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Cessna 172 3-view diagram

Why does the Cessna 172 have a more pronounced taper on the trailing edge as opposed to the leading edge?

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2 Answers 2

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That's just the natural taper you get when the spar is straight in plan view, and the spar depth and airfoil is shrinking as it gets to the tip.enter image description here.

The chord is constant out to the strut attachment so the LE and TE is parallel. As the airfoil gets thinner outboard of that, if you keep the same profile it shortens chordwise as it gets thinner. Since the taper's neutral axis, the spar, is near the front at 15 or 20% of chord, the apparent taper in plan view seems more extreme at the TE.

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  • $\begingroup$ Maybe you can add this cutaway to your answer to help visualise your point $\endgroup$
    – sophit
    Jun 19, 2023 at 18:42
  • $\begingroup$ @sophit Great idea thanks. $\endgroup$
    – John K
    Jun 19, 2023 at 21:50
  • $\begingroup$ It could be argued that there is nothing "natural" about this. It is an engineering decision on how to balance conflicting goals, including performance in various flight regimes and cost of manufacture as examples of two conflicting goals (designing for better performance would cost more to produce). $\endgroup$
    – ghellquist
    Jun 20, 2023 at 20:31
  • $\begingroup$ "Natural" simply means the normal geometric result of tapering thickness with the same airfoil profile and a neutral axis forward. You are reading way too much into it. $\endgroup$
    – John K
    Jun 21, 2023 at 2:40
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You know, I never thought of it as a "natural" taper, but something the Wright Brothers found out in their early (low subsonic) wind tunnel experiments was that taking a little off the trailing edge corners of the "Hershey Bar" wing does save a little in drag.

Some like a rounded trailing edge, but a simple taper is easier to manufacture.

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    $\begingroup$ The balance between "empirism, performance, cost of manufacturing" behind the fact that all medium passenger jets are boringly equal. If you excel in the first and third parameters, your name is Boeing or Airbus. In the second and third, your name is Lockheed Martin or Mikoyan-Gurevich If you excel in the first and second: Hi Burt Rutan, how are you? $\endgroup$
    – EarlGrey
    Jun 20, 2023 at 15:00

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