You claim the Diameter of the earth is 24,900 mi. The RE model's equator would be 12,450 mi in circumference. This means placing the RE equator on your FE model. This places the circumference of the equator to be 39113 mi.
C=pi*D DEquator = 1/2DEarth
24900/2 = 12450*pi
Now the RE equator is measured to be 24,902 mi in circumference.
Why the discrepancy when sailors, geographers, and pilots alike can come up with the latter number individually?
http://img48.imageshack.us/img48/8830/modeldw4.jpg