User:LGreg/sandbox/Approaches to Knowledge (LG seminar 2020/21)/Seminar 18/Evidence in aeronautics

Evidence in aeronautics

Aeronautics from the perspective of attempting to fly finds its roots in the 15th century with Leonardo Davinci's designs of flying machines comparable to helicopters' nowadays design. This prototype could have worked if it hadn't been for the lack of the energy required to lift it. The absence of efficient materials and technology were important factors in explaining the significant amount of time that elapsed before human flying would be achieved. At first, the pragmatic evidence was that man had to reproduce the movement of flyings wings to be able to fly, so the study of bird's movement was widely practised. . There wasn't real knowledge about the physicial properties of air until the end of the 15th century, but even during the XXth century, experiments were still made based on this belief:

• Franz Reichelt's jump from the Eiffel Tower with his own invention of a flying suit
• Otto Lilienthal constructed the first hoverer and made more than 2000 flight tests
• Professor Oehmichen who developed numerous flying machines, such as the Oemichen n°2 of 1922

However, in those cases the machines were only meant to hover, and were therefore not propelled by any forces other than the wind. Another piece of evidence was that flying machines had no real future, so much so that in 1903 the New York Times wrote that "...We hope that Professor Langley will not put his substantial greatness as a scientist in further peril by continuing to waste his time and the money involved, in further airship experiments." In 2019, Worldwide revenue generated by commercial airlines was of $872 billion, illustrating how our modern globalisation massively depends on flights. From the XVIIIth century, scientific evidence such as Bernouilli's principle and subsonnic flow, which in his own words means that “as the velocity of a fluid increases, the static pressure of that fluid will decrease, provided there is no energy added or energy taken away.” , arose. Other instrumental new pieces of evidence were the discoveries of Isaac Newton's law of mechanics or even Galilao Galilei that grounded the foundations of fluid mechanics and the forces acting on an object, considering the pressure acting on it. Those scientific approaches constituted the main foundations of aerodynamics, which seek to explore the principles behind how objects react while being in the air.

Further on, the discovery of hydrogen gas in the 18th century was a breakthrough for aeronautic and flying machines . Specific amounts of energy were needed in order to propel the first planes, which wasn't always optimum and thus led to serious crashes. . Flying appears now as an evidence, but it had to deconstruct numerous previous evidences to exist in its today's form.