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  1. IDF had kept about 100 Tiran-6/T-62s since 1973, and remain service until 1990s. I wonder if there's any modification on Tiran-6, like changing the powerpack into 8V71T+XTG-411, adapting steering wheel. I also heard that British ROF had produce a batch of 115mm barrel for IDF, while MECAR or NEXTER produced high-performance APFSDS for 115mm gun. Did IDF really use these barrels for original barrel replacement? And about protection, did IDF put Blazer ERA on Tiran-6? Or they use more advanced APS like Trophy? Thank you.
  2. The LORD was with the men of Deseret. They took possession of the hill country, but they were unable to drive the people from the plains, because they had chariots of steel. —The Book of Latter Day Saints, Ch 8, vs. 3:10, circa 25th Century CE BULLETIN: ALL INDUSTRIAL-MECHANICAL CONCERNS SOLICITATION FOR ALL-TERRAIN BATTLE TANK The Provisional Government of the Lone Free State of Texas and The Great Plains issues the following solicitation for a new All-Terrain Battle Tank. The vehicle will be the main line ground combat asset of the Lone Free State Rangers, and the Texas Free State Patrol, and will replace the ageing G-12 Scout Truck, and fill the role of the cancelled G-42 Scout Truck. The All-Terrain Battle Tank (ATBT) will be required to counter the new Californian and Cascadian vehicles and weapons which our intelligence indicates are being used in the western coast of the continent. Please see the attached sheet for a full list of solicitation requirements. Submissions will be accepted in USC only. Supplementary Out of Canon Information: I. Technology available: a. Armor: The following armor materials are in full production and available for use. Use of a non-standard armor material requires permission from a judge. Structural materials: i. RHA/CHA Basic steel armor, 360 BHN. The reference for all weapon penetration figures, good impact properties, fully weldable. Available in thicknesses up to 4 inches (RHA) 8 inches (CHA). Density- 0.28 lb/in^3. ii. Aluminum 5083 More expensive to work with than RHA per weight, middling impact properties, low thermal limits. Excellent stiffness. Fully weldable. Available in thicknesses up to 4 inches. Mass efficiency vs RHA of 1 vs CE, 0.9 vs KE. Thickness efficiency vs RHA of 0.33 vs CE, 0.3 vs KE. Density- 0.1 lb/in^3 (approx. 1/3 of steel). For structural integrity, the following guidelines are recommended: For heavy vehicles (30-40 tons), not less than 1 in RHA/1.75 in Aluminum base structure For medium-light vehicles (<25 tons), not less than 0.5 in RHA/1 in Aluminum base structure Intermediate values for intermediate vehicles may be chosen as seen fit. Non-structural passive materials: iii. HHA Steel, approximately 500 BHN through-hardened. Approximately 1.5x as effective as RHA against KE and HEAT on a per-weight basis. Not weldable, middling shock properties. Available in thicknesses up to 1 inch. Density- 0.28 lb/in^3 iv. Fuel Mass efficiency vs RHA of 1.3 vs CE, 1 vs KE. Thickness efficiency vs RHA of 0.14 vs CE, 0.1 vs KE. Density-0.03 lb/in^3. v. Assorted stowage/systems Mass efficiency vs RHA- 1 vs CE, 0.8 vs KE. vi. Spaced armor Requires a face of at least 1 inch LOS vs CE, and at least 0.75 caliber LOS vs fullbore AP KE. Reduces penetration by a factor of 1.1 vs CE or 1.05 vs KE for every 4 inchair gap. Spaced armor rules only apply after any standoff surplus to the requirements of a reactive cassette. Reactive armor materials: vii. ERA A sandwich of 0.125in/0.125in/0.125in steel-explodium-steel. Requires mounting brackets of approximately 10-30% cassette weight. Must be spaced at least 2 sandwich thicknesses away from any other armor elements to allow full functionality. 81% coverage (edge effects). viii. NERA A sandwich of 0.25in steel/0.25in rubber/0.25in steel. Requires mounting brackets of approximately 10-30% cassette weight. Must be spaced at least 1 sandwich thickness away from any other armor elements to allow full functionality. 95% coverage. The details of how to calculate armor effectiveness will be detailed in Appendix 1. b. Firepower i. Bofors 57mm (reference weapon) - 85,000 PSI PMax/70,000 PSI Peak Operating Pressure, high quality steel cases, recoil mechanisms and so on are at an equivalent level to that of the USA in the year 1960. ii. No APFSDS currently in use, experimental weapons only - Spindle sabots or bourelleted sabots, see for example the Soviet BM-20 100mm APFSDS. iii. Tungsten is available for tooling but not formable into long rod penetrators. It is available for penetrators up to 6 calibers L:D. iv. Texan shaped charge technology - 4 CD penetration for high-pressure resistant HEAT, 5 CD for low pressure/ precision formed HEAT. v. The subsidy-approved GPMG for the Lone Free State of Texas has the same form factor as the M240, but with switchable feed direction.. The standard HMG has the same form factor as the Kord, but with switchable feed direction. c. Mobility i. Engines tech level: 1. MB 838 (830 HP) 2. AVDS-1790-5A (908 HP) 3. Kharkov 5TD (600 HP) 4. Detroit Diesel 8V92 (400 HP) 5. Detroit Diesel 6V53 (200 HP) ii. Power density should be based on the above engines. Dimensions are available online, pay attention to cooling of 1 and 3 (water cooled). iii. Power output broadly scales with volume, as does weight. Trying to extract more power from the same size may come at the cost of reliability (and in the case of the 5TD, it isn’t all that reliable in the first place). iv. There is nothing inherently wrong with opposed piston or 2-stroke engines if done right. d. Electronics i. LRFs- unavailable ii. Thermals-unavailable iii. I^2- Gen 2 maximum vi. Texas cannot mass produce microprocessors or integrated circuits vii. Really early transistors only (e.g., transistor radio) viii. While it is known states exist with more advanced computer technology, the import of such systems are barred by the east coast states who do not approve of their use by militaristic entities. Armor calculation appendix. SHEET 1 Armor defeat calculator 4in-54 1200 yd SHEET 2 Armor defeat calculator 4in-54 2000 yd SHEET 3 Armor defeat calculator 6in HEAT Range calculator
  3. I haven't found an appropriate thread where to put some interesting rare stuff related to WW2 development, be it industrial one or makeshift field modifications. Let's start with two things. The first one is a relatively recently found rarity from Swedish archives - a drawing of ČKD/BMM V8H-Sv tank. The drawing and a letter was found by WoT enthusiasts in Swedish archives in 2014 (the original announcement and the drawing source is here). The drawing is from a message dated 8th September 1941. One of the reasons why this drawing was not known before may be that the Czech archives were partially destroyed by floods in 2002. Anyway it is an export modification of the V-8-H tank accepted into Czechoslovak service as ST vz.39 but never produced due to the cancelation of all orders after Münich 1938 (for the same reason negotiations about licence production in Britain failed). Also later attempt to sell the tank to Romania failed due to BMM being fully busy with Wehrmacht priority orders. The negotiations with Sweden about licence production of V8H-Sv lasted till 1942, at least in May 1942 Swedish commission was present in Prague for negotiations. The tank differed compared to the base ST vz.39 in thicker armor with different front hull shape (armor 60 mm @ 30° on the hull front and also 60 mm on the turret; all sides were 40 mm thick). The tank was heavier (20 tons) and had the LT vz.38 style suspension with probably even larger wheels. The engine was still the same Praga NR V8 (240-250 Hp per source). The armament was unchanged with 47 mm Škoda A11 gun and two vz.37 HMG. The commander's cupola was of the simple small rotating type similar to those used on AH-IV-Sv tankettes. It is known that the Swedes officially asked to arm the tank with 75 mm gun, replace the engine with Volvo V12 and adding third HMG to the back of the turret. In the end the Swedes decided to prefer their own Strv/m42. Source of the drawing The second is makeshift field modification found on Balkans. It appears Ustasha forces (and possibly some SS anti-partizan units) used several Italian M15/42 medium tanks with turrets from Pz.38(t). There are several photos of such hybrids but little more is known. On one photo it is possible to see Ustasha registration number U.O. 139. Few more photos of such hybrid. It appears that the source of all those photos to be found on the internet is this book, Armoured units of the Axis forces in southeastern Europe in WW2 by Dinko Predoevic.
