HMS Argus (I49) - Design, Description and Construction

Design, Description and Construction

Argus had her genesis in the Admiralty's desire during the First World War for an aircraft carrier that could fly off wheeled aircraft and land them aboard. Existing carriers could launch wheeled aircraft, but had no way to recover them as they lacked flight decks. In 1912, the ship builder William Beardmore had proposed to the Admiralty an aircraft carrier design with a continuous, full-length flight deck, but it was not accepted. As the limitations of existing carriers became more apparent, this design was dusted off and the Admiralty located two large, fast hulls suitable for conversion into an aircraft carrier. Construction of the Italian ocean liners Conte Rosso and Giulio Cesare had been suspended by William Beardmore and Company at the outbreak of the war, and both met the Admiralty's criteria. Conte Rosso was purchased on 20 September 1916, possibly because her machinery was more complete than that of Giulio Cesare, and the company began work on converting the ship.

The initial design had two islands with the flight deck running between them. Each island contained one funnel; a large net could be strung between them to stop out-of-control aircraft. The islands were connected by braces and the bridge was mounted on top of the bracing, which left a clear height of 20 feet (6.1 m) for the aircraft on the flight deck. Fairly early in the design process, the decision was made to delete the funnels to reduce turbulence over the flight deck. The exhaust gases were, instead, ducted aft in the space between the roof of the hangar deck and the flight deck and were enclosed by a casing through which cooler air was driven by electric fans. They normally exhausted underneath the aft end of the flight deck, but the exhaust could be vented through openings on the rear side of the hull by two large electric fans.

In November 1916, the ship's design was tested in a wind tunnel by the National Physical Laboratory to evaluate the turbulence caused by the twin islands and the bridge over them. They were found to cause problems, but no changes were made until the ship was nearly complete. In April 1918, Argus was ordered to be modified to a flush-decked configuration after the sea trials of the carrier Furious had revealed severe turbulence problems caused by her superstructure. The ship was given a bridge underneath her flight deck, extending from side to side, and she was fitted with a retractable pilot house in the middle of the flight deck for use when not operating aircraft.

Argus's stability had been a concern from the beginning. Despite having been originally conceived as a liner with a hull designed to minimise rolling, most of the changes made to the ship during her conversion added topside weight, raising her centre of gravity. Even the addition of 600 long tons (610 t) of ballast still left the ship with a very low metacentric height of only 1.6 feet (0.49 m) lightly loaded and 3.8 feet (1.2 m) at deep load. This meant that she was very steady, but heeled noticeably when turning. The ship proved to be very manoeuvrable at medium and high speeds, but steered badly at low speeds and in wind due to her large surface area.

Argus had an overall length of 565 feet (172.2 m), a beam of 68 feet (20.7 m), and a draught of 23 feet 3 inches (7.1 m) at deep load. She displaced 14,450 long tons (14,680 t) at standard load and 15,575 long tons (15,825 t) at deep load. Each of the ship's four sets of Parsons geared steam turbines drove one propeller shaft. Steam was supplied by 12 cylindrical Scotch boilers. The turbines were designed for a total of 20,000 shaft horsepower (15,000 kW), but they produced 21,376 shaft horsepower (15,940 kW) during her sea trials in September 1918, and gave Argus a speed of 20.506 knots (37.977 km/h; 23.598 mph). The ship carried 2,500 long tons (2,500 t) of fuel oil, which gave her a range of 3,600 nautical miles (6,700 km; 4,100 mi) at 10 knots (19 km/h; 12 mph).

The ship's flight deck was 549 feet (167.3 m) long and her hangar was 330 feet (100.6 m) long, 48–68 feet (14.6–20.7 m) wide, and 16 feet (4.9 m) high. Aircraft were transported between the hangar and the flight deck by two aircraft lifts (elevators); the forward lift measured 30 by 36 feet (9.1 m × 11.0 m) and the rear 60 by 18 feet (18.3 m × 5.5 m). Argus was the only British carrier serving in the Second World War capable of striking down (stowing away) aircraft with non-folding wings because of her wide lifts and tall hangar ceiling. Three fire curtains divided the hangar and another separated the hangar and the quarterdeck. She could accommodate between 15 and 18 aircraft. No arresting gear was fitted as completed. Two large cranes were positioned on the quarterdeck, beneath the rear of the flight deck. Petrol storage consisted of 8,000 imperial gallons (36,000 l; 9,600 US gal) in 2-imperial-gallon (9.1 l; 2.4 US gal) tins stowed below the waterline. The ship's crew totalled 495 officers and men.

The ship was armed with four 4-inch (102 mm) anti-aircraft guns, two on the quarterdeck and one on each side of the hull. She was also fitted with two low-angle 4-inch guns, one also on each side of the hull. The rear magazine and the torpedo warhead storage magazine were protected by a total of 2 inches (51 mm) of protective plating on all sides, but the forward magazine and bomb storage rooms only had a 2-inch thick deck to protect them.

Argus was laid down in 1914 by William Beardmore and Company in Dalmuir, as the Conte Rosso. She was renamed after her purchase in September 1916 and was launched on 2 December 1917, her building having been slowed by labour shortages. The ship was commissioned on 16 September 1918. Formally named after Argus of the 100 Eyes from Greek mythology, Argus was nicknamed the Hat Box or the Flatiron due to her flat-topped appearance.