Wittgenstein's aircraft engine

Ludwig Wittgenstein's Tractatus Logico-Philosophicus (1921) consists of numbered paragraphs, the first of which reads, 'The world is everything that is the case', and the last of which states, 'Whereof one cannot speak, thereof one must be silent.'

As Anthony Quinton explained in discussion with Bryan Magee, Wittgenstein "detested...the idea of philosophy as a trade, a 9-to-5 occupation, which you do with a part of yourself, and then go off and lead the rest of your life in a detached and unrelated way. He was a man of the utmost moral intensity. He took himself and his work with very great seriousness. When his work wasn't going well he got into a desperate and agonized condition. The result of this displays itself in his manner of writing. You feel that his whole idea of himself is behind everything that he says...[He] doesn't want to make the thing too easy - he doesn't want to express himself in a way that people can pick up by simply running their eyes over the pages. His philosophy is an instrument for changing the whole intellectual aspect of its readers' lives, and therefore the way to it is made difficult," (Talking Philosophy, p83).

Wittgenstein, however, came to philosophy by starting off as an aeronautical engineer at Manchester University between 1908 and 1910. Here, he devised and patented a new design of aircraft engine, but became interested in the mathematics used to describe his engine. The questions Wittgenstein began asking himself about the nature of mathematics, then brought him to Bertrand Russell's Principles of Mathematics. Discussing this with Frege in Germany, Wittgenstein abandoned his aeronautical career, and went to Cambridge to study logic under Russell.

Wittgenstein's engine design is rather interesting, and a couple of recent papers have explained his concept in detail. Ian Lemco outlined Wittgenstein's aeronautical research in a 2007 paper, and co-wrote an exposition of his combustion chamber design with John Cater in 2009.

Ludwig, it seems, was inspired by an idea proposed in the 1st century BC, by Hero of Alexandria, to drive a propeller by emitting jets of gas from nozzles placed in the tips of the rotor-blades. In particular, Wittgenstein proposed that the tips of the rotors contain combustion chambers, and the centrifugal force of the rotating propeller alone should be responsible for compressing the mixture of air and fuel; no need for pistons, in other words.

In modern terms, Wittgenstein proposed a tip-jet engine design. Such engines subdivide into cold-tip jets and hot-tip jets: the former are driven by, say, compressed air, created by a remote compressor, while the latter are driven by the direct exhaust jet flow of combustion. The Sud-Ouest Djinn helicopter, for example, employs cold-tip jets, while the Hiller YH-32 Hornet uses hot-tip jets.

All of which sounds not totally dissimilar to the distinction between hot-blown and cold-blown diffusers in modern-day Formula One...