Found and Explained Official on MSN

Boeing's Propeller 747 - The Never Built 747-500

An incredible never built Boeing 747-500 with propfan engines. It would have an impressive range to go London to Sydney ...
Found and Explained Official on MSN

Boeing 747X - The New Large Airplane Proposed By Boeing But Never Built

Two decks down the length of the plane, and carrying over 650 passengers, this 1990s proposed version of the Boeing 747x ...