The Hare And The Tortoise
Written by
W. E. Johns
Copyright 1935
9th of 9 stories in . It was originally printed as a WWI story named The Fledglings in The New Book Of The Air 1935. A WWII version was published in Every Boy's Annual 1950.
This tells how Wilkinson makes a wager that his new pilot will be able to shoot down more enemy planes than Biggles' new pilot can.