What are the design goals for NASA's X-57?
I just found an answer (pointed out by @RoboKaren), on another question. The only reason I am copying this is that the original question was not really about goals. This is from Mark Moore:

source: What are the advantages of the NASA LEAPTech propeller on wing technology?


  The lift augmentation has nothing to do with Magnus lift (or the
  Coanda effect). It is simply an increase in the dynamic pressure
  across the entire streamtube of the wing.
  
  At the low takeoff and landing speeds (slightly above a 61 knot stall
  speed), the induced velocity of the propeller almost doubles the
  velocity that the wing sees; and the lift is a function of the
  effective velocity squared. But due to swirl and other effects the
  wing doesn't experience a 4x increase in lift, but about 2 to 3 times.
  
  The objective of the inboard propellers is not to achieve a high
  propulsive efficiency, instead we want those inboard props to achieve
  high induced velocities - think of them as part of the high lift
  system (which happens to also provide thrust redundancy).
  
  In fact landing is the critical case, and having lower propulsive
  efficiency (and a poorer spanwise lift distribution because of the
  swirl effects) is helpful in creating sufficient drag. The inboard
  props are not active in cruise flight, but simply fold against the
  nacelle (many motorgliders already do this type of folding on the
  nose).
  
  By only using the wingtip propeller at cruise, we're able to achieve a
  ~95% propulsive efficiency (versus 75 to 85% with a typical fuselage
  nose propeller installation). The reason for this is because we have
  lower blockage and scrubbing drag, as well as being able to take
  advantage of the strong wingtip vortex by rotating against it. Since
  electric motors don't experience a power lapse with altitude (because
  it's non airbreathing) we have far too much power at altitude anyway
  so by only using the wingtip motor it doesn't cause much penalty in
  motor weight (and electric motors achieve ~6x lower weight per
  horsepower than a reciprocating engine).
  
  In terms of batteries and range, the key is to achieve high efficiency
  cruise flight and it looks like with current batteries a 200 mile
  range is achievable. By adding a small &lt;50 hp range extender motor,
  the aircraft will be able to achieve ~400 mile range. We're currently
  designing an X-plane that will fly in 2017 to substantiate all these
  numbers, with the ground test rig (wing and truck) providing an
  aerodynamic database to validate our analysis.
  
  Please note that I'm the NASA Principal Investigator of the LEAPTech
  Distributed Electric Propulsion integration approach, and the
  Convergent Electric Propulsion Technology (CEPT) X-Plane demonstrator.
  We have a team across NASA Langley and Armstrong, as well as two great
  small companies, Joby Aviation and ESAero who are retrofitting a
  Tecnam P2006T with a Distributed Electric Propulsion wing system.