|Power at 0m||185hp|
|Gun Type||1*mg Vickers|
|Gun Type||1*mg Lewis|
|Position||flexible in rear cockpit|
Two-seat biplane trainer, intended as a transition from primary trainers (U-2) to combat aircraft. It was a parallel project to N.N.Polikarpov's P-2, having similar diagonal strut instead of the lift and anti-lift wires. It was built at GAZ-1 at Moscow according to a specification from February 1925. and later received the designation P-1.
Upper and lower wings had same span, upper wing moved slightly ahead of the lower one. Forward fuselage covered with plywood, the rest of skinning - fabric. As a trainer, 2U-B3 was equipped with dual controls.
The prototype was completed on February 25, 1926. test flown at the factory and handed over to NII VVS in September. State trials were completed on January 4, 1927. All the requirements fulfilled , but the 2U-B3 was not built in series because the P-2 with more powerful engine was adopted for production. A first batch of ten aircraft, ordered in February 1927, was cancelled.