1943 proved a critical year for the Allied war effort during the fighting of World War 2 (1939-1945). The American concern of Boeing, which already had such wartime stalwarts as the B-17 "Flying Fortress" in service in great numbers, did not rest on its laurels for many projects began to take shape in the hopes of securing potentially lucrative United States Army Air Forces (USAAF) and United States Navy (USN) contracts. The Boeing "Model 394" was a short-lived, proposed product of the period, arriving at a time when victory for the Allied cause was not a foregone conclusion - so any and all manner of combat aircraft designs were entertained by authorities.
The Model 394 was penciled out at a compact, lightweight carrier-based single-seat, single-engine fighter with strictly machine gun armament fitted. It would have been used in the "fleet defense" role, primarily in the Pacific Theater of War, to provide airborne defense for American carrier groups against marauding elements of the Empire of Japan. The compact nature of the design was to play well for the space-strapped American carriers and the lightweight quality meant the platform would make for a nimble gunnery platform. Beyond this, the aircraft was viewed as an economical measure that could be produced rapidly in the thousands utilizing proven design techniques and construction methods.
The aircraft was slated to use the Curtiss-Wright / Wright XR-1820-56 "Cyclone / Cyclone 9", a 9-cylinder, air-cooled supercharged engine rated between 1,200 horsepower and 1,350 horsepower (the Wright Cyclone was already in widespread use with the B-17 bomber series by Boeing). This would be bumped up to 1,500 horsepower output for the new Boeing fighter with "War Emergency Power" (WEP) capability built-in to achieve slightly better performance for short periods of time (the primary targeted flight envelope for the aircraft was mainly low-to-medium altitudes). The engine was to drive a three-bladed propeller unit at the nose.
Structurally, dimensions included an overall length of 29.9 feet and a wingspan of 34.9 feet. Gross weight reached 6,205lb.
With the engine set in the nose, the cockpit was situated directly aft and just ahead of midships. The wing mainplanes, fitted low against the sides of the fuselage,, was similarly positioned ahead of midships. Each wing member exhibited rounded tips and considerable forward sweep of the trailing edges with the leading edges left as straight as possible. The tail unit was traditional, a single fin with low-set horizontal planes being used. For ground-running, a typical "tail-dragger" arrangement was proposed but only the main legs were made retractable.
As with other carrier-based warplanes, the Model 394 was envisioned with the usual carrier-based fighter qualities: reinforcement of the structure / undercarriage, arrestor gear equipment for deck-based landings, and wing-folding (the members hinged outboard of the main landing gear legs) folding (manually) towards the rear and resting along the fuselage sides.
Proposed standard armament was 4 x 0.50 caliber Browning M2 heavy machine guns, an American fighter plane staple of the World War 2 period. Two guns would be installed in the upper sides of the engine cowling while each wing member would be furnished with a single gun. The cowling-mounted guns would have to be synchronized to fire through the spinning propeller blades (the wing-mounted guns sat just outside of the propeller's arc).
Boeing engineers estimated a top speed of 435 miles-per-hour with a service ceiling up to 34,000 feet, and a range out to 770 miles for their little fighter. Jettisonable (external) fuel tanks would have extended the fighter's operational reach to 1,450 miles from its take-off point. Estimated rate-of-climb was to be a rather impressive 5,230 feet-per-minute under full power, a strong quality to have for when intercepting inbound airborne enemy elements.
Despite its seemingly strong qualities (at least on paper), the Model 394 was not adopted for further development by USN authorities.