The Silent Aircraft Initiative (SAI)

The Silent Aircraft Initiative (SAI) is a multidisciplinary program funded by the Cambridge-MIT Institute (CMI) to enable competitive differentiation through innovative low-noise strategies in aircraft and engine system design and operation. The research aspect of this project aims to define the physical limitations to, and corresponding benefits of, the ‘value of silence’. Assessment of these involves the technology, the business case, the regional and national economics, and the surrounding policy issues. This project involves many researchers at Cambridge University and at MIT.

Professor Willcox leads the Silent Aircraft Design and Acoustic Integration research component of the SAI project. This component provides the integrative capability required by creating a framework for aircraft conceptual design with noise as the primary objective, and using this to provide quantitative assessment of performance and noise characteristics at the aircraft system level. The first step is development of a Silent Aircraft Design Framework which integrates existing aircraft design codes with acoustic and economic models and adapts them to innovative low-noise aircraft designs. We will then use this framework plus inputs from the operations and technology components to evaluate new low noise designs.

SAI was launched in November 2003 with a bold aim: to discover ways to reduce aircraft noise dramatically, to the point where it would be virtually unnoticeable to people outside the airport perimeter.

The aim of the initiative is to develop a conceptual design for an aircraft whose noise would be almost imperceptible outside the perimeter of a daytime urban airport. This requires radically different aircraft and engine designs.

The conceptual design that has been developed addresses the generation after next of aircraft, and there are still many technical challenges to be overcome before it could become a reality in the 2030 timeframe. However, the project has also clearly identified these challenges and thus provided a direction for the work needed to address them. In addition. some of the technologies and approaches could be used in more incremental aircraft designs.

Operations team is also working with an airport, air traffic control and local airlines to develop and flight test new enhanced approach procedures with current aircraft. The approaches are an enhanced form of Continuous Descent Approaches (CDAs) which reduce noise and fuel burn by eliminating level segments, keeping aircraft higher and at lower thrust levels for longer than traditional step-down approaches.

The project is carried out in a Partnership between the University of Cambridge and MIT as part of a Knowledge Integration Community of aerospace partners, which include industry, airline and airport operators, policy makers and academics.