Cartridge Millimeter Hera M

Type Classification:

Std AMCTC dtd 1990.

Use:

This cartridge is a high explosive, rocket-assisted round with extended range capability used for fragmentation, blast and mining support of ground troops and armored columns.

Description:

The projectile consists of two pieces, a streamlined warhead and rocket motor body of boattail design. The nose of the warhead is threaded for a fuze and the warhead is filled with TNT having a deep cavity and supplementary charge. The rocket motor body contains the rocket grain and delay ignition system, contained at the rear of the body. The delay ignition system is fitted with a cap. A copper rotating band is welded to the rocket motor body. The body is threaded to the warhead to complete the projectile assembly The cartridge case contains a primer and a single bag propelling charge with a flash reducer. The base of the cartridge case is drilled and a percussion primer assembly is pressed into the base. The percussion primer assembly consists of a percussion ignition element and a perforated flash tube containing black powder.

Functioning:

Rocket "OFF-MODE" — If the projectile is unfuzed, the closing plug is removed and a fuze is assembled to the projectile and, if required, is set. The cartridge is loaded into the weapon. Upon firing, impact of the weapon firing pin results in the initiation of the percussion primer which, in turn, ignites the black powder in the flash tube. The flash tube provides for uniform ignition of the propelling charge producing a rapid expansion of the propelling gas which propels the projectile out of the weapon tube. Engagement of the projectile rotating band with the rifling of the weapon tube imparts spin to the projectile providing in-flight stability. Projectile functioning is dependent upon the fuze used and may function on impact (instantaneous or delay), function above ground either at a predetermined height based upon time of flight, or function in proximity with target area. Fuze function detonates the HE projectile filler resulting in projectile fragmentation and blast.

Rocket "ON-MODE" — The fuze is assembled to the projectile as in the rocket "OFFMODE". The cap on the delay igniter is removed, The cartridge is loaded into the weapon. Upon firing, the burning propellant gases initiate the delay ignition system. Approximately 16 seconds later (the projectile has left the tube and is traveling down-range), the delay ignition system ignites the rocket motor. The rocket motor burns for 2 seconds boosting the projectile velocity resulting in a greater projectile range. Fuze initiation, as described for Rocket "OFF-MODE", detonates the projectile HE filler resulting in projectile fragmentation and blast.

Tabulated Data:

Complete round:

Type HERA

Weight 38.51b

Cannon (weapon) used with M119

Projectile:

Body material High carbon steel forging

Color Forest green w/yellow markings

Filler and weight TNT, 5.8 lb

Fuzes PD M739 Prox

M732E2, ET M767, MTSQ M582

Suppl charge DwgNo.

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