In Russia on 9 June 1941 the chief designer VF Bolhovitinov sent to the National Commissioner Aviation industry (NKAP) a formal request for approval of the project rocket fighter-interceptors under ozunakom BI (BI). The proposal was accepted in its entirety, with the NKAP issued a new deadline for the project documentation of only 35 days, instead of three months as was suggested in the study.
The A.Ya.Bereznyaka and AMIsaeva designed aircraft with a rocket engine thrust of 1400 kg / s. The fuel system installation caused a delay in the implementation of the project. Instead of using the turbo-compressor, it was decided that the fuel in the tank is kept at a pressure of 145-148 ATM.
The reservoir is expected to deliver 115 liters of compressed liquid fuels. This variant of the engine D-1A has become the main direction of development, and the project was identified with the label "bi".
The construction of the aircraft was self-supporting, with flat trapezoidal low-mounted wing panels. The plane itself was constructed entirely of wood.
BI-1 was flown 12 times under power, seven times with Dushkin's D-1-A-1100 engine, three times with the DM-4 ramjets, and twice with Isaev's RD-1 rocket engine.
The request for a high-speed interceptor, came with opposing requirements, including a request for minimum landing speed, as well as a low stalling speed. This issue is solved by developing special split type flaps and incorporating other aerodynamic features. Only after making the first prototype, “on the fly” so to speak were some of the problems solved. The aircraft could easily be over-stressed because of the abundance of thrust from its rocket engine and consequently there was always the extreme risk of an in-flight catastrophic structural failure. The main plane lacked any sweep back, consequently over speed conditions were always a possibility, with its resultant loss of control risks. The pilot was always conscious of the tendency to enter a high speed stall, which because of the close coupled tail, recovery would be highly unlikely. Landings too were always tricky, the split type landing flaps provided little or no extra lift so landing speeds were too high for anyone but experienced pilots to make safe landings. There was also the unfortunate sudden loss of lift when the craft entered in ground effect, which meant that soft landings were next to impossible to achieve.
BI-1 With Landing Flaps Deployed - The Split Flaps Acted as Speed Brakes but Offered Little in the way of Increased Lift
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