The Wright brothers did not just think, based on calculations, that their propeller was 66% efficient, they claimed they had built a 66% efficient propeller
Good grief yet again.
Proves nothing...
Maybe the replica-makers made a better propeller than the Wrights penciled out. It was, after all, a pretty early time in terms of the theories on aeronautical design.
Maybe the Wrights sucked at math, but were awesome propeller builders.