The search for ways to improve the flight performance of the CR.714C1 would inevitably lead designers to the idea of using a larger engine. One of the suitable samples was the RC-40 engine of the Italian firm Isotta-Frascini. According to the scheme, it corresponded to Renault 12R – 12-cylinder V-shaped inverted, but developed much higher power – 730 hp. At the same time the working volume of the Italian engine was 21 liters, while the “Renault”, which produced 450 hp, – 19 liters. The project for this engine was initially designated C.715. In December 1938, two prototypes were built (factory numbers 8978 and 8979). The second of them received an Italian motor, as well as the new designation CR.760 and serial number 01.
CR.760 differed from CR.714C1 not only by the engine – its fuselage was not wooden, but had a metal set of chrome-molybdenum pipes. The capacity of the fuel tank was increased to 305 liters. Armament also became more powerful-six 7.5 mm machine guns with an ammunition of 500 cartridges per guns. The production version planed to replacement the machine guns with a pair of 20-mm guns.
The first copy of the CR.760 in the last quarter of 1939 was ground tested, but for the first time it took off on April 6, 1940, piloted by R. Delmott. In May, the aircraft flew well-known Italian pilot Arthur Ferrarin. The aircraft showed excellent flight data: the maximum speed was 570 km / h, the altitude of 4000 m reached 5 minutes. But the mass production of the Cr.760 (due to the defeat of France) was never started. The only constructed specimen became a German trophy.
The Cr.770 is an easy fighter developed by the French firm Caudron. The aircraft became the further development of the lightweight Cr.714 Cyclone fighter. Work on the aircraft was conducted since 1939 in parallel with the development of Cr.760. The aircraft was equipped with a sixteen-cylinder air-cooling engine Renault 626 with a power of 800 hp. The aircraft received a reinforced (in comparison with Cr.714) armament consisting of six 7.5-mm MAC-34 machine guns. The first flight of the aircraft took place in June 1940. Further work on the aircraft prevented the German invasion of France.
A concept which persisted throughout World War II was that of the lightweight interceptor, inspired by the matter of mass production amid the exigencies of war. The lightweight fighters’ exact roles varied as much as did their builders’ approaches to achieving them; but they all sought to wring the highest possible performance from the smallest, lightest possible airframe, built using the greatest amount of easily available materials (usually wood) in lieu of strategic materials (such as aluminum). Another thing that most of them held in common was failure. Of the many lightweight interceptors created just before or during the war, only three attained production status, and only one could truly be called successful.
During the mid-1930s, the Service Technique de l’Aéronautique of the French Armée de l’Air laid down a specification for a lightweight interceptor that was influenced by the monoplanes, which were then attracting much publicity in speed competitions. The chosen design, the Caudron-Renault CR.710, was designed by Marcel Riffard and was based on his sleek C.460, which between 1933 and 1936 had been outperforming larger, more powerful aircraft in international competitions. (During which time Renault had bought up the Caudron firm in 1933.) Like the racing plane, Riffard’s CR.710 fighter was of wooden stressed-skin construction and characterized by a long, slim fuselage. Its power plant was a 500-horsepower Renault 12R 01 twelve-cylinder inverted-V air-cooled engine. The first prototype had fixed, spatted landing gear and oval-shaped vertical tail surfaces when it first flew on July 18, 1937, and later carried two wing-mounted drum-fed 20mm Hispano-Suiza HS-9 cannon. The second prototype, CR.710-02, featured more angular vertical tail surfaces, and the CR.713 introduced retractable landing gear. A third version, the CR.714, first flew on July 6, 1938, and differed from the CR.713 primarily in armament, the cannon being replaced by four 7.5mm MAC M39 machine guns, housed in two underwing trays.
After some final modifications, the CR.714, also known as the Cyclone, was ordered into production on November 5. The production CR.714 featured an improved 12R 03 engine, which had a carburetor that allowed negative-G maneuvers. It had maximum speed of 286 miles per hour at 16,450 feet, and climbed to 13,125 feet in 9 minutes and 40 seconds.
The original production order was for twenty CR.714s, with an option for a further hundred eighty, but once the fighter entered service, the Armée de l’Air judged it to be unsuitable for combat. Six were sent to Finland but arrived too late to take part in the Winter War, and desperate though the Finns were for any combat aircraft, they never used the Caudrons in battle. The other Cyclones were assigned to two training squadrons at Lyon-Bron, made up of expatriate Polish pilots. By June 2, a total of thirty-nine CR.714s had been delivered to the Poles, who flew them operationally as Groupe de Chasse I/145, also known as the 1ère Groupe Polonaise de Varsovie, under the joint command of Commandant Józef Kepinski and his French advisor, Commandant Lionel A. de Marmier, a six-victory World War I ace.
