The First Russian Jet Bomber

Starting in January 1947 OKB Tupolev began design work on a twin jet tactical bomber powered by two Rolls-Royce Nene centrifugal-flow turbojets. With a few months of the start of the work, it became apparent that the Nene engines produced less thrust than anticipated which delayed development work. Although this jet bomber design carried the official designation Tu-14, it had the Tupolev in-house designation of "73", a continuation of the ANT number series that was discontinued as the official designation during the Second World War. The Politburo wanted the Tu-14 ready for the annual Aviation Day flypast at Moscow-Tushino. But the need to redesign the Tu-14 meant that the prototype would not be ready and Andrei Tupolev himself suggested re-engining a number of piston radial-powered Tu-2 bombers with Nene engines as a temporary measure.

The interim project was given the OKB designation "77" (ANT-77) but would have the official designation Tu-12. Work began in April 1947 even before an official decision was reached authorizing the Tu-12/"77" project. By May of that year the Soviet Air Force reviewed Tupolev's full-scale mockup. Even before the Air Force review of the mockup, Tupolev ordered work to begin in the OKB's workshops converting standard Tu-2S bombers to the Nene-powered configuration. At the end of the month the Air Force authorized conversion work to begin based on their mockup review.

For the sake of expediency, the changes to the Tu-2 bomber were kept to as few as possible. The main differences between the Tu-12 and the Tu-2 were as follows:

• The Shvetsov ASh-82FN radial engines and nacelles were replaced by longer nacelles housing the Rolls-Royce Nene turbojets. 
• The wing dihedral was reduced from 6 degress to 3 degrees.
• The fuselage was stretched with a nose extension allowing the bombardier/navigator to sit ahead of the pilot and a rear fuselage stretch to balance the change in the cockpit.  The height of the midfuselage was increased with the top of the pilot's cockpit even with the top of the aft gunner's canopy. 
• A tricycle undercarriage was fitted with the mainwheels rotating 90 degrees to lie flat at the bottom of the nacelles. 
• Additional fuel tanks were added to compensate for the increased fuel consumption of the jet engines. 
• Adjustments were made to the control system to compensate for higher speeds. 
• The tail structure was reinforced as well to handle the increase in speeds. 

In July 1947 the prototype Tu-12/"77" was rolled out and on 27 July 1947 the first flight was made in the Soviet Union of a pure jet bomber with none other than Andrei Tupolev himself aboard for the maiden flight- to which he exclaimed "Well, now we've seen for ourselves that youc an fly without an airscrew!" After a handful of successful test flights, the Tu-12 participated in the Aviation Day flypast at Moscow-Tushino and then resumed its flight test program in September of that year. The aircraft was then handed over to the Soviet Air Force to begin state acceptance trials and even though the Tu-12 was only an interim type built from converted Tu-2 bombers, it gave both Tupolev and the Soviet Air Force valuable experience in operating jet bombers. Mock combat sessions were even conducted between the small batch of Tu-12s and the MiG-9 and Yak-23 jet fighters, allowing new tactics to be devised.

Six Tu-12s were made by converting Tu-2s. One aircraft was used as an engine testbed, another was used as part of jet drone development and the remaining four were used by the Soviet Air Force for crew training and familiarization for aircrews bound for the definitive Tu-14. The experience in developing the systems for the first Soviet jet bomber would serve Tupolev well during the development of the Tu-16 "Badger" and Tu-95 "Bear" bombers.

Source: OKB Tupolev: A History of the Design Bureau and its Aircraft by Yefim Gordon and Vladimir Rigmant. Midland/Ian Allan Publishing, 2006, p117-121.