Sai Flyer 2006

The project is carried out in a Partnership...

University of Cambridge, UK

...between Cambridge University and MIT and a ‘Knowledge Integration Community’ (KIC) of aerospace partners, which include industry, airline and airport operators, policy makers and other academics. The partners listed below have provided access to industry software tools, and have been involved in reviews of the emerging designs. In addition to the KIC, other research collaborators include Georgia Institute of Technology, KTH Sweden, ISVR, NASA and NLR.

Massachusetts Institute of Technology, USA

KIC Partners include: • • • • • • • • • •

BAA Boeing Bruel & Kjaer (B&K) Civil Aviation Authority (CAA) DHL easyJet ecotec HACAN ITP Lochard

• • • • • • • • • •

Lufthansa Cargo Luton Airport Marshall Aerospace Messier Dowty Met Office National Air Traffic Services (NATS) Nottingham East Midlands Airport (NEMA) Rolls-Royce plc United Parcel Service (UPS) Wyle Labs

For more information see www.silentaircraft.org

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www.silentaircraft.org

Integrated Design of a ‘Silent’ Aircraft

Research Challenge: Develop the conceptual design of a new aircraft which is no louder than the background noise outside a typical urban airport perimeter. The aircraft should have competitive fuel burn and the design must be credible in terms of in-depth reviews by industry.

Integration

Engines

• Embedded Engines: embedding the engines in the airframe reduces the drag on the ultrahigh bypass ratio engines

• Ultra-High Bypass Ratio: 20 at take-off for low jet noise, 13.6 at top of climb

• Shielding: the large centre-body shields the engine noise from listeners on the ground and provides room for extensive acoustic liners • Vectored Thrust: enables aircraft control without noisy flight control surfaces

Airframe • Integrated Design: the blended wing design has high lift/drag ratio (~22-26) which makes the aircraft very efficient and enables a low speed approach • Noise: airframe noise from current large civil aircraft now exceeds engine noise on approach. All airframe noise contributions are cut by reducing approach speed and increasing approach angle. The low-noise design has no flaps, a drooped leading edge rather than slats, and a simplified and streamlined undercarriage

• Multiple-Fan Geared Engine Configuration: three cores and nine fans are easier to embed in airframe, reduce weight and nacelle drag, enhance boundary layer ingestion, and the low fan tip speeds lead to low noise • Variable Area Nozzle: reduces jet noise at take off with maximum efficiency at cruise • Extensive Acoustic Liners: attenuate rearward noise

• Ingesting: some of the aircraft boundary layer flow is ingested into the engines, increasing propulsive efficiency and reducing fuel burn

Economics • Airline Operators: an airline business model considers the relative profitability of a silent aircraft under a range of regulatory and environmental scenarios • Regional Growth: a regional econometric input-output model simulates the catalytic industrial benefits from aviation

Operations • Design for Low Noise Operations: the ‘Silent’ Aircraft exploits a slow, steep approach and an optimised departure profile to reduce noise on the ground • Continuous Descent Approaches (CDAs): these 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 team is developing conceptual designs for an integrated wing-body aircraft to carry 215 passengers in a typical 3-class configuration at distances of up to 5,000 nautical miles. This design and the one overleaf are two of the concepts currently being considered.

www.silentaircraft.org

• Flight Tests: the team is working with an airport, air traffic control and local airlines to certify and flight test new CDA procedures with current aircraft types