point Detonating |
| 7
| M429
| Proximity Airburst |
| 8
| M433
| Multi-Option Time Delay |
| 9
| M439
| Multi-Option Time Delay, Pilot-Selectable |
| 10
| M442
| Airburst, Motor-Burnout Delay |
| 11
| M446
| Airburst, Motor-Burnout Delay |
| 12
| Model 113A
| Airburst, Motor-Burnout Delay |
Common warheads
| Designation
| Description
| Fuzing options |
| M151
| High explosive (HE) '10 pounder'
| 1,2,5,7,8 |
| M156
| White phosphorus (WP)
| 1,2,6,7 |
| M229
| High explosive (HE); elongated M151 '17 pounder'
| 1,2,6,7 |
| XM245
| Submunition warhead with 32 XM100 CS canisters; possibly a modernized XM80/XM99
| 3 |
| M247
| High-explosive anti-tank (HEAT)/high-explosive dual purpose (HEDP)
| 4 (integral to warhead) |
| M255
| APERS warhead with 2500 28 grain (1.8 g) flechettes
| 9 |
| M255E1/A1
| APERS warhead with 1180 60 grain (3.8 g) flechettes
| 9 |
| M257
| Parachute illumination
| 10 (integral to warhead) |
| M259
| White phosphorus (WP)
| 9 |
| M261
| Multi-purpose submunition, with 9 M73 SMs
| 9 |
| M264
| Red phosphorus (RP)
| 9 |
| M278
| Infra-red (IR) parachute illumination
| 10 (integral to warhead) |
| Mk 67 Mod 0
| White phosphorus (WP)
| 1,2,6,7 |
| Mk 67 Mod 1
| Red phosphorus (RP)
| 1,2,6,7 |
| WDU-4/A
| APERS warhead with unknown number of flechettes of unknown weight
| 12 (integral to warhead) |
| WDU-4A/A
| APERS warhead with 2200 30 grain (1.3 g) flechettes
| 12 (integral to warhead) |
NOTE: Some of the warheads described were designed for the older Mk 40 rocket motor, but most likely could work with the Mk 66 motor if upgraded or modernized models were not available.
Precision guided Hydra 70
The
Advanced Precision Kill Weapon System (APKWS) II was a program to provide a
laser guided missile which would have been compatible with the existing Hydra 70 systems in service. It was cancelled in February 2007. Similar programs are the
US Navy Low-Cost Guided Imaging Rocket,
Lockheed Martin Direct Attack Guided Rocket and the
ATK/
Elbit Guided Advanced Tactical Rocket - Laser.
References
See also
External links
