Aerodynamics thread

[SDWatcher]

My point about the difference between a square and a trapezoid is called an analogy. It’s the exact same point as pointing out the difference between a 2D object and a 3D object. The point is you can’t accurately use one shape that’s different to represent the characteristics of another.

Then you may want to read message #2945 again, to understand the conditions that geometric differences, may numerically impact the calculated results. It is about numerical accuracy, for which you can't explain at all.

It’s irrelevant if the model is parameterized as a 2D surface or a flat 3D object (And in fact you *can* get a nonzero output for drag calculated against a 2D object, if you simplify drag down to interaction with just the surface of the object, since surfaces are two dimensional, so yes, I do know what I’m talking about here and you clearly don’t). The point is the same.

If you were to calculate surface interactions in numerical models, it is a boundary-layer problem, where the parameters are derived from thin sheets, which is still a 3D model. So you don't know what you are talking about, again.

They’re using a highly imprecise model to represent the thing they’re actually interested in, which is the J-20. That is the point. That’s not a straw man argument. I’m not saying the study says something thing that it doesn’t say and then attacking the thing it doesn’t say. I’m directly critiquing an element of the model that is actually part of the model.

Their model is actually unreleased and you are criticizing the paper from Virginia Tech, based on your own *speculations*, essentially making up your own problems, which are indeed quintessential strawman arguments.

 

[ougoah]

You're way to attached to your faux analysis.

It's not an all encompassing judgement. What exactly is the issue with mentioning HOBS missiles, numbers, and relating it to strategy?

 

[ougoah]

Can someone post up the VTech paper so everyone can access it? One of you are right and for now it's hard to tell because we don't know the assumptions and claims made by the paper. Both of you are arguing from different points and you're both respectively correct on principle. But the details are important. Does the VTech paper actually build its model from a flat 2D construction? How would that even work? Or was that image simply a cross section taken out of context and maybe made just for show, while the actual model uses far more accurate 3D modelling and reasonable sets of varying assumptions where they build a range of results out of. Without knowing any of the above (maybe you have both read the paper thoroughly, maybe not) 2 pages of this same line of arguing will never end. However it's not impossible that PLAAF has looked favourably on different methods to defend its airspace from a superior invasive force. It is fighting a losing battle with lower production rates of 5th gens and lower starting base. Asymmetric methods are its only hope to conventionally ward off USN and USAF for now. This overall strategy is not exclusively for air superiority nor is it exclusive of.

 

[Inst]

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[Jura The idiot]

Then you may want to read message #2945 again, to understand the conditions that geometric differences, may numerically impact the calculated results. It is about numerical accuracy, for which you can't explain at all.



If you were to calculate surface interactions in numerical models, it is a boundary-layer problem, where the parameters are derived from thin sheets, which is still a 3D model. So you don't know what you are talking about, again.



Their model is actually unreleased and you are criticizing the paper from Virginia Tech, based on your own *speculations*, essentially making up your own problems, which are indeed quintessential strawman arguments.

do you think

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is completely off like ... as if a flow around

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had been simulated while the actual hull was

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?
LOL!

 

[azretonov]

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Umm... Is this the whole "paper"? Where can I find the actual published article with you know, abstract and everything? Not that I claim anything -- I just have an academic curiosity in this matter. I've access to numerous scientific databases so just a few hints can do the job.

 

[Jura The idiot]

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Umm... Is this the whole "paper"? Where can I find the actual published article with you know, abstract and everything? Not that I claim anything -- I just have an academic curiosity in this matter. I've access to numerous scientific databases so just a few hints can do the job.

LOL apparently it's one of seven years old
Student Projects/Presentations

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Spring 2011

Airplane analysis projects

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  by Arjun Chopra, Mike Hazuda, Randall Madison and Chris Smith
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  by Anish Bhatt, Marie Harvey and Ryan Hofmeister
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  by Kris Douglas, Sam Kantor, Michael Palles and Grant Parrish

 

[azretonov]

Student Projects/Presentations

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"Student presentations" hmmm... So Its' credibility is highly questionable, since It's not an 'article' and I can hardly call it 'academic'... Still, if there is an actual publication, I'd very much like to read. But if there isn't one, we should do go on with J-20 rather than some student studies.

 

[SDWatcher]

I suppose the results should be judged by the contents, instead of whether it is a student presentation, as drag calculations with finite elements, are compatible with senior or masters-level projects. And it is considered academic and only questionable by knowledge, not by personal status.

 

[azretonov]

I can present you dozens of studies in a similar fashion -- better prepared even -- but that wouldn't make them true either now, would that? It might be sufficient for you at its' current shape and I can respect that but it is nothing to be considered academic as it doesn't have enough data presented with the 'study' to begin with. I, certainly am not claiming to be an expert on this specific matter but as an academician myself I'd rather prefer a proper study with sufficient data. That's why I've been asking for the actual publication -- the article if you would. If there isn't one to begin with, I'd hardly call this an academic study. Using it as a source is a person's own responsibility, that I wouldn't object unless it's a professional platform...