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Collimatrix

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Everything posted by Collimatrix

  1. I think Trump weakening US soft power institutions is a temporary phenomenon. The reason he's doing it isn't because he necessarily has some ideological opposition to soft power. For instance, the video that was shown to the North Korean leadership during the Singapore talks dangled the carrot of integrating North Korea into the world economy so they could enjoy the same legitimacy and prosperity that their neighbors do. The reason that Trump is at odds with US soft power institutions right now is that they are filled with people who hate his guts and want him gone. There's a reason I've joked about Trump opening gulags; the US government is full of people openly scheming to get rid of Trump. Their competence is doubtful, but not their intentions. Trump will do everything in his power to increase the importance of institutions that are loyal to him at the expense of institutions that try to undermine him. But this state of affairs cannot last forever. Either Trump will go away, and things like the State Department and various NGOs will resume some of their former importance, or Trump will prevail and large parts of the US government will be effectively restructured. Either way, things will change.
  2. Uh oh, it looks like some people are already tired of all of this winning:
  3. Collimatrix

    Israeli AFVs

    I misunderstood Serge. I thought he was referring to the air circulation system for the engine radiator when in fact he was speculating that this doubles as an IR countermeasure.
  4. Collimatrix

    Israeli AFVs

    It's possible that's what they were going for, but it's possible to camouflage a vehicle from IR sensors quite well without any active cooling.
  5. Collimatrix

    Israeli AFVs

    It has to be. Any engine powerful enough to drive a modern tank needs lots of air; either air to run through the engine core of a gas turbine or air to cool the cylinders or radiator of a diesel. This is one major disadvantage of the engine-in-front design; there needs to be a set of big-ass holes somewhere to let the air in and out.
  6. "Hill to die on" suggests a Pyrrhic last stand, but they can't even accomplish that much.
  7. ESR and VIM/VAR steels are used pretty extensively in tanks. Aside from torsion bars, they make mighty fine gun tubes and they're a good choice for inner layers of armor because they have less tendency to spall. They are used outside of military applications, but in predictably expensive and demanding fields like biomedical and aerospace. The bolts of AR-15 rifles are made of Carpenter 158, which is an electroslag refined steel. But the use of these steels is confined to applications where performance to weight ratio is paramount. The process for making them is energy intensive and demanding, and this is reflected in the price. I doubt that any suspension that's competitive on a modern MBT will have much in common with civilian vehicle suspensions. I think, in general, this is part of what has driven the cost of new military technology so high. This isn't the 1940s and you can't make a tank engine by gluing five automobile engines together. Top-of-the-line military hardware has very production commonality with civilian products anymore, and that drives the prices up.
  8. Alright, we've got documents threads in aerospace and tanks, we need some for small arms now too. Small arms technology lags other fields by decades, by here at Sturgeon's House, it only lags by months! General Design Theory Treatises: First up is a link to George M Chinn's The Machine Gun. This is the premier English-language book on automatic weapon design theory. Also, because it was a US Government publication, it is legally available for free. The book is mainly focused on the design of autocannons, but the theory is applicable to smaller systems as well. If you read this book and understand it, you are ahead of 90% of the people in the industry. Next is this US Army document on small arms design hosted at Forgotten Weapons. The theoretical information in this is largely taken from Chinn, but it adds a lot of notes from experience on what does and does not work. It also has an excellent quantitative discussion of recoil, and some notes on various concepts the US Army was playing with at the time. More Specific Documents: Extractor Lift in the AR-15 series. This interesting series of tests disproves the rationale behind "improved" "lobstertail" AR-15 extractors. In addition, it shows just how much residual blowback pressure there is in the M4 (it's more than you'd think). Why Telescoped Ammunition Sucks. It really sucks. Jim Schatz on caseless ammunition. Very interesting read from a guy who was there when it happened.
  9. Collimatrix

    Reviews of Movies I Haven't Seen

    Ant Man and the WASP This movie isn't anything groundbreaking, and honestly the anti-classist themes seem outdated. But it was a fun watch and I enjoyed it anyway. Ant Man and the WASP is basically a gender-inverted, Americanized My Fair Lady. It's a musical rom-com about a blue-blood, high society woman who falls for a pest exterminator. I think that, in this era of increasingly polarized American society, this sort of goofy love story is just the treat.
  10. Usually, reviewers see the movies they are reviewing. I am too busy. Avengers: Age of Ultron This film is a re-imagining of the 1960s British spy-fi TV series. In this gritty, noir take on the setting, an aged John Steed (Patrick Stewart) and Emma Peel (Judy Dench) have to contend with the looming specter of funding cuts and privatization. Crass, commercial mega-corporation RonCo, headed by professional wrestler Ultimate Ron, have made a bid to buy up their agency. This is a touching, poignant film with serious reflections on the role of the elderly in society. In a refreshing departure from contemporary practice, the film had a completely satisfying finale that also completely obviates any speculation of a sequel.
  11. http://www.nature.com/nature/journal/vnfv/ncurrent/fig_tab/nature14895_F1.html Apparently some South American populations share genes with Australasian populations that North Americans do not.
  12. Collimatrix

