The Belyayev Babochka was a tandem seat research aircraft designed in the USSR in 1939.
Viktor Nikolayevich Belyayev had an illustrious early career with TsAGI, AVIAVnito, Aeroflot, OMOS, AGOS, KOSOS and the Tupolev OKB.
Yukharin, at the Kazan Aviation Institute, designed a tandem seat single-engine research aircraft to investigate the properties of Belyayev's forward swept wing with raked tips, used on the Belyayev DB-LK, particularly the resistance to structural instability and aileron reversal.
The aircraft was to have had quite sharply swept forward inner wings, with the outer third swept back at a similar angle, all with ailerons, except for flaps on the inner half of the inner wings.
Aircraft of comparable role, configuration, and era