  4. I was recently looking at the Japanese wikipedia page for the Chi-Ha tank, and it had this section on the name of the tank: I have never heard of such nomenclature, and obviously I don't have access to such documents since I don't live in Japan. There is no reference for this part, so can anyone confirm that they actually did use "MTK" etc.?
  5. 70 years ago, January the 2nd, 1951. To the North of Seoul, in the mountains and hills near Go-yang-tong(高阳洞), British 1RUR dug in and fought against advancing PVA forces. 1RUR got a task force called Cooperforce to support, this is a tank unit from Royal Tank Regiment and Royal Artillery, equipped with Cromwell tanks. When Matthrew Ridgeway assigned the order of withdraw in this afternoon, the US force covering British force's left flank quickly escaped from their sector, leaving the British were completed unawared and uncovered. When the night falls, was cold and dark in the valley. 1RUR had to withdraw in the darkness. All of a sudden, a US spotter aircraft flew over the valley, drop some illumination flares upon the retreating convoy. Fierce battle broke out when flares fall down, PVA firing from all directions, the cold valley became deadly kill zone. Some PVA soldiers put away their rifles, assaulting with hand grenades, satchel charges and Bangalore torpedoes. They even set up mortars on the hill, laying shells with direct fire. 200 British soldiers and artillerymen were killed or captured in one night. 1RUR's Battalion Commander Tony Blake was believed KIA. Cooperforce was completely knocked out, all 12 tanks were destroyed or captured by light infantry. Leader Ashley Cooper were also killed.
  6. Found a few higher resolution photographs from the recent North Korean military parade. We didn't have a topic for BEST KOREAN armored fighting vehicles, so here it is. New main battle tank, Abrams-Armata clone based on Ch'ŏnma turret design (welded, box-shaped turret) and Sŏn'gun hull design (i.e. centerline driver's position). The bolts of the armor on the hull front is finally visible given the increased resolution. It might not be ERA given the lack of lines inbetween. Maybe is a NERA module akin to the MEXAS hull add-on armor for the Leopard 2A5? Other details include an APS with four radar panels (the side-mounted radar panels look a lot different - and a lot more real - than the ones mounted at the turret corners) and twelve countermeasures in four banks (two banks à three launchers each at the turret front, two banks à three launchers on the left and right side of the turret). Thermal imagers for gunner and commander, meteorological mast, two laser warning receivers, 115 mm smoothbore gun without thermal sleeve but with muzze reference system, 30 mm grenade launcher on the turret, six smoke grenade dischargers (three at each turret rear corner) IMO the layout of the roof-mounted ERA is really odd. Either the armor array covering the left turret cheek is significantly thinner than the armor on the right turret cheek or the roof-mounted ERA overlaps with the armor. The first ERA/armor element of the skirt is connected by hinges and can probably swivel to allow better access to the track. There is a cut-out in the slat armor for the engine exhaust. Also note the actual turret ring - very small diameter compared to the outer dimensions of the turret. Stryker MGS copy with D-30 field gun clone and mid engine: Note there are four crew hatches. Driver (on the left front of the vehicle), commander (on the right front of the vehicle, seat is placed a bit further back), gunner (left side of the gun's overhead mount, next to the gunner's sight) and unknown crew member (right side of gun's overhead mount with 30 mm automatic grenade launcher mounted at the hatch). The vehicle also has a thermal imager and laser rangefinder (gunner's sight is identical to the new tank), but no independent optic for the commander. It also has the same meteorological mast and laser warner receivers as the new MBT. What is the purpose of the fourth crew member? He cannot realistically load the gun... The vehicle has a small trim vane for swimming, the side armor is made of very thin spaced steel that is bend on multiple spots, so it clearly is not ceramic armor as fitted to the actual Stryker. The tank destroyer variant of the same Stryker MGS copy fitted with a Bulsae-3 ATGM launcher. Note that there is again a third hatch with 30 mm automatic grenade launcher behind the commander's position. Laser warning receivers and trime vane are again stand-out features. The sighting complex for the Bulsae-3 ATGMs is different with a large circular optic (fitted with cover) probably being a thermal imager and two smaller lenses visible on the very right (as seen from the vehicle's point of view) probably containing a day sight and parts of the guidance system. Non line-of-sight ATGM carrier based on the 6x6 local variant of the BTR, again fitted with laser warning receivers and a trim vane. There are only two hatches and two windows, but there is a three men crew inside. There are a lot more photos here, but most of them are infantry of missile system (MLRS' and ICBMs).
  7. So I got a request recently from {NAME REDACTED} as to whether we have a how-to guide or something for competitions. After a few moments of bitter, bitter laughter at the decade-plus of my life that I've spent cobbling together things that can maybe, sort-of, squint-your-eyes produce a facsimile of a realistic vehicle, I thought I'd share my process: Note: I was half-right - we definitely have supplementary info for aspiring pretend tank designers pinned to this very board. Finally, I'm inviting our forum grognards and past winners to share their process for folk that haven't been here since before the last ice age, so that all can benefit.
  8. Hi guys, Does anyone know of any military studies that analyzed the reload speeds for different tanks? The question occurred to me when I watched this video tour of the T-55's interior: https://youtu.be/TEDhB9evPvw At the 10:00 mark, Mr. Moran demonstrates how the loader would put a shell into the tank's cannon, and the effects of the turret's small size and of the loader's awkward seating make it clear that the process would be slow. My question is: how slow? Side question: Am I right to assume that storing the tank shells all over the inside of the turret like that is an inherent design flaw of the T-55 that makes it inferior in that regard to modern tanks? Thanks in advance.
  9. Sturgeon's House started with a community of people who played tank games. At the time, most of us were playing World of Tanks, but I think there were a few Warthunder and even Steel Beasts players mixed in there too. After nearly five years, we must be doing something right because we're still here, and because we've somehow picked up a number of members who work with, or have worked with tanks in real life. I know that @AssaultPlazma served as an Abrams loader, @Merc 321 and @Meplat have helped maintain and restore privately-owned armor, and @Xlucine has volunteered in a tank museum. I'm sure I'm missing several more! So, what are your favorite personal tank stories?
