Curtiss P-6 Hawk
|FIGHTER||Virtual Aircraft Museum / USA / Curtiss|
Installation of the new 600hp Curtiss V-1570-1 Conqueror engine in a P-2 airframe for participation in the September 1927 air races at Spokane led to the application of the designation XP-6. A similarly-powered aircraft utilising a P-1A fuselage, XPW-8A wings and surface radiators became the XP-6A. A third Conqueror-powered conversion of a P-1C airframe for a New York-Alaska flight, in July 1929, was assigned the designation XP-6B. Although these aircraft were intended purely to prove the Conqueror engine, the success of this power plant prompted a USAAC order for 18 P-6s on 3 October 1928, these being powered by the 600hp water-cooled V-1570-17. Although generally similar to the P-1 in construction, they embodied extensively revised fuselage contours. Deliveries commenced in October 1929, but with the 11th aircraft Prestone (ethylene glycol) cooling was introduced, the designation changing to P-6A. The V-1570-23 engine in the P-6A had a similar rating to that of the -17 that it supplanted; armament remained unchanged at two 7.62mm guns. In service, eight of the Army Air Corps P-6s were brought up to P-6A standards. Eight additional P-6s were delivered to the Netherlands East Indies and one to Japan under the export designation Hawk I. Subsequent to being converted as a P-6A, the first production P-6 was fitted with a side-mounted turbo-supercharger on its V-1570-23 engine as the XP-6D, and, in 1932, 10 P-6As were fitted with F-2F superchargers as P-6Ds. In addition, two aircraft originally ordered as P-11s (P-6 airframes with the unsatisfactory 600hp Curtiss H-1640 Chieftain engine) were completed as P-6Ds. The P-6D was 122kg heavier than the P-6A and featured a three-bladed propeller, and its performance included max speeds of 306km/h at 3050m and 317km/h at 3960m, service ceiling being 9755m.