The Hydra 70 rocket is a weapon derived from the 2.75-inch "Folding-Fin Aerial Rocket" (FFAR) developed by the US Navy for use as a free-flight aerial rocket in the late 1940s. It 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 US armed forces. To provide some stability the four rocket nozzles were scarfed at an angle to impart a slight spin to the rocket during flight.
The family of Hydra 70 (70mm) 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. 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 MK66 rocket motor, which replaced the MK40. The MK66 has a reduced system weight and provides a remote fuze setting interface.
The AH-1G Cobra and the UH-1B "Huey used M158 seven-tube and M200 19-tube rocket launchers. The M158 and M200 were used with the MK40 rocket motor. The MK40 rocket motor was replaced by the newer MK66 rocket motor. The M158 and M200 rocket launchers are not compatible with the MK66 rocket motor. The Hydra 70 rocket system is also used by the US Marine Corps, the US Navy, and the US Air Force.
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.
