7 Flight Mystery and Aerodynamic Principles
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Fig. 7.127 Albatross takes off on water and the albatross landing state (landing
gear puts down)
7.13 Aircraft Aerodynamic Noise
With the development of society and the continuous advancement of industrial technology, people have put forward more and more strict environmental
protection requirements for the civil aviation industry. How to design a more
environmentally friendly aircraft is the focus of the aviation industry. The
International Civil Aviation Organization (ICAO) has developed recommendations for aircraft aerodynamic noise certification. The United States and
Europe have developed a series of aircraft aerodynamic noise airworthiness
regulations based on this, which limits the aerodynamic noise level of civil
aircraft. The fourth phase requires after 2006, the noise level of the new civil
aircraft proposed for airworthiness application should be 10EPNdB lower
than the third stage (where EPN is the abbreviation of Effective Perceived
Noise). The effective perceived noise level is the perceived noise level in
terms of duration and pure tone correction, and its unit is EPNdB. When