  10. Restricted: for Operating Thetan Eyes Only By order of Her Gracious and Serene Majesty Queen Diane Feinstein the VIII The Dianetic People’s Republic of California Anno Domini 2250 SUBJ: RFP for new battle tank 1. Background. As part of the War of 2248 against the Perfidious Cascadians, great deficiencies were discovered in the Heavy tank DF-1. As detailed in report [REDACTED], the DF-1 was quite simply no match for the advanced weaponry developed in secret by the Cascadian entity. Likewise, the DF-1 has fared poorly in the fighting against the heretical Mormonhideen, who have developed many improvised weapons capable of defeating the armor on this vehicle, as detailed in report [REDACTED]. The Extended War on the Eastern Front has stalled for want of sufficient survivable firepower to push back the Mormon menace beyond the Colorado River south of the Vegas Crater. The design team responsible for the abject failure that was the DF-1 have been liquidated, which however has not solved the deficiencies of the existing vehicle in service. Therefore, a new vehicle is required, to meet the requirements of the People’s Auditory Forces to keep the dream of our lord and prophet alive. Over the past decade, the following threats have presented themselves: A. The Cascadian M-2239 “Norman” MBT and M-8 light tank Despite being approximately the same size, these 2 vehicles seem to share no common components, not even the primary armament! Curiously, it appears that the lone 120mm SPG specimen recovered shares design features with the M-8, despite being made out of steel and not aluminum like the light tank. (based on captured specimens from the battle of Crater Lake, detailed in report [REDACTED]). Both tanks are armed with high velocity guns. B. The Cascadian BGM-1A/1B/1C/1D ATGM Fitted on a limited number of tank destroyers, several attack helicopters, and (to an extent) man-portable, this missile system is the primary Cascadian anti-armor weapon other than their armored forces. Intelligence suggests that a SACLOS version (BGM-1C) is in LRIP, with rumors of a beam-riding version (BGM-1D) being developed. Both warheads penetrate approximately 6 cone diameters. C. Deseret tandem ATR-4 series Inspired by the Soviet 60/105mm tandem warhead system from the late 80s, the Mormon nation has manufactured a family of 2”/4” tandem HEAT warheads, launched from expendable short-range tube launchers, dedicated AT RRs, and even used as the payload of the JS-1 MCLOS vehicle/man-portable ATGM. Both warheads penetrate approximately 5 cone diameters. D. Cascadian HEDP 90mm rocket While not a particularly impressive AT weapon, being of only middling diameter and a single shaped charge, the sheer proliferation of this device has rendered it a major threat to tanks, as well as lighter vehicles. This weapon is available in large numbers in Cascadian infantry squads as “pocket artillery”, and there are reports of captured stocks being used by the Mormonhideen. Warhead penetrates approximately 4 cone diameters. E. Deseret 40mm AC/ Cascadian 35mm AC These autocannon share broadly similar AP performance, and are considered a likely threat for the foreseeable future, on Deseret armored cars, Cascadian tank destroyers, and likely also future IFVs. F. IEDs In light of the known resistance of tanks to standard 10kg anti-tank mines, both the Perfidious Cascadians and the Mormonhideen have taken to burying larger anti-tank A2AD weaponry. The Cascadians have doubled up some mines, and the Mormons have regularly buried AT mines 3, 4, and even 5 deep. 2. General guidelines: A. Solicitation outline: In light of the differing requirements for the 2 theaters of war in which the new vehicle is expected to operate, proposals in the form of a field-replaceable A-kit/B-kit solution will be accepted. B. Requirements definitions: The requirements in each field are given in 3 levels- Threshold, Objective, and Ideal. Threshold is the minimum requirement to be met; failure to reach this standard may greatly disadvantage any proposal. Objective is the threshold to be aspired to; it reflects the desires of the People’s Auditory Forces Armored Branch, which would prefer to see all of them met. At least 70% must be met, with bonus points for any more beyond that. Ideal specifications are the maximum of which the armored forces dare not even dream. Bonus points will be given to any design meeting or exceeding these specifications. C. All proposals must accommodate the average 1.7m high Californian recruit. D. The order of priorities for the DPRC is as follows: a. Vehicle recoverability. b. Continued fightability. c. Crew survival. E. Permissible weights: a. No individual field-level removable or installable component may exceed 5 tons. b. Despite the best efforts of the Agriculture Command, Californian recruits cannot be expected to lift weights in excess of 25 kg at any time. c. Total vehicle weight must remain within MLC 120 all-up for transport. F. Overall dimensions: a. Length- essentially unrestricted. b. Width- 4m transport width. i. No more than 4 components requiring a crane may be removed to meet this requirement. ii. Any removed components must be stowable on top of the vehicle. c. Height- The vehicle must not exceed 3.5m in height overall. G. Technology available: a. Armor: The following armor materials are in full production and available for use. Use of a non-standard armor material requires permission from a SEA ORG judge. Structural materials: i. RHA/CHA Basic steel armor, 250 BHN. The reference for all weapon penetration figures, good impact properties, fully weldable. Available in thicknesses up to 150mm (RHA) or 300mm (CHA). Density- 7.8 g/cm^3. ii. Aluminum 5083 More expensive to work with than RHA per weight, middling impact properties, low thermal limits. Excellent stiffness. Fully weldable. Available in thicknesses up to 100mm. Mass efficiency vs RHA of 1 vs CE, 0.9 vs KE. Thickness efficiency vs RHA of 0.33 vs CE, 0.3 vs KE. Density- 2.7 g/cm^3 (approx. 1/3 of steel). For structural integrity, the following guidelines are recommended: For light vehicles (less than 40 tons), not less than 25mm RHA/45mm Aluminum base structure For heavy vehicles (70 tons and above), not less than 45mm RHA/80mm Aluminum base structure. Intermediate values for intermediate vehicles may be chosen as seen fit. Non-structural passive materials: iii. HHA Steel, approximately 500 BHN through-hardened. Approximately twice as effective as RHA against KE and HEAT on a per-weight basis. Not weldable, middling shock properties. Available in thicknesses up to 25mm. Density- 7.8g/cm^3. iv. Glass textolite Mass efficiency vs RHA of 2.2 vs CE, 1.64 vs KE. Thickness efficiency vs RHA of 0.52 vs CE, 0.39 vs KE. Density- 1.85 g/cm^3 (approximately ¼ of steel). Non-structural. v. Fused silica Mass efficiency vs RHA of 3.5 vs CE, 1 vs KE. Thickness efficiency vs RHA of 1 vs CE, 0.28 vs KE. Density-2.2g/cm^3 (approximately 1/3.5 of steel). Non-structural, requires confinement (being in a metal box) to work. vi. Fuel Mass efficiency vs RHA of 1.3 vs CE, 1 vs KE. Thickness efficiency vs RHA of 0.14 vs CE, 0.1 vs KE. Density-0.82g/cm^3. vii. Assorted stowage/systems Mass efficiency vs RHA- 1 vs CE, 0.8 vs KE. viii. Spaced armor Requires a face of at least 25mm LOS vs CE, and at least 50mm LOS vs KE. Reduces penetration by a factor of 1.1 vs CE or 1.05 vs KE for every 10 cm air gap. Spaced armor rules only apply after any standoff surplus to the requirements of a reactive cassette. Reactive armor materials: ix. ERA-light A sandwich of 3mm/3mm/3mm steel-explodium-steel. Requires mounting brackets of approximately 10-30% cassette weight. Must be spaced at least 3 sandwich thicknesses away from any other armor elements to allow full functionality. 81% coverage (edge effects). x. ERA-heavy A sandwich of 15mm steel/3mm explodium/9mm steel. Requires mounting brackets of approximately 10-30% cassette weight. Must be spaced at least 3 sandwich thicknesses away from any other armor elements to allow full functionality. 81% coverage (edge effects). xi. NERA-light A sandwich of 6mm steel/6mm rubber/ 6mm steel. Requires mounting brackets of approximately 10-30% cassette weight. Must be spaced at least 1 sandwich thickness away from any other armor elements to allow full functionality. 95% coverage. xii. NERA-heavy A sandwich of 30mm steel/6m rubber/18mm steel. Requires mounting brackets of approximately 10-30% cassette weight. Must be spaced at least 1 sandwich thickness away from any other armor elements to allow full functionality. 95% coverage. The details of how to calculate armor effectiveness will be detailed in Appendix 1. b. Firepower i. 2A46 equivalent tech- pressure limits, semi-combustible cases, recoil mechanisms and so on are at an equivalent level to that of the USSR in the year 1960. ii. Limited APFSDS (L:D 15:1)- Spindle sabots or bourelleted sabots, see for example the Soviet BM-20 100mm APFSDS. iii. Limited tungsten (no more than 100g per shot) iv. Californian shaped charge technology- 5 CD penetration for high-pressure resistant HEAT, 6 CD for low pressure/ precision formed HEAT. v. The general issue GPMG for the People’s Auditory Forces is the PKM. The standard HMG is the DShK. c. Mobility i. Engines tech level: 1. MB 838 (830 HP) 2. AVDS-1790-5A (908 HP) 3. Kharkov 5TD (600 HP) ii. Power density should be based on the above engines. Dimensions are available online, pay attention to cooling of 1 and 3 (water cooled). iii. Power output broadly scales with volume, as does weight. Trying to extract more power from the same size may come at the cost of reliability (and in the case of the 5TD, it isn’t all that reliable in the first place). iv. There is nothing inherently wrong with opposed piston or 2-stroke engines if done right. d. Electronics i. LRFs- unavailable ii. Thermals-unavailable iii. I^2- limited 3. Operational Requirements. The requirements are detailed in the appended spreadsheet. 4. Submission protocols. Submission protocols and methods will be established in a follow-on post, nearer to the relevant time. Appendix 1- armor calculation Appendix 2- operational requirements Good luck, and may Hubbard guide your way to enlightenment!
