I had to ship an airplane, and took a different approach. I glued a couple pieces of styrofoam to a thick piece of cardboard (corrigated kind). Then I used heavy rubberbands to secure the wings of the plane to the styrofoam.
This left the plane securely help in place... sort of floating. I put this in a small box -- securing the cardboard to the bottom of the box. Then put the small box in a larger box with "popcorn" packing material around it.
It was a bit complicated, but it worked out very well.
www.naplak.com/modeling ... a free site for modelers
www.scalehobby.com/forum/index.php ... a nice Modeling Forum