The last fighter Reggiane built was the best. The Re.2005 Sagittario, which many observers considered the beautiful fighter of the war, represented the final development of the formula that bad been initiated in the 1939 with the Re.2000 Falco. The Re.2005 was completely different in many respects. Although the wings were similar in plan, the structure and profile were altered and improved. The landing gear were new, with the wheels folding outward under the wings. The plane was heavily armed, with three 20 mm cannon and two 12.7 mm machine guns. The well balanced lines of the fuselage were aerodynamically perfect. Everything about the plane was designed to the most of the 1,475 hp (1100 kw) Daimler Benz engine. Overall the Re.2005's performance was superior to that of its direct rival, the Fiat G.55 Centauro. The only difficulty was a certain structural weakness in the rear section of the fuselage. This defect appeared in the first phases of its short operational life, and at one point all flights of this aircraft were suspended until this problem was corrected.
Work on the prototype aircraft began in 1941, and the first aircraft were ready in December. But four months were lost waiting for delivery of the engine. The engine was sent from Germany by rail but disappeared in transit. It was April 1942, before the new fighter was ready for test flights. The other two Series 5 planes were readied in the meantime, The Macchi MC.205V Veltro (greyhound) and the Fiat G.55 Centauro (centaur). The MC.205V made its first test flight on 19 April 1942, the G.55 on 30 April but it wasn't until 9 May that the first Re.2005 prototype took flight. The Reggiane fighter did make a flight the week before but it had been damaged in landing because of a weak landing gear strut.
Test flights and comparative trials displayed the Re.2005's fine features. It was fast and manoeuvrable. At 6,600 feet the prototype flew at about 425 mph (686 km/h). Large scale production was not ordered immediately. Only 16 0-series and 18 pre-series were at first ordered. In February 1943, and order for 750 aircraft was finally placed, but only 48 Re.2005s ever came off the assembly line before the armistice was signed and production halted.
The plane's operational career began in May 1943, when it was assigned to the 362nd Squadrigia of the 22nd Gruppo. The unit was sent to Sicily at the time of the Allied invasion. Late in June it was based in Capua and used in operations against Allied bombers until 26 August 1943. When the armistice was signed in September, many of the surviving Re.2005s were destroyed by their pilots to prevent them from falling into German hands. Mussolini's forces in the north did manage to get six of these aircraft which they used as trainers. Some aircraft (as many as 13) were captured by the Germans. Some sources maintain that these aircraft were used late in 1943 against Allied bombing raids on Berlin. Others believe that these planes were used as interceptors in defence of the Romanian oil fields.
A request by the R.L.M. led to one Re.2005 (MM.495), known as the Reggiane Re.2005 "LW", to be modified to German standards for tests in late July 1943. It was evaluated first in Guidonia and later at the Rechlin airfield. Tests revealed improved performances with speeds of up to 628 km/h (390.4 mph)with the FIAT engine and more than 650 km/h (400 mph)with the DB engine in level flight, without using war emergency power (WEP).
A prototype of the follow-on Re 2006 was almost completed before September 1943 but not flown. It was to use the DB 603 engine with 1,750 hp (1,300 kW) and had an estimated maximum speed of 740 km/h (462 mph). Only the G.56 was flown with this engine. A twin-fuselage version and a motorjet variant, the R.2005R were considered.
On the R.2005R, speed could have been increased to 750 km/h (466 mph), but fuel consumption would have reached almost 1,000 l/h, almost four times the normal Re.2005's fuel usage at full throttle. This aircraft project wasn't considered as a serious alternative to the Re.2006.
* Crew: 1
* Length: 873 cm (28 ft 7.7 in) ()
* Wingspan: 1,100 cm (36 ft 1.1 in) ()
* Height: 315 cm (10 ft 4.0 in) ()
* Wing area: 20.4 m2 (219.6 sq ft) ()
* Empty weight: 2,600 kg (5,730 lb) ()
* Loaded weight: 3,610 kg (7,960 lb) ()
* Powerplant: 1× Fiat R.A. 1050 RC 58 Tifone, (license built DB 605A-1), 1,475 PS (1,085 kW; 1,455 hp)
* Never exceed speed: 980 km/h (609 mph)
* Maximum speed:
o 628 km/h (390 mph) at 2,000 m (6,600 ft),
o 678 km/h (421 mph) at 7,000 m (23,000 ft) 
* Cruise speed: 515 km/h (320 mph)
* Stall speed: 155 km/h (96 mph) ()
* Range: 980 km (610 mi) on internal fuel (1,130 km (700 mi) w/ 300 L drop tank; 1,270 km (790 mi) w/ 300 L + 2 × 150 L drop tanks)
* Service ceiling: 11,500 m (37,700 ft) ()
* Rate of climb: 20 m/s (3,900 ft/min) (6,000 m in 6.5 min)
* Wing loading: max. 177 kg/m² (36.11 lb/ft²)
o 2 × 12.7 mm Breda-SAFAT machine guns in upper cowling (350rpm);
o 1 × 20 mm MG 151 cannon firing through propeller hub (150rpm);
o 2 × 20 mm MG 151 cannon in wings (200rpm)
o Underfuselage (non standard) hardpoint 1,000 kg (2,200 lb) bomb or 1 × 300 L (79.3 US gal) drop tank
o Hardpoints on wings: 160 kilograms (350 lb) bombs or 2 × 150 litres (39.6 US gal) drop tanks