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  1. 17 points
    This is an article simply to show you guys here how Waffentrager is a faker. The original article ( https://www.weibo.com/ttarticle/p/show?id=2309404213101531682050) was written in Chinese and Japanese. For better understanding I will translate and edit the article and post it here. And I must tell you why I want to reveal this shit: Long time ago I found many sayings from Waffentrager’s blog which I had never heard of, so I turned to my Japanese friend and IJA tank researcher Mr.Taki and asked him to confirm a few of them. In the end it turned out that none of Waffentrager’s article is true. I once argued with him and he not only failed to give out his reference but also deleted my replies! I’m very angry! Now let’s get started. At the very beginning I recommend all of you who opened this post to take a look at Waffentrager’s original article, that will help you understand what I’m debating. Here is the link to the original article: https://sensha-manual.blogspot.jp/2017/09/the-ho-ri-tank-destroyer.html?m=0 In China we need to use VPN(aka “ladder-梯子” or “the scientific way of browsing the Internet-科学上网” in Chinese)to open that link above so at first I post out Waffentrager’s original post in the form of screenshots in my article. I’ll skip that here. Fig.1: I will skip his original article. Now, I had raised my first question here: Please take a look at the screenshot: Fig.2: My first question In the original article, Waffentrager insisted that the Type 5 gun tank was built in July, 1944 and fully assembled in August. It was also put into trials at the same time. Fig.3: Waffentrager’s original article. But, is that true? Let’s have a look at the Japanese archive: Important Fig.4: Archive code C14011075200, Item 4 Notice the part with the red, this is the research and develop plan for the Japanese Tech Research center in 1943, and had been edited in 1944. ◎砲100(Gun-100) is the project name for the 105mm gun used by Type 5 gun tank. The column under it says: “Research a tank gun with 105mm caliber and a muzzle velocity of 900m/s”. This means that the gun had just begun to be developed and from the bottom column we can know that it was PLANNED to be finished in 1945-3[完成豫定 means ”plan to be finished” and 昭20、3 means ”Shouwa 20-3”. Shouwa 20 is 1945 in Japan (you can wiki the way for Japanese to count years I’m not going to explain it here)] Next let’s move on to the Type 5 gun tank itself, here is the Japanese archive: Important Fig.5: Archive code C14011075200, Item 7 “新砲戦車(甲)ホリ車” is the very very first name of Type 5 gun tank, it should be translated into:”New gun tank(A), Ho-Ri vehicle”. “ホリ” is the secret name of it. Still from the column we can easily know that Ho-Ri was also planned to be finished in 1945-3. But under that column there is another one called:”摘要(Summary or outline)”, in this it says:”砲100、第一次試作完了昭和19、8”, In English it is: “Gun-100, First experimental construction(prototype construction) finished in Shouwa 19-8(1944-8)” What does it mean? It means that in 1944-8, Only the 105mm gun used by the Type 5 gun tank was finished! If the Ho-Ri tank itself was finished why it was not in the 摘要 column? So how could an unfinished tank mounted the prototype gun? Waffentrager is talking bullshit. Also from Mr.Kunimoto’s book, he gave the complete schedule of the 105mm gun, here it is: Important Fig.6: Kunimoto’s schedule “修正機能試験” means ”Mechanical correctional test”, it took place in 1944-8, this matches the original Japanese archive(though this chart was also made from original archives). At that time the gun had just finished, not the tank. Next is this paragraph from Waffentrager’s article: Fig.7: Weighing 35 tons From the archive above(important Fig.5) we can learn from the second large column”研究要項(Research items)” that Ho-Ri was only PLANNED to be 35 tons, and maximum armour thickness was PLANNED to be 120mm, not was. Waffentrager is lying, he used the PLANNED data as the BUILT data. I will post out the correct data below later to see what Ho-Ri is really like when its design was finished. Fig.8: 全備重量-約三五屯(Combat weight-app.35t), 装甲(最厚部)-約一二〇粍(Armour, thickest part-app.120mm) At this time, some of the people might inquire me that:”Maybe the Type 5 gun tanks were really finished! You just don’t know!” Well, I will use the archives and books to tell these guys that they are totally wrong. None of the Type 5 gun tank was finished. Always let’s look at Waffentrager’s article first. He said that a total of 5 Ho-Ri were completed. Fig.9: Waffentrager said 5 Ho-Ri were completed. He also put an original Japanese archive(C13120839500) to “enhance” his “facts”. Fig.10: Waffentrager’s archive Everyone can see the”ホリ車,1-3-1” in the document, and someone might actually believe that 5 Ho-Ri were actually built. But they are wrong! Waffentrager is cheating you with “only a part of the original document”! Here is what the original archive really looks like: Important Fig.11: Archive code C13120839500, Item 7 “整備計画” is “Maintenance plan” in English, again it was PLAN! The whole plan was made in 1944-12-26. I don’t actually know how Waffentrager can misunderstand this, maybe he doesn’t even know Japanese or Chinese! Important Fig.12: The cover of the same archive, “昭和十九年十二月二十六日” is 1944-12-26” in English. I have other archives to prove that Ho-Ri were not finished as well: Important Fig. 13 and 14: Mitsubishi’s tank production chart made by the American survey team after the war ends. From the chart you can only find out Type 4 and Type 5 medium tanks’ record. There is no existence of Type 5 gun tank Ho-Ri, or the”M-5 Gun Tank” in the chart’s way. Except for the archives, many books written by Japanese also mentioned that Type 5 gun tank were not finished: Fig.15: Kunimoto’s record. “二〇年五月完成予定の五両の終戦時の工程進捗度は、やっと五〇パーセントであり、完成車両出せずに終戦となった。” In English it’s: “When the war ended, the five Ho-Ri planned to be finished in 1945-5 had finally reached 50% completion. No completed vehicle were made when the war ended.” Here is another book written by Japanese with the help of former IJA tank designer, Tomio Hara: Important Fig.16: Tomio Hara’s book “完成をみるには至らなかった” Again he emphasized that the tank was not finished. Also when Ho-Ri’s design was finished its combat weight was raised to 40 tons, not the planned 35 tons. It was only powered by one “Modified BMW watercooled V12 gasoline engine”, rated 550hp/1500rpm. In Waffentrager’s article he said later a Kawasaki 1100hp engine were installed, but obviously that’s none sense. There was really existed a Kawasaki 1100hp engine but that is the two BMW V12 engine(Same engine on Type 5 gun tank or Type 5 medium tank) combined together for Japanese super-heavy tank O-I use. It will take much more room which Ho-Ri do not have. Fig.17: O-I’s engine compartment arrangement. There’s no such room in Ho-Ri for this engine set. And last here are the other questions I asked Fig.18: Other questions I asked I have already talked about the questions regarding C13120839500 and the engine. As for the gun with 1005m/s muzzle velocity, the Japanese never planned to make the 105mm gun achieve such a high velocity because they don’t have the enough tech back then. Also from the archive C14011075200(important fig.4) the 105mm gun was designed only to reach about 900m/s. So, after all these, how did Waffentrager replied? I will post out the replies from my E-mail(because he deleted my replies on his blog). Fig.19: Waffentrager’s first reply He kept saying that my archive is not the same as his and he is using his own documents. I didn’t believe in these shit and I replied: Fig.20: My reply Last sentence, the Ho-Ri III he was talking about is fake. There are only Ho-Ri I(The one resembles the Ferdinand tank destroyer) and Ho-Ri II(The another one resembles the Jagdtiger tank destroyer). He even photoshoped a picture: Fig.21: Waffentrager’s fake Ho-Ri III Fig.22: The real Ho-Ri I and the base picture of Waffentrager’s photoshoped Ho-Ri III in Tomio Hara’s book. Many same details can be seen in Waffentrager's fake Ho-Ri III The 4 variants of up-armoured Type 3 Chi-Nu medium tank is also fake, I will post his original article and the confirmed facts I got from Mr.Taki by E-mail. Fig.23: 4 models of up-armoured Chi-Nu by Waffentrager Fig.24: Mr.Taki’s reply Waffentrager used every excuses he could get to refuse giving out the references, and finally he deleted my comments. What an asshole! Fig.25: Our last “conversation” Fig.26 He deleted my comment. So, as you can see, Waffentrager is really a dick. He is cheating everybody because he think that we can’t read Japanese. Anyway I still hope he could release his reference and documents to prove me wrong. After all, I’m not here to scold or argue with somebody, but to learn new things. Also if you guys have any questions about WWII(IJA) Japanese tanks, feel free to ask me, I’m happy to help.
  2. 13 points
    I forgot to post out my reference: JACAR C14011075200 JACAR C13120839500 Tomio Hara: "Japanese tank" Gakken: "Tank and Gun Tank" KAMADO: "Japanese Heavy Tanks" and help from Mr.Taki.
  3. 11 points
    It's interesting. Presentation (which contains this page) which available now on ontres.se is 110 pages long about 2-and-a-half years ago i've downloaded on my computer presentation which was 119 pages long. Apparently it's exactly the same as one available now online, except for some pages on tank protection https://cloud.mail.ru/public/FVLe/iUZw87trH (according to Chrome history file, which i've backed up in dec.2015 and still have now, this pdf was without a doubt downloaded from ontres.se https://i.imgur.com/ysAJQgr.png)
  4. 10 points
    But if you try sometimes... Fighter aircraft became much better during the Second World War. But, apart from the development of engines, it was not a straightforward matter of monotonous improvement. Aircraft are a series of compromises. Improving one aspect of performance almost always compromises others. So, for aircraft designers in World War Two, the question was not so much "what will we do to make this aircraft better?" but "what are we willing to sacrifice?" To explain why, let's look at the forces acting on an aircraft: Lift Lift is the force that keeps the aircraft from becoming one with the Earth. It is generally considered a good thing. The lift equation is L=0.5CLRV2A where L is lift, CL is lift coefficient (which is a measure of the effectiveness of the wing based on its shape and other factors), R is air density, V is airspeed and A is the area of the wing. Airspeed is very important to an aircraft's ability to make lift, since the force of lift grows with the square of airspeed and in linear relation to all other factors. This means that aircraft will have trouble producing adequate lift during takeoff and landing, since that's when they slow down the most. Altitude is also a significant factor to an aircraft's ability to make lift. The density of air decreases at an approximately linear rate with altitude above sea level: Finally, wings work better the bigger they are. Wing area directly relates to lift production, provided that wing shape is kept constant. While coefficient of lift CL contains many complex factors, one important and relatively simple factor is the angle of attack, also called AOA or alpha. The more tilted an airfoil is relative to the airflow, the more lift it will generate. The lift coefficient (and thus lift force, all other factors remaining equal) increases more or less linearly until the airfoil stalls: Essentially what's going on is that the greater the AOA, the more the wing "bends" the air around the wing. But the airflow can only become so bent before it detaches. Once the wing is stalled it doesn't stop producing lift entirely, but it does create substantially less lift than it was just before it stalled. Drag Drag is the force acting against the movement of any object