Ceremonial honors traditionally reserved for surface vessels were bestowed in the christening and launching of the United States Navy’s 67-ton Martin patrol bombing plane. Named “Mars” as a bottle of champagne was smashed across its silver bow, the $2,500,000 flying warship slid down the ways at Baltimore. Now in the water, the ship, with its wingspread equal to the height of a 20-story building, is being tested. It could carry a bomb load to Europe and return, nonstop.