MR-104 Rys (“Drum Tilt”) radar
Notes: This fire-control radar was developed by the Ametist design bureau and entered service in 1961. It uses the track-while-scan (TWS) method and transmits in the C/X bands. The mechanically-stabilized antenna (4’10” diameter by 5’6” deep) is fixed in elevation at 25deg but rotates 360deg.
Each radar can control one gun (usually an AK-230) although on larger ships with a centralized fire control system, multiple guns could be tied to a “Drum Tilt”, though not actively directed by it simultaneously. “Drum Tilt” can only generate a firing solution on a single target, if the target is shot down the computation process has to start all over. A later upgrade allowed the system to store data on other targets so they could be engaged more quickly; however not all export users received the upgrade.
“Drum Tilt” is instrumented out to 23NM but it can only lock on to targets at 12NM or less; there is also a blind zone under 1NM. The system has a tendency to lose lock-ons and a skilled operator is needed for best performance.
On some classes (the “Natya” minesweepers, for example) it is the vessel’s primary radar.
USERS: USSR/Russian Federation, Algeria, Angola, Azerbaijan, Bulgaria, Cambodia, Cape Verde, Croatia, China, Congo, Cuba, Egypt, Eritrea, Ethiopia, Finland, East Germany/Germany, Guinea, Guinea-Bissau, India, Indonesia, Iraq, North Korea, Libya, Montenegro, Poland, Romania, Somalia, Syria, Ukraine, Vietnam, Yemen, Yugoslavia/Serbia-Montenegro