The Fiat CR.1 was the first in a long series of biplane fighters designed for Fiat by Celestino Rosatelli, and was an unusual sesquiplane aircraft, with larger lower and smaller upper wings. Two prototypes were produced, under the designation Fiat CR, with CR standing for Caccia Rosatelli, or Fighter/ Hunter Rosatelli. The two prototypes (MM.1 and MM.2) shared the same basic design, with a largely fabric covered wooden structure. The aircraft was an unusual type of sesquiplane, with a larger lower and smaller upper wing, the reserve of the normal design. As a result the aircraft does tend to look upside down when on the ground. The two wings were connected by rigid inverted Warren-type 'W' struts and a standard fixed undercarriage. The two prototypes differed in the shape of the tail and the engine cowling.
The CR made its maiden flight in 1923, and was evaluated against the SIAI S.52, beating it on speed and manoeuvrability. As a result it was ordered into production in 1924 as the Fiat CR.1. Two further prototypes were built to prepare the aircraft for military service, and these were followed by 249 production aircraft. Of these 109 were built by Fiat, 40 by O.F.M. of Naples and 100 by Savoia-Marchetti (SIAI). 240 of these aircraft were accepted by the Italian air force, where they served with eight fighter squadrons and with the earliest air force aerobatic teams. The CR.1 was never used in combat, having been replaced by the CR.20 before Italy became involving in fighting in Africa.
The CR.1 was used as the basis for a number of experiments with alternative engines. Three of these only produced prototypes - the Armstrong Siddeley Lynx powered CR.2, the Alfa Romeo Jupiter powered CR.5 and the Fiat A.20 powered CR.10. A fourth, which saw the Hispano-Suiza engine replaced by a 440hp Issotta Fraschini Asso Caccia engine was more successful. Enough aircraft were converted to use the new engine to allow the Asso-powered CR.1 to be used to equip the 163rd Squadron on Rhodes, where they remained in service until 1937.
Several countries considered buying the CR.1, but only Latvia placed an order, for nine aircraft. These were used by a naval fighter unit and remained in service until 1936.
Engine: Hispano-Suiza 42 8-cylinder inline-vee
Wing span: 29ft 4 1/4in
Length: 20ft 2 1/2in
Height: 7ft 10 1/2in
Empty Weight: 1,850lb
Maximum take-off weight: 2,554lb
Max Speed: 169mph
Service Ceiling: 24,440ft
Endurance: 2 hours 35 minutes
Armament: Two forward firing 0.303in Vickers machine guns