Field 122 mm divisional multiple launch rocket system BM-21 "Grad" for three decades is the most massive war machine of this class of domestic production. Designed to engage the open and covered manpower, soft-skinned vehicles and armored personnel carriers in the area of concentration, artillery and mortar batteries, command posts and other targets. Development of the system began May 30, 1960.
Main executor of the system was scheduled NII-147; SKB-203 made launcher; NII-6 solid charges; GSKB-47 combat equipment parts. From the beginning, before the designers had to create a simple to manufacture and use complex, is not inferior to foreign analogues in terms of technical harakteristikam.V as undercarriage was selected all-terrain chassis "Ural 4320" produced by the Ural Automobile Plant.
To simplify the construction of the guide tube, they were manufactured. In the original version of the staffing position of the package guides were shooting across the longitudinal axis of the vehicle. The first test launches showed complete uselessness of such a scheme because of the strong rocking platform after the start of the first shell and reduce the accuracy of shooting.
In addition to turning the guide was reinforced suspension and taken measures to stabilize the body. Now shooting (both single projectile and volley) was made possible not only strictly on the longitudinal axis of the vehicle, but also at an acute angle to it. Two pilot plants "Grad" is factory tested at the end of 1961. From March 1 to May 1, 1962 in the Leningrad Military District passed the state Polygon-service testing of complex "Grad". System "Grad" was adopted by 28 March 1963
Delivery of production samples "Castle" was launched in 1964. In the 90 years to the "Castle" were created entirely new types of munitions. In addition, work is underway to modernize the combat vehicle BM-21. The most important part of its modernization package replacement guide tubes of metal on two monoblock transport-launch of disposable containers (WPK), made from polymer composite materialov.Oni mounted on a fighting machine with a special optional adapter frame. In this case, reloading combat vehicles produced by means of hoisting equipment. Loading time is reduced to 5 minutes.
The composition of the BM-21 consists of: PU Chassis - Ural-375, Artillery unit consists of 40 guides, forming a package: four rows of 10 tubes each. The tube is intended for guiding the flight of the projectile, but also for its transport. The caliber of the pipe 122, 4 mm, length 3 m. Putting the tube packet in the vertical and horizontal planes made by means of the drive. Start all 40 rounds held for 20 seconds.
Cnaryad has a fuse, fuse cocking after removing the shell lined with 150-400 m. The unit has the possibility of remote control by pointing and shooting with the remote console at a distance of 50 meters. Translation system from traveling to combat takes 3, 5 minutes. Guidance in the vertical and horizontal plane is made by means of the electric and the sight on the type of artillery. Running forty shells takes twenty seconds.
Stabilization of projectiles in flight combination: both by regulators, folding when installed in the guide, and due to the gyroscopic effect generated by the rotation of the projectile during the flight to the target. The blades of the stabilizer, placed in the tail of the projectile, set at an angle to the direction of flight. They are made folding. To initiate the rotation of the projectile on the housing pin made its way along the spiral groove in the guide.