Atom Drive by Charles Fontenay, Science Fiction, Fantasy, Adventure

"Jonner, I figured you the last man ever to desert the rockets for a hot-rod tow-job," chided Russo Baat, captain of the Mars Corporation's gleaming new freighter, Marsward XVIII. Baat was fat and red-faced, and one of the shrewdest space captains in the business. Jonner Jons, at the other end of the table, inclined his grizzled head and smiled.

"Times change, Russo," he answered quietly. "Even the Mars Corporation can't stop that."

"Is it true that you're pulling five thousand tons of cargo, Captain?" asked one of the crewmen of the Marsward XVIII.

"Something like that," agreed Jonner, and his smile broadened. "And I have only about twice the fuel supply you carry for a 100-ton payload."