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  1. Inspired by Collimatrix's excellent topic in the Aviation section, my attempt at doing the same for tanks. Tank design is often represented as a trade-off between firepower, armour, and speed. But this ignores many other, equally important variables. Furthermore, this formula doesn't explain why the trade-offs are there in the first place. So here is my attempt to make things a bit more complicated. The Constraint: Compact, powerful and reliable engines – and the ability to use them Firepower and armour are the obvious features that made a 1940 tank obsolete in 1945. Yet even a 1945 tank is trivial compared to a WWI battleship. Or more modestly, the German 88mm, Soviet 85mm and US 90mm AA guns were prewar designs. Why not put them on a tank from the beginning? Were people just stupid back then? Up to a point, I would say ‘yes’. While it is unrealistic to think of 1945 combat aircraft, radar, or nuclear weapons in 1940 as the result of anything short of time travel, 1940 tanks could have been significantly better without anachronistic scientific or engineering breakthroughs. Like the assault rifle, this really was a case where the right people just didn't see the need or spend the money. However, it's not the only reason. A tank with a big gun and thick armour that can't move is just a pillbox. Like aircraft, WW2 tanks were fundamentally limited by their engine power. This is less obvious because additional power was typically used to ‘buy’ weight rather than speed. Yet the trend is clear. Shown below are the improvements in engine power for the German and British (cruiser) tank lines, which were in the war the longest. German Panzers I 100 hp II 138 hp III, IV 250-300 hp Tiger, Panther 690 hp British Cruisers I, II 150 hp III, IV, Crusader 340 hp (Liberty) Cromwell, Comet 600 hp (Meteor) Arguably, more powerful tank engines could and should have been introduced much earlier (the Liberty was first used in a tank as early as 1918). I will leave that aside, noting only that, relative to aircraft engines, tank engines were forced to use lower octane fuel for economic reasons (preventing tank use of the Napier Lion), and are harder to cool due to being inside a slow moving armoured box (this was a particular challenge with the Merlin's conversion to the Meteor). There's also the choice of diesel (compression ignition) vs. petrol/gasoline (spark ignition) engines. Diesels had higher torque and lower fuel consumption, but lower specific power, were heavier and cost more, and meant an extra type of fuel in your logistics train. Both Germany and the US decided against diesels for fear sufficient fuel would not be available. Once you have an engine, you still need to put power to the wheels through what the British call a ‘transmission’ and Americans call a ‘drivetrain’, which also does the steering since almost all tanks turn by making one track spin faster than the other. And you need a track that won't fall apart and a suspension that will stop the occupants falling apart. These were big problems during WW1 – the first tanks had no suspension at all! – and into the 1920s, but by the 1930s you could more or less use the power of the available engines. Even in 1945, however, the Panther and Comet were deliberately speed limited to around 30 mph. TRADE-OFFS OK, we have an engine of a given horsepower, and the ability to turn that horsepower into forward motion off-road with an acceptable degree of unreliability and discomfort. What choices do we have to make now? 1. Weight vs. mobility This is almost self-explanatory, but mobility is more than speed. Very roughly, multiplying the hp/ton ratio by two gives an approximate top road speed in mph, although looking at individual types this correlation is surprisingly loose. The 15 mph of the British infantry tanks was annoyingly slow, the 25 mph of most German tanks seemed good enough, and as mentioned above, anything over 30 mph arguably wore out the running gear and the occupants to little benefit. A high power-weight ratio was also useful to provide rapid acceleration to dash from cover to cover. But weight has other penalties that are less amenable to increased engine power: Reliability and maintenance time – pushing around more weight means more parts everywhere from the engine to the suspension will break. (US tracks lasted about 6000km on light tanks but only 2400km on medium tanks. See Exercise Dracula for the effect of maintenance downtime on overall mobility.) Fuel consumption – less range for the individual tank, more for the logistics train to haul. Bridging – if you can’t cross a bridge without breaking it, you may have to go a much longer long way round. Shipping – the M6 heavy tank was not adopted partly because it exceeded the 40-ton limit on many dockyard cranes. Tanks that were kept in service a long time such as T-34 and Panzers III and IV tended to creep up in weight as bigger guns and frontal armour were added, but for new designs bigger engines and better transmission, steering and track technology (and bridge building) roughly kept pace. Except when they didn't. 2. For a given weight: armour vs. internal volume The basic choice is a smaller box with thicker armour or a bigger box with thinner armour. Similarly, sloped armour will give more protection for a given weight, but reduces the internal volume. At the start of the war, most countries tried to armour the front, sides, and even rear to a similar standard, using mostly vertical armour. As (anti-)tank guns got more powerful, this became impractical, and focus shifted to improving the front armour, both by increasing thickness and sloping (sloping all round reduced the volume of the tank excessively, as in the pyramid shaped early T-34s). 