And also nice FM and good firepower... Russians were like British when choosing what to produce. Russian airforce choose the worst planes, British army choose the worst tanks (and sold their best designs to Russia ).
yup. but they had problems with m-72 and m-90. when they decided to install m-82, there were already la-5 in mass production. some rumors that somebody hated polikarpov "king of fighters", designer of i-15, i-16, i-180, i-185. yakovlev?
popular chkalov crashed in i-180, so polikarpov had a very bad time. no wonder he made next version late, including waiting for new engine.