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J-20 5th Gen Fighter Thread VI
- Thread starter siegecrossbow
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Your answer is I'm an idiot. So we're in a flame war and we're trading like for like.
Moreover, check out the actual discussion of J-20 radome size. No one actually disputed it at the time; you're digging it out the same way you attempted to mischaracterize my "misreading" of Kopp's chart. For an outside observer, they can clearly note that you do not need 3D photography to determine the relative distance of an aircraft with known dimensions.
The only reason you need multiple frames of reference is that if we use the perspective distortion approach on something that looks like a J-20, we can't actually tell the difference between a J-20 1:20 scale model and an actual J-20, and because of scaling issues, we can get figures 20 times greater for length and distance between a J-20 and its model. With multiple frames of reference, we can determine the relative size by using the distance between multiple frames of reference.
Moreover, check out the actual discussion of J-20 radome size. No one actually disputed it at the time; you're digging it out the same way you attempted to mischaracterize my "misreading" of Kopp's chart. For an outside observer, they can clearly note that you do not need 3D photography to determine the relative distance of an aircraft with known dimensions.
The only reason you need multiple frames of reference is that if we use the perspective distortion approach on something that looks like a J-20, we can't actually tell the difference between a J-20 1:20 scale model and an actual J-20, and because of scaling issues, we can get figures 20 times greater for length and distance between a J-20 and its model. With multiple frames of reference, we can determine the relative size by using the distance between multiple frames of reference.
My argument is about honesty. For instance, take b787. It's not impossible that he's a Soviet-trained aerospace engineer, with all the expertise needed to design modern fighter planes. But there's nothing stopping him from making stuff up or deliberately distorting facts to back his claims that the Su-35 is the best and the Su-57 is even better. Likewise, if the evidence suggests that the J-20 isn't as stealthy as, say, the F-35, the fact is, the evidence suggests the J-20 isn't as stealthy as the F-35. That doesn't mean that the J-20 isn't as stealthy as the F-35, it means that the available evidence suggests it's less stealthy. Unless we actually have the actual RCS diagrams for both the F-35 and J-20, we can't know, and it is true if we say that we can't tell their relative RCS. But to say that the evidence does not exist, and that it does not suggest a stealth penalty for the J-20, is dishonesty.
No, my answer is you make weak assumptions and then use bad analytical methods extend confident claims, and then ignore and denigrate people who point out why your analytical methods aren’t good. When you get substantive criticism you don’t actually engage with the content of the criticism. Instead you insist you must be in the right in some way or form on a backward sliding scale of weaker and weaker arguments. You seem a lot more interested in looking authoritative than learning. (Cue and point your recent attempt to point out a frame that shows condensation around the J-20 in a turn without acknowledging or recognizing that condensation without any data on atmospheric conditions tell us nothing).Your answer is I'm an idiot. So we're in a flame war and we're trading like for like.
Our multiple discussions over the years about the J-20’s radomes size includes you trying to tell me I should be happy to agree with you that the J-20’s radar is larger because that means it’s likely to be more powerful, as if that was the motivating desire behind my comments *despite* my points to the exact contrary.Moreover, check out the actual discussion of J-20 radome size. No one actually disputed it at the time; you're digging it out the same way you attempted to mischaracterize my "misreading" of Kopp's chart.
Your reading of Kopp’s chart was that the J-20 shows a large return at the nose, when Kopp himself said it wasn’t a big deal, and when *anyone* who thought about this even a tiny bit would note the readout of such analysis on the nose isn’t useful because the nose needs to be RF transparent for the radar. I’m not mischaracterizing anything here. You just don’t want to cop to your own errors.
I did not say you needed a 3D photograph, but video from two angles, and *no* outside observer has noted what you noted because *no* outsider observer here takes the kinds of baseless analytical liberties you do.For an outside observer, they can clearly note that you do not need 3D photography to determine the relative distance of an aircraft with known dimensions.
If you don’t have multiple frames of reference then you need detailed information on the camera optics. You have provided neither in your analysis. Instead of owning up to this basic critique and how hollow your analysis is you have chosen to accuse others of being fanboys.The only reason you need multiple frames of reference is that if we use the perspective distortion approach on something that looks like a J-20, we can't actually tell the difference between a J-20 1:20 scale model and an actual J-20, and because of scaling issues, we can get figures 20 times greater for length and distance between a J-20 and its model. With multiple frames of reference, we can determine the relative size by using the distance between multiple frames of reference.
