The last aircraft on the Seversky P-35 contract (36-430) was delivered in 1938 as the XP-41 (company designation Model AP-2) with a revised wing and a 1200-hp R-1830-19 air cooled radial engine with a medium-altitude two-stage turbosupercharger in place of the standard 850 hp R-1830-9 engine. The supercharger was located in a ventral position just aft of the wings and had its air intake in the left wing root. Overall length was increased from 25 feet 2 inches to 27 feet 0 inches. In addition, this aircraft had a fully retractable undercarriage, the legs and wheels folding inward into the wings and fuselage. The canopy was somewhat lower than that of the standard P-35, and was more aerodynamically streamlined.
The XP-41 made its first flight in March, 1939, shortly before the Seversky company threw out Major de Seversky as its CEO and changed its name to Republic Aviation Corporation. A maximum speed of 323 mph at 15,000 feet was attained. Maximum range was 1860 miles. Empty weight was 5390 pounds and maximum loaded weight was 7200 pounds. Armament was the same as that of the standard P-35--one 0.50-in and one 0.30-in machine gun.
On January 25, 1939, with war clouds gathering in Europe, the USAAC invited manufacturers to submit proposals for new pursuit aircraft. At this time, the Army was still thinking in terms of low-altitude, short-range fighters. Among the contenders were the Lockheed XP-38, the Bell XP-39, no less than three planes from Curtiss, the H75R, XP-40, and XP-42, plus two parallel designs from Seversky/Republic--the XP-41 (AP-2) and XP-43 (AP-4). Although the XP-40 could not match the performance (especially at altitude) of the turbosupercharged types, it was less expensive and could reach quantity production fully a year ahead of the other machines. In addition, the XP-40 was based on a already-proven airframe that had been in production for some years. Consequently, on April 26, 1939, the Army adopted a conservative approach and ordered 524 production versions under the designation P-40 (Curtiss Model 81). Although the XP-41 showed significantly better performance than that of the standard P-35, the Army preferred the other Seversky/Republic development, the high-altitude AP-4 which was eventually to emerge as the YP-43, and the XP-41 was not developed any further.