ANT-5 prototype and pre-production I-4 by P.O.Sukhoj/
All-metal sesquiplane fighter, with small cantilever lower wing. The order for this fighter
was issued in Fall 1925 by TsAGI.
Comparison of all-metal vs mixed vs wooden construction fighter was the key idea. General construction of the ANT-5 was similar
to this of ANT-2 and ANT-3/R-3.
Prototype had to be powered by single 420/525hp Jupiter-VI, which has to be
replaced by more powerful domestic M-22 on series aircraft.
Aircraft was designed by P.O.Sukhoj team and rolled out in July
1927. After factory trials ANT-5 was transferred to
In August 1928 it was followed by I-4 'Dubler' ('The Second'). Flights by
M.M.Gromov, A.F.Anisimov, A.B.Yumashev and I.F.Kazlov revealed excellent performance of the aircraft, making I-4 one of the best
fighters for late 20's. Series production was approved as early as December 1928.
Pre-production ('golovnoj') I-4 was ready on October 15, 1928. It was
heavier than prototypes and had somewhat worser assembly quality, but still could be qualified to be among the best. Series
aircraft (see I-4) had even worser quality. Corrugated skin was an obvious
drawback, as well as luck of airdynamic refinement.