Theoretical Foundations for a Total Energy-Based Perspective Flight-Path Display

Abstract

One of the most difficult aspects of manually controlled flight is the coupling between the control over the aircraft speed and altitude. These states cannot be changed independent of each other through the aircraft control devices, the elevator and the throttle. Rather, to effectively change an aircraft's speed and altitude, the controls have to be coordinated. The mediating mechanism that underlies the coordination of the controls is the management of the aircraft's energy state. This article shows that the abstraction hierarchy (AH; Rasmussen, 1986) framework can be effectively used to gain more insight into the underlying structure of the aircraft energy management problem. The derived AH representation is based on the analysis of the energy constraints on the control task. It reveals the levels of abstraction necessary to link the aircraft's physical controls to the speed and altitude goals and also how the aircraft energy is a critical mediating state of the control problem. Energy awareness can be increased by presenting explicit energy management information. The powerful and novel con-

Flight Energy Management Training: Promoting Safety and Efficiency

“…In his online book, See How It Flies, Denker (2008) explains energy conversions and the effect of the flight controls on energy. Amelink, Mulder, van Paassen, and Flach (2005) apply total energy control principles to describe how pilots can control aircraft speed and altitude. Finally, Merkt (1990;1991; explores the instructional merits of a ''top-down,'' energy-centered approach for training pilots.…”

“…Applied to flight, the law of energy conservation defines the total mechanical energy of the airplane-its energy state-as the sum of its gravitational potential energy derived from height above the ground plus its kinetic energy acquired from speed through the air (Amelink et al, 2005;Goodman & Warner, 2001;Rutowski, 1954):…”

“…Likewise, the energy lost is not destroyed-it is transferred out to another system acting as the energy ''sink.'' Once airborne, the airplane gains energy through engine thrust (T), the propulsive force generated from burning fuel, and loses energy through drag (D), the retarding force that releases heat into the surrounding air (Amelink et al, 2005;Rutowski, 1954). Consequently, energy flows continuously into and out of the flying airplane.…”

“…Note that Equation 4 represents an approximation of the energy balance relationship because it neglects to account for the change in total mechanical energy caused by the change in aircraft weight as fuel is gradually burned in flight (Rutowski, 1954). The effect of weight change may be negligible when applying the energy approach to solve short-term control problems (e.g., Amelink et al, 2005), but it is critical to solve long-term performance problems such as those involving climb and range calculations (e.g., Pennycuick, 2003). For a complete analysis of the energy balance equation as it applies to aircraft performance, see Rutowski (1954).…”

“…From an energy management view, he recognized that the throttle, which can rapidly increase or decrease the amount of thrust (energy gain), should be used to regulate the rate of change of the aircraft's total mechanical energy. Even though the latter is a function of both thrust and drag (Equation 5), the amount of drag (energy loss) mainly varies due to long-term changes in airspeed or limited deployment of high lift/drag devices that can only increase drag (Amelink et al, 2005;Lambregts, 1983). Therefore, most changes in total energy-demanded by new or corrective maneuvers-are initiated by changing thrust, not drag.…”