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In searching for some relevant photos for a lecture I am writing, I came across a question "Does lift equal weight in a climb?". The first answer, with most upvotes, is not only very confusing but half of it is complete and utter nonsense. It is obvious nonsense to anyone who knows the slightest bit about principles of flight, even at PPL level. It assumes that the writer can just redefine "lift" as he or she wishes, going on to define it half the time as a vertical force (which is wrong; it is always defined as being normal to the relative airflow, so at right angle to the flight path).

I am a new user with zero reputation so I cannot reply to this or even downvote it. Yet I teach aviation both in EASA ATOs and university, and it is troubling to me that my students and others will see obviously misleading comments like this with high upvotes because the utterly clueless user who wrote it has reputation. Those students, trying to learn about aviation, will come away more confused and with less understanding.

If you cannot stop spreading misinformation then you should be shutting down this site.

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  • $\begingroup$ Is this the question you found? $\endgroup$
    – Ralph J Mod
    Mar 20, 2023 at 15:12
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    $\begingroup$ Does this answer your question? How should we handle wrong but most-upvoted answers? $\endgroup$
    – sophit
    Mar 20, 2023 at 15:27
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    $\begingroup$ It doesn't take much reputation to be able to answer a question, maybe get involved with the community and contribute. This site works best when people with subject matter knowledge participate. $\endgroup$
    – GdD
    Mar 20, 2023 at 16:24
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    $\begingroup$ Can someone who "knows the slightest bit about principles of flight" explain to me if this question really is critically wrong, or wrong by opinion of this user? My lowly PPL leaves me somewhat unclear on the actual issue $\endgroup$
    – Jamiec Mod
    Mar 20, 2023 at 17:14
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    $\begingroup$ @Jamiec I'm only a particle physicist, not an aerodynamicist, but to me that answer looks perfectly correct (and I have up-voted it). Note that the answer slowly adds more and more "correctness" to finally arrive at the correct answer (last image). All previous images are "wrong" because they are part of the derivation and don't show the full picture yet. IMHO this is well explained in the answer. $\endgroup$
    – Bianfable
    Mar 20, 2023 at 17:25
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    $\begingroup$ @Bianfable Ok, that's what I thought too with my fairly basic understanding. Thanks for clarifying. I can only wonder if this OP only read the beginning of the question and didnt read through all the detail. Perhaps they'd like to clarify what exactly is wrong here $\endgroup$
    – Jamiec Mod
    Mar 20, 2023 at 17:41
  • $\begingroup$ @Jamiec I agree with the questioner: the first answer is definitely not clear. Lift is the component of the aerodynamic force perpendicular to the freestream, by definition. Drag is the component (always positive) parallel to the freestream, also by definition. In the special case where the aircraft is flying parallel to earth with a small AoA then lift and weight are opposed. $\endgroup$
    – sophit
    Mar 20, 2023 at 17:44
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    $\begingroup$ I 100% share your frustration and that's why I asked basically the same question some times ago but! if your students look for answers from random people on the internet then the issue is upstream in the system and not on the internet. $\endgroup$
    – sophit
    Mar 20, 2023 at 17:50
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    $\begingroup$ @sophit Did you read past the first image in that answer? That's exactly what the OP does after "But it's more usual to define lift this way". $\endgroup$
    – Bianfable
    Mar 20, 2023 at 18:25
  • $\begingroup$ @Bianfable: I agree with the questioner i.e. that "half of it is" quite confusing and doesn't answer the original question. Plus all the pictures in the answer are formally not correct. $\endgroup$
    – sophit
    Mar 20, 2023 at 18:47
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    $\begingroup$ You would be wiser to simply ban all internet research in your class. Give a zero to anyone who uses the internet. This site is hardly unique in giving information which deviates from your approved curriculum. Who's to say your curriculum is more correct? But if you think that gives you cause to tell other sites what to do, then you need to take a Civics class. Because that's not how democracies work. While you're working on the first amendment, think about freedom of the press, and the owner of the press's free choice to choose what to print. $\endgroup$ Mar 20, 2023 at 19:07
  • $\begingroup$ @Bianfable: the second picture in this answer would be more correct $\endgroup$
    – sophit
    Mar 20, 2023 at 19:18
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    $\begingroup$ @RDX72 -- re "It is obvious nonsense to anyone who knows the slightest bit about principles of flight, even at PPL level" -- sorry, but you just made a factually wrong statement, so by your own logic we should do something to delete your question or at the very least put a big red flashing "warning, inaccurate content" label on it. Do a survey of private pilots and I guarantee you the majority will believe that more lift is needed in climbing flight than in level flight, so your statement is incorrect. $\endgroup$ Mar 22, 2023 at 13:34

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I am the person who asked the question, and who accepted another answer at first, precisely because of the first pic in the most upvoted answer - which was posted because of the way I asked the question. Which originated from my experience with helicopters, where the vertical component of airstream in a climb is regularly overlooked.

Quite some time later I re-read @PhilFrosts answer, fully noticing the transitional rationale from earth-oriented axes to aeroplane-oriented ones. And then accepted the answer.

May I recommend re-reading the full answer again. It does a very good job at illustrating why lift is smaller than weight in a climb (since lift is defined relative to airstream), even though vertical forces are larger.

