The prototype G.55 pmade its maiden flight on 30 April 1942; after proving itself during competitive trials, the fighter entered quantity production and squadron service during the following year.

Accordingly, during 1941, designers shifted their attention on the new, larger and more powerful Fiat RA.1050, a license-built copy of Germany's Daimler-Benz DB 605 engine.

The first G.55 prototype flew on 30 April 1942,[9] piloted by commander Valentino Cus, immediately showing its good performance and flight characteristics.

It was armed with one 20 mm MG 151/20 cannon with 200 rounds of ammunition, installed between the cylinder banks and firing through the propeller hub.

[citation needed] The prototype was flown to Guidonia, where it was put into trials against the other fighters of the so-called Serie 5: Macchi C.205V Veltro and the formidable Reggiane Re.2005 Sagittario, all of them using the powerful, license-built Daimler-Benz DB 605 engine.

The only negative assessment noted by G.55 pilots was the pronounced left-hand yawing at takeoff due to the powerful engine torque.

[citation needed] By early 1943, increased Allied bombing raids over Italy had showed that there was no suitable high-altitude fighter to deal with them effectively.

Of these, only one was flown to South Italy to join the Italian Co-Belligerent Air Force (a second G.55, MM.91150, was obtained by the Allies in summer 1944, when test pilot, Serafino Agostini, defected with an escaped British POW, an RAF officer, sitting on his knees.

The aircraft was then taken on charge by the RAF and transferred to the Central Fighter Establishment of Tangmere, Great Britain, on 17 March 1945, with the identification number VF204 applied, was put in the depot at Ford; its final fate is unrecorded.

[11][12]) From that date on, the Centauro served with the Aeronautica Nazionale Repubblicana (ANR), the air force of the new fascist state created in North Italy by Mussolini, with the assistance of the Germans.

The parts were then assembled in Turin where the aircraft were to be flown by test pilots Valentino Cus, Rolandi, Agostini and Catella.

In early June they were assigned to 353a Squadriglia (flight) CT based in Foligno, Umbria, were, until August, were transferred nine more aircraft.

The 353a Squadriglia, commanded by Capitano Egeo Pittoni, flew many missions against the American bomber formations, but the flights were stopped when Rome was declared "Città aperta" (open city).

Only one of them flew to southern Italy, accepting the invitation of Maresciallo d'Italia Pietro Badoglio to surrender to Allied forces.

[15] The Centauro entered in service with the ANR; a decision was made to produce 500 G.55s, of which 300 were G.55/I and 200 G.55/II Serie II, armed with five 20 mm MG 151/20s and no machine guns (one in the centerline, two in the upper cowling, two in the wings).

Only 148 were delivered to the ANR units that, as the number of available G.55s dwindled, were progressively re-equipped with the Bf 109G, of various sub-versions, even though Italian pilots preferred the G.55, with cancellation of production being extremely unpopular.

The first unit in ANR to be equipped with G.55 was the Squadriglia Montefusco [it], in November 1943, operating from Piemonte until 29 March 1944, when it was absorbed by the 1st Gruppo and transferred in Veneto.

The unit operated near Milan and Varese until April 1944, then it was transferred near Parma and Pavia, then again near the Lake Garda (Brescia and Verona).

[22] The commission was led by Oberst Petersen and was formed by Luftwaffe officers and pilots and by technical personnel, among them the Flugbaumeister Malz.

After listening to the recommendations of Petersen, Milch and Galland, a meeting held by Göring on 22 February 1943 voted to produce the G.55 in Germany.

Two of the Luftwaffe G.55's remained in Turin, at the Aeritalia plants, where they were used by German and Italian engineers to study the planned modifications and the possible optimizations to the production process.

In October 1943, Kurt Tank, who previously personally tested a G.55 in Rechlin, and who had had nothing but praise for the aircraft, was in Turin to discuss G.55 production.

However, events in the war (including intention efforts by the Allies to bomb Italian aircraft factories) and the not yet optimized production process were the reasons for which the G.55 program was eventually abandoned by the Luftwaffe.

Such aircraft, based near the Italian coast, could potentially have an operational range of 300–400 km (190–250 mi), would be capable of carrying a 680 kg (1,500 lb) torpedo (a shorter and more compact version of a weapon carried by the SM.79) at relatively high speed, and would also be better able to evade enemy fighters and/or combat them on equal terms.

The ANR ordered a pre-series of 10 examples and a production series of 100 aircraft, but the conclusion of the war put an end to the project.

The G.55/S prototype survived the war and, after being converted back to the Serie I standard, it became the first G.55 to be delivered to the newly formed Aeronautica Militare Italiana (AMI).

[14][23] During 1946, Fiat restarted production of the G.55, making use of the large stock of partly complete airframes and components remaining in its factories.

[27] The production of these orders for G.55s for Italy and Argentina caused the available stocks of the Italian licence-built version of the DB 605 engine to run short.

As there was still a demand for the aircraft, it was decided to convert the type to use the more readily available Rolls-Royce Merlin engine, with the first conversion flying in early 1948.

[28][29] The conversion was successful, and the AMI decided to convert its G.55s to Merlin power, these re-entering service at the Lecce flying school in 1950 as the G.59-1A and G.59-1B (single- and two-seat versions).