travelling through a fluid. Since it slows aircraft down and makes them waste fuel in overcoming it, drag is a total buzzkill and is generally considered a bad thing. The drag equation is D=0.5CDRV2A where D is drag, CD is drag coefficient (which is a measure of how "draggy" a given aircraft is), R is air density, V is airspeed and A is the frontal area of the aircraft. This equation is obviously very similar to the lift equation, and this is where designers hit the first big snag. Lift is good, but drag is bad, but because the factors that cause these forces are so similar, most measures that will increase lift will also increase drag. Most measures that reduce drag will also reduce lift. Generally speaking, wing loading (the amount of wing area relative to the plane's weight) increased with newer aircraft models. The stall speed (the slowest possible speed at which an aircraft can fly without stalling) also increased. The massive increases in engine power alone were not sufficient to provide the increases in speed that designers wanted. They had to deliberately sacrifice lift production in order to minimize drag. World War Two saw the introduction of laminar-flow wings. These were wings that had a cross-section (or airfoil) that generated less turbulent airflow than previous airfoil designs. However, they also generated much less lift. Watch a B-17 (which does not have a laminar-flow wing) and a B-24 (which does) take off. The B-24 eats up a lot more runway before its nose pulls up. There are many causes of aerodynamic drag, but lift on a WWII fighter aircraft can be broken down into two major categories. There is induced drag, which is caused by wingtip vortices and is a byproduct of lift production, and parasitic drag which is everything else. Induced drag is interesting in that it actually decreases with airspeed. So for takeoff and landing it is a major consideration, but for cruising flight it is less important. However, induced drag is also significant during combat maneuvering. Wing with a higher aspect ratio, that is, the ratio of the wingspan to the wing chord (which is the distance from the leading edge to the trailing edge of the wing) produce less induced drag. So, for the purposes of producing good cruise efficiency, reducing induced drag was not a major consideration. For producing the best maneuvering fighter, reducing induced drag was significant. Weight Weight is the force counteracting lift. The more weight an aircraft has, the more lift it needs to produce. The more lift it needs to produce, the larger the wings need to be and the more drag they create. The more weight an aircraft has, the less it can carry. The more weight an aircraft has, the more sluggishly it accelerates. In general, weight is a bad thing for aircraft. But for fighters in WWII, weight wasn't entirely a bad thing. The more weight an aircraft has relative to its drag, the faster it can dive. Diving away to escape enemies if a fight was not going well was a useful tactic. The P-47, which was extremely heavy, but comparatively well streamlined, could easily out-dive the FW-190A and Bf-109G/K. In general though, designers tried every possible trick to reduce aircraft weight. Early in the war, stressed-skin monocoque designs began to take over from the fabric-covered, built-up tube designs. The old-style construction of the Hawker Hurricane. It's a shit plane. Stressed-skin construction of the Spitfire, with a much better strength to weight ratio. But as the war dragged on, designers tried even more creative ways to reduce weight. This went so far as reducing the weight of the rivets holding the aircraft together, stripping the aircraft of any unnecessary paint, and even removing or downgrading some of the guns. An RAF Brewster Buffalo in the Pacific theater. The British downgraded the .50 caliber machine guns to .303 weapons in order to reduce weight. In some cases, however, older construction techniques were used at the war's end due to materials shortages or for cost reasons. The German TA-152, for instance, used a large amount of wooden construction with steel reinforcement in the rear fuselage and tail in order to conserve aluminum. This was not as light or as strong as aluminum, but beggars can't be choosers. Extensive use of (now rotten) wood in the rear fuselage of the TA-152 Generally speaking, aircraft get heavier with each variant. The Bf-109C of the late 1930s weighed 1,600 kg, but the Bf-109G of the second half of WWII had ballooned to over 2,200 kg. One notable exception was the Soviet YAK-3: The YAK-3, which was originally designated YAK-1M, was a demonstration of what designers could accomplish if they had the discipline to keep aircraft weight as low as possible. Originally, it had been intended that The YAK-1 (which had somewhat mediocre performance vs. German fighters) would be improved by installing a new engine with more power. But all of the new and more powerful engines proved to be troublesome and unreliable. Without any immediate prospect of more engine power, the Yakovlev engineers instead improved performance by reducing weight. The YAK-3 ended up weighing nearly 300 kg less than the YAK-1, and the difference in performance was startling. At low altitude the YAK-3 had a tighter turn radius than anything the Luftwaffe had. Thrust Thrust is the force propelling the aircraft forwards. It is generally considered a good thing. Thrust was one area where engineers could and did make improvements with very few other compromises. The art of high-output piston engine design was refined during WWII to a precise science, only to be immediately rendered obsolete by the development of jet engines. Piston engined aircraft convert engine horsepower into thrust airflow via a propeller. Thrust was increased during WWII primarily by making the engines more powerful, although there were also some improvements in propeller design and efficiency. A tertiary source of thrust was the addition of jet thrust from the exhaust of the piston engines and from Merideth Effect radiators. The power output of WWII fighter engines was improved in two ways; first by making the engines larger, and second by making the engines more powerful relative to their weight. Neither process was particularly straightforward or easy, but nonetheless drastic improvements were made from the war's beginning to the war's end. The Pratt and Whitney Twin Wasp R-1830-1 of the late 1930s could manage about 750-800 horsepower. By mid-war, the R-1830-43 was putting out 1200 horsepower out of the same displacement. Careful engineering, gradual improvements, and the use of fuel with a higher and more consistent octane level allowed for this kind of improvement. The R-1830 Twin Wasp However, there's no replacement for displacement. By the beginning of 1943, Japanese aircraft were being massacred with mechanical regularity by a new US Navy fighter, the F6F Hellcat, which was powered by a brand new Pratt and Whitney engine, the R-2800 Double Wasp. The one true piston engine As you can see from the cross-section above, the R-2800 has two banks of cylinders. This is significant to fighter performance because even though it had 53% more engine displacement than the Twin Wasp (For US engines, the numerical designation indicated engine displacement in square inches), the Double Wasp had only about 21% more frontal area. This meant that a fighter with the R-2800 was enjoying an increase in power that was not proportionate with the increase in drag. Early R-2800-1 models could produce 1800 horsepower, but by war's end the best models could make 2100 horsepower. That meant a 45% increase in horsepower relative to the frontal area of the engine. Power to weight ratios for the latest model R-1830 and R-2800 were similar, while power to displacement improved by about 14%. By war's end Pratt and Whitney had the monstrous R-4360 in production: This gigantic engine had four rows of radially-arranged pistons. Compared to the R-2800 it produced about 50% more power for less than 10% more frontal area. Again, power to weight and power to displacement showed more modest improvements. The greatest gains were from increasing thrust with very little increase in drag. All of this was very hard for the engineers, who had to figure out how to make crankshafts and reduction gear that could handle that much power without breaking, and also how to get enough cooling air through a giant stack of cylinders. Attempts at boosting the thrust of fighters with auxiliary power sources like rockets and ramjets were tried, but were not successful. Yes, that is a biplane with retractable landing gear and auxiliary ramjets under the wings. Cocaine is a hell of a drug. A secondary source of improvement in thrust came from the development of better propellers. Most of the improvement came just before WWII broke out, and by the time the war broke out, most aircraft had constant-speed propellers. For optimal performance, the angle of attack of the propeller blades must be matched to the ratio of the forward speed of the aircraft to the circular velocity of the propeller tips. To cope with the changing requirements, constant speed or variable pitch propellers were invented that could adjust the angle of attack of the propeller blades relative to the hub. There was also improvement in using exhaust from the engine and the waste heat from the engine to increase thrust. Fairly early on, designers learned that the enormous amount of exhaust produced by the engine could be directed backwards to generate thrust. Exhaust stacks were designed to work as nozzles to harvest this small source of additional thrust: The exhaust stacks of the Merlin engine in a Spitfire act like jet nozzles A few aircraft also used the waste heat being rejected by the radiator to produce a small amount of additional thrust. The Meredith Effect radiator on the P-51 is the best-known example: Excess heat from the engine was radiated into the moving airstream that flowed through the radiator. The heat would expand the air, and the radiator was designed to use this expansion and turn it into acceleration. In essence, the radiator of the P-51 worked like a very weak ramjet. By the most optimistic projections the additional thrust from the radiator would cancel out the drag of the radiator at maximum velocity. So, it may not have provided net thrust, but it did still provide thrust, and every bit of thrust mattered. For the most part, achieving specific design objectives in WWII fighters was a function of minimizing weight, maximizing lift, minimizing drag and maximizing thrust. But doing this in a satisfactory way usually meant emphasizing certain performance goals at the expense of others. Top Speed, Dive Speed and Acceleration During the 1920s and 1930s, the lack of any serious air to air combat allowed a number of crank theories on fighter design to develop and flourish. These included the turreted fighter: The heavy fighter: And fighters that placed far too much emphasis on turn rate at the expense of everything else: But it quickly became clear, from combat in the Spanish Civil War, China, and early WWII, that going fast was where it was at. In a fight between an aircraft that was fast and an aircraft that was maneuverable, the maneuverable aircraft could twist and pirouette in order to force the situation to their advantage, while the fast aircraft could just GTFO the second that the situation started to sour. In fact, this situation would prevail until the early jet age when the massive increase in drag from supersonic flight made going faster difficult, and the development of heat-seeking missiles made it dangerous to run from a fight with jet nozzles pointed towards the enemy. The top speed of an aircraft is the speed at which drag and thrust balance each other out, and the aircraft stops accelerating. Maximizing top speed means minimizing drag and maximizing thrust. The heavy fighters had a