Bits and Pieces
Word of the Month - Alclad
NAS Grosse Ile in the 1940s
By Ian Brown, Editor - Bits and Pieces, EAA 657159
Alclad sheet aluminum is popular with aircraft homebuilders. A combination of corrosion resistance and high strength is achieved by coating heat-treated aluminum, copper, manganese, and magnesium alloy with a thin layer of high-purity aluminum. The name Alclad is a trademark of Alcoa but is also used as a generic term to describe corrosion-resistant aluminum sheet. Another interesting word deriving from this is "passivation" - the idea that the process of corrosion of the outer layer prevents any further corrosion. The first application in an actual aircraft was a U.S. Navy airship known as ZMC-2, built at Naval Air Station Grosse Ile (NASGI), Michigan, in 1927. A between-the-wars training airport, it was known to have been the training airfield of thousands of American pilots including George H. W. Bush and many from the Royal Air Force.
The only downside to Alclad is that the corrosion resistance comes at the expense of increased weight, but this effect is cancelled out, assuming a corrosion-resistant coating of some other type would have to be applied to any aircraft component.