TABLE OF CONTENTS For many aircraft, the ability to fly for long distances and/or long periods of time is among the most important design requirements. It is hard to imagine an airline buying a transport aircraft that has to land every 100 miles to refuel, a resources agency buying a pollution-monitoring aircraft that can only stay on station for an hour at a time, or an air force buying a fighter that requires multiple refuelings from tanker aircraft to complete its mission. It is common to see airliners fly non-stop from Chicago to Frankfurt, Moscow, or Tokyo, but these capabilities had to be specifically designed into the aircraft. The range and endurance that an aircraft can achieve depend on its aerodynamics (primarily, its drag polar), the characteristics of its propulsion system, the amount of fuel the aircraft can carry, and the way it is operated.
Because TSFC is modeled as constant with Mach number for turbojets and turbofans, the drag (thrust required) curve of Fig. 5.13 can be viewed as a fuel-flow-required curve. This is because multiplying the drag values everywhere by a constant value of c t would change the scale but not the shape of the curve. For a given thrust required = drag and a specified ? W f (the weight of fuel available to be burned), the endurance is given by
Equation (5.33) makes it clear that maximum endurance for a turbojet or turbofan aircraft is achieved...
