Jeff Findley wrote:
As one of many, examples, the aerodynamics of X-33 were very problematic.
As a result, the external shape of X-33 seemed to change daily. In
particular, the originally proposed fins on the two sides of the lifting
body gradually morphed into wings. Of course the contractor and NASA
refused to call them wings, since that would admit that the lifting body
concept wasn't as promising as first hoped,


It also grew the two vertical fins after wind tunnel tests showed it
wouldn't be stable.

Pat