Flight Performance Maneuver Planning for NASA’s X-57 “Maxwell” Flight Demonstrator – Part 1: Power-Off Glides

Distributed Electric Propulsion technology is expected to yield up to a fivefold increase in
high-speed cruise efficiency for NASA’s X-57 “Maxwell” flight demonstrator when compared
to a combustion-powered general aviation baseline. A portion of this increased efficiency is
due to beneficial aero-propulsive interaction inherent to the distributed propulsion
architecture. The measure of the relative increase in efficiency between a conventional and
distributed propulsion wing will be extracted from comparisons between flight test data from
the electrically powered X-57 Mod II configuration with a conventional wing, and from the
electrically powered X-57 Mod III/IV configuration with a distributed propulsion wing. Flight
test maneuvers that accommodate errors in instrumentation and the flight test environment
are developed to establish the power-off drag characteristics for all X-57 configurations.
Analysis of these maneuvers with typical errors, including pilot-in-the-loop simulation data
that incorporates simulated atmospheric turbulence effects, shows that the proposed power-off
flight maneuvers can generate accurate power-off drag predictions for the X-57. These
predictions show that the power-off differences in aerodynamic performance between the
conventional and distributed propulsion configurations can be accurately measured from
flight test data in the presence of typical data error sources.