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Monochromelody

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Monochromelody last won the day on January 2

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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. Nope, I just happen to know something about JGSDF era Don't know much about IJA
  3. 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.
  4. The Al Khalid derived from Norinco Type 90IIM MBT. It was in the early 90s, when India started to test their Arjun MBT. Pakistanis looked for a MBT design that could be produced by herself. Norinco provided their own Type 90IIM prototype, this is an MBT design which comprised many Western components, such as engine and transmission. There were 4 prototypes for Al-Khalid development, namely P1, P2, P3 and P4. P1 has a Chinese tank diesel engine with ZF LSG3000 transmission. P2 has a British Perkins CV12 Condor diesel engine with French SESM ESM500 transmission. P3 has a Ukrainian KMDB 6TD-2 2-cycle boxer engine with its own twin planetary gearbox. P4 has a German MB871 engine with ZF LSG3000 transmission, similar to South Korean K1 MBT. Norinco and Pakistanis planned to adopt one of the Western powerpack at first, but due to CoCom (Coordinating Committee for Export to Communist Countries) restrictions, China is under embargo, which means China would not import weapons form Western countries. Obviously P3 powerplant would be the only choice. All those descriptions on the internet about ESM500 in Al-Khalid is fatally wrong. The Al-Khalid pre-production batch and production version all equipped with Ukrainian KMDB 6TD-2 powerpack. It is an extremely compact design, the engine laid transversely in engine room, twin planetary gearboxes connect to both left and right end. The 6TD-2 has two crankshafts: the front one drives the mechanical supercharger, while the rear one drives the gearboxes. The cooling system covering the whole engine room, the engine itself has no mechanical connection to the cooling system, and the cooling system doesn't need mechanical drive. The cooling system based on a unique principle: exhaust gas driven ejector. The exhaust gas from the engine is injected through the outlet ducting, produce a low pressure in the outlet side, that will suck in cold air from the inlet side. This principle is also used in the T-64, T-80UD and T-84, but as far as I know, Swedish Ikv 91 is the only western tank that have similar cooling principle. As a result, the total length of powerpack is significantly shortened, much more shorter than the European powerpack mentioned above. This leads to a spare storage room between the fighting compartment and the engine compartment. This storage is for extra ammunition and fuel, when turret points 3 or 9 o'clock, the top cover of the storage could be opened from outside, containing 10 rounds for main gun, with projectiles on the outsides, semi-combustible charges on the inside. The data table from HIT also describe the ammunition capacity as 39+10, means that 22 ready rounds in the T-72 type carousel autoloader, 17 backup rounds scatter around the fighting compartment, and extra 10 rounds could be carried in the storage room. The driver of Al-Khalid control the vehicle via steering wheel and an automatic gear control box. The steering wheel and gear control box send electrical signals to the computer, then computer control the hydraulic servo actuator to perform engage and disengage of brakes and clutches, making steering and gear changes, as well as adjusting the speed and torque of the engine. Mechanically the gearboxes are nearly the same as T-64s and T-72s, but have different side reducer unit. The KMDB side reducer unit is designed as a secondary gearbox, acting like a forward-reverse selector. When both reducers were put into reverse, the vehicle can reverse using the normal forward ranges. From 1st gear to 4th gear, all could be used as high speed reverse, and that's why KMDB said this is a 7F4R gearbox system. And if only one reducer was put into reverse, the track will be driving in opposites direction, causing the vehicle turns within its tracks, a.k.a. pivot steer or center steer. T-84 also applied this driving and steering system. The advantages of Al-Khalid's powerpack is the versatility: all 3 types of MBT in the Pakistanis arsenal, T-80UD, T-84, Al-Khalid, share the same engine and gearbox.
  5. Disappeared for a long period, Mai_Waffentrager reappeared four months ago. This time, he took out another photoshoped artifact. He claimed that the Japanese prototype 105GSR (105 mm Gun Soft Recoil) used an autoloader similar to Swedish UDES 19 project. Then he showed this pic and said it came from a Japanese patent file. Well, things turn out that it cames from Bofors AG's own patent, with all markings and numbers wiped out. original file→https://patents.google.com/patent/GB1565069A/en?q=top+mounted+gun&assignee=bofors&oq=top+mounted+gun+bofors He has not changed since his Type 90 armor scam busted. Guys, stay sharp and be cautious.
