Boeing 66 XP-8

09/30/2014. Remarks by Johan Visschedijk: "The XP-8 was a new design initiated by Boeing to conform to an USAAC specification issued in April 1925, for a single-seat fighter to be powered with the new inverted Packard 2A-1500 engine of 600 hp. It was built on a bailment contract which provided that the Army would supply the engine and military equipment and test the aeroplane, which would remain Boeing property. The aeroplane was delivered in July 1927, as Boeing Model 66 but carried military markings, including the new horizontal Army tail stripes but the old all-olive drab finish. The new Army color scheme of olive drab fuselage and struts and chrome yellow wings and tail was later applied by the Army. The military designation of XP-8 and the Air Corps serial number were not officially assigned until the aeroplane was acquired by the Army on a separate purchase contract signed in January 1928.

Except for the engine installation, the XP-8 drew heavily on the earlier PW-9s and FBs for design detail. The most unusual feature was the installation of the radiator in the center section of the lower wing, which was carried below the lower longerons. The span of the upper wing was reduced by almost 2 ft (0.61 m) from the PW-9 while that of the lower wing was increased by the same amount. The type of wing and fuselage construction was the same except that diagonal tubing replaced the wire bracing between the aft fuselage bays. Armament consisted of a 0.30 in (7.62 mm) machine gun and a 0.50 in (12.7 mm) machine gun. While the XP-8 was not accepted as a service model, many of the structural improvements and refinement of line that first appeared on it were retained by later production models, notably the Model 69 (F2B-1). The XP-8 was surveyed at Wright Field in June 1929."