Also called the Kalinin BS-2 or the Zhar-Ptitsa ("Firebird"), it featured welded steel-tube construction with fabric covering, as well as a dummy nose and tail turrets.

The K-12 was painted in a garish colour scheme representing a bird.

A subscale glider to test the K-12's features flew in 1934, piloted by V.O.

The K-12 flew in autumn 1936 and was demonstrated at Tushino in August 1937.

The full-size K-12, however, was cancelled after Konstantin Kalinin was arrested and executed as an enemy of the state.