One of the early limitations of aircraft was their wooden construction and the lack of water resistant glues. Of course, aluminium was the perfect material and

One of the early limitations of aircraft was their wooden construction and the lack of water resistant glues. Of course, aluminium was the perfect material and one of the most abundant elements in the earth's crust. However it was so rare and difficult to extract that that the Washington monument is capped by a small piece. The Bayes process and subsequent improvements have since made it common and relatively cheap.