Inadvertently or by design, redundancy was built into the world's first heavier than air flying machine the Wright Flyer' ("Wright Power", Flight International, 7-13 January).
Two propellers driven by two separate chain and sprocket is probably the first redundancy device in aviation history. It is alarming to note that four-engined jets will eventually give way to twins if left to the designs of the US Federal Aviation Administration and he International Civil Aviation Organisation.
"Flexible definitions" and convoluted logic like "two is more abundant than four" are their forte.
It is heartening to note that Airbus is bringing back the glories of the Comet
Source: Flight International