On Wed, 17 Dec 2008 13:20:06 -0600, Pat Flannery
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.

It also shifted from having an internal payload bay to an external
payload housing. All three of these led to serious weight growth and
enormous doubts that the follow-on VentureStar would ever have a
meaningful payload capacity.

X-33 was a fiasco. The most serious problem was that it was not killed
soon enough.

Brian