major, inherent disadvantage in terms of top speed. This is because twin engined prop fighters have three big lumps contributing to frontal area; two engines and the fuselage. A single engine fighter only has the engine, with the rest of the fuselage tucked neatly behind it. The turret fighter isn't as bad; the turret contributes some additional drag, but not as much as the twin-engine design does. It does, however, add quite a bit of weight, which cripples acceleration even if it has a smaller effect on top speed. Early-war Japanese and Italian fighters were designed with dogfight performance above all other considerations, which meant that they had large wings to generate large turning forces, and often had open cockpits for the best possible visibility. Both of these features added drag, and left these aircraft too slow to compete against aircraft that sacrificed some maneuverability for pure speed. Drag force rises roughly as a square function of airspeed (throw this formula out the window when you reach speeds near the speed of sound). Power is equal to force times distance over time, or force times velocity. So, power consumed by drag will be equal to drag coefficient times frontal area times airspeed squared times airspeed. So, the power required for a given maximum airspeed will be a roughly cubic function. And that is assuming that the efficiency of the propeller remains constant! Acceleration is (thrust-drag)/weight. It is possible to have an aircraft that has a high maximum speed, but quite poor acceleration and vice versa. Indeed, the A6M5 zero had a somewhat better power to weight ratio than the F6F5 Hellcat, but a considerably lower top speed. In a drag race the A6M5 would initially pull ahead, but it would be gradually overtaken by the Hellcat, which would eventually get to speeds that the zero simply could not match. Maximum dive speed is also a function of drag and thrust, but it's a bit different because the weight of the aircraft times the sine of the dive angle also counts towards thrust. In general this meant that large fighters dove better. Drag scales with the frontal area, which is a square function of size. Weight scales with volume (assuming constant density), which is a cubic function of size. Big American fighters like the P-47 and F4U dove much faster than their Axis opponents, and could pick up speed that their opponents could not hope to match in a dive. A number of US fighters dove so quickly that they had problems with localized supersonic airflow. Supersonic airflow was very poorly understood at the time, and many pilots died before somewhat improvisational solutions like dive brakes were added. Ranking US ace Richard Bong takes a look at the dive brakes of a P-38 Acceleration, top speed and dive speed are all improved by reducing drag, so every conceivable trick for reducing parasitic drag was tried. The Lockheed P-38 used flush rivets on most surfaces as well as extensive butt welds to produce the smoothest possible flight surfaces. This did reduce drag, but it also contributed to the great cost of the P-38. The Bf 109 was experimentally flown with a V-tail to reduce drag. V-tails have lower interference drag than conventional tails, but the modification was found to compromise handling during takeoff and landing too much and was not deemed worth the small amount of additional speed. The YAK-3 was coated with a layer of hard wax to smooth out the wooden surface and reduce drag. This simple improvement actually increased top speed by a small, but measurable amount! In addition, the largely wooden structure of the aircraft had few rivets, which meant even less drag. The Donier DO-335 was a novel approach to solving the problem of drag in twin-engine fighters. The two engines were placed at the front and rear of the aircraft, driving a pusher and a tractor propeller. This unconventional configuration led to some interesting problems, and the war ended before these could be solved. The J2M Raiden had a long engine cowling that extended several feet forward in front of the engine. This tapered engine cowling housed an engine-driven fan for cooling air as well as a long extension shaft of the engine to drive the propeller. This did reduce drag, but at the expense of lengthening the nose and so reducing pilot visibility, and also moving the center of gravity rearward relative to the center of lift. Designers were already stuffing the most powerful engines coming out of factories into aircraft, provided that they were reasonably reliable (and sometimes not even then). After that, the most expedient solution to improve speed was to sacrifice lift to reduce drag and make the wings smaller. The reduction in agility at low speeds was generally worth it, and at higher speeds relatively small wings could produce satisfactory maneuverability since lift is a square function of velocity. Alternatively, so-called laminar flow airfoils (they weren't actually laminar flow) were substituted, which produced less drag but also less lift. The Bell P-63 had very similar aerodynamics to the P-39 and nearly the same engine, but was some 80 KPH faster thanks to the new laminar flow airfoils. However, the landing speed also increased by about 40 KPH, largely sacrificing the benevolent landing characteristics that P-39 pilots loved. The biggest problem with reducing the lift of the wings to increase speed was that it made takeoff and landing difficult. Aircraft with less lift need to get to higher speeds to generate enough lift to take off, and need to land at higher speeds as well. As the war progressed, fighter aircraft generally became trickier to fly, and the butcher's bill of pilots lost in accidents and training was enormous. Turn Rate Sometimes things didn't go as planned. A fighter might be ambushed, or an ambush could go wrong, and the fighter would need to turn, turn, turn. It might need to turn to get into a position to attack, or it might need to turn to evade an attack. Aircraft in combat turn with their wings, not their rudders. This is because the wings are way, way bigger, and therefore much more effective at turning the aircraft. The rudder is just there to make the nose do what the pilot wants it to. The pilot rolls the aircraft until it's oriented correctly, and then begins the turn by pulling the nose up. Pulling the nose up increases the angle of attack, which increases the lift produced by the wings. This produces centripetal force which pulls the plane into the turn. Since WWII aircraft don't have the benefit of computer-run fly-by-wire flight control systems, the pilot would also make small corrections with rudder and ailerons during the turn. But, as we saw above, making more lift means making more drag. Therefore, when aircraft turn they tend to slow down unless the pilot guns the throttle. Long after WWII, Col. John Boyd (PBUH) codified the relationship between drag, thrust, lift and weight as it relates to aircraft turning performance into an elegant mathematical model called energy-maneuverability theory, which also allowed for charts that depict these relationships. Normally, I would gush about how wonderful E-M theory is, but as it turns out there's an actual aerospace engineer named John Golan who has already written a much better explanation than I would likely manage, so I'll just link that. And steal his diagram: E-M charts are often called "doghouse plots" because of the shape they trace out. An E-M chart specifies the turning maneuverability of a given aircraft with a given amount of fuel and weapons at a particular altitude. Turn rate is on the Y axis and airspeed is on the X axis. The aircraft is capable of flying in any condition within the dotted line, although not necessarily continuously. The aircraft is capable of flying continuously anywhere within the dotted line and under the solid line until it runs out of fuel. The aircraft cannot fly to the left of the doghouse because it cannot produce enough lift at such a slow speed to stay in the air. Eventually it will run out of sky and hit the ground. The curved, right-side "roof" of the doghouse is actually a continuous quadratic curve that represents centrifugal force. The aircraft cannot fly outside of this curve or it or the pilot will break from G forces. Finally, the rightmost, vertical side of the doghouse is the maximum speed that the aircraft can fly at; either it doesn't have the thrust to fly faster, or something breaks if the pilot should try. The peak of the "roof" of the doghouse represents the aircraft's ideal airspeed for maximum turn rate. This is usually called the "corner velocity" of the aircraft. So, let's look at some actual (ish) EM charts: Now, these are taken from a flight simulator, but they're accurate enough to illustrate the point. They're also a little busier than the example above, but still easy enough to understand. The gray plot overlaid on the chart consists of G-force (the curves) and turn radius (the straight lines radiating from the graph origin). The green doghouse shows the aircraft's performance with flaps. The red curve shows the maximum sustained turn rate. You may notice that the red line terminates on the X axis at a surprisingly low top speed; that's because these charts were made for a very low altitude confrontation, and their maximum level top could only be achieved at higher altitudes. These aircraft could fly faster than the limits of the red line show, but only if they picked up extra speed from a dive. These charts could also be overlaid on each other for comparison, but in this case that would be like a graphic designer vomiting all over the screen, or a Studio Killers music video. From these charts, we can conclude that at low altitude the P-51D enjoys many advantages over the Bf 109G-6. It has a higher top speed at this altitude, 350-something vs 320-something MPH. However, the P-51 has a lower corner speed. In general, the P-51's flight envelope at this altitude is just bigger. But that doesn't mean that the Bf 109 doesn't have a few tricks. As you can see, it enjoys a better sustained turn rate from about 175 to 325 MPH. Between those speed bands, the 109 will be able to hold on to its energy better than the pony provided it uses only moderate turns. During turning flight, our old problem induced drag comes back to haunt fighter designers. The induced drag equation is Cdi = (Cl^2) / (pi * AR * e). Where Cdi is the induced drag coefficient, Cl is the lift coefficient, pi is the irrational constant pi, AR is aspect ratio, or wingspan squared divided by wing area, and e is not the irrational constant e but an efficiency factor. There are a few things of interest here. For starters, induced drag increases with the square of the lift coefficient. Lift coefficient increases more or less linearly (see above) with angle of attack. There are various tricks for increasing wing lift nonlinearly, as well as various tricks for generating lift with surfaces other than the wings, but in WWII, designers really didn't use these much. So, for all intents and purposes, the induced drag coefficient will increase with the square of angle of attack, and for a given airspeed, induced drag will increase with the square of the number of Gs the aircraft is pulling. Since this is a square function, it can outrun other, linear functions easily, so minimizing the effect of induced drag is a major consideration in improving the sustained turn performance of a fighter. To maximize turn rate in a fighter, designers needed to make the fighter as light as possible, make the engine as powerful as possible, make the wings have as much area as possible, make the wings as long and skinny as possible, and to use the most efficient possible wing shape. You probably noticed that two of these requirements, make the plane as light as possible and make the wings as large as possible, directly contradict the requirements of good dive performance. There is simply no way