Is Downwash a Myth in Lift Theory?

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The discussion centers on the existence of downwash in lift theory, with Doug McLean arguing that it does not exist due to zero integral in mathematical models. However, participants challenge this view, emphasizing the importance of real-world observations over theoretical calculations. They highlight evidence of downwash and question the interpretation of McLean's statements regarding downward air flow. A timestamp from 41:00 to 47:00 is suggested for those interested in this specific part of the lecture. The conversation ultimately reflects a divide between theoretical and practical understandings of lift and downwash.
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Doug Mclean talk about common lift misconceptions.I agree with most of what he said but he claims that downward air flow "downwash" do not exist because integral is zero.

I don't agree with this statement,leave mathematics and see what happening in real world.
Downwash evidence:


What do you think about that and which lift theory do you support?
 
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Wing 11 said:
but he claims
How about a timestamp given it's a long lecture?
 
A.T. said:
How about a timestamp given it's a long lecture?
41:00 - 47:00 min
 
Wing 11 said:
but he claims that downward air flow "downwash" do not exist
He doesn't say that. He just says that the downward momentum doesn't accumulate in the atmosphere as a whole. The increased reaction from the ground cancels it.
 
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