Boeing Tests Shorter Engine Inlet for Fuel Efficiency Gains

Boeing has completed another series of flight tests under its ecoDemonstrator program, this time using a Rolls-Royce Trent 1000-powered Boeing 787 with a modified shorter engine inlet. The goal was to see if such a design could reduce fuel consumption without increasing noise levels.

The tests were conducted in collaboration with Rolls-Royce at Boeing's facility in Glasgow, Montana, under the FAA's Continuous Low Energy, Emissions and Noise (CLEEN) program. A Lufthansa-provided 787 was used for the campaign.

Shorter engine inlets are of interest to manufacturers because they can reduce nacelle weight and aerodynamic drag, particularly on high-bypass turbofan engines. However, a shorter inlet provides less surface area ahead of the fan for sound-absorbing acoustic treatment, potentially making the engine noisier.

Boeing addressed this issue by fitting the modified inlet with a new acoustic treatment designed to maintain noise levels comparable to those of the existing 787 design while improving fuel efficiency by up to approximately 0.5%.