Mating and Demating, the model device — the MDD
Mating and Demating, the model device — the MDD
Space Shuttles were transported atop a specially modified Boeing B-747 — looking much like lovebugs (Plecia nearctica) to me — whenever they could not land at Kennedy Space Center. A machine was used to attach the Shuttle at the embarking point while another would be employed to detach the Shuttle at the debarking point. Two MDDs, each specialized derrick-like assemblies with three hoists attached to a lifting beam, were made — one for Edwards Air Force Base and one for the Kennedy Space Center. Two large cranes were used at Vandenberg Air Force Base. Each assembly was officially known by NASA as a Mate-Demate Device (MDD).
They are quite large as each could lift a Shuttle on or off the B-747. They are quite difficult to assess but we have a modeller — Mr. L.K. Johnson of Ridgecrest CA to thank. Mr. Johnson created a miniature MDD in 1:144 scale (~0.7% full size, or 12mm height for a person), which is about the size of a rugby ball, allowing us to see the MDD, Shuttle and B-747 carrier aircraft as if circling in a helicopter. Specifically, it is the MDD used at Edwards Air Force Base with the Space Shuttle Columbia in the assembly.
L.K. Johnson’s scratch-built miniature diorama of the NASA Mate-Demate Device in 1:144 scale with modified Boeing B-747 Shuttle Carrier Aircraft and the Columbia orbiter — photo by Joseph May
Detailing of stairways and railings — photo by Joseph May
Profile view of the MDD model — photo by Joseph May
View showing the lifting beam, in yellow, used to lift orbiters for attaching or detaching — photo by Joseph May
Detail of the lifting beam and the rear pair of the three hoists — photo by Joseph May
Rear view of the MDD miniature diorama, note the addition of vertical fins on the 747’s horizontal stabilizers — photo by Joseph May
Another derail view of the MDD lifting beam — photo by Joseph May
Saying the model is scratch built is an understatement. Over 4000 hours went into construction of the model which is 95% metal — built almost entirely of brass beams, aluminum rails, steel rails and 130 feet (39.4m) of #18 music wire. There was no stopping there! He also scribed lines for over 30,000 tiles and clad both the Columbia and B-747 with aluminum.
Our thanks to Mr. Johnson for his skill as well as his donation to NASA which exhibits the miniature at the Kennedy Space Center Launch Pad 39 stop. The actual MDDs are too large to display and soon they will be dismantled, perhaps leaving Johnson’s work as the sole 3-D representation of the MDD for us to view.
Travel for Aircraft 
You’re absolutely right about understatement! exquisite is another word. The hours spent are unimaginable! Also, an enjoyable , informative and professional presentation on your part, Joe.
Speaking of hours..I’ve done some preliminary checking, but have not been able to find out how long the process of mating and/ or demating takes? Would you know?
david lord
Great question. I’ll look and we can compare notes. Thanks, too, for the compliment. Joe
Hi and regarding the time taken to attach or detach a shuttle to a 747. I ran across a few items on teh internet and they infer the entire process from rolling the shuttle into an MDD through rolling the assembly out took 5-7 days with two of the involved directly in either attaching or detaching. Not a timetable broken down to increments of hours but I haven’t found anything more precise.