Work on converting
Roma into an aircraft carrier began in earnest at Cantieri Ansaldo, Genoa, in November 1941. Since a battleship named was already under construction, the ship's name was changed to
Aquila.
Hull The liner's interior was completely gutted to allow for replacement of the original machinery and the addition of a hangar deck and workshops. Deep bulges were added to either side of the hull to improve stability, hull form, and provide a modest degree of torpedo defense. A layer of
reinforced concrete— thick—was applied inboard of the bulges for splinter protection. The hull was also lengthened to take advantage of the increased power of
Aquila′s new machinery, and the bow flare increased to increase seaworthiness and provide additional space for air requirements. In order to improve resistance to underwater damage, the ship was heavily subdivided with 18 watertight bulkheads extending up to 'C' or 'D' deck, 11 of which were double. The designers worked in of armor over the magazines and aviation fuel tanks. The fuel tanks copied British practice and consisted of cylinders or
coffer dams separated from the ship's hull by water-filled compartments. This was a safety measure intended to prevent fracturing of the fuel system and the inadvertent spread of volatile AvGas fumes due to severe vibration or "whip" from bomb hits, near misses and torpedo hits. Self-propulsion tests at the Freude tank at La Spezia in January 1942 indicated that for a trial displacement of 26,700 tons, a speed of 29 knots could be achieved with 132,660 shp. This indicated that a sustained speed of 29.5 knots could be reached with an output of 140,000 shp, and 30 knots if the propulsion system could develop 151,000 shp without being forced.
Aquila′s new propulsion system was taken from two canceled
Capitani Romani-class light cruisers (
Cornelio Silla and
Paolo Emilio), as despite their cancellation the fabrication of their propulsion systems was in an advanced stage. Totaling eight boilers and four turbine groups, each of these was capable of generating 55,000 shp at 310 rpm, more than adequate for the needs of
Aquila. Each boiler operated at a pressure of , with the superheated steam being fed to the turbines at a pressure of and a temperature of . As installed on
Aquila, the overall output in shaft horsepower was reduced, to a maximum of 37,750 shp per turbine group at full normal power. The propellers used were also modified to a type more suitable for a larger ship - whereas the original propellers used by the Capitani Romani-class had three blades and a diameter of , those used by
Aquila had four blades and a diameter of . In order to increase survivability, the propulsion systems were grouped into four engine rooms, each with one turbine group and two boilers - a similar solution to what the Americans adopted for the
North Carolina-class battleships. This solution made it possible to simplify piping of all kinds (steam, water, oil, etc.), ventilation systems, improve living conditions for the crew, and enhance ease of supervision and maintenance. Hangar floor capacity was 26 aircraft for the
Re.2001 OR Serie II, with seven in the 32-35 meter sections and six in the 25 meter sections. Additionally, fifteen aircraft could be suspended from the hangar ceiling. A planned folding-wing version of the aircraft was to have allowed the stowage of sixty-six aircraft in the hangar.
Flight deck Aquila had a single continuous flight deck. It was partially armored with plate over the gasoline bunkers and magazines. The flight deck ended short of the bows but overhung the stern, where it featured a pronounced round-down to improve air flow. Two octagonal lifts with a capacity enabled transfer of aircraft between the hangar deck and flight deck. One was directly amidships and the second another forward, thus placing them far enough from the aft arrester wires that both could be used for striking down aircraft into the hangar immediately after a landing. A set of rails led aft from the catapults to the elevators and into the hangars. For catapult-assisted launches, aircraft would be hoisted in the hangar onto a portable collapsible catapult carriage, raised on the elevators to flight deck level and then trundled forward on the rails to the catapult starting positions, the same system as employed on
Graf Zeppelin.
Aquila′s engines and catapults were successfully tested in August 1943 but the arresting gear installed on the carrier, consisting of four cables, initially failed to work properly. This would have prevented aircraft, once launched, from landing back on board. It was therefore proposed that aircraft taking off from
Aquila would, after performing their mission, fly back to the nearest land-based airfield or simply ditch in the sea, a serious and embarrassing limitation on her capabilities as a fleet carrier. Italian and German technicians labored for months at the Perugia Sant'Egidio airfield on a mock-up of ''Aquila's'' flight deck and by March 1943 the heavily modified arresting gear was deemed usable. A postwar US Navy evaluation concluded, however, that the arrangement would have made landings exceedingly hazardous, especially given the absence of a crash barrier.
Aquila′s starboard-side island contained a single large vertical funnel for carrying exhaust gases clear of the flight deck. It also included a tall command tower and the fire control directors for the guns.
Anti-aircraft armament Six 6-barrelled Breda Model 35|/65 caliber (cal)
anti-aircraft (AA)
cannons were positioned just fore and aft on the island. In addition,
Aquila carried eight /45 cal guns taken from one of the canceled
Capitani Romani-class cruisers. Though not designed as
dual purpose weapons, these guns had an elevation of 45° and were therefore capable of providing a useful barrage against attacking enemy aircraft (by comparison, Italy's best heavy AA gun—the /50 cal—had an elevation of 85°). It was intended to mount 12 newly designed AA guns on sponsons just below flight deck level (six on either side of the hull). However, this gun—with an automatic feeder and 20 rpm rate of fire—never got beyond prototype stage. An additional 16 six-barrelled 20 mm cannons—also mounted below the flight deck—rounded out the ship's AA defense.
Aircraft Throughout 1942 and 1943, trials were conducted at Perugia and Guidonia—the
Regia Aeronautica′s equivalent to the German
Luftwaffe′s test facility at
Rechlin—to find aircraft suitable for conversion to carrier use. The Italians selected the
SAIMAN 200,
Fiat G.50/B and
Reggiane Re.2001 OR Serie II as potential candidates. In March 1943, German engineers and instructors with experience on
Graf Zeppelin arrived to advise on aircraft testing and to help train future carrier pilots culled from 160
Gruppo C.T. of the
Regia Aeronautica. They brought with them examples of a
Junkers Ju 87C Stuka dive bomber (a navalized version with folding wings, arrester hook and catapult attachment points) and an
Arado Ar 96B single-engine trainer. After conducting comparative flight trials, the Italians eventually settled on the Re.2001 as their standard carrier fighter/fighter-bomber and even the Germans concluded it had better potential than their own counterpart, the
Messerschmitt Bf 109T. All flight testing—including simulated braked deck landings—was land-based.
Aquila′s planned air complement was 51 non-folding Reggiane Re.2001 OR fighter-bombers: 41 stowed in the hangar deck (including 15 suspended from the deck head) and 10 on the flight deck in a permanent deck park. A folding-wing version of the Re.2001 was planned, which would have increased the size of
Aquila′s air group to 66 aircraft, but this never materialized. Only 10 Re.2001s were fully converted for carrier use. They were given tail hooks, RTG naval radio equipment and bomb racks for carrying of bombs. They were also armed with two Breda-SAFAT
machine guns mounted above the engine cowling. At least one Re.2001G was under test at Perugia as a naval torpedo bomber and was given a lengthened tail wheel strut to accommodate the added height of a torpedo suspended below the fuselage. ==Fate==