    European Union common defense thread

    And the EU countries clearly waste money that way too. But it's not so easy to quantify corruption. But if we look at actual combat readiness of units in Europe, I think that the picture becomes even more extreme. US units are probably not, on average, very ready for combat. But their European counterparts are much worse.
  13. If you're talking about a pure torsion bar system, then I guess. But no tank with torsion bar suspension has only torsion bars. They all have auxiliary damping systems, either friction-based or hydraulic. The advantage of hydropneumatic is that the damping action is built in, and requires no auxiliary system.
  14. Welcome to SH DIADES! Tank hulls are giant steel boxes. Torsion bars free rotate inside a hole in the hull on the swing arm end and anchor into the opposite side of the hull (ignoring rare exceptions like the T-64). Any tank with a hull rigid enough to withstand the rigors of combat is rigid enough to mount torsion bars. Hydropneumatic suspensions need to attach to the hull somewhere, and this is typically done with a small number of bolts that are not particularly spread out. So I don't think they're particularly lower stress than torsion bars. There's no magical additional cushioning that hydropneumatic suspensions give vs. torsion bars. They have significant additional built-in dampening, but as I noted above, this has some tradeoffs.
  15. Collimatrix

    Bash the F-35 thred.

    LOLWUT?
  16. Sadly, I don't have good sources on the more obscure Soviet rifle prototypes. I'm very curious if they made any counterbalanced designs that were something other than AK guts with a counterbalance mechanism stapled to it. This pistol design is essentially a counterbalanced blowback mechanism.
  17. At the end of January, 2018 and after many false starts, the Russian military formally announced the limited adoption of the AEK-971 and AEK-973 rifles. These rifles feature an unusual counterbalanced breech mechanism which is intended to improve handling, especially during full auto fire. While exotic outside of Russia, these counter-balanced rifles are not at all new. In fact, the 2018 adoption of the AEK-971 represents the first success of a rifle concept that has been around for a some time. Earliest Origins Animated diagram of the AK-107/108 Balanced action recoil systems (BARS) work by accelerating a mass in the opposite direction of the bolt carrier. The countermass is of similar mass to the bolt carrier and synchronized to move in the opposite direction by a rack and pinion. This cancels out some, but not all of the impulses associated with self-loading actions. But more on that later. Long before Soviet small arms engineers began experimenting with BARS, a number of production weapons featured synchronized masses moving in opposite directions. Generally speaking, any stabilization that these actions provided was an incidental benefit. Rather, these designs were either attempts to get around patents, or very early developments in the history of autoloading weapons when the design best practices had not been standardized yet. These designs featured a forward-moving gas trap that, of necessity, needed its motion converted into rearward motion by either a lever or rack and pinion. The French St. Etienne Machine Gun The Danish Bang rifle At around the same time, inventors started toying with the idea of using synchronized counter-masses deliberately to cancel out recoil impulses. The earliest patent for such a design comes from 1908 from obscure firearms designer Ludwig Mertens: More information on these early developments is in this article on the matter by Max Popenker. Soviet designers began investigating the BARS concept in earnest in the early 1970s. This is worth noting; these early BARS rifles were actually trialed against the AK-74. The AL-7 rifle, a BARS rifle from the early 1970s The Soviet military chose the more mechanically orthodox AK-74 as a stopgap measure in order to get a small-caliber, high-velocity rifle to the front lines as quickly as possible. Of course, the thing about stopgap weapons is that they always end up hanging around longer than intended, and forty four years later Russian troops are still equipped with the AK-74. A small number of submachine gun prototypes with a BARS-like system were trialed, but not mass-produced. The gas operated action of a rifle can be balanced with a fairly small synchronizer rack and pinion, but the blowback action of a submachine gun requires a fairly large and massive synchronizer gear or lever. This is because in a gas operated rifle a second gas piston can be attached to the countermass, thereby unloading the synchronizer gear. There are three BARS designs of note from Russia: AK-107/AK-108 The AK-107 and AK-108 are BARS rifles in 5.45x39mm and 5.56x45mm respectively. These rifles are products of the Kalashnikov design bureau and Izmash factory, now Kalashnikov Concern. Internally they are very similar to an AK, only with the countermass and synchronizer unit situated above the bolt carrier group. Close up of synchronizer and dual return spring assemblies This is configuration is almost identical to the AL-7 design of the early 1970s. Like the more conventional AK-100 series, the AK-107/AK-108 were offered for export during the late 1990s and early 2000s, but they failed to attract any customers. The furniture is very similar to the AK-100 series, and indeed the only obvious external difference is the long tube protruding from the gas block and bridging the gap to the front sight. The AK-107 has re-emerged recently as the Saiga 107, a rifle clearly intended for competitive shooting events like 3-gun. AEK-971 The rival Kovrov design bureau was only slightly behind the Kalashnikov design bureau in exploring the BARS concept. Their earliest prototype featuring the system, the SA-006 (also transliterated as CA-006) also dates from the early 1970s. Chief designer Sergey Koksharov refined this design into the AEK-971. The chief refinement of his design over the first-generation balanced action prototypes from the early 1970s is that the countermass sits inside the bolt carrier, rather than being stacked on top of it. This is a more compact installation of the mechanism, but otherwise accomplishes the same thing. Moving parts group of the AEK-971 The early AEK-971 had a triangular metal buttstock and a Kalashnikov-style safety lever on the right side of the rifle. In this guise the rifle competed unsuccessfully with Nikonov's AN-94 design in the Abakan competition. Considering that a relative handful of AN-94s were ever produced, this was perhaps not