to reconcile them; the designers either needed to choose one, the other, or come to an intermediate compromise. There was no way to have both great turning performance and great diving performance. Since the designers could generally be assumed to have reduced weight to the maximum possible extent and put the most powerful engine available into the aircraft, that left the design of the wings. The larger the wings, the more lift they generate at a given angle of attack. The lower the angle of attack, the less induced drag. The bigger wings would add more drag in level flight and reduce top speed, but they would actually reduce drag during maneuvering flight and improve sustained turn rate. A rough estimate of the turning performance of the aircraft can be made by dividing the weight of the aircraft over its wing area. This is called wing loading, and people who ought to know better put far too much emphasis on it. If you have E-M charts, you don't need wing loading. However, E-M charts require quite a bit of aerodynamic data to calculate, while wing loading is much simpler. Giving the wings a higher aspect ratio would also improve turn performance, but the designers hands were somewhat tied in this respect. The wings usually stored the landing gear and often the armament of the fighter. In addition the wings generated the lift, and making the wings too long and skinny would make them too structurally flimsy to support the aircraft in maneuvering flight. That is, unless they were extensively reinforced, which would add weight and completely defeat the purpose. So, designers were practically limited in how much they could vary the aspect ratio of fighter wings. The wing planform has significant effect on the efficiency factor e. The ideal shape to reduce induced drag is the "elliptical" (actually two half ellipses) wing shape used on the Supermarine spitfire. This wing shape was, however, difficult to manufacture. By the end of the war, engineers had come up with several wing planforms that were nearly as efficient as the elliptical wing, but were much easier to manufacture. Another way to reduce induced drag is to slightly twist the wings of the aircraft so that the wing tips point down. This is called washout. The main purpose of washout was to improve the responsiveness of the ailerons during hard maneuvering, but it could give small efficiency improvements as well. Washout obviously complicates the manufacture of the wing, and thus it wasn't that common in WWII, although the TA-152 notably did have three degrees of tip washout. The Bf 109 had leading edge slats that would deploy automatically at high angles of attack. Again, the main intent of these devices was to improve the control of the aircraft during takeoff and landing and hard maneuvering, but they did slightly improve the maximum angle of attack the wing could be flown at, and therefore the maximum instantaneous turn rate of the aircraft. The downside of the slats was that they weakened the wing structure and precluded the placement of guns inside the wing. leading edge slats of a Bf 109 in the extended position One way to attempt to reconcile the conflicting requirements of high speed and good turning capability was the "butterfly" flaps seen on Japanese Nakajima fighters. This model of a Ki-43 shows the location of the butterfly flaps; on the underside of the wings, near the roots These flaps would extend during combat, in the case of later Nakajima fighters, automatically, to increase wing area and lift. During level and high speed flight they would retract to reduce drag. Again, this would mainly improve handling on the left hand side of the doghouse, and would improve instantaneous turn rate but do very little for sustained turn rate. In general, turn performance was sacrificed in WWII for more speed, as the two were difficult to reconcile. There were a small number of tricks known to engineers at the time that could improve instantaneous turn rate on fast aircraft with high wing loading, but these tricks were inadequate to the task of designing an aircraft that was very fast and also very maneuverable. Designers tended to settle for as fast as possible while still possessing decent turning performance. Climb Rate Climb rate was most important for interceptor aircraft tasked with quickly getting to the level of intruding enemy aircraft. When an aircraft climbs it gains potential energy, which means it needs spare available power. The specific excess power of an aircraft is equal to V/W(T-D) where V is airspeed, W is weight, T is thrust and D is drag. Note that lift isn't anywhere in this equation! Provided that the plane has adequate lift to stay in the air and its wings are reasonably efficient at generating lift so that the D term doesn't get too high, a plane with stubby wings can be quite the climber! The Mitsubishi J2M Raiden is an excellent example of what a fighter optimized for climb rate looked like. A captured J2M in the US during testing The J2M had a very aerodynamically clean design, somewhat at the expense of pilot visibility and decidedly at the expense of turn rate. The airframe was comparatively light, somewhat at the expense of firepower and at great expense to fuel capacity. Surprisingly for a Japanese aircraft, there was some pilot armor. The engine was, naturally, the most powerful available at the time. The wings, in addition to being somewhat small by Japanese standards, had laminar-flow airfoils that sacrificed maximum lift for lower drag. The end result was an aircraft that was the polar opposite of the comparatively slow, long-ranged and agile A6M zero-sen fighters that IJN pilots were used to! But it certainly worked. The J2M was one of the fastest-climbing piston engine aircraft of the war, comparable to the F8F Bearcat. The design requirements for climb rate were practically the same as the design requirements for acceleration, and could generally be reconciled with the design requirements for dive performance and top speed. The design requirements for turn rate were very difficult to reconcile with the design requirements for climb rate. Roll Rate In maneuvering combat aircraft roll to the desired orientation and then pitch. The ability to roll quickly allows the fighter to transition between turns faster, giving it an edge in maneuvering combat. Aircraft roll with their ailerons by making one wing generate more lift while the other wing generates less lift. The physics from there are the same for any other rotating object. Rolling acceleration is a function of the amount of torque that the ailerons can provide divided by the moment of inertia of the aircraft about the roll axis. So, to improve roll rate, a fighter needs the lowest possible moment of inertia and the highest possible torque from its ailerons. The FW-190A was the fighter best optimized for roll rate. Kurt Tank's design team did everything right when it came to maximizing roll rate. The FW-190 could out-roll nearly every other piston fighter The FW-190 has the majority of its mass near the center of the aircraft. The fuel is all stored in the fuselage and the guns are located either above the engine or in the roots of the wings. Later versions added more guns, but these were placed just outside of the propeller arc. Twin engined fighters suffered badly in roll rate in part because the engines had to be placed far from the centerline of the aircraft. Fighters with armament far out in the wings also suffered. The ailerons were very large relative to the size of the wing. This meant that they could generate a lot of torque. Normally, large ailerons were a problem for pilots to deflect. Most World War Two fighters did not have any hydraulic assistance; controls needed to be deflected with muscle power alone, and large controls could encounter too much wind resistance for the pilots to muscle through at high speed. The FW-190 overcame this in two ways. The first was that, compared to the Bf 109, the cockpit was decently roomy. Not as roomy as a P-47, of course, but still a vast improvement. Cockpit space in World War Two fighters wasn't just a matter of comfort. The pilots needed elbow room in the cockpit in order to wrestle with the control stick. The FW-190 also used controls that were actuated by solid rods rather than by cables. This meant that there was less give in the system, since cables aren't completely rigid. Additionally, the FW-190 used Frise ailerons, which have a protruding tip that bites into the wind and reduces the necessary control forces: Several US Navy fighters, like later models of F6F and F4U used spring-loaded aileron tabs, which accomplished something similar by different means: In these designs a spring would assist in pulling the aileron one way, and a small tab on the aileron the opposite way in order to aerodynamically move the aileron. This helped reduce the force necessary to move the ailerons at high speeds. Another, somewhat less obvious requirement for good roll rate in fighters was that the wings be as rigid as possible. At high speeds, the force of the ailerons deflecting would tend to twist the wings of the aircraft in the opposite direction. Essentially, the ailerons began to act like servo tabs. This meant that the roll rate would begin to suffer at high speeds, and at very high speeds the aircraft might actually roll in the opposite direction of the pilot's input. The FW-190s wings were extremely rigid. Wing rigidity is a function of aspect ratio and construction. The FW-190 had wings that had a fairly low aspect ratio, and were somewhat overbuilt. Additionally, the wings were built as a single piece, which was a very strong and robust approach. This had the downside that damaged wings had to be replaced as a unit, however. Some spitfires were modified by changing the wings from the original elliptical shape to a "clipped" planform that ended abruptly at a somewhat shorter span. This sacrificed some turning performance, but it made the wings much stiffer and therefore improved roll rate. Finally, most aircraft at the beginning of the war had fabric-skinned ailerons, including many that had metal-skinned wings. Fabric-skinned ailerons were cheaper and less prone to vibration problems than metal ones, but at high speed the shellacked surface of the fabric just wasn't air-tight enough, and a significant amount of airflow would begin going into and through the aileron. This degraded their effectiveness greatly, and the substitution of metal surfaces helped greatly. Stability and Safety World War Two fighters were a handful. The pressures of war meant that planes were often rushed into service without thorough testing, and there were often nasty surprises lurking in unexplored corners of the flight envelope. This is the P-51H. Even though the P-51D had been in mass production for years, it still had some lingering stability issues. The P-51H solved these by enlarging the tail. Performance was improved by a comprehensive program of drag reduction and weight reduction through the use of thinner aluminum skin. The Bf 109 had a poor safety record in large part because of the narrow landing gear. This design kept the mass well centralized, but it made landing far too difficult for inexpert pilots. The ammunition for the massive 37mm cannon in the P-39 and P-63 was located in the nose, and located far forward enough that depleting the ammunition significantly affected the aircraft's stability. Once the ammunition was expended, it was much more likely that the aircraft could enter dangerous spins. The cockpit of the FW-190, while roomier than the Bf 109, had terrible forward visibility. The pilot could see to the sides and rear well enough, but a combination of a relatively wide radial engine and a hump on top of the engine cowling to house the synchronized machine guns meant that the pilot could see very little. This could be dangerous while taxiing on the ground.
  5. 9 points
    Jagdika

