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  1. 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.
  2. 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
  3. 8 points
  4. 8 points
    They let me in the tank restoration yard at Ft Benning earlier today
  5. 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.
  6. 7 points
  7. 7 points

    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:
  8. 7 points
  9. 7 points
    So, recently I stumbled upon something fairly interesting. Most of the people here know about shaped charges and how they work, the principles behind it are fairly well known. Recently however, there has been research about a new 'class' of shaped charges: Reactive Liner Shaped Charges. As the name implies it's a shaped charge with a liner made out of a reactive material. Please note that I still do not fully understand the workings of Reactive Liner Shaped Charges, this post may be changed or updated depending on new information and/or discussions. What is a reactive material, you say? One of the papers explains it like this: (Demolition Mechanism and Behavior of Shaped Chargewith Reactive Liner, Jianguang Xiao et al., 2016) In simple terms, it's a material that only explodes when you hit it really really really really hard with a hammer. Or when you fire it into a solid material at several kilometers per second. I dunno. It's one of the two. What this amounts to is a shaped charge which forms an exploding jet. Neato. But... why should you care? We already don't fire explosives at an armoured target because it's not very efficient, so why suddenly care now? To answer that I have to compare it to normal shaped charges and explain a few things about explosives. The most important thing to understand is that no explosive detonates instantly, there is always a slight delay. This delay is (almost) negligible at normal projectile velocities, but become important at high velocities. Think hypersonic velocities, like with... shaped charge jets! The main thing I am not completely sure about is whether the detonation of the shaped charge initiates the liner, or the impact with the target. The self-delay of the reactive material used in most of the tests is ~0.85 and depending on the liner angle the jet can move 2.8 to 5.2 meters before actually exploding. Of course this distance will be a lot less when penetrating because the material slows down. A reactive material with a too low self-delay might detonate during the formation of the jet, or before it actually managed to penetrate the armour (but this only applies in the situation where the reactive liner is initiated by the shaped charge). This is of course not something you want, you want the liner to detonate inside the target to do the maximum amount of damage. And that's the main reason you should care about shaped charges with reactive liners. They do a fuckton of damage. This is your brain: This is the result of a shaped charge with an aluminium liner: This is your brain on drugs: This is the result of a shaped charge with a reactive liner: To give a sense of scale, that's a 1520 by 1520 mm concrete cylinder. The shaped charge had a diameter of... 81 mm. As you can see the reactive liner does a fuckton more damage compared to a normal liner, this is because the jet literally detonates when it's inside the armour. Concrete is one of the materials that cannot deal with certain forces, which makes it weak versus explosives detonating inside of it. Steel for example cares a lot less about it, but even steel will suffer more damage from a reactive liner than a normal copper liner. The entry hole for a reactive liner is around 0.65 CD whereas for a copper liner it is 0.5 CD. A paper also states the following: The paper however does not show or describe the "tremendous increase in steel target damage". It does however give some basic information and show photos of the entry holes: The penetration capabilities of reactive liners in steel targets were "sacrificed slightly" compared to copper liners, but the paper does not elaborate any further. Here's some more information and pictures about the effectiveness of reactive liners against concrete targets, just for shits and giggles: A 'Bam Bam' is the same warhead as the 81mm one (1.8 kg) from the first photos, except scaled to 18.1 kg. The 81mm charge is called Barnie, by the way. The target is the same ~1500 mm too. As you can see the Bam Bam charge is capable of fucking up massive parts of asphalt roads/runways. A 21.6 cm shaped charge completely destroying around 42 square meters of asphalt. But hey, a 21.6 cm charge is fucking massive, lets tone it down slightly. Charges: Test setup: Results: Sadly there's a bunch of information missing in the tables. It is highly likely that different liner thicknesses were used, but these aren't given in the tables. Results can be found in the full version of Table 1: ...that's around 9-10 square meters of concrete fucked up by a ~1 kg warhead. That's fucking insane. Some other things to note is that due to the materials used in these tests (an aluminium-polymer mix) the jet velocity is significantly higher and the jet length longer than comparable copper liners: So the reactive liner used (26% Al, 74% Teflon) has a jet tip velocity that's around twice as high for shallow charges, but drops to around 1.6 at higher angles. The difference in jet tip velocity is most likely due to the lower density of the reactive liner. This is what Wang et al. said about this: This poor ductility also increases the probability of fragmentation (jet break-up), which can be seen here: So because the reactive liner has a lower density, it forms a jet quicker, but because of its poor ductility it starts to break up very quickly. Tests have shown that a stand-off that's longer than 2 CD is undesirable, whereas normal liners do not really care about a longer stand-off. However! The research done to make the Barnie warhead show that it is undesirable to have cavitation during the formation of the jet. This cavitation is visible in the above simulations, but can better be seen in this one: It is very well possible that Wang et al. had a sub-optimal liner design, since the final Barnie jet looks like this compared to a comparable aluminium liner jet: They are quite similar and the Barnie jet does not have the 'blobs' visible in the simulations from Wang et al.. And last but certainly not least, Xiao et al. calculated the TNT equivalence (RE factor) of the reactive liner: In simple terms, the kaboom-effectiveness of this reactive material is 3.4 to 7.7 times as high as TNT. But since these values on their own are kind of meaningless, lets compare them to other RE factors! The RE factor of C4 is 1.34. The RE factor of RDX is 1.6. PETN? 1.66. Torpex? 1.3. Amatol? 1.1. ANFO? 0.74. The explosive with the highest detonation velocity (Octanitrocubane)? 2.38. THIS FUCKING ALUMINIUM/TEFLON MIX!? MOTHERFUCKING 7.77. Interestingly the theoretical energy contained in the aluminium/teflon mix is only about 4 times as high as TNT. The higher values are most likely due to the addition of kinetic effects. So yeah... huzzah for reactive liners. I might add some stuff to this post later, depending on whether or not I forgot something.
  10. 7 points
    This bit from SSC bears repeating: The KKK is really small. They could all stay in the same hotel with a bunch of free rooms left over. Or put another way: the entire membership of the KKK is less than the daily readership of this blog. If you Google “trump KKK”, you get 14.8 million results. I know that Google’s list of results numbers isn’t very accurate. Yet even if they’re inflating the numbers by 1000x, and there were only about 14,000 news articles about the supposed Trump-KKK connection this election, there are still two to three articles about a Trump-KKK connection for every single Klansman in the world. I don’t see any sign that there are other official white supremacy movements that are larger than the Klan, or even enough other small ones to substantially raise the estimate of people involved. David Duke called a big pan-white-supremacist meeting in New Orleans in 2005, and despite getting groups from across North America and Europe he was only able to muster 300 attendees (by comparison, NAACP conventions routinely get 10,000). My guess is that the number of organized white supremacists in the country is in the very low five digits. The internet acts as an extremely effective amplifier for crazy people. If you were to assume the internet to be representative, you would expect that the world population is about 15% furries, 25% Turks and Kurds arguing about who is more subhuman, 20% neo-Nazis, 40% thirsty bros and 0% women. The extreme right in the US has been emboldened by Trump's victory. A lot of other previously marginalized political positions have been emboldened as well. Trade protectionists, pro-settlement Israelis, climate change doubters, old-school DEA drug warriors who want to crack down on medicinal marijuana... and lots of others. The only thing these people have in common is that they were previously marginalized. Trump wasn't supposed to win. All the analysts failed miserably at their jobs, turning what would have been a stinging reprimand into an eschatological calamity for the political establishment. Now the world seems upside down, and a lot of people on the bottom are now feeling like it's their turn to get on top.
  11. 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.
  12. 6 points
    TOW-2 of tanknet linked an article on the M247 York written by a retired USAF helicopter pilot.
  13. 6 points

