http://bewaterfreediving.com/basics-...2MhaZwPqpYUNvY
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Just looked at that article, and based on my background at a CalTech graduate in fluid dynamics and 40 years as a professional engineer let me just say.
Choke choke gag ack choke
They take a large number of terms that have been well defined and have standard definitions, throw all that away, an define their own. Technical areas all have their own little language so we can all talk to each other and know what we mean. Making up a new one just complicates a situation.
Examples: Its drag coefficient, not shape coefficient.
Its pressure drag, not frontal drag.
Friction resistance is close, friction drag is better.
Its base drag, not drag resistance.
The falling objects figure: The two half spheres are swapped. Having the curved part in front gives a lower drag coefficient.
Wave resistance: Yes! They used the actual common term!
Propulsive resistance: Normally what is used is propulsion efficiency. However with a monofin, most of the efficiency loss is from induced drag.
Yes, monofins are wings. In fact, the basic understanding of fluid dynamics is there throughout the entire article. But why O why complicate an already complicated science by defining a new language to describe it?
The drag equation is actually
Drag = 0.5 * rho * V^2 * A * Cd
where rho is the fluid density (which means this equation works for water, air, liquid hydrogen, or any fluid)
V is the speed
A is the area (frontal area is common, but for airplanes, the wing area, as seen from above, is used. In describing the fluid dynamics of just a monofin, the area of the fin would be used).
Cd, the drag coefficient. A square flat plate has a Cd = 1.2. A beautiful streamlined fish: Cd = 0.05 to 0.02.
So, use the article to get an idea of what makes drag, and what makes thrust. But please do not use, or even remember their terminology.
it has been translated from french (noted at the bottom and within the citations)
The fact that it was translated got me curious. What does "Drag coefficient translate to? Google says "coefficient de traînée". If I put "coefficient de traînée" into google, it comes back with "drag coefficient". "Shape coefficient" translates to "coefficient de forme".
This still makes it look like the author was using non-standard terms. But am I right that everyone, even in different languages, uses the term "drag coefficient" or its translation? I looked for a copy of the iconic Hoerner text "Fluid Dynamic Drag" that had been translated to French, figuring the translation would have been done years ago, before Google translate. In it drag coefficient is "coefficient de traînée".
I can only conclude that the author of the article redefined all the accepted terms for some unknown reason. Maybe he thought that monofin users needed to have the material simplified so they could understand it, which is rather insulting.
As someone who works in the translation field, if someone was handed this and didn't understand the content (very likely) then it's very possible it was translated using terms they thought were equivalent but they don't have the background to know. I wonder if the original French version is anywhere online?
yup, google translate isn't accurate either. We run into the same issues in the aerospace field when we translate for the military into or from French for pilot training. We have to have subject matter experts in the field who are bilingual and can correct issues. We kept running into certain examples exactly like this where it would take us a while to understand what term they mean, and if you are not proficient in the skill yourself and only doing the translating, you don't question the technical accuracy. I can't imagine someone with a blog has the resources to have subject matter experts on hand to deal with stuff like that.Quote:
Originally Posted by MerEmma
Yeah, definitely. That article is extremely dense and needs consultants for an accurate translation. Also, Raina, can I ask what your connection currently is to the aerospace field? That's awesome!
I have been working for years as an instructional designer creating all the training used for the Canadian Military for most things aerospace related. Currently I am writing training and assessment for the new Canadian search and rescue aircraft and we also incorporate simulation training into it :) I love it. I went back to work after some health issues and after we had to become care givers to Sean's (now passed) mom. I really enjoy it though and they all support my mermaid work too. Fun story I recently shared this information in the finfolk podsquad and some mermaid accused me of making it up because her husband was a recreational pilot in the US and she also said search and rescue isn't a big deal LOL. We run into these technical accuracy issues ALL THE TIME because the original manual for the aircraft was Brazilian and then the Canadian one is french/English. Formulas get changed, technical terms, all the time. That's why we have subject matter experts do multiple layers of review.
https://scontent-lga3-1.xx.fbcdn.net...3d&oe=5EC99E3C
https://scontent-lga3-1.xx.fbcdn.net...13&oe=5EC573EF
I love my job but I can never talk TOO much about it because a lot of the stuff we do is classified and I literally have Nato Secret Security clearance LOL. I wish I could tell people more because it's CRAZY all the amazing technology out there.
Although there can be issues in doing a good translation of technical material, I think that is not all that is going on here. The equation given for drag, drag = k * A * V^2 is not the standard equation. A translator would not change an equation just because they are not familiar with the material. The standard equation is Drag = 0.5 * density * Cd * A * V^2. Looking at these, we see that k is not equal to Cd. The only way I see this making sense is if the author defined his own term, then modified the standard drag equation to fit his term. Again, the main reason I can see for the author doing so is the rather insulting idea that including the density in the equation would make it too hard for freedivers to understand.
Another example of why this is so inconvenient: The way the author defined shape coefficient means the shape coefficient for fresh water is not the same as the one as for salt water, as they have different densities. But the drag coefficient is the same for both. In fact, you could pose a freediver in a wind tunnel, measure the drag coefficient, and use that same value for water.
I don`t know who translated it, but everything is clear and well written. Of course, the quality of this translation is not so good, as these guys can do https://thewordpoint.com/languages/f...ation-services but it is easy to read. If the translation were done by professionals, it would be more expensive.
Well i'm not at all good with the technical stuff but for the from french to english part i'm kinda able to give at least a more or less valuable opinion I guess since french is my maternal language, i've only learned english at school, so at least i kinda can give some expertise about what is making sense or not in the language i speak since birth I suppose. I am bad with physical science so i don't really get the deep meaning but i have searched and yes "coefficient de trainée" exists in technical french and so does a french physics notion named "facteur de forme" which to me seems to be what you call "coefficient de forme". Here is the french wikipedia page on the term coefficient de trainée : https://fr.wikipedia.org/wiki/Coeffi...%C3%AEn%C3%A9e and indeed they do traduce it in wikipedia english to "drag coefficient" in the english wikipedia page : https://en.wikipedia.org/wiki/Drag_coefficient, and about the "facteur de forme" they do explain it in french here : https://fr.wikipedia.org/wiki/Facteu...%C3%A9canique) but it does not have a english page equivalent so i searched and it seems that in english there is no real equivalent. At least to my very limited knowledge. So indeed there seems to be french physics term in the text which were just translated without cultural transposition and therefore that may be why it might be difficult to read for some. Sorry if I'm a litte out of topic i have limited knowledge of physics and i do not read/understand fully big texts with lot of scary equations but i did my best try to help.