The Russian Navy had been using French naval aircraft since 1911, including Farman, Borel and Léveque types. Their repairs were carried out by the S. S. Shchetinin and M. A. Shcherbakov workshops in St. Petersburg. In 1913, Dmitry Pavlovich Grigorovich became the head of the workshops and that same year designed a successful aircraft, the M.1, based on French prototypes, with a hull shaped like a boat. It gave rise to a whole family of light flying boats that proved themselves in the battles of World War I.
In autumn 1915, the fleet command demanded a heavy machine for long-range reconnaissance. Grigorovich fulfilled this order in December 1915 by building the M-9 aircraft. The value of this successful design was diminished by the licensed Salmson-Unne radial engine. The developmental version was the M-15 from 1916, equipped with the revolutionary French Hispano-Suiza V8 engine. Only about 80 M-15 machines were built. The Grigorovich M-15 was a long-range reconnaissance flying boat in a biplane configuration with the wing cellule raised above the hull, a pusher propeller, and the tail assembly mounted on a pylon in the propeller’s slipstream, which increased the effectiveness of the control surfaces.
The hull was of semi-monocoque wooden construction with partially stressed plywood skinning on openwork frames. The wings and tail assembly were of wooden construction covered with fabric, with stabilising floats under the lower wing. The M-15 specimen with the number R II C 262, built in 1917, was assigned to the fortress squadron at Arensburg on the island of Ösel (Saaremaa) in the fortified Moonsund Archipelago, which guarded access to the Gulf of Riga. The fortified islands were captured by the Germans in an amphibious operation codenamed “Albion” (10–24 October 1917). The Germans captured 20,130 prisoners, 141 guns and 10 aircraft – including the aforementioned specimen.
Tested at the Naval Aircraft Testing Squadron in Warnemünde, it eventually ended up in the German Aviation Collection in Berlin. Restoration of this aircraft was undertaken at the Polish Aviation Museum in the late 1970s and continued in 1991–1993. This specimen is unique on a global scale.
| Wingspan | 11.84 m |
| Length | 8.25 m |
| Takeoff weight | 1320 kg |
| Maximum speed | 125 km/h |
| Ceiling | 3500 m |
| Range | 5.5 hours of flight |
| Armament | 1 flexible machine gun |
| Engine | Hispano-Suiza 8V with a power output of 140 hp (103 kW) (the engine was started after overhaul at the Museum) |
