Brian Abraham
A feature of the wing which contributed greatly to its success was an innovative spar boom design, made up of five square tubes which fitted into each other. As the wing thinned out along its span the tubes were progressively cut away in a similar fashion to a leaf spring; two of these booms were linked together by an alloy web, creating a lightweight and very strong main spar.
I'm just wondering how strong it was compared to other aircraft designs for it's weight, particularly ones built around the same time in the United States