    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
  14. 6 points

    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.
  15. 6 points


    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?
  16. 6 points

    DRDO; India's Porsche

    I know we already have a topic on the Arjun, but that doesn't mean we shouldn't have another thread about how DRDO can't make anything. I mean, the Arjun program started in 1974 (according to Wikipedia) and the thing got produced 30 years later, in 2004. Should we take a look at the list of tanks that got developed at around the same time period? T-72 T-80 Type 88 Type 96 Type 74 OF-40 Merkava 1 Merkava 2 Merkava 3 Leopard 2 M1 Abrams Challenger 1 M-84 K-1 Type 90 Leclerc T-90 PT-91 Zulfiqar C1 Ariete Challenger 2 TR-85 T-84 ...and many more A keen I will have noticed that these are both second and third generation tanks, which is right, because the development of the Arjun took place during two generations of tanks. Of note is that the Israelis managed to make three Merkava variants in the time DRDO took to develop the Arjun. And if that wasn't enough, he Challenger 1 was developed, build, accepted for service, and taken out of service by the Brits in less time than it took DRDO to deliver the first batch of Arjuns. What the fuck. Alright alright I'll stop the bashing! So lets take a look at the armour of the Arjun: Okay now that we've taken a look at the armour of the Arjun, we can take a look at something of which the Indians pretend is armour. First, the turret 'armour': The first good thing to note about the turret armour is that the left front is decent. The second good thing about the turret armour is that it's so bad I can spend a whole post on burning it down. The mantlet looks thick in this model, but it looks like it's not modeled right since it seems to be fused with the frontal armour itself. This is what the actual armour in the gun mantlet looks like: It's fairly thin, like in the Leclerc, but even worse is that it does not cover the whole gap in the turret. Seriously DRDO, what the fuck? Of course there are pictures of a fully assembled model, but it seems that the completed mantlet is no more than a sheet metal box around the structure shown in the above photo. I mean, look at this: You can see the weld lines and shit on top of the 'mantlet', there is no reason to believe this is a solid steel block. These pictures bring me nicely to the next two points: 1. The turret side basically lacks any and all side armour 2. The gunner sight barely has any armour The green blocks on the turret side in the first picture are actually storage boxes, not armour. The majority of the side is only a few cm thick steel plate. Lets just compare this to the Leopard 2A4 for a second: (Thanks to @Militarysta for making this picture) You can see that the turret side protection extends way, way further back on the Leopard 2A4 than it does on the Arjun. The Arjun only has to rotate the turret slightly to be completely vulnerable to even low caliber autocannons. And as you can imagine, that's not good. You can also see that the armour block behind the gunner sight is around 660 mm LOS, the same spot in the Arjun is estimated to be around 300 mm thick. Don't worry about the lower part of the gun sight, that has no armour at all. The sight itself looks like this: So the turret has negligible side protection, horrible frontal protection, and a shit mantlet. But wait, there's more! The turret roof is really thin. If you take a look at this picture you'd say that it has a decently thick roof: See? That looks to be like a solid few cm thick. So why say the roof is really thin? Well, take a look at this as well: That hatch/cupola is raised. So what looks to be a roof that's a few cm thick is just a raised cupola. Which means that the turret roof itself is horribly thin. And since the front third is sloped forward that means APFSDS can easily yaw into the crew compartment, and lets not speak about attacks from above because that'll end in tears for the Arjun. Is there anything not shit about the Arjun turret? ... No! Actually! A sharp-eyed reader will already have noticed that the turret ammorack has absolutely no protection at all: The inside of the turret itself is a horrible fucking mess, just look at it: That's right, those cables are hanging from fucking string. Since the gun is also in the turret, surely that must be a good part of the turret, right? Right!? I mean, they had until 2004 to select or make a good gun! Aahahahahahahha, no. It's a rifled 120 mm. In 2004. Helloooooo India, welcome to Britain, 19-fucking-80s. ...well maybe they have very good ammunition! No. That's about the same as DM23. Which was introduced in 1983. 