Hydra 70
Encyclopedia
The Hydra 70 rocket
is a weapon
derived from the 70 mm (2.75 inch) Mk 4/Mk 40 Folding-Fin Aerial Rocket
developed by the United States Navy
for use as a free-flight aerial rocket
in the late 1940s.
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 US armed forces
. Today, the OH-58D(R) Kiowa Warrior and AH-64D Apache Longbow, as well as the Marine Corp's AH-1 Cobra, carry the Hydra rocket launcher standard on its weapon pylons. The name Hydra is a reference to the beast of Greek mythology.
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 also includes smoke screening, illumination, and training warhead
s. Hydra 70 rockets are known mainly by either their warhead type or by the rocket motor designation, Mk 66 in US military service.
, Hydra 70 rockets are fired from the AH-64A Apache and AH-64D Apache Longbow
helicopter
s using M261 19-tube rocket launchers, and the OH-58D Kiowa Warrior
using seven-tube M260 rocket launchers. In the U.S. Marine Corps
, either the M260 or M261 launchers are employed on the AH-1 Cobra
and future AH-1Z Viper
, depending upon the mission. 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. Hydra 70s have also been fired from UH-60 and H-6 series aircraft in US Army service.
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the M158 seven-tube and M200 19-tube rocket launchers designed for the Mk 40 rocket motor; however, these models have been replaced by upgraded variants in the U.S. Marine Corps
because they were not compatible with the Mk 66 rocket motor. The Hydra 70 rocket system is also used by the U.S. Navy
, and the U.S. Air Force
.
Hydra 70 rockets may also be used from the following fixed-wing platforms: A-4, A-6, A-7, AV-8B, A-10, F-4, F-16, F/A-18 and OV-10.
NOTE:Though 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. However, this would not be necessary, as vast quantities of upgraded models exist today.
Length: 41.7 in (1.06 m)
Burn time: 1.05 - 1.10 sec
Average thrust (77 F):
1,335 lb (Mod 2/3)
1,415 lb (Mod 4)
Motor burnout range:
1,300 ft (397 m)
Motor burnout velocity:
2425 ft/s (739.1 m/s)
Launch spin rate: 10 rps, 35 rps after exiting launcher
Velocity at launcher exit:
148 ft/s (45.1 m/s)
Acceleration:
60-70 g (initial)
95-100 g (final)
Effective Range:
500 to 8,000 m depending on warhead and launch platform
Maximum Range:
10,500 m under optimum conditions
(APKWS) II is a program to provide a laser guided missile that is compatible with the existing Hydra 70 systems in service. It was cancelled by the US Army in February 2007, but was restarted by the US Navy in 2008. 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.
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...
is a weapon
Weapon
A weapon, arm, or armament is a tool or instrument used with the aim of causing damage or harm to living beings or artificial structures or systems...
derived from the 70 mm (2.75 inch) Mk 4/Mk 40 Folding-Fin Aerial Rocket
Mk 4/Mk 40 Folding-Fin Aerial Rocket
The Mk 4 Folding-Fin Aerial Rocket , sometimes called the Mighty Mouse, was a 2.75 in diameter unguided rocket weapon commonly used by U.S. military aircraft. It was intended as an air-to-air weapon to allow interceptor aircraft to shoot down enemy bombers with greater range and effectiveness than...
developed by the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
for use as a free-flight aerial rocket
Rocket (weapon)
A rocket is a self propelled, unguided weapon system powered by a rocket motor.- Categorisation :In military parlance, powered munitions are broadly categorised as follows:* A powered, unguided munition is known as a rocket....
in the late 1940s.
Overview
The Hydra 70 family of WAFAR (Wrap-Around Fin Aerial Rocket), based on the Mk 66 universal motor, was developed from the previous 2.75 inch Mk 40 motor-based folding fin aerial rocket. The propellant grain is longer and of a different formulation than that of the MK40/MK4, however, the stabilizing rod and igniter are essentially the same design. The MK66 motors have a substantially higher thrust, 1335 lbs (Mod 2/3) 1415 lbs (Mod 4), and a longer range than the older motors. To provide additional stability the four rocket nozzles are scarfed at an angle to impart a slight spin to the rocket during flight. The Mk 40 was used during the KoreanKorean War
The Korean War was a conventional war between South Korea, supported by the United Nations, and North Korea, supported by the People's Republic of China , with military material aid from the Soviet Union...
and Vietnam
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...
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 US armed forces
United States armed forces
The United States Armed Forces are the military forces of the United States. They consist of the Army, Navy, Marine Corps, Air Force, and Coast Guard.The United States has a strong tradition of civilian control of the military...
