The architecture of modern subsonic transport aircraft has converged to almost exclusively use engines in under wing nacelles. Although highly functional and successful in use, further reduction of fuel consumption with this configuration is progressively harder. The fuel consumption associated with nacelle weight and drag may in future aircraft using large low pressure ratio fans amount to 15% of the total. To achieve higher propulsive efficiency high speed propellers, distributed fans and boundary layer ingestion have been proposed. The nacelle shape of current installations is a compromise between the different requirements set from the varying flight speed over a flight mission. In the present paper, three ideas of shape changing, transforming elements in the propulsion integration will be presented: adaption of a low drag nacelle to low speed conditions, mission variable noise shielding, and deployable propulsors.
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