a terrible loss for the Kovrov design bureau. After the end of the Soviet Union, the AEK-971 design was picked up by the Degtyarev factory, itself a division of the state-owned Rostec. The Degtyarev factory would unsuccessfully try to make sales of the weapon for the next twenty four years. In the meantime, they made some small refinements to the rifle. The Kalashnikov-style safety lever was deleted and replaced with a thumb safety on the left side of the receiver. Later on the Degtyarev factory caught HK fever, and a very HK-esque sliding metal stock was added in addition to a very HK-esque rear sight. The thumb safety lever was also made ambidextrous. The handguard was changed a few times. Still, reception to the rifle was lukewarm. The 2018 announcement that the rifle would be procured in limited numbers alongside more conventional AK rifles is not exactly a coup. The numbers bought are likely to be very low. A 5.56mm AEK-972 and 7.62x39mm AEK-973 also exist. The newest version of the rifle has been referred to as A-545. AKB and AKB-1 AKB-1 AKB AKB, closeup of the receiver The AKB and AKB-1 are a pair of painfully obscure designs designed by Viktor Kalashnikov, Mikhail Kalashnikov's son. The later AKB-1 is the more conservative of the two, while the AKB is quite wild. Both rifles use a more or less conventional AK type bolt carrier, but the AKB uses the barrel as the countermass. That's right; the entire barrel shoots forward while the bolt carrier moves back! This unusual arrangement also allowed for an extremely high cyclic rate of fire; 2000RPM. Later on a burst limiter and rate of fire limiter were added. The rifle would fire at the full 2000 RPM for two round bursts, but a mere 1000 RPM for full auto. The AKB-1 was a far more conventional design, but it still had a BARS. In this design the countermass was nested inside the main bolt carrier, similar to the AEK-971. Not a great deal of information is available about these rifles, but @Hrachya H wrote an article on them which can be read here.
  18. Kneeling is not unique to hydropneumatic suspensions, but it is easier to implement. I recall vaguely that there was a program to make a torsion bar suspension for an APC that could crouch, mainly so it could fit inside transport aircraft more easily. There was also the crouching suspension proposed for the German E-series bullshit programs to keep engineers off the Ostfront tank destroyers at the end of WWII. So it's quite possible to make a kneeling torsion bar suspension, but it usually requires some sort of chain winch or other robust mechanical connection to the suspension elements, whereas a kneeling hydropneumatic suspension requires hydraulic connections to the suspension elements, which is much easier. Also, not all hydropneumatic suspensions kneel. In fact, I think the majority of them do not. All the comparisons I have seen between hydropneumatic suspension and torsion bars have depended entirely on which system the author was advocating for. In theory torsion bars are cheaper and simpler. It's just a big rod of steel that twists as the swing arms articulate, right? Wrong. To get competitive suspension performance for a modern MBT, the torsion bar has to be made of a high grade of very refined steel. Processes like VIM/VAR and electroslag refining remove the last small amounts of tramp elements, and drastically improve the fatigue properties of the steel. But these secondary refining processes are expensive. Ideally, the torsion bar is pre-stressed too. Torsion bars are springs, and a big portion of the lifespan of a spring is a function of keeping the surface blemish-free. The outer surface of a torsion bar is the most stressed part, and any sort of flaws there will quickly propagate and cause a crack and eventually a failure. So the torsion bar needs to be kept scratch-free and corrosion-free, which adds more weight and bulk, and special handling considerations of spares. There's a lot that goes into making a good torsion bar. Hydropneumatic has a lot of big advantages on paper. All tank suspensions are springs, and their weight is going to be some sort of function of the energy density of the springing medium used to support the swing arms. A torsion bar uses energy stored in a twisted piece of steel, while hydropneumatic uses the energy stored in temporarily compressed air, translated by hydraulic liquid. Well, this one is a no-brainer! Air is way lighter than steel! But of course it isn't that simple. The pressure vessel that contains the air and the hydraulic fluid needs to be leak-proof, and it needs to be leak-proof for years under rough field conditions. Once you make a hydraulic system that's that robust, you start to eat into the theoretical weight advantage vs. the torsion bar. Also, the air is the springing medium. Air changes density and pressure as the temperature changes. That's not a deal-breaker, but the engineers need to at least think about that. Hydropneumatic suspensions make it fairly easy to kneel the tank, but doing this requires some sort of system of hydraulic pumps to move fluid in and out of the suspension units. This requires a substantial amount of power, and a bunch of additional beefy, high-pressure hydraulic lines. These things are all fairly beefy and are another potential headache if the engineers responsible for them half-ass their job. I think for new designs hydropneumatic will prove lighter. Even if the hydro suspension units themselves aren't that much lighter, the knock-on effects of being able to lower the turret basket by a few inches will be much greater than the difference in the weight of the suspension units themselves. Tanks are about half armor by weight, so it's generally more effective to make the armor package smaller than it is to make individual components lighter. But there are other considerations. Torsion bars take up space in the bottom of the hull, and hydro units take up space on the side of the hull. Therefore, torsion bars allow the tank to have thicker side hull armor. Take a look at the T-14 for an example of how extreme this can be made. Hydropneumatic units can have a very high built in damping coefficient for essentially no additional weight, which is not the case with torsion bars, which require auxiliary snubbers and dampers. However, high damping coefficients effectively increase rolling resistance when the tank is on rolling terrain, so there is some cost to efficiency here. In theory it shouldn't be too hard to have some sort of variable-geometry orifice inside the hydraulic line that could adjust damping coefficient on the fly, but so far as I know nobody has tried this.
  19. Collimatrix

