The FVM J23 was a single-seat, single-engine fighter development originating from Sweden's Flygcompaniets Verkstader at Maimen (FVM). Its design is attributed to engineers Henry Kjellson and Ivar Malmar. Work on the fighter began in 1922 but a structural deficiency largely doomed the program in the long term and just a handful of examples were completed before the end.
The J23 was of largely conventional design concerning post-World War 1 fighters save for its high-mounted "parasol" wing mainplane. It fitted its engine in the nose in the usual way and sat the single pilot in an open-air cockpit over midships. The high-mounted nature of the mainplane allowed the pilot to see over and under the member, improving basic vision out-of-the-cockpit. This was further enhanced by a section of the member's trailing edge being cut out to better serve the pilot. Beyond this, the aircraft relied on a smooth, tapering fuselage, fixed tail-dragger undercarriage, and single-finned tail unit. Wooden construction was used throughout.
Dimensions included a length of 22.7 feet, wingspan of 36.10 feet, and height of 8.3 feet. Empty weight reached 1,700lb against a Maximum Take-Off Weight (MTOW) of 2,175lb.
Power was from a BMW IIIa 6-cylinder inline piston engine developing 185 horsepower and used to drive a two-bladed propeller unit at the nose in traditional tractor fashion. Performance specs ultimately included a maximum speed of 122 miles-per-hour, a service ceiling of 26,000 feet, and a climb rate nearing 1,063 feet-per-minute.
Standard armament was 2 x 8mm m/22 series machine guns, these synchronized to fire through the spinning propeller blades. While seemingly modest, the twin-gun arrangement was a long-running standard for fighter aircraft of the post-war period.
The project eventually yielded five flyable prototypes. In 1923, they were each featured in the International Air Exhibition at Gothenburg and were extensively flight-tested into March of the following year. It was at this point in the program that a failure of the mainplane caused one of the test pilots to be killed (Axel Norberg) in an accident. The incident forever damaged the program and interest in the dangerous aircraft soon fell to naught despite modifications made to the structure to rectify the weakness.
With damage to the program all but done, the J23 was abandoned in full and all participating airframes were subsequently destroyed. The follow-up FVM J24/J24B became a promising offshoot of the J23, though now fitted with a more traditional biplane wing arrangement deemed safer by Swedish military authorities as well as a more powerful engine. This sole prototype was beaten out in competition by the French Nieuport 29C biplane namely due to lackluster performance.