. "from 1915" . . . . "beginning in 1915" . . . . . . . . . . "the end of 1915" . . . . . . "pioneered in the second half of 1915" . . . . . . "1915" . . "late 1915" . . . . "1915" . . . . "pioneering use of all-metal aircraft" . . . . "1" . . . "in 1915" . . . . "J 1" . . . . . . . . . . "until the second half of 1915" . "Junkers J 1" . . . . . . . . "Junkers J 1" . . . . . . . . . . .