Manufactured by Goodyear Aircraft Company, Akron, Ohio, the U.S. Navy utilized the aircraft for patrol missions. The car, attached to the bottom of the aircraft, was designed and buiilt by the Naval Aircraft Factory, Philadelphia, Pennsylvania. The abbreviation ZNP-K means "Z" ligther-than-air designation, "N" means non-rigid, "P" means patrol mission, and "K" was the class of airship.
During World War II, ZNP-K airships were used for anti-submarine warfare in the Battle of the Atlantic, Pacific Campaigns, and the Mediterranean Sea areas. Following the war, the "N" was dropped in April 1947, resulting in the aircraft designation becoming ZPK. After 1954, only later versions of the K-class airships were in service and attained the ZSG designation, with the "Z" meaning lighter-than-air, "S" meaning anti-submarine, and "G" representing Goodyear. Of note, during the Korean War, some new models of the airship were made with the designation of ZP4K nd ZP5K. In 1959, the last K ship, K-43, was retired.
Image: 80-G-463568: K-3 airship in flight, port view. Photograph received 1951. Official U.S. Navy photograph, now in the collections of the National Archives.