AboutPaul Soderman Expertise Aeronautics, Fluid Mechanics, Aeroacoustics, Noise Control, Muffler Design, Wind Tunnel Research.... I know nothing about India - do not ask about schools, jobs, application requirements, career choices, etc. for India. Please, no text message verbiage; I prefer full words in full sentences. Thanks.
Experience 38 years as research engineer at NASA
Publications AIAA, NASA
Education/Credentials B.S. and M.S. Aeronautical Engineering - U. of Washington
Graduate work Standford U.
Awards and Honors AIAA Associate Fellow (American Institute of Aeronautics and Astronautics)
Question Hello Paul
Following up my questions, if we can not eliminate noises so how we couldn't hear spy planes flights?
Thanks
Answer Your question is a little unclear. I believe you are asking why is it that you cannot hear spy planes. To answer that I would need to know more about the planes, but I assume that a small, light, low-speed aircraft designed for low noise would be difficult to hear beyond a certain distance. For example, a low-speed propeller with many blades can be very quiet, and a gas engine can be muffled. That is a lot different from the 747 type aircraft you asked about before.