Army Pursuits the Biplane Period, 1920-1932
Dornier Falke, TP-1, Curtiss XPW-8, & PW-9
Curtiss Army Hawks versus Boeing biplanes
For several years, the Curtiss Hawk became the dominant Army fighter type, until vigorous competition from Boeing elbowed these single-seaters aside. The Curtiss company’s engineers at Garden City, New York, began a fighter design in May 1922 using the 440-hp Curtiss D-12 and streamlined “eversharp pencil” nose developed in the Curtiss racer series.
Other features were wood-covered wings with a thin Curtiss airfoil, connected by two pairs of steel “N” struts. The welded steel tube fuselage was covered by dural back to the cockpit and fabric in the rear and tail. Engine cooling was by brass water radiators on the upper wing. Two .30-caliber guns with 600 rounds each were mounted under the cowl, unless the right-hand one was replaced by a .50-caliber gun with 200 rounds.
The first Curtiss PW-8 was built with company funds, flown in January 1923, and was sold to the Army on April 27, 1923, with two more prototypes to be built later. It became the XPW-8 when the Air Service adopted the X prefix on May 14, 1924, as the symbol for experimental planes. Twenty-five
PW-8 production models were ordered September 14, 1923.
The second prototype was tested at McCook in March 1924 with landing gear and wing refinements also used on production PW-8s delivered from June to August 1924. Made famous by Lieutenant Russell L. Maughan’s “dawn to dusk” 22-hour transcontinental flight on June 24, 1924, the PW-8 demonstrated an Air Service capability of moving squadrons from one coast to the other. The wing radiators were the least desirable feature of the Army’s last double-bay biplane fighter, for maintenance was poor and a puncture in their wide area might subject the pilot to a stream of hot water.
Boeing was also eager to provide the replacement for the MB-3A fighters built by the Seattle firm in 1922. Model 15, first flown June 2, 1923, had single-bay tapered wooden wings with a thick Goettingen 436 airfoil, Curtiss D-12 engine, a tunnel radiator, cross-axle landing gear and an arc-welded steel tube fuselage structure that owed much to through study of the Fokker D VII. Delivered to McCook Field in June, it soon showed an advantage in maneuverability over the Curtiss and Fokker designs, so the Army purchased the Boeing as the PW-9 on September 29, 1923, along with ordering more prototypes. Armament was the same two guns in the nose as on the Curtiss fighters.
These two modified XPW-9s were delivered May 6, 1924, and while performance varied on different tests with changes in propeller and weight, comparative testing against the Curtiss design won Boeing a contract for 12 PW-9s on September 19, increased to 30 on December 16, 1924.*
Deliveries of the PW-9, which had split-axle landing gear, were made from October to December 1925, and were followed by 25 similar PW-9As delivered from June 1926 to February 1927 with the D-12C engine. The last of these became the PW-9B when temporarily fitted with a
D-12D, which also powered 40 strengthened PW-9Cs delivered from July to August 1927. Last came 16 PW-9Ds ordered August 12, 1927 and delivered in April/May 1928.
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