    Britons are in trouble

    Realistically, the challenger 2 should never have existed and the entire program was a failure. It certainly didn't preserve the British industry's ability to make MBTs. Could Britain make MBTs now? I don't think they can. Should have license-produced Leo 2s or Leclercs or Abrams from day 1.
  20. Collimatrix

    Britons are in trouble

    I believe they do. For some bizarre reason, the chieftain and T95 were designed to have the same turret ring, and that ring diameter was kept through the M60 and M1. If Chally 2 has the same turret ring diameter as a chieftain, then you can plop an Abrams turret on it, at least in principle. Edit: Ogorkiewicz says chally 1 and Abrams have the same turret ring diameter. Probably chally 2 does as well:
  21. Collimatrix

    What are we playing?

  22. Collimatrix

    Contemporary Western Tank Rumble!

    According to this link: I think it's worth comparing these super-HEAT rounds for the 125mm with the RPG-29. Both achieve something like 750-800mm penetration in RHA, but the RPG-29 is 105mm vs 125mm, and the RPG-29 has two charges rather than three. So, for all its technical sophistication, 3BK31 isn't poking much better than a considerably smaller rocket-propelled projectile. But then, a gun-launched HEAT projectile has a lot of issues that a rocket-propelled one doesn't have to deal with, like much greater axial acceleration and fitting inside an autoloader. So this design is probably not the most efficient, in terms of armor penetrated relative to explosive used. But perhaps it's a very good design in terms of armor penetrated relative to fitting inside a very restrictive envelope.
  23. Yes! What's so hard to believe about this? Ever since 1883 the President can only fire the Secretary of State, the rest of the employees of that department are practically untouchable to him. In fact, it's very difficult for government employees to be fired even by their own departments. The end result of that is State employees are free to ignore the President. The only thing keeping this from being obvious is a certain desire to present a veneer of professional normalcy. The President and the State Department will attempt to make it look like they agree and that they're part of a team even when that isn't true. Usually this involves the newly-elected President conceding most of their campaign promises. Remember how G.W. Bush promised a "more humble" foreign policy? Remember how Obama was going to close Guantanamo Bay? Trump is different because he is willing to feud with the State Department. And he does. This is particularly well-documented. Trump has been trying to get control over the State Department ever since he had Tillerson in charge. Note the panic and over-reaction. It's a bloodbath! Oh the humanity! Wait, how many employees did Tillerson actually fire? ... More recently, State Department officials got caught planning to host an event that would have undermined Trump's Cuba policy. The result? The event was "postponed." These sorts of reprisals by Trump and his goons seem utterly inconsequential to State, which employs something like 70K people. And, in an absolute sense, they are. But what makes Trump different is that he is willing to push back at all. This is not business as usual.
  24. Collimatrix

    Collimatrix's Terrible Music Thread

    Have you ever wondered what the lead singer of Studio Killers sounds like when he's not autotuned (OK, less autotuned)? Now you know.
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