Essentials of Supersonic Commercial Aircraft Conceptual Design

3Weight Prediction, Optimization, and Energy Efficiency

Over the many decades of commercial airplane development designers have focused on minimizing the maximum take‐off weight. More recently, the progressively increasing fuel prices and environmental constraints have shifted the emphasis to reducing fuel burn‐off. In view of the large fuel weight fraction of a high‐speed airliner, reducing the mission fuel has to get even more emphasis than for a subsonic airliner. However, weight engineering is a highly iterative process, and an accurate weight breakdown is not available until the conceptual design phase is completed. Reference is made to [4] for a discussion on the various types of weight prediction methods and an explanation of a typical methodology that can be used for early prediction of the major weight components. The following text is primarily intended to demonstrate the sensitivity of the airplane's all‐up weight (AUW) to the flight efficiency, thereby emphasizing the importance of the lowest possible drag and high propulsive efficiency in cruising flight.

3.1 The Unity Equation

The separation of basic functions for classical airplane configurations allows us to decompose the AUW of the aircraft when taking off for flying the design range with the design payload, using the following symbols:

• – maximum take‐off weight (MTOW)
• – operating empty weight (OEW)
• – design ...