The aircraft carrier Príncipe de Asturias, in service with the Spanish Navy until 2013, was born from the American project SCS (Sea Control Ship) which had been abandoned in the mid 1970s. In that time, the chief of naval operations in the United States Navy, Elmo Zumwalt, had exposed his idea about what should be the SCS, framed inside a phylosophy of low-cost warships. The project bureau Gibbs and Cox made the draft of how that new vessel should be. The underlying idea was a widely polyvalent ship, useful for small air operations or as a command ship for mercantile convoys, specially fleets of tankers. But always with the premise of being an inexpesive vessel, for in that time they were expected massive construction programs due to the "unavoidable" war against the Soviet Union.

But due to the evolution of international events and the strategic requirements, the US Navy soon discarded the SCS, focusing the attention towards other two types of warship: the large attack aircraft carriers and the amphibious assault ships. Meanwhile, in the late 1970s the Spanish Navy was thinking in a replacement for the aged aircraft carrier Dédalo. It was discarded the long kept idea of acquiring a helicopter carrier from the US Navy, specifically the USS Guam (PH-09), which during 1972-1973 had been used as an experimental ship to evaluate the SCS concept.

Following the renounce of the US Navy to the project and the acquiescence of the projectist, the Spanish shipyard company Bazán requested the plans of the SCS. But Gibbs and Cox delivered only about a dozen of blueprints, which Bazán had to fully develop until achieving the more than 4000 necessary to build the ship. Hence the Príncipe de Asturias should be considered as a genuinely Spanish ship yet honouring her American origin. And even if improvable, the Príncipe de Asturias can be considered as one of the most brilliant projects that led to the construction of a modern aircraft carrier.

Sea Control Ship
In January 1974, during project stage, it had been decided to name "Almirante Carrero" which would be the largest ship in service with the Spanish Navy. However, with the shift in political tendencies after the death of General Franco, said name was suspended and it was speculated with other two names for the new ship: "Canarias" and "Dédalo". The 29th June 1977 the Navy gave the execution order and in October 1979 the national company Bazán, based in El Ferrol, placed the first prefabricated block in the construction yard.

The Spanish Navy was the first one in approaching the construction of the SCS (with the required American assistance) and consequently Argentina, Australia and Iran showed great interest for the project and the construction of aircraft carriers in Spain for their respective navies. But in the end, it would be Thailand the only actual customer. This country ordered in 1992 the small aircraft carrier named "Chakri Naruebet" to the shipyards Bazán, where she was launched in January 1996, being commissioned in March 1997. We can see both ships built by Bazán side to side in the photograph below.

Príncipe de Asturias and Chakri Naruebet
The Príncipe de Asturias was, in 1988, the third aircraft carrier commissioned by the Spanish Navy and she served as flagship of the Fleet. She was the biggest ship serving in the Spanish Navy until the commissioning of the aircraft carrier and amphibian assault ship Juan Carlos I. The technical characteristics, including dimensions and displacement, were almost unchanged in respect of the original SCS conceptualized in United States. The overall length reached 196 meters, the beam was 24.3 meters and draught was 9.4 meters, while minimum displacement was around 13400 tonnes, reaching 17200 tonnes at full load. The hull and the superstructure were largely built in high-resistance steel and the stability on hard sea conditions was excellent thanks to two pairs of computer-controlled stabilizers.

The Príncipe de Asturias is an aircraft carrier built with an athwartships hangar, this is, one occupying the whole beam of the ship (unlike in the flight deck cruisers built for other European navies, in which the hangar usually occupies only a part of the beam). Besides the hangar occupies about two thirds of the overall length of the ship, being the fore area destined to aviation services and crew accommodation. The two elevators were placed one just before the isle and the other astern.

The excellent stability in harsh sea conditions allowed the Príncipe de Asturias to operate beyond the capabilities of other ships. So, thanks to her lateral stability, achieved by the two pairs of stabilizers, and to her 12-degree "ski-jump", which largely compensates any pitching motion, the aircraft carrier could launch and retrieve aircraft in a sea with waves of up to four meters.

Being the Príncipe de Asturias a low-cost vessel, some of the elements which further raise the price of a warship were radically modified. This was the case of the propulsion plant, which comprises two gas turbines General Electric LM2500, with a combined output of 40000 horsepower, but actuating on a single shaft, allowing for a top speed of 26 knots. Existing only one shaft, the hydraulically-controlled five-blade propeller installed in this ship was in that time the largest one in the world, having 6.10 meters in diameter and a weight of 35 tonnes. The shaft, which rotates at a maximum of 150 revolutions per minute, has 45 meters in length and a weight of 174 tonnes, being able to harbor in its interior two tonnes of lubricant grease.

The potential problem that could represent to lose propulsion, due to breakdown or damage, in the only shaft was solved by means of two electrically-powered auxiliary propulsion units which, being capable of azimuthal rotation, constitute also an excellent aid for berthing maneuvers. They use a Kort nozzle propeller and remain retracted while unused to avoid hydrodynamic resistance. Finally, the only rudder of the ship is of semi-compensated type.

The American SCS was to be armed with two Vulcan Phalanx CIWS mountings for self-defense against incoming missiles, but the Spanish ship had installed four Meroka CIWS, a peculiar weapon system developed by Bazán as well. Each mounting is able to fire up to 3600 rounds per minute and its reliability is very high, for a fixed arrangement of twelve 20-millimeter cannons Oerlikon in two sextuple rows is used, instead of rotary cannons which have more mechanical parts susceptible of breakdown.

Meroka CIWS
The main systems in the electronic equipment originally comprised the three-dimensional exploration radar SPS-52 on the top of the mast, a tactical radar and a CIWS radar to control the point-defense mountings.

Príncipe de Asturias aircraft carrier
And finally, let us review the aircraft, the most important part in a ship of this genre. The Príncipe de Asturias was built to operate with V/STOL (Vertical/Short Take-Off and Landing) aircraft, and her hangar can shelter up to seventeen of these aircraft, while another twelve can stay parked in the flight deck. In the practice, the Príncipe de Asturias possessed the widest operativity in ships of her genre, surpassing even larger units in this regard.

A typical air wing carried could comprise six fighters AV-8B Harrier II, from twelve to fourteen heavy helicopters SH-3D Sea King (to keep a permanent air patrol around the ship) and two antisubmarine helicopters SH-2D Seasprite LAMPS (to cooperate with the escorting frigates that must accompany the aircraft carrier). Other helicopters used were the SH-60B Sea Hawk for antisubmarine warfare and the Agusta-Bell AB-212 for transport and rescue.

Príncipe de Asturias aircraft carrier
The following view of the Príncipe de Asturias allows to see the two Meroka CIWS mountings astern; the other two are placed in the sides of the hull at the beginning of the "ski-jump". Note as well the elevator astern. Having been decommissioned in December 2013, the future of this aircraft carrier remains uncertain in 2016.

Príncipe de Asturias aircraft carrier
Príncipe de Asturias aircraft carrier

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