The Variable Man

Thomas Cole, the variable man, is not himself variable, but when he is transported from the early 20th century into the 22nd century, he becomes a variable affecting the outcome of an interplanetary war.

Public Domain (P)2013 Audio Books by Mike Vendetti

It's a classic, reflective of its time

Classic tale of yankee ingenuity versus futuristic power struggles for access to the wider universe. A good Golden Age basic story that has aged pretty well.

While the narrator was clear and understandable, the listening experience would be improved with more dramatic skill and engagement rather than such a straight reading.