How Many Space Ship One's Are There?

After looking over the new pictures released on Scaled Composites' web site, I have found two images of note...

First, the pictures of Space Ship One from their launch on 6/21 (1st private manned mission to space) and the pictures of Space Ship One from previous launches show a marked difference in the thrust nozzle configuration.

Original Space Ship One

New Space Ship One

Second, Scaled has actually released the photo which demonstrates the after-effect of the loud bang Mike Melvill heard during boost phase. Apparently, part of the new thruster configuration buckled.

Buckled Thruster

Though the changes between the initial craft and record-breaking craft are minimal, it leads me to wonder how many 'Space Ship Ones' Scaled has up their sleeve. Judging from this company's ultra-secretive nature when it comes to prototype aircraft, I could image a fleet of these craft already in existence.

What do you think?

In addition to this stuff, I just looked at the Discovery footage of the launch. I think it's safe to say that this isn't exactly the most stable space craft built. Although, Melvill had some issues with a guidance controller, the issues were fixed during the boost phase. You can see the craft in 'feathering' mode on it's way down in the video and its view is all over the place due to its instability.

Space Ship One Video

i think that there's only one SS1... the costs would be too high to build another, dispite how much money and secrecy Scaled has. as for the differences? i think that they added more structure around the thruster nozel to make the craft more streamlined and have less drag.