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: