10/31/2011. Remarks by Johan Visschedijk: "The XFL-1 experimental shipboard fighter was developed in parallel with the XP-39 Airacobra, and was flown for the first time on May 13, 1940. Powered by a 1,150 hp Allison XV-171O-6 twelve-cylinder liquid-cooled engine, the XFL-1 differed from its land-based counterpart primarily in having a tailwheel undercarriage, arrester hook, and underwing radiators.
The airframe was re-stressed for shipboard operation, and proposed armament comprised a single 0.50 in (12.7 mm) machine gun or a 1.46 in (37 mm) cannon firing through the propeller hub and a pair of fuselage-mounted 0.30 in (7.62 mm) guns, although, in the event, no armament was installed. The XFL-1 failed its carrier qualification trials and further development was abandoned at the beginning of 1942."