Well, here is a thread from the Spartan Games forum that has some nice pictures of one a guy painted:
http://forum.spartangames.co.uk/smf/index.php?topic=2956.0
Relative to the base (which is a 40
mm square), I would say the airship is rougly 12cm or so.
EDIT
Silly me, I just took a closer look at that thread and the
OP posted these measurments of it:
Snori Whitebeard wrote:
The dimensions are
from nose spike to end of wing tip in length its just shy of 4"
widest point is 2.5"
the model is 1 1/4" deep and just over 3" on its stand.