The Buyan class, (Russian: Буян, lit. 'Buyan'), Russian designations Project 21630 Buyan and Project 21631 Buyan-M, are series of corvettes (small artillery and missile ships in Russian classification) developed by Zelenodolsk Design Bureau for the Russian Navy. Since 2010, all subsequent vessels are being constructed as improved Project 21631 subclass, incorporating greater tonnage, stealth technology and the 3S14 vertical launching system for either Kalibr or Oniks anti-ship cruise missiles, significantly enhancing combat capabilities. The ships are primarily designed for operations within littoral zones to protect Russia's vast coastal areas. Due to the small tonnage, they can operate even within shallow parts of oceans and seas and Russia's river system. The export variant is known as Project 21632 Tornado.In August 2010, some information about the newly modified Project 21631, dubbed as Buyan-M, were published. The Project 21631 ships are said to be an up-to-date variant of Project 21630 Buyan small artillery ship, armed with the nuclear-capable Kalibr cruise missiles (SS-N-27 Sizzler) with a claimed range of at least 1,500 km and electronic countermeasure equipment.[6][7] Ships of Project 21631 are designed to defend the national economic zones of Russia. The ships' small size and displacement enable them to operate within inland river systems, including traversing the Moscow Canal which allows them to deploy to various seas around European Russia. This is a particular advantage for the Buyan-M series, because while the Intermediate-Range Nuclear Forces Treaty (INF) prohibits long-range cruise missiles from operating on land they can operate from ships, so a river-based corvette can deploy missiles without being subject to restrictions.[citation needed] The lead ship of this project, Grad Sviyazhsk, was laid down on 27 August 2010 and commissioned on 27 July 2014.

Type: Guided missile corvetteDisplacement:
Buyan:500 tons (standard)[1]Buyan-M:949 tons (full)[2]Length: Buyan: 62 m (203 ft)[1]Buyan-M: 75 m (246 ft)[2]Beam:
Buyan: 9.6 m (31 ft)[1]Buyan-M: 11 m (36 ft)[2]Height: Buyan & Buyan-M: 6.57 m (22 ft)Draft:
Buyan: 2 m (7 ft)[1]Buyan-M: 2.5 m (8 ft)[2]Propulsion: Buyan & Buyan-M: 2 shaft CODAD, 4 x Zvezda M520, 14,584 shp (10,880 kW) and Kolomna Diesel, Pumpjet.Speed:
Buyan: 28 knots (52 km/h; 32 mph)[1]Buyan-M: 26 knots (48 km/h; 30 mph)[2]Range:
Buyan: 1,500 nmi (2,800 km; 1,700 mi)[1]Buyan-M: 2,300 nmi (4,300 km; 2,600 mi) at 12 knots[2]Endurance: Buyan & Buyan-M: 10 days[2]Complement: Buyan: 29-36[1]Buyan-M: 52[2]Sensors andprocessing systems: Buyan:5P-26M Pozitiv-M phased array radar system (Pozitiv-ME1.2 for export)[3]MR-231 navigation radar[3]5P-10-03 Laska fire control system (5P-10-03E for export)[3]МР-123 fire control systemAnapa-M anti-saboteur sonar system (Anapa-ME for export)[3]Buyan-M:5P-26M1 Pozitiv-M1 phased array radar systemMP-231-2 navigation radar5P-10-03 Laska fire control systemМР-123-02 fire control systemAnapa-M anti-saboteur sonar systemElectronic warfare& decoys:
Buyan: 2 × 10 PK-10 decoy launchers[3]Buyan-M: TK-25 radar jammers[4]Armament:
Buyan:1 × 100 mm A-190-01 naval gun[3]2 × 30 mm AK-630 CIWS1 × 40 retractable A-215 Grad-M1 × 4 3M47 Gibka surface-to-air missiles1 × DP-65 anti-saboteur grenade launcher2 × 14.5 mm KPV typeBuyan-M:1 × 100 mm A-190-01 naval gun[3]2 × 30 mm AK-630-M2 CIWS1 × Pantsir-M CIWS (Stavropol)2 × 4 UKSK VLS cells for Kalibr or Oniks anti-ship cruise missiles2 × 4 Komar surface-to-air missiles[5]1 × DP-65 anti-saboteur grenade launcher2 × 14.5 mm KPV type