3a. For a given volume: guns vs. crew vs. ammo vs. suspension... Everyone wants a bigger gun, but you need to fit other things in too. For example, a three-man turret crew (commander, gunner, loader) worked better than one or two men, because everyone could focus on one job. But when the British upgunned their Crusader and Valentine tanks from 2-pdr to 6-pdr guns, there was not enough room in the turret for the third man. Of course, if you run out of ammo, or your crew are bumping into something every time they move, your tank will not fight very well either. (A bigger gun has a double penalty: it reduces the room for other things, including ammo, and also makes each round bigger. The IS-2 looks stunning on paper, but remember that 122mm gun only has 28 rounds and has a slower rate of fire due to its separate loading ammunition.) The Soviets limited the height of their tank crews for this reason. If you just want to shoot an enemy soldier or two, the main gun is overkill, so almost all tanks have a ‘coaxial’ machine gun next to it in the turret. Is it worth having a second machine gun in the hull and someone to shoot it? This was nearly universal during the war but fell out of fashion soon afterwards, as bigger guns needed more room for ammunition. (I also imagine most people trying to sneak up on a tank didn't do so from the front.) A few designs even had little secondary MG turrets, a hangover from prewar, but these were quickly abandoned. Tank suspension is a whole topic of its own. Broadly the choice was between types that allowed more independent wheel movement for a better ride but took up valuable room inside the tank (and were harder to repair in the field) like Christie and torsion bar, and types that gave a worse ride but were completely external (and easier to repair) like VVSS/HVSS, leaf spring and Horstmann. Also, lots of small wheels are better to spread weight evenly and not sink into mud or snow, but fewer bigger wheels are better if you want to drive fast over bumps. The Germans tried to have the best of both worlds with many overlapping large wheels, which was complicated and tended to freeze solid in the Russian winter. And obviously you need fuel, and a radio or two, a boiler for tea if you're British, compressed air tanks for cold weather starts if you're Russian, and other stuff I haven't mentioned or thought of... 3b. For a given volume: height vs. width A taller tank is easier for the enemy to spot. A wider tank lets you have a bigger turret ring and therefore a bigger gun. So it seems like a low, wide tank is the ideal. But make your tank too wide and it can't fit on railways – the British were particularly constrained with a narrow railway loading gauge, but even the Germans had to put narrower tracks on their Tigers and Panthers to transport them by rail – or narrow roads and bridges. Also, height allows more ground clearance to get over obstacles and greater gun depression to shoot at the enemy while hull down. Finally, height can actually substitute for width to some extent in fitting a bigger gun: a tall hull as in the Sherman allows the turret ring to be extended over the tracks, or a tall turret as in the Challenger (and later Strv 74) allows the gun to recoil (and the crew to squeeze in) above the turret ring. Length tends to be the residual in the equation, within limits - too long and you can't steer, too short and the crew gets motion sickness. The Sherman was stretched as required to go from short radial to longer inline engines. Similarly the Challenger was basically a stretched Cromwell. 4. For a given sized turret/gun: AP vs. HE Tanks sometimes shoot at enemy tanks, but mostly at other, softer things. If you need to punch through armour with AP rounds, you want a high velocity gun (penetration increases with roughly the square of the velocity, but only linearly in calibre). If you want to blow things up, it's all about calibre (HE capacity increases with the cube of calibre, or even a bit more when you consider the minimum size of the fuze and thickness of the shell wall). So for a gun that will fit in a given sized turret, you can have a smaller calibre high velocity hole puncher or a larger calibre, low velocity HE lobber. While you can build specialised guns for each job (and even different tanks to put them in, as the Germans did, which is going a bit far), it's better to have one kind of gun that can do both reasonably well in most of your tanks, since you never know what they will run into. Conveniently, while tank armour increased throughout the war, common building materials and the human body stayed the same. Therefore, while AP rounds needed ever greater performance, HE didn't. Around 3 inch calibre, with increasing velocity as the war went on, proved a good compromise. The Americans and British both picked the medium velocity 75mm over the high velocity 6-pdr, as did the Soviets with the 76.2mm over their own 57mm AT gun. The higher velocity 76mm, 17-pdr and 77mm then gave the needed AP upgrade while the Soviets went for 85mm (probably because they already had the AA gun rather than any ideal calibre calculation). The Germans also ended up with high velocity 75mm guns on most of their late war tanks (except the 88s on the Tigers, again copied from the AA calibre). 5. For a given budget: quality vs. quantity Obviously, a bigger tank uses more steel and other resources, and fancy gadgets like better radios, optics and steering systems have a cost. The Tiger was hugely expensive compared to the German mediums (and, more speculatively, other countries' tanks). The Panther was surprisingly cheap for its size, but partly by skimping on the final drive, which crueled its reliability. This trade-off applies to distribution as well as production. If you need to move your tanks across the ocean like the Americans, or even by rail across the steppe like the Germans and Soviets, a bigger and better tank at the factory gate meant fewer delivered to the battlefield for the same freight tonnage. So we are back where we started with weight vs. mobility, except in terms of numbers rather than the individual tank's capability.