    WWII Japanese Tanks in China

    All photos were taken by myself in year 2016 during my visit to Beijing. Tanks are from the Military Museum of the Chinese People's Revolution and the Tank Museum(currently closed). Enjoy. No.1: Type 94 Light armored car (Tankette) in the Tank Museum This is the early version of the Type 94 Tankette. It was found in a river in 1970s. It is the best preserved Type 94 Tankette in the world. No.2: Type 97 Medium Tank in the Tank Museum This is a late version Type 97 medium tank. It carries the old small 57mm gun turret but has the revised engine ventilation port. This tank was donated by the Soviet 7th mechanized division before they withdrew from China in 1955. No.3: Type 97 Medium Tank Kai in the Military Museum of the Chinese People's Revolution This Type 97 Medium Tank Kai's combat serial number is 102. It belonged to the former China North-East tank regiment. It took part in the attack of Jinzhou against KMT army on 1948-9-14, and did great contribution for knocking out their bunkers and MG nests by shooting and ramming. Thus after the battle this tank was awarded with an honored name:"The Hero(功臣号)“ About the tank itself, it was assembled by the Chinese army themselves by using destroyed or damaged Chi-Ha parts after the surrender of Japan. This particular tank was built up with a normal Type 97's chassis(57mm gun version) early model, and a Type 97 Kai's Shinhoto(New turret for the 47mm gun). However there are other saying claim that this tank was modified by the Japanese. It was the first tank that roared over the Tiananmen Square during the Founding Ceremony of China on 1949-10-1. The same tank on 1949-10-1. China's tank army origins from old IJA tanks. No.4: Type 97 Medium Tank in the Military Museum of the Chinese People's Revolution Sorry, only one photo was taken. This Type 97 Medium Tank has a chassis from Type 97 Medium Tank Kai and a turret from a normal Type 97 Medium Tank. It was merged together by the Chinese army. No.5: Type 95 Armored Track(Train track) Vehicle in the Military Museum of the Chinese People's Revolution Only two samples survived. One is in China here and one is in Kubinka, Russia (Maybe now it is transfered to the Patriot Park? I don't know). Hope you enjoy the photos I took! No repost to other places without my permission.
  6. 8 points
    I have compiled some data on the payload fraction (payload to LEO / Gross mass) of various rocket systems; From this, several thing can be seen; Solid rocket boosters utterly ruin your payload fraction. Despite having a significantly higher specific impulse than other engines (365 seconds for the RS-68 vs. 285 seconds for the RD-275), hydrogen-fueled launch systems only have a slightly better payload fraction than hypergolic systems, or are even significantly worse. Larger rockets generally have a larger payload fraction (Saturn I vs. Saturn V, Falcon 9 vs. Falcon Heavy). Titan II and Titan IV are not entirely comparable. STS is a stupid pile of trash. Kerolox first stage provide significantly better payload fractions in almost all cases, while avoiding the difficulties associated with liquid hydrogen. Hypergolics generally have inferior performance to both, but are significantly easier to handle, and the difference is not extreme. Data via wiki, except where noted (the gross weights for Delta IV Heavy and Atlas V 551 were horribly off, especially for the latter). Encylopedia Astronautica data mostly agreed, but that site is severely lacking in info on the Falcon family. @Sturgeon@Collimatrix@T___A
  7. 7 points
    LostCosmonaut

