The Grigorovich M-23bis was a Soviet biplane flying boat built during the 1920s.
Dmitri Grigorovich developing the M-23 as a derivative of the Grigorovich M-9 with a more powerful engine.
The aircraft was completed at GAZ-3 "Krasnyj Letchik" (The Red Pilot) in mid-Summer 1923, but the unsuccessful hull shape meant that it failed to take off.
The M-23bis was sent back for modifications, but in late 1923 was destroyed by a flood at the Krestovsky Island hangar.
[1] Data from Aircraft of the Soviet Union : the encyclopaedia of Soviet aircraft since 1917,[2] Russian Aviation Museum : M-23[3]General characteristics Performance