  2. Here at Sturgeon's House, we do not shy from the wholesale slaughter of sacred cows. That is, of course, provided that they deserve to be slaughtered. The discipline of Military Science has, perhaps unavoidably, created a number of "paper tigers," weapons that are theoretically attractive, but really fail to work in reality. War is a dangerous sort of activity, so most of the discussion of it must, perforce, remain theoretical. Theory and reality will at some point inevitably diverge, and this creates some heartaches for some people. Terminal, in some cases, such as all those American bomber crews who could never complete a tour of duty over Fortress Europe because the pre-war planners had been completely convinced that the defensive armament of the bombers would be sufficient to see them through. In other cases though, the paper tiger is created post-facto, through the repetition of sloppy research without consulting the primary documents. One of the best examples of a paper tiger is the Tiger tank, a design which you would think was nearly invincible in combat from reading the modern hype of it, but in fact could be fairly easily seen off by 75mm armed Shermans, and occasionally killed by scout vehicles. Add to this chronic, never-solved reliability problems, outrageous production costs, and absurd maintenance demands (ten hours to change a single road wheel?), and you have a tank that really just wasn't very good. And so it is time to set the record straight on another historical design whose legend has outgrown its actual merit, the British EM-2: EM-2ology is a sadly under-developed field of study for gun nerds. There is no authoritative book on the history and design of this rifle. Yes, I am aware of the Collector's Grade book on the subject. I've actually read it and it isn't very good. It isn't very long, and it is quite poorly edited, among other sins devoting several pages to reproducing J.B.S. Haldane's essay On Being the Right Size in full. Why?!!?!! On top of that, there's quite a bit of misinformation that gets repeated as gospel. Hopefully, this thread can serve as a collection point for proper scholarship on this interesting, but bad design. Question One: Why do you say that the EM-2 was bad? Is it because you're an American, and you love trashing everything that comes out of Airstrip One? Why won't America love us? We gave you your language! PLEASE LOVE ME! I AM SO LONELY NOW THAT I TOLD THE ENTIRE REST OF EUROPE TO FUCK OFF. Answer: I'm saying the EM-2 was a bad design because it was a bad design. Same as British tanks, really. You lot design decent airplanes, but please leave the tanks, rifles and dentistry to the global superpower across the pond that owns you body and soul. Oh, and leave cars to the Japanese. To be honest, Americans can't do those right either. No, I'm not going to launch into some stupid tirade about how all bullpup assault rifle designs are inherently a poor idea. I would agree with the statement that all such designs have so far been poorly executed, but frankly, very few assault rifles that aren't the AR-15 or AK are worth a damn, so that's hardly surprising. In fact, the length savings that a bullpup design provides are very attractive provided that the designer takes the ergonomic challenges into consideration (and this the EM-2 designers did, with some unique solutions). Actually, there were two problems with the EM-2, and neither had anything to do with being a bullpup. The first problem is that it didn't fucking work, and the second problem is that there was absolutely no way the EM-2 could have been mass-produced without completely re-thinking the design. See this test record for exhaustive documentation of the fact that the EM-2 did not work. Points of note: -In less than ten thousand rounds the headspace of two of the EM-2s increased by .009 and .012 inches. That is an order of magnitude larger than what is usually considered safe tolerances for headspace. -The EM-2 was less reliable than an M1 Garand. Note that, contrary to popular assertion, the EM-2 was not particularly reliable in dust. It was just less unreliable in dust than the other two designs, and that all three were less reliable than an M1 Garand. -The EM-2 was shockingly inaccurate with the ammunition provided and shot 14 MOA at 100 yards. Seriously, look it up, that's what the test says. There are clapped-out AKs buried for years in the Laotian jungle that shoot better than that. -The EM-2 had more parts breakages