HMS Hermes (95) - Development

Development

Like Hōshō, Hermes was based on a cruiser-type hull, and she was initially designed to carry both wheeled aircraft and seaplanes. The ship's design was derived from a 1916 seaplane carrier design by Gerard Holmes and Sir John Biles, but was considerably enlarged by Sir Eustace d'Eyncourt, the Director of Naval Construction (DNC), in his April 1917 sketch design. Her most notable feature was the seaplane slipway that comprised three sections. The seaplanes would taxi onto the rigid submerged portion aft and dock with a trolley that would carry the aircraft into the hangar. A flexible submerged portion separated the rear section from the rigid forward portion of the slipway to prevent the submerged part from rolling with the ship's motion. The entire slipway could be retracted into the ship, and a gantry crane ran the length of the slipway to help recover the seaplanes. The design showed two islands with the full-length flight deck running between them. Each island contained one funnel; a large net could be strung between them to stop out-of-control aircraft. Aircraft were transported between the hangar and the flight deck by two aircraft lifts (elevators); the forward lift measured 30 by 30 feet (9.1 by 9.1 m) and the rear 60 by 18 feet (18.3 by 5.5 m). This design displaced 9,000 long tons (9,100 t) and accommodated six large Short Type 184 seaplanes and six smaller Sopwith Baby seaplanes. The ship's armament consisted of six 4-inch (102 mm) guns.

The DNC produced a detailed design in January 1918 that made some changes to his original sketch, including the addition of a rotating bow catapult to allow the ship to launch aircraft regardless of wind direction, and the ship was laid down that month to the revised design. Progress was slow, as most of the resources of the shipyard were being used to finish the conversion of Eagle from a battleship to an aircraft carrier. The leisurely pace of construction allowed for more time with which to rework the ship's design. By mid-June the slipway had been deleted from the design and the ship's armament had been revised to consist of eleven 6-inch (152 mm) guns and only a single anti-aircraft gun. By this time, the uncertainty about the best configuration for an aircraft carrier had increased to the point that the Admiralty forbade the builder from working above the hangar deck without express permission. Later that year the ship's design was revised again to incorporate a single island, her lifts were changed to a uniform size of 44 by 20 feet (13.4 by 6.1 m), and her armament was altered to ten 6-inch guns and four 4-inch anti-aircraft guns. These changes increased her displacement to 10,110 long tons (10,270 t).

Construction was suspended after Hermes was launched in September 1919 as the Admiralty awaited the results of flight trials with Eagle and Argus. Her design was modified in March 1920 with an island superstructure and funnel to starboard, and the forward catapult was removed. The logic behind placing the island to starboard was that pilots generally preferred to turn to port when recovering from an aborted landing. A prominent tripod mast was added to house the fire-control systems for her guns.

The last revisions were made to the ship's design in May 1921, after the trials with Argus and Eagle. The lifts were moved further apart to allow for more space for the arresting gear and they were enlarged to allow the wings of her aircraft to be spread in the hangar. Her anti-ship armament was reduced to six 5.5-inch (140 mm) guns and her flight deck was faired into the bow.