. Today, the OH-58D(R) Kiowa Warrior and AH-64D Apache Longbow, as well as the Marine Corp's AH-1 Cobra, carry the Hydra rocket launcher standard on its weapon pylons. The name Hydra is a reference to the beast of Greek mythology.
Mk 66 rocket motor variants
| Designation | Description |
|---|---|
| Mk 66 Mod 0 | 70 mm (2.75 in) WAFAR universal motor; common motor for the GD Hydra 70 series of rockets; original prototype; for US Army |
| Mk 66 Mod 1 | Mk 66 variant; production variant; for US Army |
| Mk 66 Mod 2 | Mk 66 Mod 1 variant; HERO (Hazards of Electromagnetic Radiation to Ordnance) safe; for US Navy and US Air Force |
| Mk 66 Mod 3 | Mk 66 Mod 1 variant; HERO safe; Mk 66 Mod 2 for US Army |
| Mk 66 Mod 4 | Mk 66 Mod 2/3 variant; incorporates a Salt rod to reduce exhaust gases; for all services |
| Mk 66 Mod 5 | Mk 66 Mod 4 variant; Incorporates propellant venting during fast cook off |
| 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
Materiel
Materiel is a term used in English to refer to the equipment and supplies in military and commercial supply chain management....
, anti-personnel, and suppression missions. The Hydra 70 family of folding-fin aerial rockets also includes smoke screening, illumination, and training warhead
Warhead
The term warhead refers to the explosive material and detonator that is delivered by a missile, rocket, or torpedo.- Etymology :During the early development of naval torpedoes, they could be equipped with an inert payload that was intended for use during training, test firing and exercises. This...
s. 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. ArmyUnited States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...
, Hydra 70 rockets are fired from the AH-64A Apache and AH-64D Apache Longbow
AH-64 Apache
The Boeing AH-64 Apache is a four-blade, twin-engine attack helicopter with a tailwheel-type landing gear arrangement, and a tandem cockpit for a two-man crew. The Apache was developed as Model 77 by Hughes Helicopters for the United States Army's Advanced Attack Helicopter program to replace the...
helicopter
Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by one or more engine-driven rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally...
s using M261 19-tube rocket launchers, and the OH-58D Kiowa Warrior
OH-58 Kiowa
The Bell OH-58 Kiowa is a family of single-engine, single-rotor, military helicopters used for observation, utility, and direct fire support. Bell Helicopter manufactured the OH-58 for the United States Army based on the 206A JetRanger helicopter. The OH-58 has been in continuous use by the U.S...
using seven-tube M260 rocket launchers. In the U.S. Marine Corps
United States Marine Corps
The United States Marine Corps is a branch of the United States Armed Forces responsible for providing power projection from the sea, using the mobility of the United States Navy to deliver combined-arms task forces rapidly. It is one of seven uniformed services of the United States...
, either the M260 or M261 launchers are employed on the AH-1 Cobra
AH-1 Cobra
The Bell AH-1 Cobra is a two-bladed, single engine attack helicopter manufactured by Bell Helicopter. It shares a common engine, transmission and rotor system with the older UH-1 Iroquois...
and future AH-1Z Viper
AH-1Z Viper
The Bell AH-1Z Viper is a twin-engine attack helicopter based on the AH-1W SuperCobra, that was developed for the United States Marine Corps. The AH-1Z features a four-blade, bearingless, composite main rotor system, uprated transmission, and a new target sighting system. The AH-1Z is part of the...
, depending upon the mission. 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
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...
setting interface. Hydra 70s have also been fired from UH-60 and H-6 series aircraft in US Army service.
The AH-1G Cobra
AH-1 Cobra
The Bell AH-1 Cobra is a two-bladed, single engine attack helicopter manufactured by Bell Helicopter. It shares a common engine, transmission and rotor system with the older UH-1 Iroquois...
and the UH-1B "Huey"
UH-1 Iroquois
The Bell UH-1 Iroquois is a military helicopter powered by a single, turboshaft engine, with a two-bladed main rotor and tail rotor. The helicopter was developed by Bell Helicopter to meet the United States Army's requirement for a medical evacuation and utility helicopter in 1952, and first flew...
used a variety of launchers including the M158 seven-tube and M200 19-tube rocket launchers designed for the Mk 40 rocket motor; however, these models have been replaced by upgraded variants in the U.S. Marine Corps
United States Marine Corps
The United States Marine Corps is a branch of the United States Armed Forces responsible for providing power projection from the sea, using the mobility of the United States Navy to deliver combined-arms task forces rapidly. It is one of seven uniformed services of the United States...
because they were not compatible with the Mk 66 rocket motor. The Hydra 70 rocket system is also used by the U.S. Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
, and the U.S. Air Force
United States Air Force
The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...