1984 saw a medium-high L/D (20+ L/D) penetrator for the US, 1987 for Germany and 1986 for the Soviet Union. We got high L/D (30+ L/D) penetrators in the early 90s. India's still rocking that good-ol' 17 L/D trash. Sooooo will the hull be any better? No. Access hatch in the upper glacis. On TS I was talking to @Collimatrix about how the driver's position most likely makes the upper glacis in front of him thinner, but that turned out not to be true, since... ...his position doesn't reach the fucking glacis in the first place. Not only that, look at how fucking horsewank thin that glacis is. With how thin it is, it's most likely just solid steel instead of NERA, even though the Indians claim it uses NERA, and they have this to say about their NERA: Literally fucking what I could probably go on and on and on about the retardation that's called Arjun, but I won't. I have subjected myself to too much stupidity already since I had to go to fucking places like defenceforumindia which was completely fucking malarious. And if you don't know what that word means, it's a combination of malaria and hilarious since reading defenceforumindia is equal parts sickening and hilarious.
  17. 6 points
    From David M. Fortier According to initial reports the gunman drove to the store across from the church and exited his vehicle. He was dressed in all black, with face mask and wearing a ballistic vest. He was armed with a Ruger 5.56x45mm AR rifle equipped with an inexpensive red dot sight, white light, sling and a vertical grip. He began shooting walking towards the church, moved to the right of the church and continued firing and then entered the church shooting. He fired as he walked to the front of the church, stopped, turned and continued shooting as he walked back out. It is believed his rifle was loaded with Hornady TAP or VMAX ammunition based upon a loaded cartridge left at the scene. 23 people were killed in the church, two outside the church and one died at a hospital. 20 more were wounded. Ages of the victims range from 5 to 72 years old. A neighbor heard the gunfire and responded by grabbing an AR-15 rifle and taking up a shooting position. He fired on the gunman as he exited the church. It appears the gunman was hit by the armed citizen, possibly in the neck, as he dropped his rifle, a Ruger AR, and fled to his vehicle. The armed citizen continued to engage the gunman attempting to stop him and prevent him from fleeing. He fired at least one shot which blew out the back window of the vehicle. The shooter drove away at a high rate of speed. In order to prevent the gunman from escaping and causing further harm the armed citizen flagged down a vehicle. The armed citizen quickly informed the driver of the vehicle, a pick-up truck, the situation and entered the vehicle. The driver of the pick-up truck set out in pursuit of the fleeing gunman while contacting the police via his cell phone. During the pursuit the driver of the pick-up closed the distance with the fleeing gunman while reaching speeds of 95 mph. The pick-up truck driver was able to get within a few feet of the fleeing gunman's vehicle, which then slowed, before the gunman lost control of his vehicle and went off the road at an intersection. The armed citizen exited the pick-up and covered the gunman's vehicle with his rifle to prevent the gunman's escape. The driver of the pick-up stated the gunman made no movements inside his vehicle. The driver of the truck placed his vehicle in park and informed the police of the gunman's location. The police arrived on location approximately 5 to 7 minutes later. The gunman died at the scene, and as the driver of the truck stated he made no movements and there were no shots fired for the 5 to 7 minutes before police arrived. Evidence indicates he bled out and died from a gunshot wound or wounds inflicted by the armed citizen. Police stated the gunman's vehicle contained multiple firearms and he may have been headed to another location to continue his shooting spree, but was killed instead. The shooter, Devin Patrick Kelley, was 26 years old, father of two. High School classmates of his are quoted as saying he was an outcast who preached "atheism" and said "anyone who believes in God is stupid". He served in the US Air Force from 2009 to 2013 and was Court-Martialed and discharged in 2014 after assaulting his wife and child and serving 12 months in the brig. Under Federal Law a Domestic Violence conviction would prohibit him from legally owning a firearm but evidently was not disqualified as he purchased his rifle at an Academy store. So, for a motive he was a militant atheist who hated Christians. As a militant atheist me might have ties to the Left but that remains to be proven. Without a doubt the armed citizen is a hero who likely saved many more lives by his quick thinking and willingness to step in and take action. His ability to properly employ a long gun against an armed and moving gunman while under great stress saved lives and put an end to the shooting spree. His actions demonstrate how a legally owned firearm can be used to save lives if the person behind the gun has the mettle and ability to properly put it to use."
  18. 6 points