  11. Hi guys, I recently read about upgrade packages to old tanks like the M-60 and T-55, but kept seeing comments from people saying they would still be obsolete. Is this because the M-60 and T-55 are made entirely of steel (and not composite) armor? I have this theory that thick steel armor is probably totally obsolete, and is just dead weight in the age of lighter weight composite armor. You can bolt on upgrades to an M-60 or T-55, but you're still hamstrung by the fact that either tank will be carrying around tons of useless steel. Am I right? Also, if we wanted to upgrade old tanks like that, wouldn't the best idea be to develop a new turret--with lighter, modern composite armor and better technology inside--and just drop it into the old tanks? The hulls would still be made of heavy steel, but that could be helped a bit by adding applique armor. Here are some of the upgrades I read about: https://youtu.be/NG89Zh9qQrQ http://www.army-guide.com/eng/product1907.html
  12. Anti-air bobcat design to take away driver's hearing in maximum efficiency SH11 155mm SPG
  13. Let's say you're developing a tank with a unique (AKA non-historical) gun for one of our competitions here on SH. It would be nice to have an idea of the size of the gun, its shells, and what their performance both in terms of shell weight and velocity but also penetration, wouldn't it? Well, fortunately there is a way to do this with reasonably accurate results using your solid modeling software and some free to use browser tools. First, you want to have a general idea of the size and performance of your gun. For this example, I decided I wanted an optimized, high velocity 85mm caliber gun with a case about as big as the 7.5cm KwK 42 (as it happened, I ended up with a case that had significantly greater volume, but that fact is unimportant for this example). The cartridge I decided on has a 130mm wide rim and a 640mm long case, of course in 85mm caliber. My first step was to model this case in SolidWorks: You will also need to model your projectile, in this case a tungsten-carbide cored APCR round: Next, we need a bit of freeware: A Powley computer. Originally developed by DuPont engineers for small arms ammunition, the Powley computer is an accurate enough tool to use for much larger tank rounds as well! When you click the link, you'll be greeted with this screen: You'll note the dimensions are in inches and this thing called "grains" (abbreviated "gn"). The grain is an archaic Imperial mass unit equal to 1/7000th of a pound which is still used in the small arms field, today. Another quirk of small arms has the case capacity - a volume measurement - listed in grains as well. This is in fact grains of water (gn H2O), or the weight of water that will fill the case to the top. To find this, simply multiply the volume in cubic centimeters by 15.43 - which is also the exchange rate between the metric gram and grains mass. Finding the volume of the case is easy with a solid modeling program; simply model the interior as a solid and find the volume of that solid: Filling in my Powley inputs gives me this: Note that I typically use the diameter of the projectile across the driving bands for "Bullet Diameter", but it really makes very little difference. So far, though, we haven't actually produced any results. That's because our gun is well outside the bounds of DuPont production IMR powders, hence the output "Much slower than (IMR) 4831" in the lower left. So, we need to override the computer by checking the box next to the blue "Pressure" function, and typing in a pressure value in CUP that is reflective of tank guns of whatever era we are trying to represent. My tank gun is trying to represent something from about the late 1940s/early 1950s, so I'm going to use 45500 CUP EDIT: USE 41000 CUP for APCBC and 42800 CUP FOR APCR (or better yet, do your own calibration!): This gives me an estimated muzzle velocity of 3,964 ft/s for my L/50 barrel. Not bad! Note the outputs on the left, which tell you a bunch of fun facts about your round but aren't terribly relevant to what we're doing here today. Next, we need to put this gun's performance in terms of penetration. The way I like to do this is through comparative analysis. The first thing we need is to know to find penetration the ballistic performance of our round. We can estimate this using JBM's ballistic calculator and a few rules of thumb. When opening the calculator, the first thing you'll see is this: We care about basically none of these settings except BC, velocity, and maximum range. Caliber, projectile weight, chronograph distance, etc are all pretty irrelevant to us. Keep the environmental settings (temperature, pressure, etc.) set to their defaults. First, change the ballistic coefficient type from G1 to G7 using the dropdown menu. Then, change the muzzle velocity from 3000 to whatever the muzzle velocity was that was calculated by the Powley computer. Finally, set the maximum range to your desired distance - in my case 2,000 yards. For my round, I now have inputs that look like this: We also need to get some idea of how fast our projectile loses velocity, something we can't know for certain without actually building a real gun and test firing it - or at least without some really sophisticated simulations. However, projectiles with the same shape tend to fly the same way, and that's something we can exploit here. To figure this out, we need a graph showing us the performance of a real-life gun. Fortunately, there is a handy one for an IRL gun similar to what I'm designing, the 90mm M3 from World War II, and its M304 HVAP-T, which is broadly similar in construction and shape to my 85mm APCR projectile: Based on this chart, we see that the M304 should drop from its 3,350 ft/s muzzle velocity to about 2,500 ft/s at 2,000 yards. Doing a little trial and error with JBM tells me that this means the M304 has a G7 ballistic coefficient of about 1.13. Now, our projectile will not have the same ballistic coefficient, due to it being a different size and mass. But, we can figure out what its ballistic coefficient would be by finding its sectional density and comparing that to the sectional density of M304. To find sectional density, take the projectile's weight in grains and divide it by the square of the projectile's diameter in inches, times 7000. So for M304, we get: And for my 85mm, we get: This means that the ballistic coefficient for an identical-shape projectile with our size and weight will be about 1.019/1.330 - or 76.6% as much - as that of the 90mm M304. That means a BC of 0.866 G7 should be approximately correct for my 85mm APCR round. Let's plug that in: And then scroll down to the bottom to click "calculate", which gives us a big ol' chart that goes out to 2,000 yards: O-Kay! Now we have some data. It looks like at 2,000 yards, my projectile holds about 2,800 ft/s striking velocity. It's important to note here that what we really care about isn't the striking velocity of the projectile per se, but the velocity and energy of the projectile's core. The core is what's actually doing a lot of work to the armor, so for now let's stop thinking in terms of the whole projectile, and take a look at these two cores, that of the M304 90mm HVAP, and that of my 85mm APCR round. The core of the 90mm M304 is an approximately 8 pound lump of tungsten-carbide that is about 45mm in width. My penetrator is also 8 pounds, but it's longer and thinner in proportion - just 40mm wide, rather than 45mm. This means my penetrator will penetrate more armor at a given striking velocity, and we can estimate how much more by taking the specific energy of the rounds and comparing them. That is, the energy in Joules of the penetrator alone, divided by the penetrator's diameter squared: So the specific energy at 2,000 yards is about 826J/mm^2. Now, we need to find out at what impact velocity the M304 penetrator produces this same specific energy. Do do that, we go backwards, using the figures for M304: Therefore, the equivalent impact velocity for my 85mm APCR round at 2,000 yards is 3,150 ft/s for the M304. That means, in theory, that the M304 would have to impact a target at 3,150 ft/s to produce equivalent penetration of RHA to my 85mm APCR striking at just 2,800 ft/s. Now, we head back to that chart: On the left side of the graph, we put our cursor on the line that corresponds to approximately 3,150 ft/s velocity, and follow it over until it hits the curved line that corresponds with the angle of plate we care about - arbitrarily, let's pick 20 degrees. Then, we follow that point straight down until it hits the x-axis: Therefore, we estimate that at 2,000 yards, my 85mm has just over 10 inches of RHA penetration - not bad at all for a lowly APCR round!
  14. Since we don't have a thread for British and Commonwealth tanks of WWII, I thought I would start one. Check out this manufacturers instructional video on the Crusader.
