 The Boeing YP-29 originated as the Model 264, developed as a private venture under a bailment contract negotiated with the U.S. Army.Development of three prototypes was initiated in the interval between the testing of the XP-936 (P-26 prototype, company Model 248) and the delivery of the first P-26A (Model 266) to the U.S. Army.The Model 264 was an updated and modernized P-26, differing in having fully cantilever wings of elliptical-design, wing flaps, enclosed "greenhouse" canopy, and retractable undercarriage.