 = Tupolev Tu @-@ 12 = 
 
 The Tupolev Tu @-@ 12 ( development designation Tu @-@ 77 ) was an experimental Soviet jet @-@ powered medium bomber developed from the successful piston @-@ engined Tupolev Tu @-@ 2 bomber after the end of World War II . It was designed as a transitional aircraft to <unk> Tupolev and the VVS with the issues involved with jet @-@ engined bombers . 
 
 = = Development = = 
 
 The Tupolev Tu @-@ 73 jet @-@ engined bomber project was suffering delays in early 1947 and Tupolev suggested re @-@ <unk> the Tu @-@ 2 medium bomber with imported British Rolls @-@ Royce Nene jet engines to produce a jet bomber as quickly as possible . Design work began well before official approval was received on 31 May 1947 for one Tu @-@ 2S to be converted in the <unk> 's workshop and another five to be converted at <unk> ( Factory ) Nr. 23 , but construction of the prototype had already begun in early May under the bureau designation Tu @-@ 77 . 
 Changes from the standard Tu @-@ 2 were <unk> to speed production and they consisted of the following : 
 Two Nene jet engines replaced the standard <unk> <unk> @-@ <unk> radial engines . 
 The wing dihedral was reduced to 3 ° from 6 ° . 
 The fuselage was lengthened 400 mm ( 16 in ) and the rear fuselage was heightened by 300 mm ( 12 in ) . 
 A new <unk> <unk> was fitted , with the main gear units <unk> into the engine <unk> . 
 Additional fuel tanks were fitted and the design of the tanks was changed to accommodate the change from gasoline to kerosene . 
 The control system was revised and trim <unk> were fitted to the <unk> . 
 The wing and tail were reinforced . 
 The 20 mm ( 0 @.@ 79 in ) <unk> cannon were removed from the wing roots and a 23 mm ( 0 @.@ 91 in ) <unk> @-@ <unk> NS @-@ 23 cannon was mounted in an external <unk> on the starboard side of the nose . 
 
 = = = Testing and evaluation = = = 
 
 The prototype was completed in July and was first flown on 27 July 1947 . Two aircraft were shown at the <unk> Aviation Day <unk> on 3 August 1947 . It completed its manufacturer 's trials in September and underwent the State acceptance trials from 4 October 1947 to 27 February 1948 where it was redesignated as the Tu @-@ 12 . The <unk> VVS ( <unk> @-@ <unk> <unk> <unk> <unk> @-@ <unk> <unk> – Air Force Scientific Test Institute ) report summarized the differences between the Tu @-@ 2 and Tu @-@ 12 as " a considerable gain in speed , an improved rate of climb , a higher service ceiling , but poorer field performance and a considerably greater fuel load required to achieve the same range as the Tu @-@ 2 . " Both the lack of a pressurized cabin that greatly reduced its effectiveness at high altitude and the lack of <unk> equipment for the wing and tail leading edges and the cockpit glazing were noted as major problems . At high speeds it was virtually impossible to traverse and elevate the manually operated <unk> @-@ 68 and Lu @-@ 68 gun turrets . The vibration of the NS @-@ 23 cannon when firing rendered the equipment in the <unk> 's cabin unusable and damaged the cabin glazing . Turning on the <unk> friend or <unk> ( <unk> ) system adversely affected the <unk> system and the radios . New generators had to be installed as the originals did not produce enough electrical power . 
 The trials conducted by the <unk> VVS included engagements between the Tu @-@ 12 and the Soviet <unk> @-@ 9 and <unk> @-@ 23 jet fighters which were very useful in evaluating the offensive armament of the fighters , the defensive armament of the bomber and the proper tactics involved for both types of aircraft . The tests demonstrated the <unk> of the current 12 @.@ 7 mm ( 0 @.@ 50 in ) armament and meant that every Soviet bomber <unk> would have a defensive armament using power @-@ operated turrets that carried guns 20 mm or larger . 
 The five aircraft modified by the factory were given the <unk> <unk> @-@ 45 engine , the Soviet unlicensed copy of the Nene engine , and all six aircraft , used by the VVS for aircrew <unk> and training . The aircraft completed were later relegated to test duties . One aircraft was used for drone tests and another , redesignated as the Tu @-@ <unk> , mounted various pulse jet engines on a <unk> above the fuselage . 
 
 = = <unk> = = 
 
 Soviet Union 
 Soviet Air Force 
 
 = = Specifications ( Tu @-@ 12 ) = = 
 
 Data from <unk> , Tupolev Aircraft since 1922 
 General characteristics 
 Crew : 5 
 Length : 16 @.@ 45 m ( 53 ft 11 ½ in ) 
 <unk> : 18 @.@ 86 m ( 61 ft 10 ½ in ) 
 Wing area : 48 @.@ 80 m2 ( 525 @.@ 30 <unk> ) 
 Empty weight : <unk> kg ( 19 @,@ 826 lb ) 
 Gross weight : 15 @,@ 720 kg ( 34 @,@ <unk> lb ) 
 <unk> : 2 × Rolls @-@ Royce Nene I <unk> , 22 <unk> ( 5 @,@ 000 <unk> ) thrust each each 
 Performance 
 Maximum speed : <unk> km / h ( <unk> mph ) 
 Range : 2 @,@ 200 km ( 1 @,@ 367 miles ) 
 Service ceiling : 11 @,@ 370 m ( 37 @,@ 305 ft ) 
 Armament 
 1 × 23 mm NS @-@ 23 cannon 
 2 × 12 @.@ 7 mm <unk> <unk> machine @-@ guns 
 3 @,@ 000 kg ( 6 @,@ 614 lb ) of bombs 
 
 