Pure aluminum is easy to form but lacks mechanical strength. Melting aluminum with small amounts of other elements such as silicon, magnesium, copper, zinc, and nickel in various combinations increases the tensile strength without adding weight. The airship industry thrived during the 1920s and 30s because of the development of aluminum alloys that make the structures safer, improved suspension, reduced noise and vibrations, and decreased cracking when stressed. These qualities also revolutionized the auto industry by adding fuel efficiency to the list of aluminum’s advantages.