.
Hydra 70 rockets may also be used from the following fixed-wing platforms: A-4, A-6, A-7, AV-8B, A-10, F-4, F-16, F/A-18 and OV-10.
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 fuses or remote-set multi-option fuses.
- Cargo warheads with air burstAir burstAn air burst is the detonation of an explosive device such as an anti-personnel artillery shell or a nuclear weapon in the air instead of on contact with the ground or target or a delayed armor piercing explosion....
-range, with setable fuses using the "wall-in-space" concept or fixed standoff fuses. - Training warheads.
Fusing options
| # | Designation | Description | Arming Range, Acceleration or Time |
|---|---|---|---|
| 1 | M423 | Nose Mount, Point Detonating for slow speed platforms (helicopters) | 43 to 93m |
| 2 | M427 | Nose Mount, Point Detonating for high speed platforms | 180 to 426m |
| 3 | XM436 | Air burst Air burst An air burst is the detonation of an explosive device such as an anti-personnel artillery shell or a nuclear weapon in the air instead of on contact with the ground or target or a delayed armor piercing explosion.... , Motor-Burnout Delay |
|
| 4 | XM438/M438 | Nose Mount, Point Detonating | |
| 5 | M440 | Point Detonating | |
| 6 | Mk 352 Mod 0/1/2 | Point Detonating | |
| 7 | M429 | Proximity Air burst Air burst An air burst is the detonation of an explosive device such as an anti-personnel artillery shell or a nuclear weapon in the air instead of on contact with the ground or target or a delayed armor piercing explosion.... |
|
| 8 | M433 | Nose Mount, Resistance Capacitance (RC) | SuperQuick (PD) 10 to 45m Delay in 5m increments including 3m Bunker penetrating option |
| 9 | M439 | Base Mount, Resistance Capacitance (RC), Payload Discharging Pilot-Selectable | Discharges SMs between 500 and 7200m (700 to 6900m on AH-1s) 27Gs |
| 10 | M442 | Air burst Air burst An air burst is the detonation of an explosive device such as an anti-personnel artillery shell or a nuclear weapon in the air instead of on contact with the ground or target or a delayed armor piercing explosion.... , Motor-Burnout Delay |
Discharges Flare at 3000m, 17-22G required for arming |
| 11 | M446 | Base Mount, Air burst Air burst An air burst is the detonation of an explosive device such as an anti-personnel artillery shell or a nuclear weapon in the air instead of on contact with the ground or target or a delayed armor piercing explosion.... , Motor-Burnout Delay |
|
| 12 | Model 113A | Base Mount, Air burst Air burst An air burst is the detonation of an explosive device such as an anti-personnel artillery shell or a nuclear weapon in the air instead of on contact with the ground or target or a delayed armor piercing explosion.... , Motor-Burnout Delay |
Common warheads
| Designation | Description | Weight | Payload | Fuse Type | Fusing options |
|---|---|---|---|---|---|
| M151 | High explosive (HEPD) '10 pounder' | 9.3 lbs (4.2 kg) | 2.3 pounds Comp B-4 HE | M423 | 1,2,5,7,8 |
| M156 | White phosphorus (WP) | 9.65 lbs (4.38 kg) | 2.2 lbs (1.0 kg) WP | M423 M429 | 1,2,6,7 |
| M229 | High explosive (HEPD); elongated M151 '17 pounder' | 17.0 lbs (7.7 kg) | 4.8 pounds Comp B-4 HE | M423 | 1,2,6,7 |
| XM245 | Submunition warhead possibly a modernized XM80/XM99 | 32 XM100 CS canisters | 3 | ||
| M247 | High-explosive anti-tank (HEAT)/high-explosive dual purpose (HEDP) | 8.8 lbs (4.0 kg) | 2.0 lbs Comp B HE | M438 PD | 4 (integral to warhead) |
| M255 | APERS warhead | 2500 28 grain (1.8 g) flechettes | 9 | ||
| M255E1/A1 | Flechette Flechette A flechette is a pointed steel projectile, with a vaned tail for stable flight. The name comes from French , "little arrow" or "dart", and sometimes retains the acute accent in English: fléchette.-Bulk and artillery use:... warhead |
14.0 lbs (6.4 kg) | 1179 60 grain (3.8 g) flechettes | M439 | 9 |
| M257 | Parachute illumination | 11.0 lbs (5.0 kg) | One M257 Candle (Flare) 1 million candela | M442 | 10 (integral to warhead) |
| M259 | White phosphorus (WP) | 9 | |||
