L.Andersson Soviet Aircraft and Aviation 1917-1941 (Putnam)

Grigorovich M-24 (MR-4)

   A number of Grigorovich M-9 and M-20 flying-boats were produced by the GAZ No. 3 Krasnyi letchik factory in Leningrad after the Revolution. In order to produce a more up-to-date flying-boat for naval reconnaissance D P Grigorovich, who had created most of the flying-boats used by the air service of the Imperial Russian Navy during the First World War, was instructed by the Naval Aviation Department of the Glavvozdukhflot on 12 April 1922 to design a development of the successful M-9. His first attempt was the M-23bis powered by a 280hp Fiat engine. A prototype was completed by GAZ No. 3 in the summer of 1923, but it did not fly and it was destroyed by floods at Krestovskii Island in the autumn of the same year.
   A new prototype designated M-24 was developed on the initiative of Grigorovich's assistant A N Sedel'nikov and was built and flown in October 1923. This was a two-bay biplane flying-boat with the lower wings having dihedral. Auxiliary floats were below the outer sections of the lower wings. Power was provided by a water-cooled 220hp Renault engine with frontal radiator and pusher propeller mounted below the upper wing and supported by a number of struts. The engine was enclosed by a cowling. The fragile-looking tail unit, which was very similar to the one used on the M-9, included horn-balanced rudder and elevator. An open cockpit for an observer was located in the bow and equipped with a machine-gun. Armament also comprised a second fixed machine-gun and 100kg of bombs. The M-24 could be fitted with skis for operation from ice or snow.
   Twelve of the forty M-24s built by GAZ No. 3 had been ordered and paid for by the Leningrad division of the ODVF on 12 September 1923. They were given presentation names and were officially handed over to the 2nd Otdel'nyi morskoi razvedivatel'nyi aviatsionnyi otryad at Leningrad together with an additional two aircraft in two batches of four and one of six between January and June 1924. The 2nd Otdel'nyi morskoi razvedivatel'nyi aviatsionnyi otryad, which had earlier flown Grigorovich M-9s and M-20s, was at the same time assigned the name Krasnyi Balt'ets (Red Sailor of the Baltic Fleet). The M-24s were named Volodarsky, Krasnyi Putilovets, Krasnyi Petrogubjin, Petrogradskaya Pravda, Volkhovstroi, Leningrad, Leningradskie profsoyuzy, Vladimir Il'ich, Pskovichanin, Krasnaya Kareliya, Krym SSSR, Bryanskii Rabotchii, Toplivnik and Cherepanin.
   At the same time as the M-24 came into service it became obvious that the design was something of a failure and a special commission was formed in order to investigate the deficiencies. The type was withdrawn from service but due to the lack of suitable naval aircraft it was decided to try to modify the M-24. The only other aircraft available to the VVS naval squadrons in 1924 were about thirty Savoia S.16s and twenty Junkers Ju-20s were in the process of being delivered. Grigorovich was at the time working at GAZ No. 1 in Moscow and the redesign of the M-24 was made by others. The 220hp Renault engine was boosted to 260hp by replacing the original pistons with new ones made of aluminium. Production was resumed and the twenty additional flying-boats that were delivered late 1924 were sometimes referred to as the M-24bis.
   Of the sixty M-24s built (c/ns including 1718-1760) only twenty-eight were in fact accepted and taken on charge by the VVS and very few of these were actually issued to operational units. All twenty-eight were in service by September 1924. Two Junkers Ju-20s were received by the 2nd Otdel'nyi morskoi razvedivatel'nyi aviaotryad in 1924 and this type replaced the M-24s of that unit in the following year. The 1st Otdel'nyi morskoi razvedivatel'nyi aviaotryad at Peterhof received a few M-24s but had converted to the Ju-20 by the beginning of 1925. The Savoia S.16bis-equipped 3rd Otdel'nyi morskoi razvedivatel'nyi aviaotryad at Sevastopol also had two M-24s in 1925, before the type was relegated to the advanced training role in the summer of the same year.
   The MR-1 designation was allotted to the M-24 at about the same time, but this was soon changed to MR-4 when the floatplane version of the R- 1 was designated MR-1. Seventeen MR-4s were retained as trainers. Some were transferred to the Naval Aviation otryad of the Military School of Aerial Observers in Leningrad. The last example was still on hand by December 1928 in the 51st Aviaotryad (formerly the 1st Otdel'nyi morskoi razvedivatel'nyi aviaotryad), although the type was formally withdrawn from use during that year.
   An offer to Dobrolet of a number of M-24s free of cost was rejected, but one M-24bis was transferred to Mosoaviakhim some time around May 1929.

M-24 (M-24bis)
   220 (260)hp Renault
   Span 16m; length 9m; wing area 55nv
   Empty weight 1,200kg; loaded weight 1,650 (1,700)kg
   Maximum speed 130 (140) km/h; ceiling 3,500 (4,000) m; range 400km

A.Durkota, T.Darcey, V.Kulikov The Imperial Russian Air Service (Flying Machines)

Dimitry Pavlovich Grigorovich

M.17, M.18, M.19, M.20, and M.24 Flying Boats

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  The final flying boat in this series was the M.24. Known as the Commune, this type was built at the Krasniy-Lyotchik Works in St. Petersburg in 1924. The M.24 was a modified version of the M.9, but with a 220hp Renault engine. Although the exact number produced is unknown, this type served with the Bolshevik forces until 1926.