    The Cartridge Collecting Thread

    I have finally acquired a round of 9x39mm:
  19. 6 points

    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?
  20. 6 points
  21. 6 points
  22. 5 points
    Whoever said that clearly wasn't beaten enough as a child.
  23. 5 points
    https://andrei-bt.livejournal.com/627446.html Object 787 restored
  24. 5 points
  25. 5 points

    Tanks guns and ammunition.

    The explosive compound in ERA (well, any military explosive compound) will only detonate when a certain pressure is reached. If the impact does not reach that pressure, the explosive will not detonate. As long as the pressure doesn't go above a certain threshold it doesn't matter what's hitting the explosive, it simply won't explode. I suppose there's a way to poke a hole through ERA without setting it off, but I haven't yet figured out how exactly. It is. If you look at various tests with actual ERA, you'll see that the jet isn't noticeably being yawed/deflected, no matter the ERA angle: You can however see that the higher the angle of the ERA compared to the jet, the more disturbed the jet is. This is simply because the ERA is capable of feeding more material into the jet, degrading it. Actually, here are a bunch of photos of a shaped charge jets versus NERA at different angles: And again, the more material is fed into the jet, the worse it becomes. However, ERA and NERA do actually deflect the jet, but only very slightly. I'm talking about ~50 m/s down for a 55 degree angle ERA sandwich. 50 m/s might sound a lot, until you realise that these jets move forward at a few thousand meters per second. So the downward velocity is negligible. The reason the forwards moving flyer plate caused more damage to the jet is because of... vectors, basically.. Or as Kobylkin and Dorokhov put it: Also, this is what the paper says about the pictures you linked: Here are the pictures in higher res by the way, for future use: