Iroquois class destroyer

"Iroquois"-class destroyers are a class of presently three commissioned helicopter-carrying, guided missile destroyers of the Canadian Forces. The class originally had four ships, with HMCS "Huron" being paid off and later sunk in a live-fire exercise.

Launched in the 1970s, the "Iroquois"-class was the first military ship design to employ gas turbines exclusively, using two turbines for cruise power, and another two fast starting "boost" turbines for speeds of up to 29 knots (such an arrangement is known as COGOG). They were originally fitted out for anti-submarine warfare, but a major upgrade program in the 1990s overhauled them for area-wide anti-aircraft.

Original design

The ships were originally intended for long-range anti-submarine warfare. Their primary weapon for this role was their complement of two CH-124 Sea King helicopters, which could be launched in even high sea states due to their "bear trap" winch system. The ships included a hangar that provided an enclosed working space for both helicopters at the same time. The helicopters were backed up by two triple-mount torpedo launchers firing Mk.44 and Mk.46 Mod 5 torpedoes and a Limbo Mark 10 depth charge mortar.

For other duties the ships also mounted a 5" OTO Melara multi-purpose gun and two four-round Sea Sparrow launchers for point anti-aircraft defence. The missile batteries were located on the interior of the ship on either side of the superstructure, requiring some time for them to unlimber for firing.

The ships were powered primarily by two Pratt & Whitney FT12-AH3 of 7,400 shp each, backed up by two more FT4-A2's gas turbines of 50,000 shp each for boost. The power from these turbines was used to run the twin shafts through a series of helical gears. One unique feature was the distinctive Y-shaped "Playboy Bunny" funnels, which were designed to exit the exhaust gasses to either side of the helicopter deck.

The ships were 425 × 50 × 14 feet (129.8 × 15.2 × 4.4 metres) and 4,700 tons displacement. The normal crew complement was 285.

Gulf War modification

HMCS|Athabaskan|DDH 282 was deployed on Operation FRICTION, the Canadian Forces contribution to the international coalition naval task force serving in Operation DESERT SHIELD and Operation DESERT STORM (the Gulf War).

"Athabaskan" was the flagship of the Canadian Naval Task Group and was hurriedly modified at CFB Halifax in August 1990 prior to the deployment. These modifications included a new mine-avoidance sonar, a Phalanx 20mm CIWS (mounted over the Limbo mortar well, which was made inoperative) and shoulder launched Blowpipe and Javelin missiles.

TRUMP modifications

The entire class underwent major retrofits as a part of the Tribal Class Update and Modernization Project (TRUMP) in the early 1990s. These refits had the effect of re-purposing the ships for area air defence; following TRUMP the "Iroquois"-class were referred to as air defence destroyers. Their former anti-submarine role was largely transferred to the sclass|Halifax|frigates.

The main weapon of the new design is the Mk.41 VLS, firing 29 SM-2 Block III long-range anti-aircraft missiles. In order to provide room for the VLS, the original 5" gun was replaced with the smaller but much faster firing Oto Melara 76 mm gun, relocated from the deck to the bridgework above it. A Phalanx CIWS was also added for self-defence. The torpedo tubes were retained, but the Sea Sparrow system was removed.

The modernization also replaced the original Pratt & Whitney FT-12 cruise turbines with newer 12,788 shp 570-KF engines from Allison. The speed remained the same, however, as the weight had increased to 5,100 tons full load. The original split funnel was replaced by a simpler single one, as the exhaust proved not to be a problem.

The TRUMP was intended to be a stop-gap measure since the radar systems on these ships are outdated. Following TRUMP, the "Iroquois"-class were intended to be decommissioned by 2010. Defence budget cuts during the mid-1990s resulted in "Huron" being left without a crew. "Huron" was paid off in 2005, and sunk in a live-fire exercise in 2007 by her sister ship "Algonquin".

There has been some preliminary work on a replacement design, known to Canadian naval-observers as the sclass|Province|destroyer however this was confined largely to studies of a much-improved phased array radar system being developed for the Royal Netherlands Navy and German Navy known as APAR. Current speculation is that the ships themselves would be similar to an enlarged "Halifax"-class frigate. Such a design would have similar capability to the "Iroquois" but only embark one helicopter. There appear to be no current plans to actually build such a class.

General characteristics

*Length: 129.8 m
*Beam: 15.2 m
*Draft: 4.7 m
*Displacement: 5100 tonnes full load
*Power plant:
** two shaft COGOG system
** two Allison 570-KF cruise gas turbines, 5.6 MW at the shaft total
** two Pratt & Whitney FT4-A2 boost gas turbines, 37 MW at the shaft
*Speed: 29+ knots (54 km/h)
*Aircraft: 2 CH-124 Sea King helicopters
*Complement: 280
*Armament:
** four 8-cell VLS, Standard SM-2MR Block IIIA surface-to-air missiles
** one 76 mm/62 OTO Melara (Super Rapid) dual-purpose gun system
** one Phalanx 20 mm Close-In Weapons Systems
** two triple Mark-46 12.75 in (324 mm) torpedo tubes firing Mark-46 Mod 5 torpedoes
** 0.5 in (12.7 mm) machine guns
*Radar: AN/SPQ 501 (Signaal DA-08), AN/SPQ 502 (Signaal LW-08)
*Sonar: SQS-510 hull, SQS-510 VDS

hips in class

External links

* [http://www.navy.forces.gc.ca/ Canadian Navy]
* [http://www.hazegray.org/navhist/canada/postwar/tribal/]