  15. Since Xlucine suggested it in the general AFV thread, here is a new version of the old Tank ID thread that used to exist at the WoT forums, back before the great exodus to SH. The rules are simple. Post a picture of some sort of AFV and everyone has to try to name what it is. Try to avoid posting a new picture until the previous picture is identified. Generally, the person who was first to correctly ID the picture in question gets to post the next picture, unless they want to pass. If a picture is not ID'd in a day or two, the person that posted it should say what it is and bask in their own sense of superiority. They should then post a new picture for the sake of keeping the thread moving. Please, no fictional tanks, paper napkin drawings that never made it to prototype or pictures where the vehicle in question is obscured or particularly hard to see. Also, if posting a picture of an unusual variant of a relatively common vehicle, be sure to note that you are looking for the specific variant name, not just the general family of vehicles it belongs to (for example, if I post a picture of a Panzer IV with the hydrostat drive, I would say in the post something like "What makes this Panzer IV unusual?" since everyone can ID a Panzer IV) It is perfectly ok to shame those that make spectacularly wrong guesses. That's just how we roll around here. I'll start
  16. 各位最近可能在WT论坛上见过这张图片,在一些争论陆上自卫队90式战车的讨论串里: Some of you may have seen this pic recently on WT forum, in some thread arguing the protection of JGSDF Type 90: Discussion on WT forum 我就直说吧,表格里的中文注解说了,这不过是个“猜想”,GUESSING。 To be straight, the Chinese annotation in the table said it is just a GUESSING. 注解内容可能完全是编造的,但不幸的是,不同语言间的障碍使你们无法看穿这点。 This annotation could be totally nonsense but unfortunately a barrier between languages prevent you guys see throught it. 实际上,这又是一份关于陆上自卫队10式战车的文件,说的并不是90式。 In fact, again, this document itself is about JGSDF Type 10 MBT, not Type 90. 同样的花招,不一样的人,是吧? Same trick, different people, huh? ↑陆上自卫队的10式战车规格书 JGSDF specification handbook of Type 10 MBT ↑59页,附录B,性能(规定)以及诸元 page 59, Appendix B, performance (regulations) and data 下面简要说说这些性能规定如何编写、如何加密。 Let's talk about these regulations and how they were made and encrypted. 大家可能知道日语中有平假名和片假名,和拉丁语中的字母还有大写字母是差不多的。 You may know that Japanese have Hirakana and Katakana, like Latin have letters and capital letters. 正如图中所示,一些最关键的数值和描述用平假名、片假名、罗马字(拉丁字母)隐去了。 As you can see, some of the most crucial numbers and descriptions are covered by a Hirakana or Katakana or Romaji(Latin letters). 这些数值和描述被归在一起,编入附属的手册,称为“别册”。 These numbers and descriptions were collected and listed in some append book, called Bessatsu(別冊). 在查阅别册时,就好比在看试卷的答题卡。但如果把别册里面的数值和描述涂黑,你就根本不知道说啥。 When you look up to the append book, just like viewing the answer sheet of an exam paper. But when numbers and descriptions were censored, you'll never know what it said. 比如说,正面防护: For example, the frontal protection: “耐弾性 - 正面 - 正面要部は、【あ】に射距離【え】m相当存速において、貫徹されない。” 读起来是这样的: 耐弹性 - 正面 - 正面重要部位可抵御【あ】以相当于射击距离【え】米存速的射击,不会贯穿。 It read like this: Protection - Frontal - Frontal crucial part should withstand 【あ】 firing at a distance of 【え】meter speed reduce equivalent, and not penetrate. 【あ】代表某种弹药,可能是尾翼稳定穿甲弹,但不知道是量产弹种还是实验弹种。 【あ】stands for certain type of ammunition, probably APFSDS, but don't know whether it is production shot or experimental. 【え】代表某个射击距离,可以是1000、1500或2000(米),但这么远的距离,炮弹会受到风力和重力影响,故无法精确瞄准靶车的防护区域。 【え】stands for certain firing distance, could be 1000 , 1500 or 2000 (meters), but on such a long distance, shot could be effect by wind and gravity, thus cannot aim on the protection area of target vehicle precisely. 一个常见的解决方式是在更近的距离上开火,比如说200到550米,同时减少推进药量,使得穿甲弹的终点速度符合特定距离的速降。这是一种等效方法。 The usual solution is to fire from a much closer range, from 200 to 550 meters, while reducing the propellant charge so that the end speed of AP shot could match the speed drop on certain distance. This is an equivalant method. 有的人争辩说90式战车可以抵挡另一辆90式战车发射的穿甲弹(JM33),距离大约250米。这一说法源自一段未知视频片段,具体什么视频他们自己也没看过。较近的射击距离是为了能更好的瞄准,为此可能使用了减装药来模拟远距离终点速度,但也无法证明。 Some people argue that Type 90 MBT can withstand AP shot (JM33) firing from another Type 90 MBT, on a distance about 250 meters. The source of this statement came from an unknown video clip, which they have never seen. Firing on closer range is for better aim, and they could have use reduced charge to simulate a much longer range, but we cannot prove.
  17. Part 5 of a multi-part series. This one's got the goods. Sherman and firefly. Early crusader. Early Valentine. The British really went through a phase where they slapped 2 pounders onto everything. Father. Son. Holy ghost. Comet, aka Hipster Centurion. Centurion, aka The entire History of South African tanks post-WW2. T-shirt cannon Churchill. Combat engineers get no respect. This thing is tiny and has an insane steering system. Somehow this thing is even smaller. Those twin barrels are for a flamethrower of some sort, because the Italians were world-class optimists.
  18. Greetings I am Darjeeling and I come from Hong Kong. Recently as Turkey launched the OB so I investigate in the TAF as I am a apoist. The following article will mainly focus on the best armoured unit of TAF. All the data are collected from internet and I need help to complete it. [Introduction on armour unit organisation] Turkish tank brigades included three tank battalions while in the mechanised brigades just 1 tank battalion. Each tank battalion consists of 41 tanks. The staff and management team consists of 2 tanks, 39 armored rest distributed to 3 tank Wrotham. Each tank company consists of 13 tanks while 1 tank company commander and platoon 4 to 3 tanks. Since the showing the TO&E of all armoured units should be too long, the following will only present some "Ace armoured unit". ===== Version 1.1 Welcome for any suggestions/addition on this issue 1)M60T units M60T is a modernised M-60 which is capable with T-72s. Turkey utilizing large numbers of these tanks have been seen deploying to the southern border in the previous years. They were used during incursions into Syria and Iraq in earlier operations to combat Kurdish forces in both nations. Here are what I confirmed: - 5th Armoured Brigades (Confirmed in internet data) - 20th Armoured Brigades (Confirmed in internet data) - 172nd Armoured Brigades (Confirmed in internet data) They are believed to have equipped with M60T. As each Turkey tank battalion consists of 41 tanks, a total of 123 out of 170 should have counted. I believe there maybe one brigades unknown. Example in real combat: >M60T act as spearhead and attaching a YPG town but being ambushed. Two tanks were destroyed. https://m.youtube.com/watch?v=78lnBhcA_n0 2) Leopard 2 units Turkey has 354 of highly capable Leopard 2 German manufactured tanks. Leopard are currently deployed in Syria in OB and the previous OB. It is most likely that these more capable MBTs are with units tasked with guarding Turkey’s border with Russia and the Caucasus, where they would have to fight against a much more capable adversary. Here are what I confirmed: - 2nd Armoured Brigade (Confirmed in Operation ES as casualties) - 3th Armoured Brigade (Confirmed in the 2016 failed coup) - 5th Armoured Brigade (Confirmed in Operation OB as casualties) So it is obviously that more efforts needed to be done on Leo2. Only half of them counted. The Leo2a4 of TAF is the outdated version that it's last update is in 1992. So this explained why it performed so bad in ES. Total 10 tanks were confirmed lost in the battle and even captured by ISIS. Yet, while facing the poor equipped and trained YPG/J, only 3 Leo 2 was destroyed in OB. 2 was taken out because the engine was penetrated and taken out by Air Force (prevent captured by YPG/J). The only effort of YPG/J is penetrating a Leo 2 from flank and lead to the blow. Example in real combat: >Leo 2 receive a direct hit by YPG but it was not destroyed. High survivability showed. https://m.youtube.com/watch?v=YafzmkvVRiI 3) M60A3 units M60A3 is a 2nd Gen-MBT in TAF. They are mostly used as supporting fire unit to assist the infantry. Yet, the performance of M60A3 relatively bad. Here are what I confirmed: - 16th Mechanised Brigade (Confirmed in Operation ES as casualties) - 39th Mechanised Brigade (Confirmed in Operation OB as casualties) Example in real combat: >M60A3 being hit as no soldiers protect it in ES https://m.youtube.com/watch?time_continue=28&v=pg-rbEC0jXI&ebc=ANyPxKqRFXar7bNqSS5wcCJspZFJMnyoQD0qixyUheJgMdLHy5q0eQakNmCBv16NSoGjfAoNbcP4cGDbJHXTpR7eJhobZW8EPw ————— PPS:This is my post about order of battle of OB about TAF https://www.reddit.com/r/syriancivilwar/comments/81nml8/keep_updateturkish_order_of_battle_of_ob_up_to/?st=JEE2UT1F&sh=d04daee9
  19. Sooooo...after doing a site-wide search and perusing Google, I'm surprised not to have found anything about tank suspension, other than a somewhat doubtful thread on the WoT forums. Would my learned colleagues of SH be able to assist me in understanding and identifying the different types of tank suspension? I think I've got leaf-spring more or less mastered, as well as both VVSS and HVSS (thanks, JGT!) but was somewhat embarrassed not to be able to differentiate between the suspension of a Type 97 Chi-Ha and an FV4201 Chieftain. UPDATE: I think I understand tank suspension better now. Thanks, everyone!
