To: rodquiman
I believe the B-747 was already flying prior to the bidding on the C-5A program.
Little known fact:
Douglas bid on the C-5A and like the others had to build a scale mockup in order to show the ability to load and unload cargo. Lockheed and I assume Boeing made their mockup of wood where Douglas made their mockup to a smaller scale and the outer skin was metal which gave a truer replication of the skin lines and the station lines which could be scaled off of for lofting purposes.
Because the mockup was smaller than the actual C-5A Douglas had to build smaller scale tanks and vehicle as well as any other outsized materials carried in the C-5A.
The reason for this is that if Douglas won the contract they had a mockup that was just about the size of the 747 and could be used in the lofting of the lines to build a competitor for the 747.
