Pre-revolutionary Imperial Russia (before 1917) did not have a single national unified system but instead relied on those provided by the manufacturers of the aircraft, like Sikorsky Ilya Muromets or Anatra Anasal. Pre-war Soviet System The Soviet system used from shortly after the revolution in 1923 and until gradually superseded after 1940, was divided by function, with numbers assigned in order by the government. Duplicate designations were common, as were multiple meanings for individual letters. Designers and manufacturers also had their own internal designations which could be confused for the official government designations. For instance, Tupolev's designs used the designator ANT, for A.N.Tupolev and Yakovlev's designs used AIR, for A.I.Rykov, the communist leader he reported to. Not all designations were taken up, some numbers were assigned to projects that were subsequently cancelled, often at a very early stage of development. Type prefixes (Cyrillic characters in parenthesis) A (А) - Avtozhir (autogiro) A-4 - TsAGI A-7 - Kamov ARK (AРК) - ARKtichyeskii (arctic = arctic exploration aircraft) ARK-3 - Chyetverikov ARK-4 - Chyetverikov ARK-5 - Polikarpov R-5 B (Б) - Bombardirovshchik (bomber) (Generic designation - not used for specific types) BI (БИ) - Blitzniy Istrebitel (short/close-range fighter) BI-1 - Bereznyak-Isayev BB (ББ) - Blizhniy Bombardirovshchik (short-range bomber) BB-1 - Sukhoi Su-2 BB-2 - Grushin BB-22 - Yakovlev Yak-2 BB-22bis - Yakovlev Yak-4 BSh (БШ) - Bronirovannyi Shturmovik (Armored Ground Attack aircraft) BSh-1 - Vultee V-11 BSh-2 - Ilyushin Il-2 DI (ДИ) - Dvukhmestnyi Istrebitel (two-seat fighter) DI-1: Polikarpov DI-2: Polikarpov DI-3: Grigorovich DI-4: Laville DI-6: Kochyerigin/TsKB-11 DI-8: Tupolev ANT-46/Tupolev SB DIP (ДИП) - Dvukhmotorny Istrebitel Pushechny (twin engine cannon fighter) DIP: Tupolev ANT-29 DB (ДБ) - Dalniy Bombardirovshchik (long-range bomber) DB-1: Tupolev ANT-25 DB-2: Tupolev ANT-37 DB-3: Ilyushin TsKB-30, redesignated Il-4 DB-4: Ilyushin TsKB-56 (prototype only) DB-240: Yermolayev, redesignated Yer-2 DB-A - Bolkhovitinov DB-LK - Belyayev FB (ФБ) - Frontovoy Bombardirovshchik (front-line bomber) FB: Tupolev Tu-2 G (Г) - Gruzovoi (cargo, usually converted heavy bomber) G-1: Tupolev TB-1 as transport G-2: Tupolev TB-3 as transport GST (ГСТ) - Gydro Samolyot Transportnyj (cargo hydroplane) GST - Consolidated PBY Catalina I (И) - Istrebitel (destroyer = fighter) I-Z - Grigorovich I-1 - Polikarpov I-1 - Grigorovich (duplicated designation) I-2 - Grigorovich I-3 - Polikarpov I-4 - Tupolev ANT-5 I-5 - Polikarpov. Initially Tupolev I-5/ANT-12, later Polikarpov I-6 redesignated I-5. I-6 - Polikarpov. Renamed to I-5 after winning competition with Tupolev I-5. I-7 -