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If you were genuinely concerned about honesty you’d have simply acknowledged that the videos are kinda useless for gleaning any useful information. I do not think you are a fundamentally dishonest person Inst, but dishonesty in defense of well intended ignorance is still dishonesty.My argument is about honesty. For instance, take b787. It's not impossible that he's a Soviet-trained aerospace engineer, with all the expertise needed to design modern fighter planes. But there's nothing stopping him from making stuff up or deliberately distorting facts to back his claims that the Su-35 is the best and the Su-57 is even better. Likewise, if the evidence suggests that the J-20 isn't as stealthy as, say, the F-35, the fact is, the evidence suggests the J-20 isn't as stealthy as the F-35. That doesn't mean that the J-20 isn't as stealthy as the F-35, it means that the available evidence suggests it's less stealthy. Unless we actually have the actual RCS diagrams for both the F-35 and J-20, we can't know, and it is true if we say that we can't tell their relative RCS. But to say that the evidence does not exist, and that it does not suggest a stealth penalty for the J-20, is dishonesty.
latenlazy:
First, my point is that modern DSLRs minimize lens distortion through software; look up a review of a DSLR and look at how cameras, through software alone, remove barrel distortion from the optics. Second, put another way: if we see a video of a J-20 doing a 45 degree/second turn, would you treat it as evidence for the J-20's maneuverability? But we don't have one, so you're spending time bashing video analysis. Admittedly, it's a lot of difficult work, and delivers information of relatively low-quality, but it is still information and it can be stenciled together to provide flight characteristics of the aircraft, as with my canteloupe example.
First, my point is that modern DSLRs minimize lens distortion through software; look up a review of a DSLR and look at how cameras, through software alone, remove barrel distortion from the optics. Second, put another way: if we see a video of a J-20 doing a 45 degree/second turn, would you treat it as evidence for the J-20's maneuverability? But we don't have one, so you're spending time bashing video analysis. Admittedly, it's a lot of difficult work, and delivers information of relatively low-quality, but it is still information and it can be stenciled together to provide flight characteristics of the aircraft, as with my canteloupe example.
As to the J-20 having the largest radar aperture, you should try not to make a joke out of yourself. This isn't merely through my measurements, we have big shrimps claiming the J-20 has the largest radar aperture of any 5th generation fighter. Moreover, the ratio of radar aperture to radome diameter is pretty constant for all radars. So, what's your point?
As a hobby photographer I can tell you that software solutions for lens distortions 1) Must be included in post processing, so you’d need to demonstrate that post processing was done on the video 2) They don’t fix scale or proportion or distance. They just counter distort to make bent lines straight. Depending on how that’s done it can further distort the actual scale, proportion, and distance of the objects in the frame.latenlazy:
First, my point is that modern DSLRs minimize lens distortion through software; look up a review of a DSLR and look at how cameras, through software alone, remove barrel distortion from the optics. Second, put another way: if we see a video of a J-20 doing a 45 degree/second turn, would you treat it as evidence for the J-20's maneuverability? But we don't have one, so you're spending time bashing video analysis. Admittedly, it's a lot of difficult work, and delivers information of relatively low-quality, but it is still information and it can be stenciled together to provide flight characteristics of the aircraft, as with my canteloupe example.
That said, you misunderstood my point. I wasn’t just talking about lense distortion. I was also talking about knowing exactly what field of view the lense is so that we know what the perspective grid at x distance from the camera looks like. Especially with small distant objects in the frame though even knowing the perspective grid details get so small you’re unlikely to get precise depth measurements. And good luck getting a proper measuring stick with a single object without knowing for sure that there’s at least one frame where the object of interest is facing the camera at right angle along the dimension you intend on using for distance reference.
And no if you did the exact same thing and calculated a turn of 45 degrees/second I would not treat it as evidence of anything, not without very clear parameters and conditions qualified that are missing. I’m bashing your video analysis because admitting that we know nothing is better than pretending that we know something off shoddy data. Having bad data is *worse* than having no data. Would you want your doctor to “stencil” in a diagnosis of your ailments off poor quality data? I somehow doubt it.
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Oh. So testimonial evidence works when it favors what you argue but we should be suspect of it when it doesn’t? What happened to being skeptical of official source claims about the J-20’s manueverability. Nice double standard there.As to the J-20 having the largest radar aperture, you should try not to make a joke out of yourself. This isn't merely through my measurements, we have big shrimps claiming the J-20 has the largest radar aperture of any 5th generation fighter. Moreover, the ratio of radar aperture to radome diameter is pretty constant for all radars. So, what's your point?
@ougoah:
Note we have a statement of PLAAF test pilots claiming that the J-20, in their simulator, has good maneuverability in subsonic but excellent in supersonic. So your claim that the PLA never says anything about their pilots is false.
Yes that's true but they've never given specifics. I don't see the point of your argument re. F-22 pilots willing to give ITR and STR details and PLAAF pilots not giving any for J-20 is evidence for its less than competitive performance. Okay if your point was that F-22 performance is better than they are willing to show and discuss, then J-20 must be far off F-22's performance since what PLAAF is willing to show is less than impressive compared to what is revealed for the F-22. I've nothing to say to that. While it isn't necessarily untrue, you're assuming both parties are comfortable revealing the same margin of performance. It's definitely possible J-20 performance hasn't been completely shown and the statements about its fantastic supersonic handling, while unsubstantiated, is also not disproven.
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