tis , ▁working ▁at ▁the ▁Val st s ▁Ele kt rote hn isk ā ▁Fab ri ka ▁( VE F ) ▁at ▁R iga ▁comm enced ▁design ▁of ▁a ▁single - se at ▁advanced ▁tra iner ▁as ▁a ▁follow ▁on ▁to ▁his ▁earlier , ▁similar ▁V EF ▁I - 1 4 ▁aircraft . ▁ ▁The ▁I - 1 5 ▁was ▁a ▁low - wing ed ▁mon op lane ▁of ▁all - wood en ▁construction , ▁power ed ▁by ▁a ▁single ▁de ▁Hav ill and ▁Gi ps y ▁Six ▁air - co o led ▁engine , ▁and ▁fitted ▁with ▁a ▁fixed ▁tail w heel ▁under car riage . ▁ ▁In ▁April ▁ 1 9 3 9 , ▁the ▁first ▁prototype , ▁the ▁I - 1 5 a , ▁power ed ▁by ▁a ▁ 2 0 0   hp ▁( 1 4 9   k W ) ▁Gy ps y ▁Six ▁I ▁driving ▁a ▁two - bl aded ▁fixed - p itch ▁wooden ▁prop eller , ▁made ▁its ▁ma iden ▁flight , ▁while ▁a ▁second ▁prototype , ▁the ▁I - 1 5 b , ▁was ▁power ed ▁by ▁a ▁ 2 2 0   hp ▁( 1 6 7   k W ) ▁Gy ps y ▁Six ▁II ▁engine ▁driving ▁a ▁variable - p itch ▁prop eller , ▁and ▁armed ▁with ▁a ▁single ▁synchron ised ▁machine ▁gun ▁followed , ▁this ▁demonstr ating ▁improved ▁performance . ▁ ▁The ▁two ▁I - 1 5 ▁pro tot ypes ▁were ▁transferred ▁to ▁the ▁Lat v ian ▁Air ▁Force ▁for