- #1
Aeroplane wing structure -- airflow question
Click For Summary
Discussion Overview
The discussion centers around the airflow behavior over an airplane wing's cross-section, specifically addressing why air that splits at a certain point on the wing meets at a trailing point at different times. The conversation explores concepts related to lift, airflow speed, and the implications of various explanations regarding these phenomena.
Discussion Character
- Debate/contested
- Technical explanation
- Conceptual clarification
Main Points Raised
- Some participants assert that the air above the wing reaches the trailing edge before the air below, challenging the notion that they meet simultaneously.
- A participant references a video to support their claim about the timing of airflow reaching the trailing edge.
- Another participant requests the source of the text being referenced, indicating a need for clarification on the material being discussed.
- Concerns are raised about the credibility of the coaching institute's material, suggesting that it may not accurately represent the physics involved.
- One participant explains that the speed of air over the top of the wing is greater and discusses the complexities of lift, mentioning computational fluid dynamics (CFD) as a method to analyze airflow.
- A suggestion is made to review additional resources, including an Insights article on lift, to further understand the topic.
Areas of Agreement / Disagreement
Participants express differing views on the timing of airflow meeting at the trailing edge, with no consensus reached on the explanations provided. The discussion remains unresolved regarding the accuracy of the referenced text and the understanding of airflow dynamics.
Contextual Notes
The discussion highlights uncertainties regarding the interpretations of airflow behavior and the reliability of educational materials. There are also references to complex fluid dynamics that are not fully explored in the conversation.
- #2
russ_watters
Mentor
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The air does not meet at point b simultaneously - in fact the air above the wing gets there first. Does your text explicitly say something about this?Hemant said:
- #3
A.T.
Science Advisor
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It doesn't. See 25sec into this video:Hemant said:
- #4
- #5
berkeman
Admin
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Can you provide a link to that text, or at least the title and author and edition? Thanks.Hemant said:
- #6
Frigus
- 337
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Sir I got this text from my coaching institute.berkeman said:Can you provide a link to that text, or at least the title and author and edition? Thanks.
- #7
berkeman
Admin
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Hemant said:
Well, since it is suspect at this point, it would be good to get more information about it so we can figure out if the person putting it together doesn't understand the subject really well, or if perhaps there is some other issue with your/our understanding of what they wrote.
Perhaps you could forward a link to this PF thread to your "coaching institute" to see if they have a response? Thanks.
- #8
Frigus
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Can anyone explain me why the speed of air splitted on top has more speed.
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- #9
FactChecker
Science Advisor
Homework Helper
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You will see many intuitively simple explanations of lift. They are all wrong or at least incomplete. The real explanation of the lift force is unsatisfyingly complicated.
If small packets of air are traced along so that they satisfy all the physics equations (a very complicated process of computational fluid dynamics (CFD)), they end up with a net downward motion after the wing has passed. They also travel faster over the top and reach the trailing edge sooner than the packets beneath the wing. The net downward motion of the air is an action for which the equal and opposite reaction is a lift force on the wing.
Here is a Youtube video, referencing the Coanda Effect, that might interest you.
PS. The motion of the air also exerts a nose-down rotational moment on the wing.
If small packets of air are traced along so that they satisfy all the physics equations (a very complicated process of computational fluid dynamics (CFD)), they end up with a net downward motion after the wing has passed. They also travel faster over the top and reach the trailing edge sooner than the packets beneath the wing. The net downward motion of the air is an action for which the equal and opposite reaction is a lift force on the wing.
Here is a Youtube video, referencing the Coanda Effect, that might interest you.
PS. The motion of the air also exerts a nose-down rotational moment on the wing.
Last edited:
- #10
berkeman
Admin
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We have some Insights articles that may help you learn about lift. This one by member @boneh3ad is a good one to start with:Hemant said:
https://www.physicsforums.com/insights/airplane-wing-work-primer-lift/
- #11
Frigus
- 337
- 163
Thanks to all 
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