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Sturgeon's House

Collimatrix

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Everything posted by Collimatrix

  1. AMD has officially announced their 7nm-based chiplet-based CPU lineup. Their value-oriented 8-core CPUs were announced at Computex, along with a hulking 12 core part, while they delayed the announcement of the monstrous 16 core Ryzen 9 3950X until E3. (taken from here) Leaked benchmarks of what are probably an engineering sample indicate that the 3950X is probably the most powerful mainstream desktop CPU in the world. The new Navi GPUs were also shown at E3. As expected, the larger die-size "big Navi" is still nowhere to be seen. But the outlook on the introductory Navi cards is better than expected. They will be available starting July; same time as the new CPUs. Performance wise, they're not going to set the world on fire. But they have some interesting upscaling and latency reduction technology, and they do compete reasonably well with Nvidia's second-tier offerings. This video summarizes things well:
  2. Sounds like a bunkerfaust but scaled up.
  3. It looks like the suspension has been changed to independently-sprung road wheels with external coil springs.
  4. I just noticed something: You know how one of the identifying features of the T-64 is that, against all logic and safety considerations for the driver, the IR lamp is on the left? Look at this Object 435. They clearly moved the lamp later on in the design process!
  5. How was the rear gun supposed to work? It looks sort of like the gun on the TU-22M.
  6. Off the top of my head: 105mm Smoothbore was a German weapon. I think it's this one on the Keiler prototype: There was a later Rheinmetall 105mm that was rifled, essentially a roided-up L7 that fired stub-cased APFSDS and maintained backwards-compatibility with existing stocks of L7 ammo. That strikes me as a decent idea. The Brit 110mm was a rifled weapon and it was, by circuitous path, a halfway point between the L7 and L30. Yes, you read that correctly. There is a round of the ammunition on display in Bovington. The 110mm was a post-L11 design. The idea was, initially, to simply take an L7 and neck it out, just as the L7 was a necked-out 20 pounder. The pressures were cranked up a bit, but this caused case sticking. The gun was changed to a stub-cased design, and ultimately to a bagged case design similar to the L11, but with a new (and much better) breech sealing design. Some iteration of the 110mm was tested as armament for the Abrams, but rejected. The breech design was eventually recycled and used in the L30 120mm gun on the Chally 2. There's a little bit about it in this book, but otherwise what I've been able to learn about it is from scattered discussions around the interwebs.
  7. And another reason why polearms were usually the bulk of weapons, and why most Japanese arms didn't get the full "folded a thousand times" treatment.
  8. WHA's better stiffness also means slightly lighter sabot mass... or it did before the advent of segmented penetrators. This paper has more. Note that the paper is very out of date, as it mentions aluminum sabots as being the standard with no immediate replacement in sight. But it does cover several of the relevant considerations. It almost certainly occurs in complex targets. It's a function of how the rod material reacts to high rate loading. The softening of the material exceeds the work hardening rate. Doesn't really matter what it's smashing into, just that it's smashing really fast. Based on the USAF paper on autocannon ammunition design, I think that DU penetrators are a no-brainer for small-caliber, armor-piercing autocannons. The degree to which it simplifies projectile design, and the massive increase in behind-armor effect mean it is clearly superior. I could buy that whether DU or WHA is better for tank ammo hinges on other considerations.
  9. North Korea is insulting Biden using Trump's terms such as 'low IQ' individual Maybe this is a sign the talks will resume soon.
  10. At 7:45 he mentions the "famous green busses!" LOL
  11. I had read that the J2M had laminar-flow airfoils. Do you have any more information on that?