    Advanced MiG-3 Variants

    Intro The MiG-3. All flying aircraft today have been re-engined with the V1710, and look slightly different. The MiG-3 was one of the first fighters developed by the famous Mikoyan-Gurevich design bureau. An improvement on the troubled MiG-1, the MiG-3 was designed for combat at high altitude. Introduced in 1941, it gained less fame than its contemporaries like the Yakovlev and Lavochkin fighters. Germany's virtually nonexistent strategic bomber force, and the low-altitude nature of combat on the Eastern Front meant the MiG-3 was forced out of its element, and its performance suffered. Combined with the MiG's difficult flight characteristics and the horrible strategic situation for the Soviets in 1941, this meant the MiG-3 achieved little success. While the MiG-3 did not spawn a successful series of fighters (like the Yak-1, Yak-9, and Yak-3, for instance), numerous variants were considered, and many of them were built in at least prototype form. However, for many reasons, such as lack of need or nTheonavailability of suitable engines, none of these variants entered large scale production. I-230/MiG-3U The resemblance to the baseline MiG-3 is easily seen. via aviastar The I-230 was one of the more straightforward developments of the MiG-3. Development on the I-230 (also known as the MiG-3U) began in late 1941, with the objective to correct numerous flaws identified in the MiG-3. First was the armament; the MiG-3 had only two 7.62mm ShKAS machine guns and a single 12.7 Berezen (BS) machine gun, firing through the propeller. On the I-230, these were replaced with two 20mm ShVAK cannons (again synchronized to fire through the propeller). Outwardly, the I-230 looked very similar to the production MiG-3, although the new aircraft was made mostly of wood instead of steel tubing and duralumin. The wing area and wingspan were increased (to 18 m^2 and 11 meters, versus 17.4 m^2 and 10.2 meters for the production MiG-3), and the fuselage was lengthened by .37 meters. Soviet engineers originally intended to fit the I-230 with the AM-39 engine. However, by the time the I-230 airframe was completed in early 1942, the AM-39 was not yet available. As a result, the first I-230 was forced to use an engine built from both AM-38 and AM-35 parts (designated AM-35A). This engine was roughly 40 kilograms heavier than the intended engine, but produced a respectable 1350 horsepower. Even with such an odd engine, the I-230 flew by the end of 1942, achieving a top speed of over 650 km/hr at altitude. (Some sources say the I-230 first flew in May 1943, this is likely for the machines with AM-35A engines). Four more prototypes were built with AM-35A engines. These aircraft would serve in defense of the Moscow region while undergoing flight testing. While the design showed promise, by this point the AM-35 was obsolete and out of production. Additionally, some other deficiencies were identified. The I-230 was found to be difficult to land (a flaw shared with the MiG-3), and the engine tended to leak oil into the rest of the aircraft at high altitudes. As a result, the I-230 was not built. I-231 The I-231 was a further evolution of the I-230, using the AM-39 engine that had originally been intended for use in the I-230. One of the I-230 aircraft had its engine replaced with the more powerful AM-39. This required modification of the cooling system; the radiator was enlarged, with another secondary radiator installed. There were also a few other modifications, such as moving the horizontal tail surfaces downward slightly, the fuselage fuel tank was enlarged and some modifications to the radios. Armament was the same as the I-230; two 20mm ShVAK cannons. First flight of the I-231 was in October 1943. However, in early November, the prototype was forced to make an emergency landing after the supercharger failed at high altitude. Two weeks later, flight testing of the repaired I-231 resumed. The prototype, with the more powerful AM-39 (1800 horsepower), reached a top speed of 707 km/hr at an altitude of about 7000 meters. It also climbed to 5000 meters in under 5 minutes. Flight testing continued in early 1944, and in March, the I-231 was damaged after overrunning the runway during landing. The program suffered another setback when the repaired I-231 suffered an engine failure, damaging the precious AM-39 engine. Following this last mishap, work on the I-231 was discontinued. The similarities between the radial and inline engined models are still visible. via airvectors I-210/MiG-9 M-82 I-210 with radial engine. via airpages.ru The I-210 was a more substantial modification of the MiG-3 which began in the summer of 1941. Production of the Shvestsov M-82 radial engine had recently begun, and many design bureaus, including MiG, were instructed to find ways to incorporate the engine into their designs. In the case of the MiG-3, this was especially important, as the Soviet government sought to discontinue the AM-35 to free up production space for the AM-38 used by the all-important Il-2. In theory, the M-82, with 1700 horsepower, would provide a significant performance increase over the AM-35. Soviet engineers projected that the M-82 equipped MiG-3 (now known as the I-210) would reach nearly 650 km/hr at altitude. It was also projected that performance would be massively improved at low altitude, important for combat on the Eastern Front. The new aircraft was received the designation “MiG-9 M-82”, denoting that it was a substantially new type (this designation would later be reused for a twin-jet fighter in the late 1940s). In addition to fitting of the M-82, there were several other differences between the MiG-3 and the I-210. Armament was increased to three 12.7mm UBS machine guns (two 7.62mm ShKAS were fitted initially, but soon removed). Several systems related to the engine, including the oil coolers and fuel system were also updated. The fuselage was widened slightly to accommodate the new engine. The I-210 first flew in July 1941. However, it became quickly apparent that it was not meeting its performance targets. The top speed at an altitude of 5000 meters was a mere 540 km/hr, far inferior to to projects (as well as the production MiG-3!). Part of this was due to having a different model of propeller installed than what was intended. However, wind tunnel testing and inspection showed that the engine cowling was poorly designed and sealed to the rest of the airframe, causing significant drag. Several months were required to correct the various defects, and it was not until June 1942 that three I-210s were ready for trails. During testing, the three aircraft were assigned to the PVO for use on the front. State trials began in September, and the I-210 fared poorly. Maximum speed was still only 565 km/hr, far inferior to existing types. Overall, the I-210 was judged to be unsatisfactory and inferior to the La-5 and Yak-7. The aircraft did not enter production, although the three completed prototypes would serve in Karelia until 1944. I-211/MiG-9E The failure of the I-210 was not the end of efforts to install a radial engine into the MiG-3 airframe. In late 1942, work on the I-211 began. A new Ash-82 engine, an improved variant of the M-82 installed on the I-210, was fitted. With the help of the Shvetsov bureau, the aerodynamics of the engine and its cowling were substantially improved. Further modifications reduced the empty weight of the “MiG-9E” by 170 kg. The three 12.7mm machine guns were replaced by two 20mm ShVAK cannons. Testing of the I-211 began in August 1942 (other sources variously say that testing did not begin until early 1943, my interpretation is that this is when state trials officially happened). Performance was markedly superior to the I-210; the I-211 reached a top speed of 670 km/hr, and was able to climb to altitudes in excess of 11000 meters. However, the La-5, which was already in production using the M-82 engine, had similar performance. Moreover, the La-7 was in development, and was felt to have better potential. In all, only ten I-211s were built. Interestingly, at least one source claims that a variant of the I-211 equipped with a Lend-Lease R-2800 engine was considered. There is no evidence that such an aircraft was actually built. I-220/MiG-11 The I-220 (and the rest of its series up to the I-225) were substantially different from the production MiG-3, sharing little aside from the basic design and concept. These aircraft took the original mission of the MiG-3, interception of targets at high altitude, to the ultimate extreme. The initial request that led to development of the I-220 was issued in July 1941, in response to high-altitude overflights by Ju-86P reconnaissance aircraft. These aircraft, capable of operating at over 13000 meters, were outside the reach of almost any Soviet fighter. A few Ju-86Ps at slightly lower altitude were intercepted by MiG-3s before the start of the war, so the MiG-3 was a natural starting point for a high-altitude interceptor. Work on the I-220 prototype began in late 1942. Originally, it had been planned to install the AM-39 engine, but it was not ready at the time construction began on the prototype. Instead, one source (OKB MiG, Page 48) states anAM-38F engine was installed, which still provided more power (1700 hp) than the AM-35 on the MiG-3. However, it had the drawback of losing power at high-altitudes; the AM-38F would be an interim installation at best. A different source reports that an AM-37 was the first engine installed. In addition to the new engine, the wingspan was lengthened by .80 meters, with a slight sweep added to the outer portion of the leading edge. The radiator was relocated from the belly of the aircraft to inside the wing center section, with new air intakes added at the wing roots. Armament was increased to four ShVAKs, making the I-220 one of the heaviest armed Soviet fighters. The I-220 first flew in January 1943. Testing of the aircraft proceeded, as the AM-39 was still not yet ready. Despite being handicapped by the AM-38F engine, the I-220 prototype was still able to reach 650 km/hr during testing in January 1944. It was agreed that the aircraft had potential, but would need the AM-39 to reach its maximum performance. The second I-220 prototype was eventually fitted with the AM-39, but by that point it had been decided to substantially redesign the aircraft. I-220 vs. I-221 I-221/MiG-7 While the I-220 had done well, it had not been able to reach the altitudes its designers had hoped for. Numerous changes would be required to get the best possible performance out of the airframe. The most obvious area for improvement was the engine. Rather than the AM-38F, an AM-39A with a turbocharger was installed. Not only was the AM-39 more powerful than the AM-38, but the twin turbocharger would allow the engine to continue developing power at altitude. Additionally, the wingspan was increased further, to 13 meters. Armament was reduced to two ShVAK cannons, to save weight. Significantly, the I-221 was fitted with a pressurized cockpit, to allow the pilot to survive at extreme altitude. By the time the I-221 made its first flight in December 1943, the Ju-86 threat had disappeared. One of the high-altitude intruders had been intercepted by a Yak-9PD (a high-altitude version of the Yak-9 designed and built in three weeks), though it had not been destroyed, overflights ceased. Nevertheless, the Yak-9PD was very much an interim solution, armed with only one ShVAK and requiring 25 minutes to climb to 12000 meters. So, development of the I-221 continued. The test program of the I-221 was cut very short. On the eighth flight of the aircraft, in February 1944, the pilot bailed out at altitude, after seeing flames coming from the turbocharger and smoke in the cockpit. The pilot survived unharmed, but obviously the I-221 was completely destroyed. I-222/MiG-7 Side view of I-222. via ruslet.webnode.cz The I-222 was a continued development of the I-221. Not only did it have several additional performance improvements, but it was the closest of MiG's high altitude fighters to a “production ready” aircraft. The AM-39A engine was replaced with a more powerful AM-39B, with twin turbo-superchargers, plus a new four-bladed propeller. An improved intercooler was also installed (clearly visible under the central fuselage). To improve the I-222's potential utility as a combat aircraft, 64mm of armored glass was installed in the windscreen, and the cockpit pressure bulkheads were reinforced with armor plate. The fuselage contours were also modified to give the pilot better rearward visibility. Armament was two B-20 cannons, replacing the ShVAKs. The I-222 made its first flight in May 1944. Relatively little testing was done before the aircraft went to the TSAGI wind tunnel for further refinement. It emerged in September and underwent further testing. Test flights proved that the I-222 had truly exceptional performance. A speed of 691 km/hr was reached, quite respectable for a piston-powered aircraft. The truly astonishing performance figure was the ceiling of 14500 meters, well in excess of any German aircraft (save for the rare and latecoming Ta-152H). Though the I-222 could likely have been put into production, Soviet authorities assessed (correctly) that by late 1944 there was little threat from high-altitude German aircraft. Nuisance flights by Ju-86s were of little consequence, and German bomber programs such as the He-274 universally failed to bear fruit. Testing of the I-222 continued through late 1945, when the program was cancelled. I-224/Mig-7 As can be seen the I-224 is similar to the I-222. From OKB MiG by Butowski and Miller The I-224 was a development of the I-222 with an improved AM-39FB engine. Several other minor improvements, such as an improved propeller and modified cooling system. The new aircraft first flew in September 1944. After five flights, it was heavily damaged in an emergency landing. Difficulties continued after the aircraft was repaired in December; the engine had to be replaced in February due to the presence of metal particles in the oil. Like the I-222, the I-224 demonstrated very good performance at altitude, also climbing to over 14000 meters and recording speeds over 690 km/hr. But by now, it was October 1945, and the war was over. It was decided to fit the I-224 with a fuel-injected AM-44 engine. This was not completed until July of 1946, and by then the time of the piston-engine fighter had passed. Both the I-222 and I-224 programs were shut down in November. I-225/MiG-11 From OKB MiG by Butowski & Miller The I-225 was born from the second I-220 prototype. Although the I-225 was still designed for operation at high-altitude, it was decided not to optimize the aircraft for such extreme heights as the I-222 and I-224. It was hoped that this would allow for a higher top speed and heavier armament, among other improvements. A turbocharged variant of the AM-42 engine (similar to that used on the Il-10 ground attack aircraft) was fitted, providing 2200 horsepower at takeoff. The pressurized cabin was deleted to save weight, and allow the cockpit to be optimized for better visibility. Armament was the same as the I-220; four ShVAK cannons. Armor was added to the windscreen, as well as the pilot's headrest. Improved instrumentation and a new radio system was also added. As predicted, the I-225 had exceptional performance. The aircraft was capable of speeds in excess of 720 km/hr, and demonstrated good handling characteristics. Unfortunately, the first I-225 prototype was lost after only 15 flights, due to an engine fire. A second prototype was completed with an AM-42FB engine, and first flew in March 1945. This second prototype was fitted with four B-20 cannons instead of ShVAKs, This prototype was also reported to be capable of over 720 km/hr, as well as able to climb to 5000 meters in under 4 minutes. However, due to continued vibrations, the AM-42 was replaced with an AM-44 in January 1946. This did not solve the issues though, and the I-225, like its predecessors, was not selected for production. All work on the I-225 was shut down in March 1947. Remarks While none of the advanced MiG-3 variants entered production, they did provide the Mikoyan-Gurevich bureau with valuable engineering and design experience. In a different world, one might imagine that some of their designs could have found a niche. The I-210/1 and I-230/1 would have little reason to be built in a world where Yakovlev and Lavochkin fighters exist in the way they did. However, if Germany or another enemy had a developed strategic bombing arm, then the I-220 series fighters could have found a use. Either way, by 1945, it was clear that jet aircraft were the future. Even the Soviets, who had a relatively late start on jet engines, quickly developed aircraft like the MiG-9 and Yak-15 whose performance exceeded any of the MiG-3 variants. Sources: OKB MiG, a History of the Design Bureau and its Aircraft, by Piotr Butowski and Jay Miller http://www.airvectors.net/avmig3.html http://www.aviastar.org/air/russia/a_mikoyan-gurevich.php https://ruslet.webnode.cz/technika/ruska-technika/letecka-technika/a-i-mikojan-a-m-i-gurjevic/ (I-230, I-210, I-211, I-220, I-221, I-222, I-224, and I-225 pages) http://www.airwar.ru/fighterww2.html (I-230, I-231, I-210, I-211, I-220, I-221, I-222, I-224, and I-225 pages) http://soviethammer.blogspot.com/2015/02/mig-fighter-aircraft-development-wwii.html
  8. 7 points
    In case some of the netizens on WT forum and Reddit doubt my source of reference, I will post them out here. All the original archives I used are accessible for the public can be found in the Japan National Archive center's website here: https://www.jacar.archives.go.jp/aj/meta/reference And here is the two archives mentioned by both Waffentrager and me: C14011075200: https://www.jacar.archives.go.jp/aj/meta/image_C14011075200?IS_KIND=RefSummary&IS_STYLE=default&IS_TAG_S1=d2&IS_KEY_S1=C14011075200& C13120839500:https://www.jacar.archives.go.jp/aj/meta/listPhoto?NO=1&DB_ID=G0000101EXTERNAL&ID=%24_ID&LANG=default&image_num=6&IS_STYLE=default&TYPE=PDF&DL_TYPE=pdf&REFCODE=C13120839400&CN=1 And books I used: Many documents and archives regarding WWII Japanese tanks have already been public viewable, there is always someone don't know.
  9. 7 points
    Talk about Type90, i got some information from Chinese document which mention about the armor composite used on Type88 which is the prototype for Type90 recently. Not sure the exact truth but i would like to share. “Japanese Type88 tank's turret and hull composite armor were trying to use different ceramic material (Alumina、Silicon oxide or Silicon carbide ceramic cut in rectangle or hexagon),each layer using binder to bonded together. The protection of this armor can reach up equal to 400mm thick of armour steel (BK) and is capable of defeat 120mm high density KE projectile (muzzle velocity>1600m/s) fired from 200meters at 0 degree, and also capable to protect against the 120mm HEAT shell which capable of penetrating 600mm of armor. Besides, there are many of different type of armor plate, the use of ceramic material and it's ability of protection giving the armor research development a new direction” image10 Type88 tank's spaced (composite) armor structure. 陶瓷板=Ceramic plate 毫米=mm Other than this,japan seems are developing some kind of Kevlar composite It says:"Japan is currently develop a Kevlar fiber with Titanium alloy or aluminum structured multi-layer composite armor " Of course those are just for the prototype of type90, but we can try guessing the armor from this source: <<间隔(复合)装甲——现代坦克的主要装甲结构>>(1982) (Composite armor--the main structure of the armor for modern MBT) (1982) <<国外复合装甲中非金属材料的应用和研究概况>>(1983) (Summarize of the use and research of non-metallic material in foreign composite armor)(1983) ft. Akula_941
  10. 7 points
    @Collimatrix @Mighty_Zuk @SH_MM @LoooSeR @Militarysta @Xlucine Yeah I took 'some' liberties with the jet, but that mainly has to do with this being a rough first look at Nozh, I'll do a more properly shaped jet later. tl;dw: Yes, a copper jet can cut through a wolfram penetrator but the jet is not nearly long enough. Edit: This is also a frictionless simulation so the jet penetrating the steel plate doesn't slow it down at all. All in all, this is a best case scenario for Nozh.
  11. 7 points
  12. 7 points
    Mighty_Zuk

