SNCAC NC - 600 The SNCAC NC - 600 was a prototype French twin - engined long - range fighter aircraft , developed by SNCAC from the earlier Hanriot H . 220 fighter . The type never entered service , with development being ended by the French surrender in June 1940 . Design and development . In October 1934 , the French " Service Technique de l ' Aeronautique " ( or Air Ministry ) issued a requirement for a three - seat fighter , with Hanriot designing the H . 220 to meet this requirement , competing with designs from Potez ( the 630 ) , Breguet Aviation ( the 690 ) and Romano ( the R - 110 ) . The H . 220 was a twin - engined monoplane of all metal construction . The fuselage was a short , oval - section monocoque which accommodated the crew of three in tandem enclosed cockpits . The shoulder - mounted wings were braced by a single short strut on each side , and was fitted with full span trailing edge flaps and split ailerons . Armament was intended to be two fixed forward firing 20 mm cannon and two machine guns in the rear cockpit . The unflown prototype , fitted with two Renault 12Roi air cooled V12 engines , was exhibited at the 1936 Paris Air Show . The prototype was re - engined with Gnome - Rhône 14M radial engines before it made its maiden flight at Avord on 21 September 1937 . Tests showed that the aircraft was unstable , with numerous changes being made to the tail surfaces to try and rectify the problems before the prototype was badly damaged in a forced landing caused by an engine failure on 17 February 1938 . This crash - landing wrecked the fuselage of the H . 220 , and SNCAC , ( " Société Nationale de Constructions Aéronautiques du Centre " ) , which had been formed by the merger of Hanriot and Farman as part of the nationalisation of the French aviation industry in 1937 , took the opportunity to carry out a major redesign , rebuilding the prototype to the new design . The rebuilt and resigned prototype , redesignated the H . 220 - 2 , had a new fuselage , built out of two half shells joined by a central keel , with a twin - tail replacing the conventional single - fin tail surfaces of the earlier design . The aircraft ' s wings , however , were unchanged . The aircraft first flew in this form on 17 March 1939 . Meanwhile an order for six aircraft had been placed in 1938 for evaluation purposes under the designation NC - 600 . The design was now intended to meet a 1936 specification for a long - range fighter , competing with the Potez 670 and the SNCASE SE . 100 . The H . 220 - 2 was exhibited at the 1939 Brussels Air Show to represent the NC - 600 , but the real NC - 600 was a further redesigned aircraft , with new wings and revised tail surfaces , and was now being offered as a two - seat aircraft . The proposed armament was also revised , with two additional fixed forward firing machine guns and the two rear - firing guns replaced by a single flexibly mounted cannon . The NC - 600 prototype flew on 15 May 1940 , but again other types were preferred , with orders being placed for 40 Potez 671s and at least 300 SE . 100s . Work on the six - aircraft evaluation batch was stopped by the German occupation of SNCAC ' s Bourges factory .