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  • $\begingroup$ Sorry but, as I've also written in the comments above, that answer is confusing at least! One cannot define lift as needed! "It depends on exactly how you define "lift" and "weight"... seriously?! Lift is defined as the the component of the aerodynamic force perpendicular to the freestream, full stop. The pictures in the chosen answer are also not correct because they do not show the freestream so it is formally not possible to draw the relevant lift and drag... I agree though that the second part is correct (but still confusing in my opinion). $\endgroup$
    – sophit
    Mar 21, 2023 at 8:33
  • $\begingroup$ @Koyovis I ratify your decision to accept the answer you had chosen. The answer provided by me for the question in the present instance, is not in opposition to your decision, but rather to explain an aspect of my experience regarding the sometimes intractable nature of language and understanding. Seemingly, those issues are apparent here and stand in stark contrast. $\endgroup$ Mar 24, 2023 at 16:34
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Let’s stop and think about this for a moment. We understand OP’s frustration with the answer to the question about lift and an aircraft in climbing flight. But let’s think about the proposition for answering the question. We do not know the state of knowledge of the general reader when we develop and post an answer to a question. This can become troublesome, particularly for the person answering the question. Permit me to say, I should know… Here are some thoughts -

  1. The question must be stated clearly regarding the subject of the question. This climbing-flight question clearly meets this objective.

  2. In many cases, a lot of time is spent trying to answer the question by thinking through and evaluating what the asker is trying to find out. The provided answer clearly lays this thinking out.

  3. The answer must be stated in an understandable way by stating the relevant facts in a clearly understood context. Not all readers of the answer are “on the same page” regarding their state of knowledge about the facts of flight. My view is that this was done in a satisfactory way by this answer.

Meeting these objectives is not always easy. Many hours can be spent developing an answer that gets “off in the weeds.” Sometimes conceptual elements are difficult to connect in a meaningful way. Sometimes the simplest answers can become the most difficult to provide. But these are not excuses for providing incorrect or inaccurate answers. Every question should be given the best possible effort to provide the simplest, most accurate and correct answer. Sometimes correct answers require a lot of thought. In some instances, answers may require months of research and analysis; yes, right here on SE. I have provided some of them.

Consequently, when answers are provided to meet the broadly varying aspect of knowledge the audience may have, the answer can be seen by someone with specialized knowledge as inaccurate or incorrect. Or, as can sometimes be the case, the person reading the answer already has a world view that conforms to their conceptual way of thinking, and not to the factual world that exists. In these instances, the answer may be perceived as being incorrect or wrong, even though right. The bridge of knowledge is too far to cross for some; I have had to take down an answer because of this consequence.

Here, let me offer a simplified explanation of how this can happen. In the present case, OP’s original question wanted to know something about lift related to an aircraft that was climbing. Many people do not understand what lift is in terms of aircraft flight. In the general sense, a conceptual view of lift is in opposition to weight, as in lifting a weight. In the aerodynamic sense, lift is a force perpendicular to the path of flight. The dilemma faced by the answerer is how to reconcile this difference without writing an extended text on aerodynamics and forces on an aircraft in flight. Remember, as was stated in context, not all of the readers of this question know what these forces are, and they may think lift is in opposition to weight. They may have a different world view of the subject based on their own experience or expertise, not on the facts as they actually exist.

Understandably, seeing these aspects may not be in the view or aspect of knowledge had by the OP of this current question, the one seeing the provided answer as incorrect. Nevertheless, in my mind, Mr. Frost has made every attempt to frame the context of his answer in correct terms. He has made a clear answer in terms of weight, and how both thrust and lift bear that weight for an aircraft in climbing flight. This was done with clear deference to the broadly varying state of knowledge had by an audience that may be reading Koyovis’ posted question about lift and an aircraft in climbing flight. Unfortunately, there is nothing we can do, once we post an answer, to address the world view had by the reader of our answers. Sometimes our answers can be seen as so wrong that they have to be rewritten to address these issues. Did I mention that I had to take down an answer because of this??

In closing, allow me to offer a brief and humble explanation of my root concern regarding the question at hand, that being perceived incorrect answers. My actions on SE have been to only provide answers, not ask questions. I have seen many issues queried, particularly on occasion regarding aircraft accidents. Although I have provided answers or comments about the unintended and fatal consequences of actions taken by pilots, I have specifically avoided answering questions regarding consequences in aircraft accidents. The prospect of some aspect of legal liability regarding an answer is quite chilling. And when I encounter issues questioning the correctness of an answer I have provided, I become concerned. In particular, I become quite concerned. My answers are fully researched and validated. My own fear is that if someone acts on the belief that my answer was correct and then suffers an adverse consequence, I may find myself in court. When people comment on an answer, particularly in a way that is critical or in an attempt to get me to revise the answer, dictate what the answer should be, or bully to suit their needs, how do I address this? If persons suffer adverse consequences by taking actions based on my answers, what am I to do? If I even think, from my own position of expertise, that this potential is looming or has become apparent, I will take down the answer. I am not interested in entanglements with legal issues. I’ll just play it safe and prevent suffering unseen grief. I understand, though, some may feel this is an unfounded fear. But I still have to discern for myself the best course of action to be taken.

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  • $\begingroup$ Re "When people comment on an answer, particularly in a way that is critical or in an attempt to get me to revise the answer, dictate what the answer should be, or bully to suit their needs" -- I sure hope that that wasn't aimed at comments like this one, which was only meant as constructive criticism-- aviation.stackexchange.com/questions/97987/… -- sorry to hear you feel there is "bullying" going on at ASE, but is it possible that another reader might describe it differently? $\endgroup$ Mar 25, 2023 at 12:39

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