  20. 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.
  21. 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.
  22. The idea to produce a Romanian MBT was considered after 1968 invasion of Czechoslovakia and it started at the beginning of 70s when Romanian Communist Party embarked in an effort of industrialization of the country. Along with MBTs, an entire variety of armored vehicle was produced ranging from APCs and IFVs to SPGs. I'll start with tanks and I will gradually add posts to this thread. Keep in mind that I am not a specialist and I am open to advice/suggestions. There is very little reliable info available online, some sources give contradictory information but I’ve selected the info from reliable sites and included some considerations of military personnel who served on this tank or worked in the said factories(mainly from http://www.rumaniamilitary.ro website articles and comments); I tried to avoid internet articles, some are poorly documented and contain mistakes and even urban legends. Pretty often Romanian TR tanks series are mistakenly considered T-55s local copies which is quite wrong. Although Romania received the license of T-55 from USSR, it never produced this tank but rather imported it from USSR and Czechoslovakia due to WP internal rules of importing equipment of each other. The Czechoslovak products were preferred due to their better quality/reliability. TR-77-580 The first Romanian tank project yielded results in 1972, as a strategic part of the national defense doctrine. One of the reasons for which Romania’s political leadership accelerated industrialization was for military purposes, including tanks. The first Romanian tank was supposed to be medium one, with a 500 hp engine and was to be named with the TR designation, an acronym for Romanian Tank. The factory was supposed to be located in Marsa, in Sibiu county, in Romania’s western area however subsequently staff and production were moved to ‘August 23rd’ Enterprises in Bucharest where it were put into use various machines received from China. Another reason was the fact that Romanian Army did not considered T-55s as suitable for its doctrine and they requested a better armored medium, with better cabin for crew, better armor, NBC, anti-nuke protection and more ammo stored and better firepower. The only chapter were the first series (TR-77-850) failed was the maneuverability since the tank was 11 tons heavier and only the second generation engine of 850 HP solved this issue (middle 80s). The fist experimental model, the TR-77, came out in 1976, as a pre-mass production. After tests, the TR-77-580 came out and that same year, mass production started, with a target of 210 tanks a year. Compared with T-55, Romanian TR-77-580 had a stretched hull and an extra road wheel on each side to be able to fit the new engine, but the first series received the 580 HP engine and only later the 800 HP was gradually added. Just by looking at the tank, you may be mistaken that it was either a T-54 or a T-55, however this is basically a T-55 on steroids with double the armor, lengthened hull, a domestic anti-tank gun that looks similar to the D-10T (which was continuously improved and developed until 90s), and two extra pairs of roadwheels that are smaller in diameter. Armor: Unlike the T-55, the TR-77 got a thick stratified armor with 320mm on the turret front, and 200mm of armor on the hull (2 100mm plates), along with armored side skirts unlike the rubber side skirts of the T-55AM. This is already superior to the nominal armor of any other tank of its category with just RHA, and stratified armor is of course even better. The armor was theoretically better than the M60A1, T-62, Leopard I, and even the Chieftain. The use of a frontal 200 mm was at first controversial, and had a direct impact on the weight, of around three tons. Chief feature of the series is more than double the armor of T-55 using new technologies. At 200 mm thickness, it surpasses M60 even if only laminated type of armor; turret has 320 mm stratified which makes it one of the best armored tanks compared with most Western models of the same era. Gun: The TR-77-580 is armed with Romanian rifled 100mm A308 which is a variant of the 100mm anti-tank gun (M1977/A307) which also had a naval version (A430). It used 100mm BM 412 Sg ammunition that some sites claim that it is APDS but it’s mainly said to be a form of APFSDS ammunition. This ammo come later into service, at the same time with TR-85 (which was developed in middle 80s based on the experience acquired with TR-77 and using Chinese help). Other ammo used was BK-412 as HEAT ammunition, OF 412 as HE. It has a stabilizer, electric horizontally and hydraulic vertically. The gun itself was very resistant and it wasn’t uncommon to shot 250 rounds to a single exercise which I think says a lot about its durability. Rate of fire is from 7 to 15 rounds per minute, limited only by loader and muzzle velocity is 900 m/s for HE and 1400 m/s for APFSDS-T. Maneuverability: During its development, TR-77-580 was designed for a 830-860 hp engine allegedly derived from the Leopard I. Also Romanian engineers studied Israeli Centurions captured by Syria. This was partially the reason why the tank was lengthened and why it has 2 more road wheels than the T-55 and later it was upgraded with new engine and these variants were named TR-800/TM-800. For the first series it was used a local copy of the T-55’s V-55U engine which put out about 580 HP hence the name of the tank. The TR-77-580’s road wheels are evenly spaced out while the TR-800/TM-800 and the TR-85 has 2 widely spaced out wheels in the front while the back 4 are very close together. The delay in development of the 860 HP engine made the acceleration weaker than T-55s one. Probably mobility wise it is on par with Chieftain. Variants: TR-77-580 – Basic variant, chief feature of the series is more than double the armor of T-55 and is stratified. At 200 mm thickness, it surpasses M60 and deserves 12 FAV; turret has 320 mm stratified; It could be seen in the first pictures from this post. TR-77-580M – One of the first upgrades was to a LRF and ballistic computer; here is a pic with a TR-77-580 TR-77-580M1 – Main feature was its back elongated turret for better accommodation of crew, more ammo stored which would result in a better ROF than T-55s (9 rounds per minute). The pic shows one stripped of equipment and ready to be phased out; The number of tanks of this variant was small because they considered that it needs the 800 HP engine first. It was tested in 1979 by 912th Tank Battalion in Murfatlar although other sources claim is a late model. In middle/late 80s this model received 830 HP engine. The models in the photos are now exposed in a military units (not active anymore) and are stripped of equipment (skirts, boxes, MG, periscopes, IR projector, thermal sleeve and bore evacuator on the gun). Starting in 1983, a decision was made to raise the number of produced tanks to 500, once the new TR-85 model came out. By 1985, only 406 Romanian TR-77-580 tanks were made. To resume this tank weighed 42 tons, had a 580 hp Diesel engine, a top speed of 50 km/h, and a range of 380 km. It had an electric-hydraulic stabilizing system and 200 mm armor on frontal glacis and 380 mm stratified one on turret. Its armament was a 100 mm cannon that could fire six shots a minute, two machine guns and a crew of 4.
