Preliminary Assessment of a Distributed Electric Propulsion System for the SUSAN Electrofan

The SUSAN Electrofan is a new hybrid electric large regional jet aircraft concept being
studied by NASA that leverages advanced propulsion system technologies such as distributed
electric propulsion (DEP) and boundary-layer ingestion (BLI) to reduce fuel consumption
and emissions. In order to evaluate the individual benefits of these technologies toward the
SUSAN Electrofan’s wing-mounted propulsion systems, three configurations are proposed. The
first consists of two underwing pylon-mounted podded propulsors and serves as a baseline,
while the second features an underwing pylon-mounted DEP concept with 16 ducted fans in a
mail-slot nacelle. The third and final configuration mounts the mail-slot nacelle directly onto
the pressure side of the wing to also take advantage of BLI. This paper presents preliminary
investigations into the design and performance of the first two propulsion system configurations.
This begins with an initial propulsor and mail-slot design where the aeropropulsive design space
is explored, and adverse effects are addressed through iterative geometry modifications. The
propulsion system configurations are then installed onto a wing–body model to account for
integration effects and assess the relative aerodynamic and shaft power performance of each
concept. Results indicate the potential benefits of DEP, which come from significant reductions
in total drag, provided by operation at much lower propulsor fan pressure ratios.