than any other rifle tested. -The EM-2 had more parts than any other rifle tested. -The fact that the EM-2 had a high bolt carrier velocity and problems with light primer strikes in full auto suggests it was suffering from bolt carrier bounce. As for the gun being completely un-suited to mass production, watch this video: Question Two: But the EM-2 could have been developed into a good weapon system if the meanie-head Yanks hadn't insisted on the 7.62x51mm cartridge, which was too large and powerful for the EM-2 to handle! Anyone who repeats this one is ignorant of how bolt thrust works, and has done zero research on the EM-2. In other words, anyone who says this is stupid and should feel bad for being stupid. The maximum force exerted on the bolt of a firearm is the peak pressure multiplied by the interior area of the cartridge case. You know, like you'd expect given the dimensional identities of force, area and pressure, if you were the sort of person who could do basic dimensional analysis, i.e. not a stupid one. Later version of the British 7mm cartridge had the same case head diameter as the 7.62x51mm NATO, so converting the design to fire the larger ammunition was not only possible but was actually done. In fact, most the EM-2s made were in 7.62x51mm. It was even possible to chamber the EM-2 in .30-06. I'm not going to say that this was because the basic action was strong enough to handle the 7x43mm, and therefore also strong enough to handle the 7.62x51mm NATO, because the headspace problems encountered in the 1950 test show that it really wasn't up to snuff with the weaker ammunition. But I think it's fair to say that the EM-2 was roughly equally as capable of bashing itself to pieces in 7mm, 7.62 NATO or .30-06 flavor. Question Three: You're being mean and intentionally provocative. Didn't you say that there were some good things about the design? I did imply that there were some good aspects of the design, but I was lying. Actually, there's only one good idea in the entire design. But it's a really good idea, and I'm actually surprised that nobody has copied it. If you look at the patent, you can see that the magazine catch is extremely complicated. However, per the US Army test report the magazine and magazine catch design were robust and reliable. What makes the EM-2 special is how the bolt behaves during a reload. Like many rifles, the EM-2 has a tab on the magazine follower that pushes up the bolt catch in the receiver. This locks the bolt open after the last shot, which helps to inform the soldier that the rifle is empty. This part is nothing special; AR-15s, SKSs, FALs and many other rifles do this. What is special is what happens when a fresh magazine is inserted. There is an additional lever in each magazine that is pushed by the magazine follower when the follower is in the top position of the magazine. This lever will trip the bolt catch of the rifle provided that the follower is not in the top position; i.e. if the magazine has any ammunition in it. This means that the reload drill for an EM-2 is to fire the rifle until it is empty and the bolt locks back, then pull out the empty magazine, and put in a fresh one. That's it; no fussing with the charging handle, no hitting a bolt release. When the first magazine runs empty the bolt gets locked open, and as soon as a loaded one is inserted the bolt closes itself again. This is a very good solution to the problem of fast reloads in a bullpup (or any other firearm). It's so clever that I'm actually surprised that nobody has copied it. Question Four: But what about the intermediate cartridge the EM-2 fired? Doesn't that represent a lost opportunity vis a vis the too powerful 7.62 NATO? Sort of, but not really. The 7mm ammunition the EM-2 fired went through several iterations, becoming increasingly powerful. The earliest versions of the 7mm ammunition had similar ballistics to Soviet 7.62x39mm, while the last versions were only a hair less powerful than 7.62x51mm NATO. As for the 7mm ammunition having some optimum balance between weight, recoil and trajectory, I'm skeptical. The bullets the 7mm cartridges used were not particularly aerodynamic, so while they enjoyed good sectional density and (in the earlier stages) moderate recoil, it's not like they were getting everything they could have out of the design. note the flat base In addition, the .280 ammunition was miserably inaccurate. Check the US rifle tests; the .280 chambered proto-FAL couldn't hit anything either.