  23. Tank design is often conceptualized as a balance between mobility, protection and firepower. This is, at best, a messy and imprecise conceptualization. It is messy because these three traits cannot be completely separated from each other. An APC, for example, that provides basic protection against small arms fire and shell fragments is effectively more mobile than an open-topped vehicle because the APC can traverse areas swept by artillery fires that are closed off entirely to the open-topped vehicle. It is an imprecise conceptualization because broad ideas like "mobility" are very complex in practice. The M1 Abrams burns more fuel than the Leo 2, but the Leo 2 requires diesel fuel, while the omnivorous AGT-1500 will run happily on anything liquid and flammable. Which has better strategic mobility? Soviet rail gauge was slightly wider than Western European standard; 3.32 vs 3.15 meters. But Soviet tanks in the Cold War were generally kept lighter and smaller, and had to be in order to be moved in large numbers on a rail and road network that was not as robust as that further west. So if NATO and the Warsaw Pact had switched tanks in the late 1950s, they would both have downgraded the strategic mobility of their forces, as the Soviet tanks would be slightly too wide for unrestricted movement on rails in the free world, and the NATO tanks would have demanded more logistical support per tank than evil atheist commie formations were designed to provide. So instead of wading into a deep and subtle subject, I am going to write about something that is extremely simple and easy to describe in mathematical terms; the top speed of a tank moving in a straight line. Because it is so simple and straightforward to understand, it is also nearly meaningless in terms of the combat performance of a tank. In short, the top speed of a tank is limited by three things; the gear ratio limit, the power limit and the suspension limit. The tank's maximum speed will be whichever of these limits is the lowest on a given terrain. The top speed of a tank is of limited significance, even from a tactical perspective, because the tank's ability to exploit its top speed is constrained by other factors. A high top speed, however, looks great on sales brochures, and there are examples of tanks that were designed with pointlessly high top speeds in order to overawe people who needed impressing. When this baby hits 88 miles per hour, you're going to see some serious shit. The Gear Ratio Limit Every engine has a maximum speed at which it can turn. Often, the engine is artificially governed to a maximum speed slightly less than what it is mechanically capable of in order to reduce wear. Additionally, most piston engines develop their maximum power at slightly less than their maximum speed due to valve timing issues: A typical power/speed relationship for an Otto Cycle engine. Otto Cycle engines are primitive devices that are only used when the Brayton Cycle Master Race is unavailable. Most tanks have predominantly or purely mechanical drivetrains, which exchange rotational speed for torque by easily measurable ratios. The maximum rotational speed of the engine, multiplied by the gear ratio of the highest gear in the transmission multiplied by the gear ratio of the final drives multiplied by the circumference of the drive sprocket will equal the gear ratio limit of the tank. The tank is unable to achieve higher speeds than the gear ratio limit because it physically cannot spin its tracks around any faster. Most spec sheets don't actually give out the transmission ratios in different gears, but such excessively detailed specification sheets are provided in Germany's Tiger Tanks by Hilary Doyle and Thomas Jentz. The gear ratios, final drive ratios, and maximum engine RPM of the Tiger II are all provided, along with a handy table of the vehicle's maximum speed in each gear. In eighth gear, the top speed is given as 41.5 KPH, but that is at an engine speed of 3000 RPM, and in reality the German tank engines were governed to less than that in order to conserve their service life. At a more realistic 2500 RPM, the mighty Tiger II would have managed 34.6 KPH. In principle there are analogous limits for electrical and hydraulic drive components based on free speeds and stall torques, but they are a little more complicated to actually calculate. Part of the transmission from an M4 Sherman, picture from Jeeps_Guns_Tanks' great Sherman website The Power Limit So a Tiger II could totally go 34.6 KPH in combat, right? Well, perhaps. And by "perhaps," I mean "lolololololol, fuck no." I defy you to find me a test report where anybody manages to get a Tiger II over 33 KPH. While the meticulous engineers of Henschel did accurately transcribe the gear ratios of the transmission and final drive accurately, and did manage to use their tape measures correctly when measuring the drive sprockets, their rosy projections of the top speed did not account for the power limit. As a tank moves, power from the engine is wasted in various ways and so is unavailable to accelerate the tank. As the tank goes faster and faster, the magnitude of these power-wasting phenomena grows, until there is no surplus power to accelerate the tank any more. The system reaches equilibrium, and the tank maxes out at some top speed where it hits its power limit (unless, of course, the tank hits its gear ratio limit first). The actual power available to a tank is not the same as the gross power of the motor. Some of the gross horsepower of the motor has to be directed to fans to cool the engine (except, of course, in the case of the Brayton Cycle Master Race, whose engines are almost completely self-cooling). The transmission and final drives are not perfectly efficient either, and waste a significant amount of the power flowing through them as heat. As a result of this, the actual power available at the sprocket is typically between 61% and 74% of the engine's quoted gross power. Once the power does hit the drive sprocket, it is wasted in overcoming the friction of the tank's tracks, in churning up the ground the tank is on, and in aerodynamic drag. I have helpfully listed these in the order of decreasing importance. The drag coefficient of a cube (which is a sufficiently accurate physical representation of a Tiger II) is .8. This, multiplied by half the fluid density of air (1.2 kg/m^3) times the velocity (9.4 m/s) squared times a rough frontal area of 3.8 by 3 meters gives a force of 483 newtons of drag. This multiplied by the velocity of the tiger II gives 4.5 kilowatts, or about six horsepower lost to drag. With the governor installed, the HL 230 could put out about 580 horsepower, which would be four hundred something horses at the sprocket, so the aerodynamic drag would be 1.5% of the total available power. Negligible. Tanks are just too slow to lose much power to aerodynamic effects. Losses to the soil can be important, depending on the surface the tank is operating on. On a nice, hard surface like a paved road there will be minimal losses between the tank's tracks and the surface. Off-road, however, the tank's tracks will start to sink into soil or mud, and more power will be wasted in churning up the soil. If the soil is loose or boggy enough, the tank will simply sink in and be immobilized. Tanks that spread their weight out over a larger area will lose less power, and be able to traverse soft soils at higher speed. This paper from the UK shows the relationship between mean maximum pressure (MMP), and the increase in rolling resistance on various soils and sands in excruciating detail. In general, tanks with more track area, with more and bigger road wheels, and with longer track pitch will have lower MMP, and will sink into soft soils less and therefore lose less top speed. The largest loss of power usually comes from friction within the tracks themselves. This is sometimes called rolling resistance, but this term is also used to mean other, subtly different things, so it pays to be precise. Compared to wheeled vehicles, tracked vehicles have extremely high rolling resistance, and lose a lot of power just keeping the tracks turning. Rolling resistance is generally expressed as a dimensionless coefficient, CR, which multiplied against vehicle weight gives the force of friction. This chart from R.M. Ogorkiewicz' Technology of Tanks shows experimentally determined rolling resistance coefficients for various tracked vehicles: The rolling resistance coefficients given here show that a tracked vehicle going on ideal testing ground conditions is about as efficient as a car driving over loose gravel. It also shows that the rolling resistance increases with vehicle speed. A rough approximation of this increase in CR is given by the equation CR=A+BV, where A and B are constants and V is vehicle speed. Ogorkiewicz explains: It should be noted that the lubricated needle bearing track joints of which he speaks were only ever used by the Germans in WWII because they were insanely complicated. Band tracks have lower rolling resistance than metal link tracks, but they really aren't practical for vehicles much above thirty tonnes. Other ways of reducing rolling resistance include using larger road wheels, omitting return rollers, and reducing track tension. Obviously, there are practical limits to these approaches. To calculate power losses due to rolling resistance, multiply vehicle weight by CR by vehicle velocity to get power lost. The velocity at which the power lost to rolling resistance equals the power available at the sprocket is the power limit on the speed of the tank. The Suspension Limit The suspension limit on speed is starting to get dangerously far away from the world of spherical, frictionless horses where everything is easy to calculate using simple algebra, so I will be brief. In addition to the continents of the world not being completely comprised of paved surfaces that minimize rolling resistance, the continents of the world are also not perfectly flat. This means that in order to travel at high speed off road, tanks require some sort of suspension or else they would shake their crews into jelly. If the crew is being shaken too much to operate effectively, then it doesn't really matter if a tank has a high enough gear ratio limit or power limit to go faster. This is also particularly obnoxious because suspension performance is difficult to quantify, as it involves resonance frequencies, damping coefficients, and a bunch of other complicated shit. Suffice it to say, then, that a very rough estimate of the ride-smoothing qualities of a tank's suspension can be made from the total travel of its road wheels: This chart from Technology of Tanks is helpful. A more detailed discussion of the subject of tank suspension can be found here. The Real World Rudely Intrudes So, how useful is high top speed in a tank in messy, hard-to-mathematically-express reality? The answer might surprise you! A Wehrmacht M.A.N. combustotron Ausf G We'll take some whacks at everyone's favorite whipping boy; the Panther. A US report on a captured Panther Ausf G gives its top speed on roads as an absolutely blistering 60 KPH on roads. The Soviets could only get their captured Ausf D to do 50 KPH, but compared to a Sherman, which is generally only credited with 40 KPH on roads, that's alarmingly fast. So, would this mean that the Panther enjoyed a mobility advantage over the Sherman? Would this mean that it was better able to make quick advances and daring flanking maneuvers during a battle? No. In field tests the British found the panther to have lower off-road speed than a Churchill VII (the panther had a slightly busted transmission though). In the same American report that credits the Panther Ausf G with a 60 KPH top speed on roads, it was found that off road the panther was almost exactly as fast as an M4A376W, with individual Shermans slightly outpacing the big cat or lagging behind it slightly. Another US report from January 1945 states that over courses with many turns and curves, the Sherman would pull out ahead because the Sherman lost less speed negotiating corners. Clearly, the Panther's advantage in straight line speed did not translate into better mobility in any combat scenario that did not involve drag racing. So what was going on with the Panther? How could it leave everything but light tanks in the dust on a straight highway, but be outpaced by the ponderous Churchill heavy tank in actual field tests? Panther Ausf A tanks captured by the Soviets A British report from 1946 on the Panther's transmission explains what's going on. The Panther's transmission had seven forward gears, but off-road it really couldn't make it out of fifth. In other words, the Panther had an extremely high gear ratio limit that allowed it exceptional speed on roads. However, the Panther's mediocre power to weight ratio (nominally 13 hp/ton for the RPM limited HL 230) meant that once the tank was off road and fighting mud, it only had a mediocre power limit. Indeed, it is a testament to the efficiency of the Panther's running gear that it could keep up with Shermans at all, since the Panther's power to weight ratio was about 20% lower than that particular variant of Sherman. There were other factors limiting the Panther's speed in practical circumstances. The geared steering system used in the Panther had different steering radii based on what gear the Panther was in. The higher the gear, the wider the turn. In theory this was excellent, but in practice the designers chose too wide a turn radius for each gear, which meant that for any but the gentlest turns the Panther's drive would need to slow down and downshift in order to complete the turn, thus sacrificing any speed advantage his tank enjoyed. So why would a tank be designed in such a strange fashion? The British thought that the Panther was originally designed to be much lighter, and that the transmission had never been re-designed in order to compensate. Given the weight gain that the Panther experienced early in development, this explanation seems like it may be partially true. However, when interrogated, Ernst Kniepkamp, a senior engineer in Germany's wartime tank development bureaucracy, stated that the additional gears were there simply to give the Panther a high speed on roads, because it looked good to senior generals. So, this is the danger in evaluating tanks based on extremely simplistic performance metrics that look good on paper. They may be simple to digest and simple to calculate, but in the messy real world, they may mean simply nothing.
