SCB-27

SCB-27 was the United States Navy designation for a series of upgrades to the "Essex" class aircraft carriers (both the short-hull and long-hull ("Ticonderoga") versions), conducted between 1947 and 1955. These upgrades were intended to allow the World War II-era carriers to operate jet aircraft.

Modifications

The SCB-27 modernization was very extensive, requiring some two years for each carrier. To handle the much heavier, faster aircraft of the early jet-era, the flight deck structure was significantly reinforced, able to support aircraft weighing up to convert|52000|lb|kg|0, namely the North American AJ Savage. Stronger elevators, much more powerful catapults, and new Mk 5 arresting gear was installed. The original four twin 5"/38 gun mounts were removed, clearing the flight deck of guns. The new five-inch gun battery consisted of eight weapons, two on each quarter beside the flight deck. Twin 3"/50 gun mounts replaced the 40mm guns, offering much greater effectiveness through the use of proximity fuzed ammunition.

The island was completely redesigned, made taller, but shorter in overall length with the removal of its gun mounts. In addition, the boiler uptakes were rebuilt and angled aft to accommodate a single radar and communications mast atop the island. To better protect aircrews, ready rooms were moved from the gallery deck to below the armored hangar deck, with a large escalator on the starboard side amidships to move flight crews up to the flight deck. Internally, aviation fuel capacity was increased to convert|300000|USgal|L|0 (a 50% increase) and its pumping capacity enhanced to convert|50|USgal|L|1 per minute.cite book | last = Friedman | first = Norman | title = U.S. Aircraft Carriers: An Illustrated Design History | year = 1983 | publisher = Naval Institute | location = Annapolis | language = English | isbn = 0-87021-739-9 ] Fire fighting capabilities were enhanced through the addition of two emergency fire and splinter bulkheads to the hangar deck, a fog/foam firefighting system, improved water curtains and a cupronickel fire main. Also improved were electrical generating power, and weapons stowage and handling facilities. All this added considerable weight: displacement increased by some twenty percent. Blisters were fitted to the hull sides to compensate, widening waterline beam by eight to ten feet. The ships also sat lower in the water, and maximum speed was slightly reduced, to 31 knots.

Modification sub-types

The two sub-types of SCB-27 modifications were primarily a result of changes in catapult technology in the early-1950s. SCB-27A vessels utilized a pair of H 8 slotted-tube hydraulic catapults, while the later SCB-27C vessels were fitted with a pair of C 11 steam catapults, a British innovation. To accommodate the catapult machinery, the SCB-27C vessels were slightly wider abeam and heavier than their SCB-27A sisters. Additionally, the SBC-27C carriers were equipped with jet blast deflectors, enlarged forward elevators, deck cooling, fuel blending facilities, emergency recovery barrier and storage and handling for nuclear weapons, which was not included in all of the SCB-27A carriers.

Program history

USS "Oriskany" (CV-34), laid-up incomplete at the conclusion of World War II, served as the prototype and was re-ordered to the SCB-27A standard. All of the SCB-27 modernized "Essex" carriers, save USS "Lake Champlain" (CV-39), were further modified, under the SCB-125 modernization program.

Modified vessels

"Source:www.history.navy.mil" [cite web|url=http://www.history.navy.mil/photos/usnshtp/cv/scb27cl.htm|title=U.S. Navy Ship Types - SCB-27 modernization of "Essex"/"Ticonderoga" class aircraft carriers|publisher=U.S. Navy Historical Center|date=2001-10-08|accessdate=2006-12-04]

References

Portions of this entry were drawn from: [http://www.history.navy.mil/photos/usnshtp/cv/scb27cl.htm Naval Historical Center SCB-27 information and photos]