Trent Henry, aka "Nothing", had a free one on his site, but it appears to be discontinued now. The saved site in the Internet Archive doesn't include the downloads from it either, unfortunately. I don't know if it was ever available anywhere else. He also had a Boeing Blended-Wing-Body, and a Boeing Sonic Cruiser, as well. I wish they were still availble, I can't seem to locate my own copies at the moment.
Scott K.