The Sky Trap by Frank Belknap Long, Science Fiction, Fantasy

The stratoship lurched suddenly. The deck heaved up under Lawton's feet, hurling him against Captain Forrester and spinning both men around so that they seemed to be waltzing together across the ship. The still limp gym slugger slid downward, colliding with a corrugated metal bulkhead and sloshing back and forth like a wet mackerel.

"Slashaway," Lawton muttered. "Slashaway, old fellow."

Slashaway opened blurred eyes, "Phew " he muttered. "You sure socked me hard, sir."

"You went out like a light," explained Lawton gently. "A minute before the ship lurched."

"The ship lurched, sir?"