For all the Cyclone’s racy looks, the Poles soon became disenchanted with their new mount. It required a long takeoff and landing run; the landing gear release often jammed; the variable-pitch propeller mechanism was prone to failure; the rate of climb was slow and so was the aileron response. Worst of all was the 12R 03 engine, which had trouble starting, was plagued by a weak crankshaft, had a tendency to overheat, and suffered from fuel and oil leaks. Sous-Lieutenant Witold Dobrzynski was killed in a crash on May 19, and three other Caudrons were written off in landing accidents on May 25. After inspecting GC.I/145 on May 25, Air Minister Guy La Chambre considered grounding the interceptors. Kepinski chose to keep them in spite of their faults, however. His men wanted to fight, and with the German offensive in the West under way, they had little choice but to make do with the fighters they had until their intended replacements, Bloch MB.152s, became available.
On June 2, GC.I/145’s Cyclones flew from Villacoublay to the former RAF airfield at Dreux. Combat was joined on June 3, when Commandant de Marmier, Lt. Tadeusz Czerwinski, and Sous-Lt. Aleksy Zukowski dived on three He 111s and shot down two over Villacoublay. The unit carried out further patrols, but its next fight did not occur until June 8, when a flight led by Capitaine Antoni Wczelik engaged at least fifteen Messerschmitt Me 110Cs over Rouen. One Caudron was damaged, but the French confirmed the destruction of two Me 110s by Czerwinski, one each by Wczelik and Zukowski, and one shared between Sous-Lt. Jerzy Godlewski and Caporal Piotr Zaniewski. Kepinski and Sous-Lt. Czeslaw Glówczynski, who was already credited with three and a half enemy planes during the German invasion of Poland, scored probable victories over another two Me 110s.
Perhaps inevitably, GC.I/145’s luck took a turn for the worse the next day, when seventeen Cyclones encountered twenty-five Dornier Do 17s escorted by twenty Me 109Es. Malfunctioning radios prevented the CR.714 pilots from making a coordinated attack, and while Wczelik’s flight hurled itself at the bomber formation, other Poles found themselves engaged in individual duels with the German fighters. Glówczynski was credited with one of the Messerschmitts, along with probable credits for a second Me 109 and a Do 17 (he would add one more German to his score on December 30, 1941, as a Spitfire pilot in the RAF). Sous-Lieutenant Jerzy Czerniak and Sgt. Mieczyslaw Parafinski were credited with one Me 109 each, while Wczelik, Lt. Julian Kowalski, and Sgt. Antoni Markiewicz shared in the destruction of another of the bombers (the Germans reported no Do 17 losses, but Fw. Fritz Specht of II Gruppe, Kampfgeschwader 54 returned to his base at Köln-Butzweilerhof on one engine with the tail and rudder of his Heinkel He 111P badly damaged after being attacked by enemy fighters over Evreux). Lieutenant Jan Obuchowski, Sous-Lt. Lech Lachowicki-Czechowicz, and Caporal Edward Uchto were killed, however, and Kowalski was wounded in the right arm, although he managed to land his damaged plane at Bernay. In addition, the riddled Caudrons of Commandant Kepinski and Sous-Lts. Jerzy Godlewski and Bronislaw Skibinski crash-landed in the Norman countryside, Czerniak crash-landed his shot-up plane at Dreux, and most of the other CR.714s returned in various damaged states.
Twelve of the group’s thirteen remaining CR.714s were operational as they attacked fifteen Do 17s and twelve Me 109s over Étampes on June 10. The Poles’ radios failed again, as de Marmier led them in a head-on attack against the bombers. One Dornier fell to de Marmier, a second to Czerniak, and Zukowski downed a third, while Capitaine Piotr Laguna accounted for an Me 109 over Henonville following a long pursuit. Kepinski was wounded in a lung by Me 109s, but in spite of a considerable loss of blood, he managed to make a wheels-up landing in a field. Capitaine Juliusz Frey, Lt. Waclaw Wilczewski, and Lt. Zdislaw Zadronski were also compelled to force land their shot-up planes.
Kepinski’s executive officer, Capitaine Laguna, took command of what remained of GC.I/145, but there was little left to take charge of. On June 11, French technicians removed the instruments from eleven of the group’s defective Caudrons and then burned them. The remaining twelve Cyclones were withdrawn to Sermaize, from whence eight of GC.I/145’s pilots were assigned to GC.I/1 and eight to GC.I/8, both of which were equipped with MB.152s. The Poles continued to fly missions until June 18, when they learned of France’s capitulation. Released from French service, they departed by ship from La Rochelle on the twentieth, to carry on their fight in Britain. Using hit-and-run tactics to make the most of their faulty fighters, the aggressive Poles of GC.I/145 had managed to shoot down twelve German aircraft and probably downed two others in the course of the Caudron-Renault CR.714’s brief fighting career.