Complex sentence: O'Brian has chosen a "deus ex machina" which has the glamor and high-tech promise of a new creation--helicopters sufficiently advanced for this escape appeared only in the late 30's.
Split into simpler sentences: O'Brian has chosen a "deus ex machina" which has the glamor and high-tech promise of a new creation. Helicopters sufficiently advanced for this escape appeared only in the late 30's.