Dr. G;
"I reckon they built that up from a scale model, they just miscalculated by a factor ..."
That isn't an unthinkable mistake. Where I worked years ago (the National Radio Astronomy Observatory in Green Bank, WV), one of our European scientists made a drawing of a small thing he wanted built and sent it to the machine shop. Unfortunately he had scaled it in millimeters and the shop built it in inches. Since he had not shown his scale in "mm" it was a natural error.
Regards, Neil Tucson, AZ