The Macchi-Castoldi Line of Italian Fighter Aircraft

Mario Castoldi, one of the great unheralded designers of WW2

In a lot of ways the development and history of the Macchi-Castoldi series of fighter aircraft used by the Regia Aeronautica during the Second World War parallels that of the Supermarine Spitfire. Unlike many other contemporary fighter aircraft, both lines of fighters weren't derived from earlier fighter designs but sprang from the design work of the elegant racing seaplanes of the 1920s and 1930s and both fighter lines were developed and refined continuously during the course of the war to improve their performance. The Spitfire was born from the Supermarine Schneider series of racing seaplanes designed by Reginald Mitchell. The Macchi-Castoldi series of fighters were the products of Italian engineer Mario Castoldi and his work on the Macchi racing seaplanes that were Schneider Trophy winners as well. Castoldi joined Macchi in 1922 with his first winning racing seaplane design being the Macchi M.39 that won the 1926 Schneider Trophy. Castoldi spent three years working on his ultimate racer, the Macchi M.C.72 that was planned to retake the Schneider from a series of British wins with Reginald Mitchell's designs. Though the M.C.72 didn't complete in a race due to not being ready in time, in 1934 it set a world speed record of 440 mph that still stands to this day for piston-engined seaplanes. For comparison, the world speed record at the time for landplanes was held by the Hughes H-1 with a speed of 352 mph. Castoldi began work on his first fighter aircraft based on his racing seaplane designs when the Hawker Hurricane and Supermarine Spitfire started their flight test programs. Castoldi, however, was handicapped from the start with a lack of a suitable engine like the Rolls-Royce Merlin that wasn't just only a powerful engine but being a liquid cooled inline engine, could be installed in a low drag nose cowling. The only engine that had the power Castoldi wanted was the Fiat A.74 twin-row fourteen cylinder radial developing 870 hp. In addition, the Regia Aeronautica had very stringent visibility demands from the cockpit and this required a hump-backed fuselage which along with the Fiat radial engine, eliminated any of the clean lines that would have belied its racing aircraft origins. The design was entered into the "Program R" competition for a fighter aircraft that had two hours' endurance and twin 12.7mm machine guns. Designated the M.C.200 Saetta (Arrow), it first flew on 24 December 1937. 

M.C.200 Saetta

Proving to be a highly maneuverable aircraft with good ground handling due its wide spaced landing gear (something that always bedeviled both the Spitfire and Bf 109 on account of their narrow track landing gear), the M.C.200 lacked the elegance of the Spitfire but was an impressive performer capable of 500mph in a dive and a quantum leap over the current Regia Aeronautica fighter aicraft, the Fiat C.R.42 Falco biplane. The M.C.200 was declared the winner against the other entrants in 1938 and ordered into production with deliveries beginning in 1939. Thoroughly conventional in its design and construction, the M.C.200 was unique in having its ailerons interconnected with the wing flaps so that they drooped slightly during takeoff and landing to improve field performance. When the first M.C.200s were delivered to the pilots of 4 Stormo (Wing), the pilots were resistant to giving up their Falco biplanes and felt that the enclosed cockpit would delay their egress in an emergency. Castoldi switched to a partially open cockpit design as a result of pilot demands. The pilots of 1 Stormo were more accommodating of the new monoplane fighter, though, as those pilots had participated in the Spanish Civil War and took little convincing that monoplane fighters were the wave of the future. Initial operations had uncovered some unpleasant spin characteristics that had to be rectified with a modified wing and this delayed operational capability further. Only 29 Saettas were in service by the time World War 2 broke out in September 1939 as a result. Interestingly, Italy did solicit export orders for the Saetta and did get a contract for 12 aircraft from Denmark! They were ordered for the Danish Naval Air Service but the order was never finalized after the German invasion of Denmark on 9 April 1940. Two months later when Italy entered the war there were 156 Saettas on strength with the Regia Aeronautica. The M.C.200 Saetta was to have participated in the invasion of France, but another unpleasant quirk was found with high speed stalls. Again the wing required modification and the Saettas went into action over Malta against the Hawker Hurricane. Though slightly slower, the Saetta could hold its own against the Hurricane and proved just as sturdy. Saettas would see extensive service flying escort missions on strikes against Allied shipping in the Mediterranean and were also sent to the Balkans, North Africa, and even participated in Operation Barbarossa on the Eastern Front. 

M.C.201 prototype

M.C.202 Folgore in North Africa

As the development of the M.C.200 Saetta proceeded in 1938, Castoldi was asked to work on a modified Saetta that would use the new Fiat A.76 radial that produced 1,000 horsepower. Castoldi refined the M.C.200 design with an aerodynamic clean up that dropped the hump-backed fuselage and featured an enclosed cockpit for drag reduction. Designated M.C.201, it wasn't enough of an improvement over the production M.C.200 to warrant changing production. Contributing to the termination of the M.C.201 program was Castoldi's next design which was much more promising, the M.C.202 Folgore (Lightning). The Folgore was more of what Castoldi wanted in a fighter design as it featured the German Daimler-Benz DB 601 liquid cooled inline engine that also powered the Messerschmitt Bf 109. With the slimmed down airframe of the M.C.201 and its enclosed cockpit combined with the powerful and low drag DB 601 engine, the M.C.202 Folgore was an instant winner from the time it made its first flight on 10 August 1940. It evoked the lean lines of Castoldi's pre-war racing seaplanes and much of the Saetta production jigs and tooling could be used with sped its introduction into service. Early Folgores used imported DB 601 engines before Alfa Romeo was license-building the DB 601 as the R.A.1000 developing 1,175 hp. The Folgore's empennage was identical to the Saetta and the wings were also identical apart from the installation of fuel tanks in the inboard sections. Armament was basically the same and rather light compared to contemporary aircraft, but some Folgore variants also included an additional pair of wing mounted machine guns and one production batch had underwing fairings for 20mm cannons. The first Folgores went into action with 1 Stormo on 25 November 1941 in Libya. In battles over North Africa, the Folgore gave good account of itself being more maneuverable than both the Hurricane and Spitfire. The M.C.200 Saettas were soon relegated to ground attack missions as the Folgore became the Regia Aeronautica's primary fighter aircraft. Despite this, however, the Saetta remained in production due to production issues with Alfa Romeo on the DB 601 engines. Like the Saetta-equipped units, Folgore squadrons were sent to the Eastern Front but in smaller numbers than the Saetta. 

