Flight Physics of Fuel-Saving Formation Flight

Abstract

Fuel-saving formation flight is a concept to enhance the fuel efficiency of the air transportation system that is known already since several decades. Even though there has been a lot of research effort in the recent years, the basic principles how formation flight can lead to fuel savings still seem to remain unclear within numerous journalistic publications, but also in scientific papers a usage of misleading wording can be found. More specifically, the reason for the fuel savings is often explained to be a drag reduction of the following aircraft, but this is not a correct description because in reality the drag of the follower aircraft remains nearly unchanged and can be even slightly higher compared to a normal cruise flight outside of a formation. Thus, the aim of this paper is to explain the basic principles of fuel-saving formation flight in an easily understandable way, yet still under the claim of scientific correctness. A special focus is on the disproof of the aforementioned common misconception using simplified calculations to allow an easy understanding and using more detailed models to present more precise numbers that substantiate the statements.