 Boeing set out to use this engine in a fighter designed specifically for carrier operations, using the same welded-tubing fuselage and wooden-frame wings as for the Model 15, and adding a large spinner to reduce air drag around the engine (this was dropped in production).Armament was either two machine guns, or one .30 in and one ; the lower wing had attachments for up to four bombs, plus a fifth could be hung from the fuselage.First flight of the F2B prototype was November 3, 1926.