Shell 155mm HEER

It is a high explosive extended range(HEER) shell. The shell comprises of a forged and machined special steel body. The body is in the optimised geometry to improve the ballistic co-efficient (Reduced drag). The rear of the body is externally threaded to receive the Base Bleed unit(BBU). The BBU reduces the drag and gives additional thrust to carry the shell further. The nose of the shell body is provided with top screw which is threaded to recveive the fuze or a plug with carrying 'T' handle while in storage. A plain copper Alloy driving band on the body of the shell is provided to give a gyratory force which ensures the stability of the shell in the trajectory. The driving band also acts as a gas check preventing movement of hot gases past the shell. The shell body is filled with high quality TNT. The top screw contains initiator.

When the Gun is fired, the burning propellant generates expanding gas and propellas the shell through the barrel. Simultaneously the igniter in the BBU of the shell ignites the Base Bleed charge contained in it. While in trajectory, the shell spins and the gushing out gases from the BBU full up the Vaccum behind the shell (Created due to high velocity of the shell) and prolong the eddies formation by other streamlining the air flow past the Base. The BBU also give additional thrust enabling the shell to reach further. Depending on the type and mode of the fuze setting, the initiator of the shell is ignited by the fuze. The initiator amplifies the high pressure wave through the bottom of the screw. The body of the shell explodes.

SPECIFICATIONS

PROXIMITY FUNCTION

Low Sensitivity				: Wet ground conditions

High sensitivity			: Dry ground conditions

Normal sensitivity			: Normal ground conditions

IMPACT FUNCTIONS

Long delay				: Recochet burst

Short delay				: Penetration burst

Instantaneous Action			: High sensitivity for example 
                                          Snow covered ground

Instantaneous Action			: Normal sensitivity

The Zelar fuze has a back up function, if the normal function fails, the fuze functions as a super quick impact fuze.

QUALITY

Quality is ensured at every stage of manufacture. Shells are filled and a carrying handle of 'T' shape is fitted under strict Quality Control & Proof carried out for their performance requirements.

RELIABILITY

Reliability of shells and cartridge is ensured by independent testing of each sub system/sub assemblies and also further as a complete store for its functioning requirements.

STOWAGE DIMENSION OF UNIt LOAD

PACKING

The shells are packed in unit loads in wooden pallets containing 12 shells in each unit.

CHARACTERISTICS/TECHNICAL DATA

Mass of the shell with fuze              : 42.25 kg

Mass of the shell without fuze           : 41.3 kg

Length of shell with fuze                : 884 mm

Length of shell without fuze             : 787 mm

Filling type, standard                   : TNT

Filling mass                             : 8.5 kg

Compatible fuzes                         : Zelar PDM 572

Compatible charges                       : Charge 8, Charge 9

Maximum range                            : 30 km

Maximum permissible chamber pressure     : 440 mpa

Shelf life                               : 15 years

Temperature operating                    : -20 to 60 deg C.

Temperature storage                      : Mean value during the year
                                           less than + 35 deg C Min.
                                           Temp -40Dec C, MAx.+55oD 
                                           + 1150 W/Ms solar radiation
                                           Equivalent to approx + 70oc

UN CLASSIFICATION

Compatibility                            : D

Hazard division                          : 1.1

Fire fighting classification             : 1