Aircraft designer and head of OKB-293, Viktor Fedorovich Bolkhovitinov attended the TsAGI conference along with two of his top engineers, A.

The young Bereznyak had made an impression in 1938 with a high-speed airplane design that some thought could break the world speed record.

At this point in time, Russian rocket engines were built with typical aviation piston-engine manufacturing technology, weighing 48 kg (106 lb), it could be broken down into discrete forged-steel sections – a conical head with 60 centrifugal injectors, the cylindrical chamber, and the nozzle – joined with bolts and copper gaskets.

The next day, Operation Barbarossa brought the Soviet Union into World War II, and the rocket-powered interceptor suddenly became important.

Dushkin was not happy about the idea of bypassing his fuel pump design, but they backed the plan and cosigned a letter that was eventually shown to Joseph Stalin.

The new design was called "BI" for Blizhnii Istrebitel (close-range fighter), but the letters were also understood by everyone to stand for its inventors: Bereznyak and Isaev.

The original plan to include four machine guns was replaced by a design with a pair of 20 mm (0.79 in) ShVAK cannon.

Pressurized to 60 bar (6,000 kPa), the tanks were made from a high-strength chromium-manganese-silicon steel ("Chromansil") that was not especially resistant to corrosion.

This alarmed Bolkhovitinov's team, because their patron had a rocky history with Yakovlev, but Alexander Sergeevich and aircraft designer Ilya Florov studied the test results and gave them sound advice for improvements.

Yaw instability was corrected by enlarging the rudder and adding two circular plates to the tail horizontal stabilizer.

[2] Nitric acid presented a constant problem, corroding parts and causing skin burns and respiratory irritation.

The nozzle section was blasted into the lake, and the engine head struck the back of the pilot's seat, knocking Bakhchivandzhi against the instrument panel and injuring him slightly.

On 15 May at 19:02 (UTC), Bakhchivandzhi made the first real flight of BI-1, reaching an altitude of 840 m (2,760 ft) and a maximum speed of 400 km/h (220 kn; 250 mph).

On landing, the aircraft descended too rapidly because of insufficient forward speed, breaking the main-landing-gear on touchdown.

In July, Dushkin recalled Pallo to help work on the "302" rocket-aircraft project, meanwhile Bolkovitinov asked Isaev to take over and master the technology of liquid fuel rocket engines.

Isaev got permission to visit Valentin Glushko, the leading Soviet expert on rocket engines, who was then working in a special lab for political prisoners.

Glushko taught Isaev the complex techniques of chamber-wall heat transfer calculation and engine design, developed by himself and Fridrikh Tsander in the early 1930s.

Isaev's propellant feed system was simple, but it produced an uneven fuel pressure that diminished as compressed air was used up.

Bolkovitinov and his engineers wrestled with this problem, designing pressure regulators and even a piston fuel pump driven by compressed air, but none of these improvements were realized.

Backchivadzhi made the second flight on 10 Jan 1943, reaching 1,100 m (3,600 ft) but with the engine still throttled back for a maximum speed of 400 km/h (220 kn; 250 mph).

The third flight was made on 12 Jan (some sources say 10 Feb) by a temporary test pilot, Konstantin Gruzdev, while Bakhchivandzhi was consulting on Kostikov's "302" project.

Estimates of Bakhchivandzhi's final velocity range from 800 to 900 km/h (430 to 490 kn; 500 to 560 mph), but the recording instruments were too damaged by the crash for a reliable measurement.

The 27 March is considered a black day in Soviet aviation history, also being the date that Yuri Gagarin died in a MiG-15UTI crash.

In addition to the new engine, various changes were made to the aircraft's design: a larger rudder, smaller false keel, and different wing fillets.

Two BI engineers became the founders of two design schools: Bereznyak founded OKB-155, which was the USSR's leading design bureau in development of cruise missiles, and Isayev became the founder of OKB-2, which specialized in low and medium thrust liquid-propellant rocket engines for rockets and space vehicles.