Macchi C.202 - Design

Design

Castoldi, whose background included working on Schneider Trophy racers design, followed Celestino Rosatelli as the main designer of new fighters for the RA. His new project was robust and small, utilizing a conventional but complex structural arrangement based on his experience with wooden designs, and at the same time paying great attention to its aerodynamics (Castoldi designed the MC.72, the world's fastest aircraft of its time).

The wing and fuselage structures were of a conventional metal design, having a single vertical tail with two elevators, and a wing of relatively conventional design with two main spars and 23 ribs. The ailerons, elevators and rudder were metal structures with fabric covering. Apart from the ailerons, the entire trailing edge of the wing was dominated by a pair of all metal split flaps. The undercarriage was of a standard design; the two widely set hydraulically operated main gears retracting inwardly into the wing, while the tail wheel was non-retractable. As with the C.200, to counteract the torque of the engine, Castoldi extended the left wing by 21 cm (8.5 inches). This meant that the left wing developed more lift, offsetting the tendency of the aircraft to roll to the left due to the rotation of the propeller, which was an ingenious solution to a problematic issue faced by all aircraft designers.

The empty weight of the new C.202 (approximately 2,350 kg/5,180 lb) gradually increased throughout production, and due to the thickness of metal used it was also comparatively heavy, yet this class of aircraft was still considered lightweight compared to other contemporary fighter designs. The Macchi's mass was around 300 kg (660 lb) higher than the comparable Bf 109E German fighter, consequently, the power-to-weight ratio was considerably lower while wing loading was higher

Australian air ace Clive Caldwell felt the Folgore would have been superior to the Messerschmitt Bf 109 had it been better armed. The C.202 was lightly armed by the standards of the time carrying the same armament as the C.R.32, a 1933 design. The C.202 carried as standard two 12.7 mm (.5 in) Breda-SAFAT machine guns. The Breda design was as heavy as the Browning M2, the model from which it was derived. However, the Breda fired 12.7x81 mm "Vickers" ammunition, not 12.7x99 mm, with the result that the energy at the muzzle was 10,000 joules vs. 16,000. The rate of fire was about 18 rounds/second or 0.63 kg (1.39 lb).

Initially, all the armament was fitted within the nose of the Macchi. Ammunition carried was up to 800 rounds (standard: 700 rounds). An additional pair of Breda 7.7 mm (.303 in) machine guns was fitted in the wings in the VII series onward, but these, along with 1,000 rounds of ammunition, added 100 kg (220 lb) to the aircraft's weight. Consequently, they were typically removed by pilots to save weight, since they were relatively ineffective against most enemy aircraft in 1942. A synchronizing unit allowed the nose guns to fire through the propeller disk, but with a 25% loss in ROF (Rate of Fire). A "San Giorgio" gun sight, a reflection unit, was also fitted in the cockpit.

The fuselage housed the main armament and the Alfa Romeo R.A. 1000 RC.41-I Monsone engine which drove a Piaggio P1001 three-blade, variable-pitch, constant speed propeller. Situated behind the engine and under the 12.7 mm (.5 in) ammunition boxes there was a 270 L (71.3 US gal) self-sealing fuel tank. Another 80 L (21.1 US gal) fuel tank was placed behind the pilot, with two additional tanks, each with a capacity of 40 L (10.5 US gal), being housed in the wing roots; the total fuel capacity was 430 L (113.6 US gal) . The main coolant radiator was housed in a rectangular fairing under the fuselage beneath the cockpit, and the oil cooler was placed under the nose within a streamlined, rectangular housing. From the cockpit aft, the fuselage was formed into a round monocoque structure; the aft fuselage tapered into the tail and contained the radio, oxygen and flight control mechanisms. The canopy was hinged on the starboard base and opened sideways. Behind the canopy the pilot's headrest was fixed to a triangular turn-over pylon which was covered by a streamlined, tapered fairing. This fairing was shaped into an inverted 'T' which enabled the pilot to have a reasonable field of view to the rear. The unpressurised cockpit had an armour plate fitted behind the armoured seat for protection. While early C.202s had a very short "stub" radio mast projecting from the fairing, most used a tall, slim mast.

On 21 August 1941, Tenente Giulio Reiner, one of the most skillful and experienced pilots of 9° Gruppo, flew the "military control flight" in Lonate Pozzolo, The Ufficio tecnico (Technical Bureau) recorded the maximum speed of 1,078.27 km/h in the Folgore in a vertical dive, with 5.8 G. forces while pulling out of the dive. Ingegner Mario Castoldi, the designer of the 202 questioned whether Reiner had properly flown the test. In fact, during the vertical dive, Reiner had to face very strong vibrations throughout the airframe and in the control stick, while the flying controls were locked and the propeller blades were jammed at maximum pitch. The clean aerodynamics offered by the inline engine permitted dive speeds high enough for pilots to encounter the then-unknown phenomenon of compressibility.

Some defects of the new fighter could be easily fixed, such as the landing gear lowering inadvertently when pulling out of a steep dive, the machine gun bonnet that broke, the ammunition belts that jammed and the air cleaner intake that, because of the engine vibrations, first crystallized and then sheared itself. Other defects, like the unreliability of the radios and of the oxygen systems, and the limited armament, could not.