Niteroi class frigate

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

The Niterói Class Frigates were designed and built by the British shipyard Vosper Thornycroft in the 1970s. These ships were designated 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, also known as the Type 21 frigate, or Amazon class.

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, four of an anti submarine version built in England. These ships had an Ikara missile launcher in Y position aft of the flight deck. This was removed as part of the modernisation programme. The remaining two general purpose ships were built at the Arsenal da Marinha no Rio de Janeiro with assistance from VT. These ships had a second 4.5 inch 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.

General characteristics
Type:	frigate
Displacement:	3,355 tons standard , 3,707 tons full load
Length:	129.2m
Beam:	13.5m
Draught:	5.5m
Propulsion:	, 2 shaft CODOG 2 Rolls Royce Olympus gas turbines, 56000 hp 4 MTU Diesels 18,000 hp
Speed:	30 knots (22 knots diesels only)
Range:	5,300 nm - at 17 knots / 4,200-at 19 knots /1300 nm -at 28 knots
Endurance:	45 days
Complement:	217
Sensors and processing systems:	(before modernization): 1 air search radar AWS2 a lungo raggio; 1 radar surface search ZW-06; 2 fire control radar RTN-10X; Ikara fire control radar (not in F42/43); 1 hull sonar EDO610E, 1 VDS EDO700E (not on F42/43); C3I CAAIS; (differences after modernization): AWS2 replaced by RAN-20S; RTN-10Xs replaced by RTN-30Xs; optronic Saab EOAS-400, surface search radar Terma 'Scanter Mil', navigation radar Furuno 1942 Mk 2, upgraded EDO-610E, C3I SICONTA Mk 2
Electronic warfare and decoys:	ESM RDL-2/3; (after modernization: ESM Cutlass B1W, ECM ET/SLQ-1 operating 8-16 GHz); 2 12x102 mm rocket launchers (using the former Seacat ammo depots)
Armament:	(after the modernization) Missile antiship MM-40 Exocet; Anti-aircraft missile ASPIDE (Sea Cat launcher was removed, together with the 60 missiles) 1 Vickers gun 4.5 inch Mk 8 (114 mm), (22 km range); 2 BAE Systems Bofors Trinity Mk 3 anti-Aircraft single-gun turrets; 2x 3 torpedo tubes for Mk-46 torpedoes; 4 M2 Machine Gun; double-barrel Bofors Boroc anti-submarine rocket launcher
Aircraft carried:	1 Westland Super Lynx Mk.21A (locally designated as AH-11A) or 1 Eurocopter AS-350/355 Squirrel (locally assembled by Helibrás as UH-12/UH-13 'Esquilo')
Aviation facilities:	pad and hangar