With the introduction of its P-6 series of biplane fighters, Curtiss would finally establish itself as a leading manufacturer of what were designated pursuit aircraft in America at the time. Learning from its previous series of fighters (as well as taking much from those of Boeing), Curtiss created the P-6 series by installing its own 600 h.p. V-1570 Conqueror engine in the same airframe as its successful P-1C. The fourth P-2 (a P-1 with a 500 h.p. Curtiss V-1400 engine), with the serial 25-423, became the prototype XP-6, which is seen here with the insignia of the 17th Pursuit Squadron on the fuselage (obscured by the lower wing) and the designation “Curtiss X-P-6” on the rudder.

In June 1930, the first 1925 P-1 airframe (serial 25-410) became the XP-17 when it was fitted with an inverted Wright V-1470 air-cooled engine. One of the very few air-cooled V-12s, the aircraft had a rather awkward cowl to accommodate cooling airflow. Several cowling configurations were tested for the 480 h.p. engine, but the latter was not developed and the XP-17 was scrapped in March 1932. This had not been the first engine change for 25-410, however; in 1926 the airframe had been fitted with an inverted Liberty engine for the Kansas City air races.

Having examined a Bristol F.2B two-seat fighter, the Curtiss Aeroplane & Motor Co of Buffalo, New York, developed an entirely new fighter powered by an equally new American engine. The result was the 1918 Curtiss 18T-1 Wasp triplane (a biplane 18B Hornet was also built), fitted with a 400 h.p. Kirkham K-12 engine. The US Navy received two, as did the Army. This is Navy 18T-1 A3325, also used for Army testing.

The Curtiss PW-8 was developed from the R-6 racer that took first and second places in the 1922 Pulitzer Trophy Race. In April 1923 the US Army placed a contract for three XPW-8s to be tested by the Air Service with 440 h.p. Curtiss D-12 engines (developed from the Kirkham engine). The first example was photographed in the snow and displays the radiators mounted as part of the upper wings’ skins, as originally fitted to the racer.

As their D-12 engines tick over, a well-dressed lady watches two PW-8s of the 95th Pursuit Squadron, 1st Pursuit Group, prepare to take off from Selfridge Field, Michigan, in 1925. Despite the type’s troublesome wing-mounted brass radiators, which were vulnerable to gunfire from above, Curtiss won a contract to build 25 PW-8s in September 1923. PW-8 24-203 was flown by Lt Russell Maughan on June 23, 1924, during the first dawn-to-dusk crossing of the USA.