  12. Bad news for AMD's Navi GPUs: Executive summary: The most recent information and rumors has some of AMD's next-gen Navi GPU lineup becoming available in Q3 of 2019. However, the more muscular cards, the ones that are expected to (slightly) outpace NVIDIA's current best offerings are delayed until 2020. Furthermore, the Navi cards themselves may be a bit of a disappointment. Analysts are already pretty sure that Navi has encountered one major delay, which is why they were not announced at the January CES show. On top of that, the cards are reportedly experiencing thermal and clock speed issues. So, optimistically, the Navi lineup will be hot and loud for their performance, but will offer better performance to price than the current NVIDIA 12nm Turing cards. Moreover, both the PS5 and next-generation XBOX will use some variant of the AMD Navi chip, so it is likely that the next generation of games (certainly console ports) will be optimized for AMD hardware. However, with the delay of the high-end Navi cards until 2020, the time during which AMD will have the fastest GPUs on the market will be very short indeed. The very best of the Navi GPUs are expected to best the very top of NVIDIA's current Turing lineup (again, most likely at the expense of running rather hot and requiring big, noisy fans), but by early-ish 2020 when they show up, whatever NVIDIA has planned for their next-generation GPUs will have to be very close to market as well. I think the big takeaway is that the 10nm and 7nm nodes are very hard to design for. Intel has had big delays, AMD has had delays, and NVIDIA and Samsung have probably had big delays that they've managed to keep more quiet. Bottom line; the rate of improvement of gaming hardware is slowing down. Compare the GTX 1080 TI vs the RTX 2080. NVIDIA was able to make a card that was better than their previous best effort, but only just barely and at enormous cost. Sure, part of the cost was NVIDIA's thick margins, but a large part of it was also that the development of new microlithography nodes is now yielding less juice per squeeze than it used to. There's a good case to be made that the answer to "should I buy an RTX 2080 or a Radeon VII" is "see if you can get a deal on last generation's GTX 1080 TI; because those are about 90% as good."
  13. OK, I have a very obscure question. The T-80U, even before the T-80UD, was a T-80 that Kharkov had stuck their dick into. The turret on T-80U is recycled from the Object 478, which is what would have become the next-generation T-64 had it been selected for production. Did LKZ have their own ideas on what a follow-on to the T-80B would be like?
  14. I'm not sure what you're asking exactly. The AMX-30's gun, as I understand it, used exactly the same firing chamber dimensions as the L7, but it had a different rifling twist rate that was selected specifically for the Obus G. The rifling twist rate needed is a function of the moments of inertia of the shell, distance between the center of pressure and center of gravity, and shell velocity. With a shell with rotating and non-rotating components, I imagine this gets... interesting to calculate.
  15. Theoretical Modelling of Shaped Charges in the Last Two Decades (1990-2010): A Review This is the second paper I've ever seen that mentions multi-point initiation of shaped charges.
  16. You can see that there are ball bearing races in there also, at the front and back. But a shell in a rifled gun rotates at approximately a billionty RPM, and a ball bearing isn't actually perfectly frictionless. It just has extremely low friction. But even an extremely low fraction of the enormous G-force in a gun tube multiplied by a billionty RPM is enough to disturb proper jet formation: By floating the inner body of the shell on a cushion of gas, the acceleration on the inner and outer shell bodies is made approximately equal, and the axial force on the ball bearings is reduced to a low enough value that negligible torque acts on the inner shell.
  17. I'm curious as well. Scrapping a lot of large, older vessels with high maintenance and crew requirements to save money makes sense, but I didn't think that the Russian ship-building yards were in a position to provide replacements.
  18. This video explains why, so far, integrated graphics have sucked: and note how this explanation will not be true anymore once AMD starts producing their 7nm chiplet-based designs in earnest. Coreteks has a new video talking about AMD's roadmap for the future: (Note also his prediction of Amazon/Twitch announcing a streaming games service similar to Stadia. We shall see!) But something we should be keeping in mind is that Intel is getting into the GPU game soon, and that Intel is working on heterogeneous chiplet architecture as well. So, most likely AMD will lead with the CPU+GPU glued together chips, but Intel will only be months/a couple of years behind them.
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