MK 66 rocket motors

Hydra 70 is the name associated with the family of 2.75-inch (70 millimeter) rockets. Hydra 70 refers to the Mark 66 rocket motor with any warhead/fuze combination. The MK 66 rocket motor was designed to provide a common 2.75-inch rocket for helicopters and high-performance aircraft. Compared to the MK 40 motor, it has a longer tube, an improved double base solid propellant, and a different nozzle and fin assembly. Increased velocity and spin provide improved trajectory stability for better accuracy. The launch signature and smoke trail have been significantly reduced. The MK 66 Mod 1 is not hazards of electromagnetic radiation to ordnance safe. It can be inadvertently ignited by electromagnetic radiation, especially by radio frequencies found aboard Navy ships. Both the Mod 2 and Mod 3 have HERO filters, and the Mod 2 filter may prevent the AH-1 rocket management system from inventorying. The Mod 1 is the standard motor for Army use as will be the Mod 3 when it is fielded.