Fiat CR.20

{{Infobox aircraft

| name = CR.20

| image = Fiat C.R.20 Aviano, 1936.jpg

| caption =

| type = Fighter

| manufacturer = Fiat

| designer = Celestino Rosatelli

| first_flight = 19 June 1926

| introduction =

| retired =

| produced =

| number_built = c. 250 CR.20
c. 46 CR.20 Idro
c. 235 CR.20bis
c. 204 CR.20 Asso

| status =

| unit cost =

| primary_user = Regia Aeronautica

| more_users = Lithuanian Air Force
Hungarian Air Force

| developed_from =

| variants =

}}

The Fiat CR.20 was a biplane fighter designed and produced by the Italian aircraft manufacturer Fiat. It represented an intermediate step from the early biplane CR.1 and the later, successful series CR.30, CR.32 and CR.42.{{Cite web |title=Fiat Cr.20 |url=https://www.militaryfactory.com/aircraft/detail.php?aircraft_id=1602 |access-date=19 February 2024 |website=militaryfactory.com}}

Development of the CR.20 was headed by the aeronautical engineer Celestino Rosatelli, who selected a sesquiplane configuration. The engine was a water-cooled {{convert|306|kW|hp|abbr=on}} Fiat A.20 V-12 engine.{{Cite web |title=Fiat CR.20 |url=http://www.historyofwar.org/articles/weapons_fiat_cr20.html |website=historyofwar.org}} Major variants were the CR.20 Idro, a pontoon floatplane, and the CR.20 Asso, using a more powerful (336 kW/450 hp) Isotta Fraschini engine. CR.20bis, produced from 1930, differed from the original version only with the addition of a more advanced landing gear.{{Citation needed|date=January 2021}}

==Design and development==

The Fiat CR.20 was a sesquiplane fighter.NACA 1927, p. 1. It had an all-metal framework which comprised both steel and various light metals.The exterior covering was of fireproof fabric, except for the front part of the fuselage close to the engine, which was instead covered by duralumin sheeting. The fuselage was relatively streamlined, which was obtained via the use of duralumin ribs and tubes that directly supported the fabric covering. The pilot was seated relatively high up in relation to the top of the fuselage; this provided a good field of vision both above and below the upper wing. Overall, the aircraft was relatively compact, which had the benefit of minimising inertia in all directions and thus improving its manoeuvrability.

The wings were staggered, and had dihedral. The number of wing struts, arranged as a warren girder was minimised as to reduce the drag incurred as well as to simplify the mounting. The ribs employed an arrangement of triangular bracing composed of thin duralumin tubes while the wing spars formed box girders, consisting of two metal strips that were riveted together. Shearing stresses were adequately distributed by the twin spar webs, the flanges of which extended along the entire length of the spars and were reinforced at certain points. The stress distribution was designed to require the least possible variation in the cross section of the spars to form a girder of near uniform strength.NACA 1927, pp. 1-2. The wing struts were composed of sheet metal in a conventional manner and possessed an aspect ratio of 2.5, as was then typically used on Fiat-built aircraft. The three struts forming each half of the cabane were joined in a manner that imposed no obstruction to the aircraft's cockpit.NACA 1927, p. 2.

The fuselage framework consisted of four steel longerons, which were connected by a combination of transverse frames and triangular bracing. The structure of the fuselage's forward section terminated at the second bulkhead, that beyond effectively being a projecting bracket. The mounting for the engine was relatively simple; however, attention was paid to providing good accessibility for various elements, including the magnetos, water, fuel, and oil pumps and most aspects of the power plant. No bracing was present between the lower longerons due to the location of the fuel tank; instead, the horizontal girders continued through to the lower wing to join with the fuselage. The honeycomb radiator, which was located within the forward fuselage, used specialised elastic supports that avoided any vibration-related disturbances. The air passages of the radiator were arranged to facilitate maximum airflow, and thus the most efficient cooling, while the aircraft was climbing. The pilot could exercise control of the radiator via a shutter.NACA 1927, pp. 2-3.

It was powered by a Fiat A.20 V-12 water-cooled piston engine, which was capable of producing 410 hp, driving a twin-bladed fixed-pitch propeller . The speed of the engine enabled the attainment of a high specific power despite a relatively small bulk. The front end of the engine was specifically shaped to facilitate the installation of the radiator and thus achieve optimal efficacy, weight, and bulk, as well as protection of vulnerable elements from enemy fire. The twin double-spark high-tension magnetos were located aft of the engine and were relatively easily to inspect. A specialised starter, assisted by starting magnetos, was also present.NACA 1927, p. 3.

The armament consisted of four machine guns, all located within the fuselage. Two of these fired through the propeller arc as they were situated quite close to the pilot and featured an orthodox installation. The other two were mounted on the either side of the fuselage at the height of the longeron that supported the engine. The ammunition boxes, which were located on the sides of, and underneath, the engine cowling, were suitably protected.NACA 1927, pp. 3-4. The aircraft had a relatively large carrying capacity.NACA 1927, p. 5.

Considerable attention was paid to maximising the safety of the aircraft, to avoid needing high piloting skills to operate it. To minimise the risk of an onboard fire, the pilot could jettison the fuel tank. . Torque was corrected against by making the left half-cell somewhat longer than the right.{{what|date=May 2025}} . Special attention was paid to the positioning of both the fuel and oil tanks relative to the aircraft's centre of gravity, as well as to the location of the landing gear (in order to lessen the tendency to capsize on rough ground). The angle of attack was such as to achieve maximum lift and therefore to minimise the aircraft's landing speed.NACA 1927, p. 4. Despite these measures, the CR.20 was capable of performing various aerobatic manoeuvres and also possessed relatively high horizontal and climbing speeds.NACA 1927, pp. 4-5.