Essentials of Supersonic Commercial Aircraft Conceptual Design

7Aerodynamic Drag in Cruising Flight

Aerodynamic drag in horizontal flight is usually expressed in terms of aerodynamic efficiency . This term suggests that, similar to energy efficiency, would have a value between zero and one, which could be confusing to engineers who are not familiar with analysis of flight mechanics. For instance, Concorde's aerodynamic efficiency in cruising flight at Mach 2 was , whereas for typical contemporary passenger transport and long‐range jetliners, would have an order of magnitude between 15 and 18, typically. In deriving the sensitivity of to the variation of geometric variables it is often attractive to use the term glide ratio since is usually the independent variable. This leads to expressions which are simpler to solve for optimum independent variables ...