Niteroi class frigate

Constituição on 15 July 1996 during UNITAS '96
Class overview
Name:	Niterói class, Mk10
Builders:	Vosper Thornycroft, Navy Arsenal in Rio de Janeiro
Operators:	Brazilian Navy
Built:	1975–1986
Completed:	7
Active:	7
General characteristics
Type:	Frigate
Displacement:	3,355 tons standard 3,707 tons full load
Length:	129.2 m (424 ft)
Beam:	13.5 m (44 ft)
Draught:	5.5 m (18 ft)
Installed power:	Two Rolls-Royce Olympus gas turbines (56,000 hp (42,000 kW) combined) Four MTU diesel engines (18,000 hp (13,000 kW) combineD)
Propulsion:	Combined diesel or gas, two shafts
Speed:	30 knots (56 km/h; 35 mph) (maximum) 22 knots (41 km/h; 25 mph) (diesels only)
Range:	5,300 nautical miles (9,800 km; 6,100 mi) at 17 knots (31 km/h; 20 mph) 4,200 nautical miles (7,800 km; 4,800 mi) at 19 knots (35 km/h; 22 mph) 1,300 nautical miles (2,400 km; 1,500 mi) at 28 knots (52 km/h; 32 mph)
Endurance:	45 days
Complement:	217
Sensors and processing systems:	Before modernization: AWS2 air search radar ZW-06 surface search radar 2 × RTN-10X fire control radar (not in F42/43) EDO-610E hull-mounted sonar EDO-700E variable-depth sonar (not in F42/43) Computer-Aided Action Information System (CAAIS) After modernization: RAN-20S air search radar Terma 'Scanter Mil' surface search radar 2 × RTN-30X fire control radar Saab EOS-400 optronic director upgraded EDO-610E hull mounted sonar SICONTA Mk 2 C3I system
Electronic warfare & decoys:	Before modernization: RDL-2/3 ESM Two 12×102 mm rocket launchers After modernization: Cutlass B1W ESM ET/SQL-1 ECM Two 12×102 mm rocket launchers
Armament:	After modernization: Exocet MM40 anti-ship missiles; Aspide anti-aircraft missiles 1 × Vickers 4.5" Mk 8 (114 mm) 2 × Bofors 40 mm Mk3 Sea Trinity 2 × triple torpedo tubes for Mk-46 torpedoes 4 × M2 Browning machine gun 1 × double-barrel Bofors Boroc anti-submarine rocket launcher
Aircraft carried:	Westland Super Lynx Mk.21A (locally designated as AH-11A); or Eurocopter AS-350/355 Squirrel (locally assembled by Helibrás as UH-12/UH-13 'Esquilo')
Aviation facilities:	Helipad and hangar

The Niterói-class frigates are a class of frigates of the Brazilian Navy.

The Niterói class were designed and built by the British shipyard Vosper Thornycroft (VT) in the 1970s. These frigates were designated the Mk 10 by Vosper Thornycroft and are the largest of a series of ships built by that shipyard for both foreign buyers and the Royal Navy.

All of them were extensively modernized between 1996 and 2005 under the 'ModFrag' program. The projected completion was 2001, but due to lack of funds and sea trials to verify the new software, the entire program had been slipped to 2005.

A total of six ships were built. Two of the anti submarine (ASW) and both of the general purpose (GP) version were built in England. The remaining two ASW ships were built at the Arsenal da Marinha in Rio de Janeiro with assistance from VT. The ASW ships had an Ikara missile launcher in Y position aft of the flight deck. This was removed as part of the modernisation programme. The GP ships had a second 4.5-inch (114 mm) gun in "Y" position. A seventh ship was built as the navy's main training unit. The ship is identical to the other ships of the class, but is not fitted with weapons or sensors.