 This new cockpit enclosure satisfied the requirement for pilot protection at 250 mph operating speeds.Nevertheless, the landing speed of the YP-29 was considered too high for Army operational use and the YP-29 was returned to the factory for the installation of wing flaps.Following service testing by the Army and Boeing, which included trials with controllable pitch propellers, the service test designation was dropped and changed to P-29 after the engine was changed to a Pratt & Whitney R-1340-39.