| M261 | Multi-purpose submunition (MPSM) | 13.5 lbs (6.1 kg) | 9 M73 Submunitions | M439 with M84 electric detonator | 9 |
| M264 | Red phosphorus (RP) Smoke | 8.6 lbs (3.9 kg) | 72 RP Pellets | M439 | 9 |
| M267 | MPSM Practice | 13.5 lbs (6.1 kg) | Three Marking SMs, 6 Metal Weights | M439 with M84 electric Detonator | 9 |
| M274 | Practice (Smoke) | 9.3 lbs (4.2 kg) | 2 ounces of potassium perchlorate and aluminum powder | M423 | 1 |
| M278 | Infra-red (IR) parachute illumination | 11.0 lbs (5.0 kg) | One M278 IR Flare | M442 | 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 | |||
| WTU-1/B | Practice | 9.3 lbs (4.2 kg) | Inert | None | None |
| WDU-4/A | APERS warhead | 9.3 lbs (4.2 kg) | 96 flechettes of unknown weight | 12 (integral to warhead) | |
| WDU-4A/A | APERS warhead | 9.3 lbs (4.2 kg) | 2205 20 grain (1.3 g) flechettes | 12 (integral to warhead) |
NOTE:Though 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. However, this would not be necessary, as vast quantities of upgraded models exist today.
Mk 66 rocket motor technical data
Weight: 13.6 lbLength: 41.7 in (1.06 m)
Burn time: 1.05 - 1.10 sec
Average thrust (77 F):
1,335 lb (Mod 2/3)
1,415 lb (Mod 4)
Motor burnout range:
1,300 ft (397 m)
Motor burnout velocity:
2425 ft/s (739.1 m/s)
Launch spin rate: 10 rps, 35 rps after exiting launcher
Velocity at launcher exit:
148 ft/s (45.1 m/s)
Acceleration:
60-70 g (initial)
95-100 g (final)
Effective Range:
500 to 8,000 m depending on warhead and launch platform
Maximum Range:
10,500 m under optimum conditions
Precision guided Hydra 70
The Advanced Precision Kill Weapon SystemAdvanced Precision Kill Weapon System
The Advanced Precision Kill Weapon System is a developmental program to provide a laser guided missile which is compatible with existing Hydra 70 unguided rocket systems in service.-Overview:...
(APKWS) II is a program to provide a laser guided missile that is compatible with the existing Hydra 70 systems in service. It was cancelled by the US Army in February 2007, but was restarted by the US Navy in 2008. Similar programs are the US Navy Low-Cost Guided Imaging Rocket
Low-Cost Guided Imaging Rocket
The Low-Cost Guided Imaging Rocket is a weapons system under development for the US Navy in a joint program with South Korea. The program aims to provide a precision guided 2.75 inch rocket for use with existing Hydra 70 systems in service, as such it has many similarities with the Advanced...
, Lockheed Martin
Lockheed Martin
Lockheed Martin is an American global aerospace, defense, security, and advanced technology company with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It is headquartered in Bethesda, Maryland, in the Washington Metropolitan Area....
Direct Attack Guided Rocket
Direct Attack Guided Rocket
The Direct Attack Guided Rocket is a weapons system under development by Lockheed Martin. The program goal is to provide a low cost 2.75 inch precision guided rocket which is compatible with existing Hellfire II systems and launchers in service...
and the ATK
ATK
ATK may refer to:*America's Test Kitchen, a cooking show on PBS*Alliant Techsystems, a mid-level United States aerospace and defense contractor*Accessibility Toolkit, a GNOME software development toolkit*ATK motorcycles, an off-road motorcycle manufacturer...
/Elbit Guided Advanced Tactical Rocket – Laser.
See also
- U.S. Army Aviation and Missile Command
- SNEB rocket (68mm) SNEBThe SNEB rocket is an unguided air-to-ground rocket projectile manufactured by the French company TDA Armements, designed for launch by combat aircraft and helicopters. Two other rockets were developed in the and caliber...
- CRV-7
- Zuni 5 in (127 mm)Zuni (rocket)The Zuni is a unguided rocket deployed by the United States armed forces. The rocket was developed for both air-to-air and air-to-ground operations. It can be used to carry various types of warheads, including chaff for countermeasures. It is usually fired from the LAU-10 rocket pod holding four...