MR-123 Vympel (“Bass Tilt”) radar

(USSR)

Notes: This widely-used gunfire director was developed by the Ametist bureau and entered service in 1972. It is installed aboard a huge variety of ships. While somewhat resembling “Drum Tilt”, it is much more advanced and operates in a completely different method. Each “Bass Tilt” can control up to three guns of two different calibers (with one of each being actively operated simultaneously). The system operates in the C/I/J bands at a 0.5 microsecond pulse.

A complete system (antenna, control console, power supply cabinet, and cabling) weighs 1 ½ tons of which the antenna is 1,585lbs. The dielectric radome is flanked by a laser rangefinder and CCTV camera. The monocolour PPI display is instrumented out to 25NM but 18NM is a more realistic maximum range. Range accuracy is +/- 17’.

In the mid-2000s, Ametist developed a further model called Laska. This incorporates more ECCM and can auto-engage four targets simultaneously. As of 2010 it had found no buyer.

“Bass Tilt” rotates at 15rpm, with a feed horn behind the 3’9” diameter flat antenna supplying the signal. The flat antenna transmits a 3deg beam which rises 3.6deg every rotation, until it reaches +36deg elevation where the whole process starts over again.

If a target is detected, “Bass Tilt” stops rotating and the system mechanically switches feed horns to a monopulse method (this takes 3 seconds). In this mode, maximum elevation is +85deg. The radar feeds information both to the display and to the fire control computer.

(Below: A “Bass Tilt” with the radome removed, aboard the ex-East German “Tarantul-I” class corvette Hiddensee which was operated by the USN out of Solomons Annex, MD during the mid-1990s. The pivoting flat antenna can be seen, with the feed horns behind it.) (US Naval Institute photo)

“Bass Tilt” can be regarded as wholly compromised; the USN obtained an ex-East German set and studied it extensively vs. American aircraft in the 1990s. User navies Bulgaria, Poland, and Romania are now in NATO.

USERS: USSR/Russian Federation, Bulgaria, Georgia, East Germany/Germany, Greece, Guinea, Guinea-Bissau, India, Iraq, Poland, Romania, Ukraine