Airfoil Explained for 16-Year-Old Confused By It

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Discussion Overview

The discussion centers around the concept of airfoils and how they generate lift, particularly aimed at clarifying the topic for a younger audience. Participants explore various models and theories related to aerodynamics, including the Equal Transit Theory, and address misconceptions about lift generation in different flight orientations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about airfoils and the conflicting information found online regarding aerodynamics models.
  • Another participant suggests that lift is generated by the downward deflection of air, questioning whether this occurs on the top or bottom of the airfoil.
  • A response clarifies that air around the airfoil bends downward, with a focus on how the airflow over and under the wing interacts, emphasizing that they cannot be treated as separate systems.
  • The explanation includes a mention of the void concept and pressure differences, though it is noted that these are simplified representations of the actual flow dynamics.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the specifics of lift generation, as there are multiple interpretations and models discussed, particularly regarding the role of airflow above and below the airfoil.

Contextual Notes

There are limitations in the explanations provided, including the simplification of complex aerodynamic interactions and the reliance on visualizations that may not fully capture the underlying physics.

Who May Find This Useful

This discussion may be useful for students or individuals seeking to understand the fundamentals of aerodynamics and airfoil design, particularly those who are new to the topic or struggling with conflicting information.

Hoophy
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Go easy on me I'm only 16 ;) I am utterly confused with the concept of "Airfoils", I have been doing some research on the web and so far all I have found is confusing descriptions that I do not understand and people arguing over which aerodynamics model for Airfoils is correct. The arguing and such only seem to increase my confusion. What I have taken from this so far is that the the Equal Transit Theory is incorrect, can somebody please explain to me how an Airfoil actually generates lift? Also I am confused about planes flying upside-down and flat Airfoils still managing to provide lift. Thank you for your assistance!
 
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So if I'm understanding this correctly lift is generated when air is deflected downwards? Here's my problem, does the air on top get deflected downward and if so how (structurally) does this happen, or is air on the bottom getting deflected and if so how? Is it air on the top and bottom? Is it something completely different?
 
All of that air in the vicinity of an airfoil gets bent downward (in the case of positive lift, anyway).

For the air on the bottom, you can (sort of) imagine it like the air is hitting the bottom and being deflected downward, though this is only partially true, as it doesn't take into account the influence of the upper half (as mentioned in the article with the skipping stone fallacy). Still, it may be useful to visualize.

For the top, consider that if the air flew over the top of an airfoil with positive angle of attack and did not bend downward, there would be a void created. This void would be at zero pressure, while the free stream is at some higher pressure, so it would tend to push the air flow back down against the wing. In reality that void never forms in the first place and the air "simply" bends down to follow the contour of the surface.

Those are the simplistic, half-truth answers that ought to help with visualizing what is actually occurring. The truth is, though, that the flow over and under the wing affect each other. They are one system where changes to one will affect changes to the other. In other words, you can't really treat the upper and lower regions separately like I just did any get the correct answer, but it ought to help with qualitatively understanding what is going on.
 
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Thank you so much for taking the time to help me out, I really appreciate your answers they were well constructed and clear. You have answered my question.
 

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