Photo reconnaissance and mine laying are among the many missions which can be performed by the Martin P4M-1 Mercator, shown in flight after its initial takeoff from Martin Airport near Baltimore on August 31. An experimental airplane is scheduled to be given its first public showing by the U.S. Navy at the National Air Races at Cleveland, Ohio, September 3, 4, and 5. The airplane pictured is the first of 19 Mercators being built for the Navy by The Glenn L. Martin Company. Although looking like a twin-engine airplane, the same nacelles which house the Pratt & Whitney wasp Major engines also contain Allison J-33 jet engines for additional power when needed. November 23, 1949. (Photo by The Glenn L. Martin Company).