    Israeli AFVs

    A new article from "Ynet News" adds new info on the Barak and other programs. Just a reminder, Barak is an upgraded Merkava 4M. https://www.yediot.co.il/articles/0,7340,L-5043863,00.html It's in Hebrew, but I have taken upon myself to translate the important bits here (some new, some old, I will mark it): 1)The Barak weighs 70 tons. (new) Ex: In Israel, exact figures are almost never given. It's not because it's OPSEC, but because that's the sort of mentality here. Only the engineers will handle that, and the plebs get rounded numbers. So it could mean about 69, or it could be 73. However up until now it's always been 60-65 tons, so we could see some solid amount of equipment added to the tank, which will be interesting. On the downside, it means weight reduction measures probably weren't taken and I shouldn't explain why excessive weight is bad. 2)Utilizes an AI-managed "mission computer". (new/old) Ex: Okay so we've heard plenty of times that many actions will be automated, and that means AI. It was said however mostly in the context of the firing loop. Now they say the mission computer, otherwise known as BMS, will automatically manage certain comms with other assets that will also include the Namers and Eitans among others. Info that was previously manually input by the TC (commander). The AI will be able to make various decisions based on the targets it identifies, whether based on the optics or the APS, and advise the crew on certain actions, and make terrain-mapping related decisions such as pointing optimal firing positions or dangerous areas. 3)Female voice selected to alert crews via BMS. (new) Ex: Easy to distinguish from a male voice, so it won't blend in with the crew's voices, and the crew will not ignore it (they tend to ignore messages from crewmen). Among the alerts it will give are "Missiles", "Short range ATGM", and "Turning over" which means it will not only alert the crew of the type of threat and thus approximate time to impact, but also of terrain related issues to minimize accidents. 4)It was tested as a fully autonomous vehicle. (new) Ex: But there is no operational requirement, for obvious reasons, so it's merely a test. 5)Hybrid powerplant. (new) Ex: To cope with the higher weight and to save on fuel, hybrid is the way to go. This could also give it an amazing torque and make it a "little" speed demon. And as an environmentalist it really gives me some relief. 6)IronVision helmet system tested last month (October). (old) Ex: I thought it was scheduled to be tested in April, but nonetheless it's good news it happened. The date for operational fielding has remained unchanged, and even rounded down to 2020, so there's no delay but a re-scheduling. 7)IronVision to be tested soon on Company-sized force. (new) Ex: Means less time required for full operational testing, if they segment the operational testing phases to do in parallel with the program. 8)Starting next year, 3 times as many Trophy-equipped vehicles will be manufactured as this year. (new) Ex: While the production rate is still minimal, to keep the work stable and allow to double the output when needed urgently, the front-line units will benefit greatly and at a quick rate from this decision. It also comes in light of the recent contract for 1,000 Trophy systems, and the decision to not only equip the Namers and Eitans with it, but also the Merkava 3. 9)USA is purchasing 100 Trophy systems (brigade-sized). (new/old) Ex: Some speculated on either possibility. Either the contract was merely for the support of the installation of systems, or for the purchase of a brigade-worth of systems. Now it's confirmed that they are indeed equipping an entire brigade. Big wall of text, I know, so I give you here Brig. Gen. Baruch Matzliach holding Israel's big stick's big stick:
  13. 7 points
    Gripen287

    Railguns

    Hello all, Gripen here. Long-time reader, first-time poster here. I'm drinking Founder's Breakfast Stout and come bearing documents about railguns (is there a preferred method of posting/uploading documents?): https://drive.google.com/open?id=1bZeNQNqLwoOxyGORELf7H80qI0ENFJ5M https://drive.google.com/open?id=0B21XX6zvOt4fdHpxVGdvaFdpR28 https://drive.google.com/open?id=1QUAUdaP_QGBmA9DTby6pWYINon8XZFn_ https://drive.google.com/open?id=0B21XX6zvOt4fWHJRdHZIdGlRWDQ https://drive.google.com/open?id=0B21XX6zvOt4fQjVyYkpWaG1CRkk And for the inductively minded: https://drive.google.com/open?id=0B21XX6zvOt4fZDM3SHM3SWE5N2M Did I do it right?
  14. 6 points
    Collimatrix

    Help me understand tank suspension

    @EnsignExpendable wrote a bit about this some time ago. Technology of Tanks does have a good summary of the matter, but it's such an expensive book that I recommend going straight to the piracy option and getting the shitty OCR version. Ogorkiewicz's more recent Tanks: 100 Years of Evolution has a condensed, but far less detailed commentary on the development of tanks suspension. Here is my heavily editorialized summary of tank suspension: Tank suspension is what gives the track some "give" while the tank is moving at speed over rough terrain. The main purpose of tank suspension is to keep the crew from being incapacitated by the tank shaking up and down while the tank is moving off-road. It has some minor benefits to weapon and sight stabilization, but the technology of weapon and sight stabilization is so advanced at this point that it doesn't really matter today. The very first tanks had no suspension whatsoever; the entire run of the track was rigidly attached to the tank's hull. This meant that there was no shock absorption whatsoever when these old tanks went over bumps, but this was basically acceptable because the first tanks were also very slow, and tended to poison their crews with carbon monoxide anyway. In the interwar period, tank suspension tended towards systems where several road wheels share a common spring element. In some cases, four road wheels would be attached to a common leaf spring by series of levers and balances. More commonly, pairs of road wheels would share a common spring as in the HVSS and VVSS suspension of the Sherman, but also the bizarro longtitudinal torsion bar design in the Ferdinand. The interwar period also saw the first independent suspension systems. In independent suspension each road wheel acts upon its own spring. Independent suspensions give a better ride quality for the crew at high speed, but they suffer from greater pitching oscillation (nose of the tank rocking up and down) than the older-style suspension where pairs of road wheels share a common spring, especially at lower speeds. Independent suspensions are also heavier. Christie suspension is independent, as are the majority of torsion bar systems (the Soviets screwed around with some non-independent systems, and there was the Ferdinand). The majority of tank designers switched from the older spring-sharing systems to the newer independent systems, as in the US T20 series of medium tanks where the M4 evolved into the M26 and lost its volute spring suspension for torsion bars. The British went backwards and switched from the independent Christie suspension of Comet to the spring-sharing Horstmann suspension in Centurion. This is because the British are bad at tank design, although Centurion was a decent tank once you ripped out the old engine and transmission and put an AVDS and Allison tranny in there. The British would stay with the Horstmann suspension through Chieftain and until Challenger 1. Again, Chieftain was generally a bad tank, and the British made the world's best tank in 1916, and have been trailing since then. The majority of publications will categorize tank suspension by what springing medium the swing arms are tensioned by. This is completely stupid and conveys almost no useful information. It doesn't tell me anything about the comparative automotive performance of the M60 vs the Pz. 68 to know that one has the swing arms tensioned by long, twisting rods of spring steel while the other tensions the arms with a stack of frisbee-shaped discs of spring steel. The shape of the piece of steel being bent to absorb energy from the suspension elements is literally the least useful piece of information about the suspension performance. More useful information would be the limits of the articulation of the swing arm, spring coefficients, swing arm length, damping coefficients, and unsprung mass of the suspension components. Also useful would be the location of the center of mass of the tank relative to each of the road wheels and swing arms and its moment of inertia about the pitch axis. But this more specific information is hard to come by.
  15. 6 points
    Andrei_bt

