Seversky AP-2 / AP-7
A progressive development of the basic P-35, the AP-2 (Army Pursuit No 2) differed essentially in having a modified centre wing structure incorporating wells for an entirely new flush-housed inward-retracting undercarriage. Together with a shallower cockpit canopy, these refinements were expected to raise maximum speed above the 483km/h mark. The AP-2 was powered by a 1,050hp Pratt & Whitney R-1830-9 Twin Wasp engine and armament was proposed to comprise the standard combination of one 7.62mm and one 12.7mm machine gun. It was ascertained that the flush-retracting undercarriage did not result in as much drag reduction as anticipated, but performance was still markedly superior to that of the P-35. Seversky's bid price was considered too high, however, and the AP-2 was rejected by the USAAC. It had been entered in the September 1937 Bendix Trophy contest, but prior to this event suffered an undercarriage failure while landing at Floyd Bennett Field. Much of the airframe was re-used for the AP-7.
Representing an attempt to obtain maximum performance from the basic P-35 design without introducing radical changes, the AP-7 employed much of the airframe of the earlier AP-2 but was powered by a 1,200hp Pratt & Whitney R-1830 Twin Wasp engine. As first completed early in 1938, the AP-7 reverted to the semi-retractable main wheel arrangement of the P-35, and in this form was used by the celebrated aviatrix Jacqueline Cochran to capture the 1938 Bendix Trophy, having been used by Maj Alexander P de Seversky two days prior to this event to establish a new US transcontinental record with an elapsed time of 10 hr 3 min 7 sec. The AP-7 was subsequently fitted with a new wing, with an improved leading-edge profile, and an inward-retracting undercarriage similar to that of the AP-2. It was intended that the modified AP-7 should participate in the 1939 Bendix Trophy contest, but was withdrawn after two aborted take-offs and later sold in a somewhat irregular transaction to Ecuador's Fuerza Aerea.