måndag 17 september 2012

How to Answer a Question You Cannot Answer

The question how a wing generates lift gets the following answer on Wikipedia under Lift Force:
  • There are several ways to explain how an airfoil generates lift. Some are more complicated or more mathematically rigorous than others; some have been shown to be incorrect.
  • Most of them are intended to explain the phenomenon of lift to a general audience. Several theories introduce assumptions which proved to be wrong, like the equal transit-time theory.
The idea, used by many agencies expected to have an answer like NASA or AIAA, is to say that the answer to be presented is suitable for a "general audience" and as such it is not the correct answer, while suggesting that there is a correct answer certainly known to the agency, but that this correct answer is not suitable for presentation to a "general audience". 

This is believed to be a very smart way of covering up that the agency does not really know any correct answer: Give an incorrect answer (and there are many to choose from) and claim that for sure there is a correct answer, which however is not suitable for the general audience. 

You can study this very clever and effective tactics in the preceding sequence of posts on Incorrect or Empty Flight Theory. Have fun.

PS1 One may compare with different answers to the question from where babies come, which can vary depending on the audience. The question has to be answered, in one way or the other, because it is a very good question, and even an incorrect answer is then an answer, but it is not science.

PS2 As an real-life illustration study my Interview with Glenn Research Center:
  • The correct theory of lift is fairly complex. saying that the answer is complex means just that ... it is complex, it isn't simple. But we know what it is.
  • Many people look for simple answers to questions, when the answer may not be simple. When the answer is really complex, people make simplifying assumptions so that they can get a simple answer. Unfortunately, with fluid mechanics, when you make simplifying assumptions you can get the wrong answer. That's what has happened with the incorrect theories and their inability to produce meaningful results.

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