  3. Disclaimer: Yeah naturally Japanese tanks arent a big focus here, so I usually ignore posting things of the matter here. But like the O-I article I posted here oh so long ago, this article comes with the results of some days spent in the archive reading and (continuing to do) translating pages of reports that havent been read in like, decades. So with that said, hope you enjoy. Still a matter I'm unfinished diving into. --------- Type5 Ho-Ri : The Japanese Ferdinand As of recently, I've gone through the Japanese National Archive files, looking through to find documents that relate to my studies. While I was there, I stumbled across something that caught my interest. Of said documents, the one of most importance was a file called "Military Secrets No.1". The reports were held by the Ministry of Defense, Army records section, Munitions Mobilization district. Contained in these files were a 3-page production chart of late war tracked vehicles of the Japanese army. Located within the chart I found a number besides the Type 5 Ho-Ri tank destroyer. A vehicle that until recently was only known to have made it to wooden mockup stages. In this lengthy article I will cover my findings on the tank project. Unfortunately visual representations of the tank are still being looked at. So I will use existing found sources for this. National Institute for Defense Studies " Military secret No.1 " In September of 1942, the Japanese Army Staff came to the realization that they had no choice but to design a series of tanks to compete with the arrival of the American Sherman tank. Three concepts were proposed by the Staff, each with their own gun selection; Kou (47mm), Otsu (57mm), and Hei (75mm). As combat data filtered back to Japanese high command, the model Kou concept would later merge with Otsu concept, becoming the basis for the design of the Type4 Chi-To. The Hei proposal would eventually lead to the development of the Type5 Chi-Ri. Additional impetus for new development projects came from a change in the Weapons Administration Headquarters Research Policy in July 1943, a change which was made as a result of analyzing and examining the situation of the tank warfare between the German army and the Soviet Union. Through analysis of this data, the Army's tank doctrine shifted to an emphasis on developing tanks which prioritized the anti-armor mission instead of prioritizing infantry support with limited anti-tank capability. Upon the promulgation of this policy, the Japanese Army decided to develop a series of tank destroyers alongside the medium tanks being designed. As a result, the Type5 Chi-Ri, Japan’s primary medium-tank project, would become the basis for a new anti-armor vehicle. This was a natural choice for IJA command; the Chi-Ri project was more mature. Additionally, it held the most advanced technology Japan produced at the time, technology which would become ubiquitous in the designs that would be made until Japan's defeat in 1945. Testing model of Chi-Ri. Used to trial the series of cannons and turrets designed for the tank. In the photograph it is captured by US forces after the gun had been dismantled for further trials. By Japan's defeat in 1945, three models of Chi-Ri entered production. The tank destroyer built upon the chassis of the Chi-Ri would eventually be called the Ho-Ri. Development of this vehicle began shortly after the development of the Chi-Ri, when it had been decided that the tank would use the coil spring suspension system that Japanese manufacturers were already familiar with. After this decision was made, the Army also began work on designing the tank destroyer’s superstructure and casemate. The first design the Army came up with mimicked the Chi-Ri chassis entirely, though the turret was replaced with a reinforced rear-mounted superstructure. The Experimental 10cm Cannon With the development of a new series of tank destroyers taking place, the Army decided to design and produce a new high capacity anti-tank gun to fit the role. On July 22 of 1943, the Army Military Customs Council began designing a 105mm caliber anti-tank gun. Once the design of the cannon had been completed, construction of the cannon took place around a steel shielding that was to be the Ho-Ri's superstructure plating. The trial placement was capable of traversing 10 degrees to the left and the right, elevating by 20 degrees, and depressing by 15. The gun weighed 4.7 tons, with a barrel length of 5.759 m. During one of the first council meetings that took place on the 30th of June, however, the council gave Major Ota and Lieutenant Colonel Neima of the Army Weapons Administrative Division, the two chief engineers of the Experimental 10cm project, the task of achieving the requirement that the gun meet 200mm penetration at 600 meters distance and 1000m/s velocity. Naturally, the tank gun was not capable of this, and, instead, the Experimental 10cm had a muzzle velocity of 915m/s with AP (900m/s with HE), and achieved a performance of 150mm penetration at a distance of 1000 meters. The 10cm Experimental Anti Tank gun relied on a system similar to the Type5 75mm Anti tank cannon in relying on an autoloading mechanism for the tank. This mechanism was known as a semi-automatic loading system, different to the ordinary "autoloader" you see in other vehicles. Unlike the typical autoloading