An homage to the recently retired space shuttle program, this set is the Shuttle Carrier Aircraft (SCA). The SCA is a modified Boeing 747 that was used to transport the Space Shuttle from various landing sights back to the Kennedy Space Center in Cape Canaveral, FL. It was also used to launch the Space Shuttle Enterprise for in-atmosphere flight tests.
This model has been designed to work with the existing Lego Space Shuttle from Lego set 10231 (as seen attached to the SCA in the image above). The model has functional flaps, ailerons, elevators, and a rudder. It also has fully retractable landing gear. I have designed the nose in a similar fashion to the Lego Space Shuttle, and it has an interior cockpit in much the same style.
I'd love to see this become a production model, and I hope the rest of you share my enthusiasm!