Introduction
The Hydra 70 is derived from the 2.75-inch (70 mm) diameter 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. The main change made to produce the Hydra was the Mk. 66 motor which uses a new propellant that offers considerably more thrust. The fins of the Mk 40 flipped forward from the rear when the rocket left the launching tube, but in the Hydra they are curved to match the outside diameter of the rocket fuselage and flip sideways to open, which is referred to as WAFAR (Wrap-Around Fin Aerial Rocket) instead of FFAR (folding-fin aerial rocket). To improve stability during the time while the fins are still opening, the four motor nozzles have a slight cant angle to impart a spin while the rocket is still in the launch tube.
Warheads
Hydra 70 warheads fall into two categories: -Unitary warheads with impact-detonating fuzes or remote-set multi-option fuzes. -Cargo warheads with air burst-range, with settable fuzes using the “wall-in-space” concept or fixed standoff fuzes.
Unitary Warheads
- High explosive (HEDP) ‘10 pounder’.
- High explosive (HEDP); elongated M151 ‘17 pounder’.
Cargo Warheads
- Multi-purpose submunition (MPSM).
- Parachute illumination.
- APERS (anti-personnel) warhead.
Hydra Types
M151
- High explosive (HEDP) ‘10 pounder’.
- Contact Fuse.
- Range 4.5km.
M229
- High explosive (HEDP); elongated M151 ‘17 pounder’.
- Penetrating Fuze.
- Range 4km.
M261
- Multi-purpose submunition (MPSM) Contaings 9 bomblets capable of penetrating light armor and include fragmentation effects for anti-infantry purposes
- Air burst distance 500.
- range 4.5km.
M255
- APERS (anti-personnel) warhead contains over 1,000 flechettes that are capable of penetrating light armor.
- Air burst distance 200.
- Range 4.5km.
M257
- Parachute illumination.
- Triggers 1.5 seconds after launch, Equates to about 1.5km.