system, the loading crew of the gun system placed the individual shells on the chamber, the system automatically ramming the shell into the breech and forwarding to operation. This gave the effect of automating half the loading routine, as the name suggests. The Experimental 10cm was put into service with the Ho-Ri in 1945. The technical name for the model to be used on the prospective production model was known as the Type5 10cm anti tank cannon. The shell rammer used a horizontal chain closing type, and the automatic loading machine was attached to the back of the gun. It was used because loading ammunition of 123 cm total length and 30 kg weight was deemed too strenuous on a small Japanese physique. Various artillery parts had been diverted and referred to in order to shorten the time of development. The autoloading machine adopted the mechanism of the Type3 12 cm AA Gun for inspiration. The automatic loading mechanism was a continual source of problems, but was repeatedly refurbished to eliminate the drawbacks. Photograph of the Experimental 10cm Anti tank cannon during trials. Note: The shielf and protector are used on Ho-Ri prototype. Gun was first tested separately and then placed in tank prototype. Ho-Ri Designs Originally, the Ho-Ri was to keep the secondary 37mm that had been mounted on the Chi-Ri design. The reason for this addition was due to the limited gun-traverse on casemate tank destroyers. Additionally, the primary cannon could only do so much for itself. Hence, to combat many anti tank threats which the Americans could have dedicated to the assault on Japan, the 37mm was seen as being an efficient method of providing additional firepower against infantry and combat vehicles. To this end, the 37mm gun offered a range of APHE and smoke shells. The 37mm was capable of an elevation of 20 degrees and depression of -15 degrees. The mount itself also offered a horizontal traverse of 20 degrees. The 37mm gun could also be used as a ranging device for the main cannon, however this most likely would not have been needed due to the high velocity of the main gun. Outline of the Ho-Ri design I. Technically entered modified construction of one of the 3 Chi-Ri units. The development of the Ho-Ri design was split into two concepts. One being a rear mounted superstructure on the Chi-Ri chassis with a central stationed engine, and the other having a centralized superstructure with a rear engine placement. The Ho-Ri engine selection was different from the traditional diesel that the Army had kept with for most of their tank production. Japan used a BMW designed gasoline V12 aircraft engine . The main reason for this change was due to industrial capacity of Japan reaching its peak, aircraft development was still a heavy priority and many assets were available for useage. The output of the tank was 550hp/1500rpm. The Ho-Ri II’s design also enabled the option of adding a 20mm AA station on the rear hatch for additional protection. However, the likelihood of it being useful is up for debate. In addition, central placement of the superstructure enabled 60 rounds for the main cannon to be stored instead of the Ho-Ri I’s 40 rounds. In terms of armour, both vehicles were to keep the Chi-Ri hull, hence the maximum frontal armour of these tanks was only 75mm. On the superstructure, however, armor thickness was increased to 100mm. By the time both designs, which had been developed in parallel, were presented to Army General Staff it was too late; the war was almost over, and the thickness of the armor was no longer sufficient against US armaments. Nevertheless, the design showed promise. Thus, while neither design was chosen for production, the Ho-Ri I was adopted as the main influence for the third revision of the tank. This third vehicle is commonly labeled as Ho-Ri III. Technically, however, none of the Ho-Ri vehicles were numerically designated. Ho-Ri III wooden mockup. Ho-Ri III took the basis of the Ho-Ri I, and revamped it to fit the needs of the military. The frontal plate of the tank was sloped at a 70 degree angle and increased to 120mm thickness. In this configuration, the tank was capable of withstanding most anti tank measures the Unites States could bring to the home islands of Japan. The designers of the tank built a wooden mockup form of the revision 3 design and presented it to the general staff, at an unknown date. The Ho-Ri kept its general composition the same as the prior designs, but this change was what the Army Staff ultimately decided to go with and schedule the Ho-Ri for prototype construction. The tank would have a crew total of 6; driver, gunner, two loaders, radio operator, and commander. The past designs made use of the 37mm that the Chi-Ri hull had present, however, with the chosen slope change on the Ho-Ri III, this was no longer present and a crew member spot was open. The 6th crew member was placed as the second loader to assist with the autoloading mechanism and provide shells for the primary loader. The construction of the prototype was completed in 1944. The tank achieved a speed of 40kmh during the trials. The tests were seen as a success, resulting in the Army ordering 5 units of the tank. The tank was put in service as the Type5 Ho-Ri, as the production model started in 1945. However, by the time of the war's end, the series of tanks only made it to 50% completion. Only one operable prototype had been completed fully. Reports of the trial are still being processed at this time [11/15/16]. My research continues. I have been spending days now trying to go through everything and get the details of the tank out to the light. Once all the documents are collected together and organized, translated, and put back together I will write a follow up article to this. You can view full post with all images on my blog post: http://sensha-manual.blogspot.com/2016/11/type5-ho-ri-japanese-ferdinand.html