M.C.205 Veltro in RSI markings

Castoldi wasn't resting on his laurels with the Folgore, though, as he continued to refine the design further and on 19 April 1942 the M.C.205V Veltro (Greyhound) first took flight. While looking very similar to the M.C.202 Folgore, the Veltro used the more powerful Daimler Benz DB 605 engine that produced 1,475 hp. In fact, the Veltro prototype was a Folgore that had been modified to take the DB 605 engine. Like the transition from the Saetta to the Folgore, the transition from the Folgore to the Veltro was relatively easy as much of the same production equipment could be used. Early M.C.205V Veltro aircraft had the same armament as the Folgore before the production standard became two wing-mounted 20mm cannons and the 12.7mm twin guns on the top of the nose. The M.C.205V Veltro went into action for the first time in June 1943 during the Battle of Pantelleria- with the surrender of Axis forces in Tunisia, the Allies prepared for the invasion of Sicily but first had to secure the small island of Pantelleria as well as the rest of the Pelagie Islands of Lampedusa, Linosa, and Lampione. The Veltro then went into action defending Sicily during Operation Husky in July 1943. Despite the fact that the Veltro could easily hold its own against the P-51 Mustang, they were overwhelmed by the sheer size of the Allied invasion force. When the Italian government capitulated on 8 September 1943, the Regia Aeronautica was a shell of its former self with only 33 M.C.200 Saettas, 53 M.C.202 Folgores, and 35 M.C.205V Veltro fighters in serviceable condition along with a variety of other aircraft. But the Macchi-Castoldi fighters were the crown jewels of the Regia Aeronautica and the Germans had no intention of respecting the Italian Armistice. Only 23 Saettas and 6 each of the Folgores and Veltros were able to make it to Allied airfields to become part of the Allied-supported Co-Belligerent Air Force. Most of the fighters were either destroyed by their Italian crews or taken in by the Repubblica Sociale Italiana (RSI) that held out in northern Italy determined to continue fighting with the Germans. 

M.C.205N Orione

Castoldi had always considered the Veltro an interim design, though, as he again refined the design further to make full use of the performance of the DB 605 engine. The new design was the M.C.205N Orione (Orion) and while it used the same empennage that was used on the Saetta, Folgore and Veltro, the fuselage was slimmed down for drag reduction and the wing span increased. Four 12.7mm guns were mounted in the forward fuselage- two on the upper nose just like on the prior Macchi-Castoldi fighters but a second set were mounted in fairings on the fuselage sides above the wing roots. Like the Bf 109, the Orione featured a nose-mounted 20mm cannon. The second Orione prototype replaced the 12.7mm guns near the wing roots with a 20mm cannon in each wing. The first Orione made its first flight on 1 November 1942 and the second Orione flew on 19 May 1943. The Italian government afforded production priority to the Veltro as it could use existing jigs and tooling while the Orione would need new tooling. It had also been decided at this point that the successor to the Veltro would be the Fiat G.55 Centauro as it showed more promise at high altitudes where American bomber aircraft operated.

M.C.206. Only one prototype built, but destroyed before flown

This wasn't quite the end of the Macchi-Castoldi line, though. Always refining his designs with several parallel concepts in the works, the successor to the M.C.205N Orione was the M.C.206. Being the consummate engineer, Castoldi set out to improve upon the deficiencies of the M.C.205V Veltro and the M.C.205N Orione. Still using the DB 605 engine, a single M.C.206 was nearly complete when it was destroyed in an Allied bombing attack in the spring of 1944. The more powerful DB 603 engine that was used on the Focke Wulf Ta 152 spurred Castoldi to revise the design again with the M.C.207 which had it been built would have been the ultimate Macchi-Castoldi fighter. With 1.700 hp available, the M.C.207 was a larger aircraft with four 20mm wing cannon. Work began on the M.C.207 prototype, but it was never finished before the war ended in 1945. 

The ultimate Macchi-Castoldi, the M.C.207. Prototype started, never completed

While the quantities of the Macchi-Castoldi fighters were modest compared to other fighter aircraft of the Second World War, the fighters were well-regarded by the Allies as adversaries. The Italian aircraft industry was never fully mobilized on war footing and this was one factor that was detrimental to Italian fortunes in the war. Germany proved to be a less than ideal ally through it all, often holding up deliveries of Daimler Benz engines, failing to provide requested assistance to the Italian aircraft industry. In addition, many skilled Italian workers in the industry were forcibly moved to work in German aircraft factories. Mario Castoldi retired from aviation with the end of the war in 1945, passing away in 1968. 

Source: Famous Fighters of the Second World War by William Green. Doubleday and Co, 1975, pp 71-83. Images: Wings Palette, Wikipedia, World of Warplanes forum.