When was the American single-engined, single-seat, all-metal fighter and ground-attack aircraft first flew in which design Donovan Reese Berlin was associated?
Don R. Berlin: Donovan Reese Berlin (June 13, 1898 – May 17, 1982) was an American military aircraft designer and aircraft industry executive. Don R. Berlin:  Among the many designs with which he is associated, are the Curtiss P-36 Hawk, Curtiss P-40 Warhawk and Fisher P-75 Eagle.
i don't know