  4. Most historical arms and armor were made of metal, leather and stone. This is the thread for historical weapons and armor made of weird shit. This is an example of armor made from the Gilbert islands made of thick, woven coconut fiber. The helmet is made from a pufferfish. I've seen a set similar to this in another museum. The woven fiber body armor looked like it would be reasonably effective. Coconut husk is pretty tough and the vest was very thick. I wasn't so sure about the helmet. The Gilbertese were also the foremost users of shark's tooth weapons, although other Polynesians used them as well: Several historical examples I've seen are these strange, branching designs: Polynesians were not the only ones to use teeth in their arms. The Mycenian Greeks made helmets out of boars teeth. One such helmet is described in the Iliad, and there are a few archeological discoveries of such: And finally, a club used by Inuits made from the penis-bone of a walrus:
  5. Too often technology is portrayed a steady, linear series of more or less inevitable improvements. This is an easier illusion to maintain if you don't know anything about the subject. In fact, the history of technology is littered with insane, unworkable garbage. Things that didn't work, barely worked, might-have-beens, things that would perhaps be worth revisiting, things fit only for ridicule, and some things that make no sense whatsoever: Yes! Terrify your enemies with your new gunspoon! Note the direction of the trigger and the direction of the muzzle. What the hell were these even for? Attaching solid fuel rockets to a bicycle! We totes verified this idea in Kerbal Space Program, it'll be fine. An external combustion motor that uses ether instead of steam! Nothing could possibly go wrong with this! A turbine powered by boiling mercury! There is definitely nothing at all that could go horribly wrong with this! Douglas Self's Museum of Retrotechnology Site has all of these wondrous devices and more. Feast your mind on the retardation of the engineers and inventors of yesteryear, and be amazed that anyone is left alive on this planet. "Steampunk" ain't got shit.
  6. Since the AMX-30 is about to be added to World of Tanks, I thought now would be a good time to take a look at the design. Conventional wisdom would have that the AMX-30 is a sort of retarded little brother to the leo 1. The designs did originally stem from a joint Franco/German tank project, which, like most multinational programs, fell apart when the partners involved realized they couldn't both be in the driver's seat. Actually, the AMX-30 and Leo 1 differ significantly in design priorities. The first surprise from a more careful look at the AMX-30 is that the armor is actually pretty good for the period: (And before Olifant and Xlucine freak about the inefficiency of hull sponsons, here is a picture of a bare hull, which shows that the sponsons are only used to support the turret ring and do not extend the entire length of the hull) Compared to T-54/55: 100 mm @ 60 degrees is 200mm LOS, while 80mm at 68 degrees is 213mm LOS. Over most of the front of the glacis, the AMX-30 actually has slightly better protection than the T-55! The ratio of trigonometric to effective thickness against APDS/AP type threats is about 2 for both of these inclinations: So, for sub 40 tonne vehicles, both the AMX-30 and T-55 had respectable protection on the hull. Indeed, the weak points of both vehicles would be the turret, which had similar LOS thickness, but at less slope and therefore less effective protection against AP/APDS. The extreme slope angle of the hull would also stand a good chance of deflecting period HEAT ammunition, which often did not fuse properly against highly sloped plates. Compared to the Leo 1: We see that, frontally at least, the French tank is much better protected (they're both paper-thin on the sides). Add to this the fact that the AMX-30 had a healthy -8 degrees of gun depression, and it starts to look like a pretty competent design. One of the tricks the AMX-30's designers used to keep the tank efficient and compact was an unusual layout of the torsion bars: (Thanks to Walter_Sobchack for the image) In a typical tank with torsion bar suspension, the turret basket sits on top of the torsion bars and the torsion bar bushings. This creates a dead space underneath the turret basket. The height from floor of the turret to the ceiling must be tall enough for the loader to perform their job (ideally standing, but in some cases crouched), so the height lost to the torsion bars must be made up above the turret ring. This forces the roof of the turret higher, and so increases the total armored volume of the tank, which increases weight. In the AMX-30 the third road wheel swing arm is reversed into a leading, rather