Curtiss XP-42

The Curtiss XP-42, a conversion of a P-36A Mohawk airframe, was employed as a testbed at Wright Field, Ohio, beginning in March 1939 to determine whether stream-lining could reduce drag in a radial-powered fighter and make it competitive with more advanced fighters employing inline engines. This concept was seen as an alternative to adapting the P-36A airframe to an inline powerplant, as had been done with the prototype P-40 Warhawk. Delivered to the Army in March 1939, the XP-42 was powered by a 783kW Pratt & Whitney R-1830-31 Twin Wasp radial enclosed by a bullet-shaped, sheet-metal cowling extended forward to culminate in a large, pointed spinner. An airscoop below the spinner provided cooling air, while smaller intakes above the engine provided air to the carburettor. It was immediately clear that this sleek, long-nosed configuration offered none of the advantages of the inline engine employed not only by the P-40 but also by such types as the Messerschmitt Bf 109 and North American Mustang. The aerodynamic nose shape provided almost no reduction in drag, and cooling problems proved almost insurmountable. While the XP-42 was marginally faster than the open-cowl P-36A, its performance did not compare favourably with the P-40 or with other, newer fighters of the immediate pre-war period.

A variety of nose configurations was tried on the XP-42, altering its fuselage length with each change, but none vindicated the enclosed radial engine and Curtiss's production facilities, in the event, were taken up with the inline-powered P-40. When hostilities began, the XP-42 had been ruled out as a possible production aircraft but continued to aid in research. In 1942, the XP-42 tested an all-flying stabilizer, similar to the stabilator found on modern jets. The XP-42 had begun flying in natural metal finish and was camouflaged during one of its minor rebuilds. The airframe, which contributed knowledge to designers and engineers, was eventually taken out of service as other wartime priorities beckoned. Curtiss would continue to explore new fighter ideas with XP-46, XP-60 and XF-87, but the company's predominant role in the fighter field was fast becoming history.