George Lucas baloney
Bill Sweetman's drawing is an A-12 fighter with X-30 engine nacelles pasted on and spiced with a MiG-25 sideview. George Lucas could easily produce a better image. Unfortunately George Lucas would have it fly with an air breathing engine in a hard vacuum (it would look cool though!).
Gary
p.s. The real Aurora would have been an unmanned drone that was a tweek on the D-21's design, e.g. a pure ramjet with regeneratively cooled leading edges.