  24. Well, if you include TUSK as armor kit for the Abrams, then you also have to include the different Theatre Entry Standards (TES) armor kits (three versions at least) of the Challenger 2. The base armor however was most likely not upgraded. The Leclerc is not geometrically more efficient. It could have been, if it's armor layout wasn't designed so badly. The Leclerc trades a smaller frontal profile for a larger number of weakspots. It uses a bulge-type turret (no idea about the proper English term), because otherwise a low-profile turret would mean reduced gun depression (breech block hits the roof when firing). There is bulge/box on the Leclerc turret roof, which is about one feet tall and located in the centerline of the turret. It is connected to the interior of the tank, as it serves as space for the breech block to travel when the gun is depressed. With this bulge the diffence between the Leopard 2's and Leclerc's roof height is about 20 milimetres. The problem with this bulge is, that it is essentially un-armored (maybe 40-50 mm steel armor); otherwise the Leclerc wouldn't save any weight. While the bulge is hidden from direct head-on attacks, it is exposed when the tank is attacked from an angle. Given that modern APFSDS usually do not riccochet at impact angles larger than 10-15° and most RPGs are able to fuze at such an angle, the Leclerc has a very weakly armored section that can be hit from half to two-thirds of the frontal arc and will always be penetrated. The next issue is the result of the gunner's sight layout. While it is somewhat reminiscent of the Leopard 2's original gunner's sight placement for some people, it is actually designed differently. The Leopard 2's original sight layout has armor in front and behind the gunner's sight, the sight also doesn't extend to the bottom of the turret. On the Leclerc things are very different, the sight is placed in front of the armor and this reduces overall thickness. This problem has been reduced by installing another armor block in front of the guner's sight, but it doesn't cover the entire crew. The biggest issue of the Leclerc is however the gun shield. It's tiny, only 30 mm thick! Compared to that the Leopard 2 had a 420 mm gun shield already in 1979. The French engineers went with having pretty much the largest gun mantlet of all contemporary tanks, but decided to add the thinnest gun shield for protection. They decided to instead go for a thicker armor (steel) block at the gun trunnions. Still the protection of the gun mantlet seems to be sub-par compared to the Leopard 2 (420 mm armor block + 200-250 mm steel for the gun trunion mount on the original tank) and even upgraded Leopard 2 tanks. The Abrams has a comparable weak protected gun mantlet, but it has a much smaller surface. The Challenger 2 seems to have thicker armor at the gun, comparable to the Leopard 2. Also, the Leclerc has longer (not thicker) turret side armor compared to the Leopard 2 and Challenger 2, because the armor needs to protect the autoloader. On the other tanks, the thick armor at the end of the crew compartment and only thinner, spaced armor/storage boxes protect the rest of the turret. So I'd say: Challenger 2: a few weakspots, but no armor upgrades to the main armor Leclerc: a lot of weakspots, but lower weight and a smaller profile when approached directly from the turret front M1 Abrams: upgraded armor with less weakspots, but less efficient design (large turret profile and armor covers whole turret sides) So if you look for a tank that is well protected, has upgraded armor and uses the armor efficiently, the current Leopard 2 should be called best protected tank.
  25. I'm sure that all the SH regulars will know this backwards and forwards, so this is more for the benefit of newer people, or people who stumble in via google, or people who want a quick link they can throw out as an answer to anyone who asks the question. So, what's with the goofy-ass road wheel design on German WWII AFVs? A puzzled and terrified worker struggles to comprehend and assemble the suspension of a tiger I You may have run into a variety of explanations for this running gear design; that it provided a smoother ride, that the design saved rubber, or possibly some other rubbish. Like the myth that frontal drive sprockets provide more traction (seriously, how in the hell is that supposed to make any sense?), these wrong explanations of the merits of interleaved road wheels seem to rise from some quote taken out of context. The interleaved road wheel running gear may have saved some rubber relative to an alternative design that was particularly wasteful of it. But interleaved road wheels are not particularly economic in this respect because, and I realize this is a complicated concept to explain so I'll try my best, they have more wheels. Interleaved road wheels do allow for large wheel diameters, and a larger diameter wheel will spread wear out over a larger circumference. So interleaved road wheels might allow for the rubber on the wheels to last longer, although their construction would require more in the first place. Interleaved road wheels would not improve ride quality either. The ride quality of a tank is not a function of the size or number of wheels it possesses, but of how they are sprung. So, it is possible that in certain competitive trials an interleaved road wheel design outperformed a design that lacked this feature. I could readily believe, for instance, that the tiger (H) had a better ride quality on rough terrain than the tiger (P), or that the SDKFZ. 251 had a smoother ride than the M3. However, this would be because the tiger (H) and SDKFZ. 251 have independently sprung road wheels on torsion bars while the tiger (P) and M3 do not. Torsion bar layout of the tiger II Volute spring suspension of the M3 half track So, what do interleaved road wheels do? They have two principal effects; one is a small benefit, and the other is an enormous detriment. The small benefit of interleaved road wheels is that they spread the weight of the vehicle out more evenly on the track links: The weight of a tank is not completely evenly spread out on the contact area of its tracks. This is because tracks are not rigid. If they were, they would be mainly ornamental and tanks' engines would just be for show. More of the weight of a tank is concentrated under the parts of the track that the road wheels are sitting directly on top of. Additionally, once a tank starts to sink into the soil a bit, larger road wheels work better than smaller ones because the larger ones have more contact area. But you can only fit so many large diameter road wheels in the space of a tank's hull. Dynamic! So, the only way to have lots of road wheels and have big road wheels at the same time is to interleave them. Simple as that. If you would like an exhaustive look at the development of the semi-empirical MMP equation, read this. The major, crippling downside to interleaved road wheels is that it makes changing the road wheels extremely time consuming. A pair of workers perform maintenance on a panther tank, and contemplate the futility of all human achievement Lucas Friedli reprints in his book on big cat maintenance a report from a training unit complaining that replacing the inner road wheels of a tiger tank took ten hours. That is completely outrageous, and was a contributor to the poor operational availability of the big cats. For this reason, interleaved road wheels have rarely been used after World War Two; only on a few French prototypes and a Swedish APC: PBV 302 variant with interleaved road wheels Some bizarre French tank
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