Today in 1950 , NBC began airing the science fiction  series Dimension X .  It flew by the seat of its pants as an non-sponsored, sustaining program, but did just fine for itself.  It enjoyed immense success and popularity, and would eventually evolve into another chestnut, X Minus One .   Staff writer Ernest Kinoy adapted top-notch sci-fi works by the likes of Robert Heinlein, Isaac Asimov , and Kurt Vonnegut; acting talent included Joseph Cotten , Leslie Wood, and John McGovern.   The inaugural episode was "Outer Limit," adapted from a Graham Doar story about aliens carrying a warning to mankind.  It had graced the pages of The Saturday Evening Post just months earlier (Dec. 24, 1949).  As always, Norman Rose hosted, with Bob Warren announcing.