than trailing configuration. This leaves a nice big gap where the turret basket can live, which eliminates the wasted space. AMX-30 is, so far as I know, unique among production tanks in using this suspension design. There was at least one Soviet prototype, the Object 277, that used a similar arrangement. While the AMX-30's suspension was unusually compact for a torsion bar type suspension, it was utterly unremarkable in performance. With 278mm of combined bound and rebound, it was essentially comparable to the M60A1 with 292mm. While this was quite a bit better than the British centurion and chieftain, which had utterly primitive suspension that lacked even independently sprung road wheels, it was a far cry from the Leopard 1, which boasted 407mm of independent road wheel travel. Armament and fire control in the AMX-30 was quite modern; even progressive. Unlike the T-55 and hilariously awful and primitive British designs, the AMX-30 had an optical rangefinder. Because the rangefinder had a wide 2 meter base, and because the commander sat behind the gunner, the rangefinder was operated by the commander as a concession to maintaining an efficient ballistic shape for the turret. The commander's station featured a cupola with 10 direct-vision periscopes (or "windows" as they are sometimes called), a ten power binocular telescope, and a counter-rotating override feature. The gunner was given two observation periscopes in addition to the gunsight, and the loader had a generous three periscopes. The vision from the turret of the AMX-30 was, by tank standards, excellent. Primary armament was the OCC 105 F1. This gun was quite comparable to the Royal Ordnance L7 seen in most other Western tanks of the period, except that it had a slightly longer barrel, a compressed air bore evacuation system, and a slower rifling twist rate. The French are unique in their rejection of passive bore evacuators, preferring the older style of compressed-air based system. The German big cats also featured a compressed air bore evacuator, so there is the tantalizing possibility that the French systems are based on that. If this is true, it would be a germ of truth in the myth that the 75mm gun on the AMX-13 is based on the panther's armament. I have not seen conclusive evidence one way or another. The reduced rifling twist rate of the OCC 105 F1 was to facilitate the famously weird Gessner "Obus G" projectile. Obus G, as I am sure everyone reading this already knows, was a shaped charge warhead where the shaped charge rode inside an outer shell separated by a layer of ball bearings. This allowed the outer portion of the projectile to spin while the shaped charge would not spin, as spin degrades the effectiveness of shaped charges. This design combined the accuracy of a spin-stabilized projectile with the HEAT performance of a fin-stabilized projectile. Actually, Obus G was slightly more effective than the M456 HEAT round of the L7. The slow rifling twist of the OCC F1 precluded the use of APDS projectiles. Any APDS projectile long enough to be effective would have too great an aspect ratio to be stabilized by the loose twist of the cannon. However, in the long run this was an advantage, as the slow twist rate proved well-suited to APFSDS type rounds when these were introduced in the 1980s. In another unusual move, the secondary armament of the AMX-30 was a 12.7mm weapon rather than the usual 7.62mm. This, if the user so desired, could be increased to a 20mm autocannon. Not exactly "coaxial," the secondary armament could be elevated to 40 degrees (vs. 20 degrees for the main armament), to be used against helicopters and low-flying aircraft. Prior to upgrades late in its service life, the AMX-30 was let down by that most syndrome of armored fighting vehicles; a dodgy powertrain. Prior to the 1979 upgrade, the AMX-30 had a rather fragile transmission that required a skilled driver in order for the tank to remain mobile. Apart from this regrettable downside of not working, the AMX-30's powerpack was admirably compact and helped keep the overall size and weight of the tank low. Had it not been let down by an unreliable powertrain, the AMX-30 could have been a big success on the export market. More other Western tank designs of the period, the AMX-30 showed excellent design discipline in keeping the tank small and light. Despite the characterization of the armor protection as useful only against small-caliber threats, the AMX-30 boasted frontal protection that was better than the Leopard 1 and comparable to the T-55. Alas, for the majority of its career, the AMX-30 was yet another reminder that in the absence of a robust powertrain no amount of clever design features will redeem a tank. (Would be much obliged if someone would repost this to HAV after re-uploading whichever pictures need re-uploaded to imgur. I am too tired now and CBA)
  7. The Manhattan Project gets all the glory(it deserves it), but the Soviets quickly developed their own atomic weapons. They had some help through espionage, but I think it might be another piece of McCarthyism to dismiss Soviet atomic scientists. Here is a post on the Nuclear Secrecy Blog on the early program. Good insight, but not the end-all-be-all of information on the subject. A Model of the First Lightning/Joe 1 bomb?
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