    Contemporary Western Tank Rumble!

    everyone can make a mistake )
  16. 6 points
    BAE Systems has submitted its proposal to the U.S. Army to build and test the Mobile Protected Firepower (MPF) vehicle for use by the Infantry Brigade Combat Team (IBCT).
  17. 6 points
    Sure. You can get the first book as a pdf here. The General Board reports are available here; Tank Gunnery is number 53.
  18. 6 points
    TOW-2 of tanknet linked an article on the M247 York written by a retired USAF helicopter pilot.
  19. 6 points
    Khand-e

    The Cartridge Collecting Thread

    Recovered Petals and cup from 14.5x114mm APDS. Rare 5.8x39mm rounds, made as a competing round to the 5.8x42mm
  20. 6 points
    Akula_941

    The Cartridge Collecting Thread

    The first ever real cut-off of 5.8x42 DVC-12 AP rounds bullet weight 5.47g penetrator is tungsten carbide 3.5g that little BB is made by lead
  21. 6 points
    Xoon

    Colonization Of The Solar System

    Colonization Of The Solar System This thread is for discussing the colonization of the solar system, mainly focusing on Mars and the Moon since they are the most relevant. Main topics include transportation, industry, agriculture, economics, civil engineering, energy production and distribution, habitation, ethics and politics. First order of business, our glories tech messiah Elon Musk has set his eyes on Mars: Reason stated? Because being a interplanetary species beats being a single planetary species. How does he plan to do this? By sending two cargo ships by 2022 to Mars for surveying and building basic infrastructure, then two years later in 2024 sending 4 ships, two cargo ships and two crewed ships to start the colonization. First thing would be to build fuel refineries and expanding infrastructure to support more ships, then starting to mine and build industry. This could mark a new era in human history, a second colonization era, this time without the genocides. The economic potentials are incredible, a single asteroid could easily support the entire earths gold, silver and platinum production for a decade. The moon holds a lot of valuable Helium 3, which right now is worth 12 000 dollars per kilogram! Helium is a excellent material for nuclear reactors. Speaking about the moon, several companies have set their eyes on the moon, and for good reason. In my opinion, the moon has the possibility of becoming a mayor trade hub for the solar system. Why is this? Simply put, the earth has a few pesky things called gravity, atmosphere and environmentalists. This makes launching rockets off the moon much cheaper. The moon could even have a space elevator with current technology! If we consider Elon Musk's plan to travel to Mars, then the Moon should be able to supply cheaper fuel and spaceship parts to space, to then be sent to Mars. The Moon is also rich in minerals that have not sunk to the core yet, and also has a huge amount of rare earth metals, which demands are rapidly increasing. Simply put, the Moon would end up as a large exporter to both the earth and potentially Mars. Importing from earth would almost always be more expensive compared to a industrialized Moon. Now how would we go about colonizing the moon? Honestly, in concept it is quite simple.When considering locations, the South pole seems like the best candidate. This is because of it's constant sun spots, which could give 24 hour solar power to the colony and give constant sunlight to plants without huge power usage. The south pole also contain dark spots which contains large amount of frozen water, which would be used to sustain the agriculture and to make rocket fuel. It is true that the equator has the largest amounts of Helium 3 and the best location for rocket launches. However, with the lack of constant sunlight and frequent solar winds and meteor impacts, makes to unsuited for initial colonization. If the SpaceX's BFR successes, then it would be the main means of transporting materials to the moon until infrastructure is properly developed. Later a heavy lifter would replace it when transporting goods to and from the lunar surface, and specialized cargo ship for trans portion between the Moon, Earth and Mars. A space elevator would reduce prices further in the future. Most likely, a trade station would be set up in CIS lunar space and Earth orbit which would house large fuel tanks and be able to hold the cargo from cargo ships and heavy lifters. Sun ports would be designated depending on their amount of sunlight. Year around sunlight spots would be dedicated to solar panels and agriculture. Varying sun spots would be used for storage, landing pads and in general everything. Dark spots would be designated to mining to extract its valuable water. Power production would be inistially almost purely solar, with some back up and smoothing out generators. Later nuclear reactors would take over, but serve as a secondary backup energy source. The plan: If we can assume the BFR is a success, then we have roughly 150 ton of payload to work with per spaceship. The first spaceship would contain a satellite to survey colonization spot. Everything would be robotic at first. Several robots capable of building a LZ for future ships, mining of the lunar surface for making solar panels for energy production, then mining and refinement for fuel for future expeditions. The lunar colony would be based underground, room and pillar mining would be used to cheaply create room that is also shielded from radiation and surface hazards. Copying the mighty tech priest, a second ship would come with people and more equipment. With this more large scale mining and ore refinement would be started. Eventually beginning to manufacturing their own goods. Routinely BFRs would supply the colony with special equipment like electronics, special minerals and advanced equipment and food until the agricultural sector can support the colony. The colony would start to export Helium 3 and rocket fuel, as well as spacecraft parts and scientific materials. Eventually becoming self sustaining, it would stop importing food and equipment, manufacturing it all themselves to save costs. I am not the best in agriculture, so if some knowledge people could teach us here about closed loop farming, or some way of cultivating the lunar soil. Feel free to do so. Mining: I found a article here about the composition of the lunar soil and the use for it's main components: In short, the moon has large amounts of oxygen, silicon, aluminum, calcium, iron, magnesium and titanium in it's soil. How do we refine them? By doing this. Aluminum could be used for most kinds of wiring to requiring high conductivity to density ratio. Meaning power lines, building cables and such. Aluminum is not very suited for building structures on the surface because of the varying temperatures causing it to expand and contract. Iron or steel is better suited here. Aluminum could however be used in underground structures where temperatures are more stable. Aluminum would also most likely end up as the main lunar rocket fuel. Yes, aluminum as rocket fuel. Just look at things like ALICE, or Aluminum-oxygen. Aluminum-oxygen would probably win out since ALICE uses water, which would be prioritized for the BFRs, since I am pretty sure they are not multi-fuel. More on aluminum rocket fuel here: https://forum.kerbalspaceprogram.com/index.php?/topic/88130-aluminum-as-rocket-fuel/& http://www.projectrho.com/public_html/rocket/realdesigns2.php#umlunar https://blogs.nasa.gov/Rocketology/2016/04/15/weve-got-rocket-chemistry-part-1/ https://blogs.nasa.gov/Rocketology/2016/04/21/weve-got-rocket-chemistry-part-2/ Believe it or not, but calcium is actually a excellent conductor, about 12% better than copper. So why do we not use it on earth? Because it has a tendency to spontaneously combust in the atmosphere. In a vacuum however, this does not pose a problem. I does however need to be coated in a material so it does not deteriorate. This makes it suited for "outdoor" products and compact electrical systems like electric motors. Yes, a calcium electric motor. Lastly, a few articles about colonizing the moon: https://en.wikipedia.org/wiki/Colonization_of_the_Moon https://www.sciencealert.com/nasa-scientists-say-we-could-colonise-the-moon-by-2022-for-just-10-billion https://www.nasa.gov/audience/foreducators/topnav/materials/listbytype/HEP_Lunar.html NASA article about production of solar panels on the moon: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050110155.pdf Map over the south pole: http://lroc.sese.asu.edu/images/gigapan Feel free to spam the thread with news regarding colonization.
  22. 6 points
    Sturgeon

    The Cartridge Collecting Thread

    I have finally acquired a round of 9x39mm:
  23. 6 points
    Collimatrix

    General AFV Thread

    I didn't say anything about penetration either. See? That's what I said. I never claimed that HESH is impotent because it cannot penetrate. I am saying HESH is impotent because it's impotent. But do you know what's funny? We had this exact same argument two years ago, and you argued in the same cringing, cowardly manner you are now. Also, you said some hilariously insane shit, like claiming that gun-launched HESH rounds are "30+ kg." Bitch, an entire M830 MPAT round is under 30 kg! RDX has a density of under 2 gm/cm^3. A 120mm wide 30 kilogram cylinder of RDX would be 1.3 meters long, or about 30% longer than an entire round of M829. Do you know what I love though? That you can maintain this attitude of haughty superiority when you say things that are so easy to show are wrong. You must slay with chicks. I can just imagine you walking up to a woman at a bar and spitting a line of bullshit about being a space shuttle door gunner in the dinosaur wars while there's visibly diarrhea leaking down your leg. How do you manage it? What is your secret, great master?
  24. 6 points
  25. 6 points
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