Vadim Borisovich Shavrov, aeronautical constructor, coworker of DP Grigorovich at OMOS and historian in his encyclopedic work “Aeronautical Construction in the USSR up to 1938” defines the M-6 (Russian: Григорович М-6) as a temporary version in the towards the M- 9:
M-6 with 150 hp Sunbeam engine. The hull of the flying boat was similar to that of the M-5 but with an enlarged keel. The forms were not very successful and the takeoff from the water was difficult.
Mijaíl Maslov, another prominent researcher and historian and author of innumerable works of recognized historical value, has not found clear evidence and in relation to the M-6 he writes:
Possibly this denomination was assigned to a new Grigorovich flying boat with a 150 hp Sunbeam engine that showed unsatisfactory results during the tests. In any case, to date no documents have been found that confirm the existence of a model with that name.
The aeronautical historian AO Alexandrov in his book “The airships of the Imperial Fleet 1894 – 1917 expresses, however, another theory that is still interesting:
There is evidence that SS Schetinin clandestinely built five copies of the Curtiss F model for the Black Sea Fleet, which were delivered between October and December 1915 at a unit cost of 5,595 rubles per unit.
According to Alexandrov, it could have happened that this adventure of creating the necessary flying boats without a license had led SS Schetinin to seriously think about the possibility of establishing an important production contract without development expenses and given the possibility that the M-5 model would not approved (especially since the Baltic Fleet rejected this flying boat in favor of the French FBA) to have an “Ace up the sleeve” in the form of a proven and successful design that could be presented to the Navy under the name public M-6 in order to avoid pretensions of the North American firm.
It is noteworthy that no Navy document mentions the M-6 model and the 5 copies of the Schetinin Curtiss F delivered to the Black Sea Fleet in the documents are only referenced with their registration number and sometimes with the letter “k” at the end.
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