T.I.E. Fighters under construction based on Joe Johnston’s sketch. From the book Making Star Wars:
“In World War II the super dive-bombers had an artificially created siren wail created by air ducts,” Johnston says. “They didn’t serve any purpose except to create this noise, which would terrify people. It was intended that the TIE should achieve the same effect with just a menacing appearance. It was supposed to look terrifying even though it wasn’t necessary that all that stuff have a specific function.”
The acronym TIE was created by Lucas but not defined. “I came up with ‘twin ion engine fighter,’ ” Johnston adds. “There were other ideas, like ‘Third Intergalactic Empire,’ but I thought ‘twin-I engine’ made more sense.” Later the wail would be added by Ben Burtt.
Of the TIE fighters, Lucas says, “they were influenced by some paintings by John Berkey.”