Okay, this model is really a cheat. I have used the lower section of the full-sized Jupiter 2 exterior with its landing gear as a base. The full-sized spaceship had diameter of only 43’-6”. The miniatures of the spaceship were scaled for a diameter of 48’-0”. The full-sized interior/exterior of the spaceship had a diameter of 47’-4”.
This version of the Jupiter 2 has the 47’-4” diameter of the full-sized interior/exterior.
The other cheat comes from how tall the upper deck portion is. To scale the miniatures all had an upper deck portion of 6’-0”. The same 6’-0” was on the upper deck portion of the full sized exterior spaceship. The full sized interior/exterior had sloped sides that continued up into the scaffolding of the stage. Here the upper deck is 7’-8” in order to house the spaceship upper deck interior.