The Makeshift Rocket — Poul Anderson

A spaceship engineer held captive by would-be revolutionaries plots a daring escape in a rocket constructed of odds and ends and powered by beer in this hilarious romp from a master of golden-age speculative fiction

The last thing the crew of the Mercury Girl expected to find on the terraformed worldlet known as Grendel was a band of Irish revolutionaries. As far as the ship's engineer, Knud Axel Syrup, is concerned, being taken prisoner by the more-than-slightly-nutty Shamrock League Irredentist Expeditionary Force could be a lot worse. At least there's plenty of cold brew available to keep him occupied . . . and more than a little tipsy. But these crazed Fenians are spoiling for a fight, and the last thing Syrup needs is to get caught in the middle of a war between the Shamrocks and their sworn rivals, the Anglians.
 
Luckily Syrup has a plan. With the help of a somewhat-ditzy dancer named Emily and an alien in six-legged lederhosen, he intends to pull off a daring escape from the miniplanet in a spaceship constructed of pretzel boxes, old bicycle parts, and anything else he finds lying around, trusting their liftoff to the considerable propulsive power of beer.
 
Multiple award winner Poul Anderson is one of science fiction's most respected maestros, and here he displays another side of his creative genius with his tongue planted firmly in his cheek. Hilarious, outrageous, and delightfully imaginative, The Makeshift Rocket is a wonderfully wild and wacky romp through a very different cosmos with one of the genre's best pilots at the controls.