Eyeballing the Scale Pic, makes me want to say 15 meters, but I don't trust my ability to eyeball things.
Okay, given that, it looks closer to 12 or 13 meters than fifteen, definitely more than ten though. Thank you Squishypon3.
This is as good a place as any to say how much I think Uber have got the scale in PA spot on. Much as I love Supreme Commander more than is healthy, the scale in that was bloody ridiculous. The Dox-equivalent were meant to be 9m tall, but they sure as hell didn't look it, and somebody worked out that if that height was correct, they travelled at 175mph. Supcom scale: http://forums.gaspowered.com/viewtopic.php?f=2&t=40536&sid=9b83291895e1a4987d34ca166dcb03d7