  6. Jagdpanzer 38(t) Hetzer, is a famous late-war Jagdpanzer. On the very early version of Hetzer, it did got a muzzle brake, but such device was removed on later models. After war, Switzerland bought some Hetzer from Czechslovakia, named as G-13. Muzzle brake became standardise on G-13. But, have you ever seen a Hetzer with a muzzle brake like this? (below) Some source like Tanks-Encyclopedia describe this as "early production Hetzer with muzzle brake" but I really can't tell which German KwK or PaK have such British style muzzle brake, like those on Cromwell tanks. There are two possible reason for this strange version: 1. A very early Hetzer lost its muzzle brake and the crew found a British vehicle wreckage, ie. Cromwell or Churchill or even AEC armour car, took the muzzle brake as an ad-hoc replacement. 2. A very early Hetzer lost its main gun and the crew found a British QF 75 mm gun, and fit it into the gun cradle. The QF 75 mm gun uses exactly the same ammunition as the M3 75 mm gun. Further pics: Is there any evidence in Patton museum about this vehicle?
  7. https://tieba.baidu.com/p/2377512442 Do you guys know Sherman M60? It's an Israeli-Chilean upgrade version, equipped with an OTO-IMI 60mm High Velocity Medium Support gun, or HVMS 60. This gun is capable for firing APFSDS and could penetrate 120mm/60° RHA at 2000m. Chilean Army also used these powerful guns to upgrade their M24s and M41s.
  8. Nicholas Noran a.k.a. "Chieftain" mentioned about this in his program "Chieftain's hatch", but it was a mistake. The ИС-4s use a ЗК-steering mechanism, named after its designer. Г. И. Зайчик(1905-1977) М. К. Кристи(1890-1965) According to the ИС-4 heavy tank operator's manual(Руководство по эксплоатации тяжёлого танка ИС-4), published by Soviet Red Army in 1949, the tank could pivot on one track when in neutral position. Pivot on spot is different from pivot on one track. R=B/2 is pivot on spot, R=B is pivot on one track. Some historical document films also shows ИС-4 pivot on one track.
  9. The US CD-850 is another instance for triple differential steering system. On the British Merritt-Brown, when the vehicle goes forward, the sun wheel and ring gear of the planetary always counter rotate. On CD-850, when the vehicle goes forward, the sun wheel and ring gear rotate toward the same direction. The neutral steering of CD-850 is similar to the Merritt-Brown system.
  10. Another approach to neutral steering is the triple differential steering system. Henry Edward Merritt, an engineer and gearbox designer, is famous for his unique invention, Merritt triple differential transmission. The first British mass production tank with triple differential transmission is the Churchill tank. The Churchill tanks have a Merritt-Brown H4 gearbox, 4 stands for four gears forward, H stands for horizontal, because the two rows of gears in the gearbox are horizontally located. A great advantage of Merritt's design is compactness. The transmission incorporate the range gears and steering mechanism into a single box, thus reduce the longitude size. The H4 transmission can provide four gears forward, one gear reverse, and a neutral position for neutral steer. The basic design itself is simple, but how to explain it could be a little bit difficult. Three differentials are arranged like this: The left and right differentials are used for combining the driving power flow and steering power flow, and the steering differential is used for creating different speed of the steering gears. The bevel pinion gears are not easy to produce, so the design transformed into cylindrical gears. ↑The Z5 gearbox on Cromwell cruiser tank When driving forward, the sun wheel and ring gear of planetary F1 and F2 always counter rotate. The carrier of F1 and F2 rotate on an average speed of the ring gear(forward) and the sun wheel(reverse), and because the ring gear rotates faster, the carrier rotates on the same direction with the ring gear, so the vehicle goes forward. When steering brake J1 actuated, the sun wheel of F1 is stopped, now the carrier of F1 accelerate. The steering differential C then drives the sun wheel of F2 back rotate even faster(double time), so the carrier of F2 decelerate. When in a Cromwell/Centurion/Chieftain/Scorpion, the driver pulls right steering lever, which actuated the left steering brake, makes the track on left side go faster, the track on right side go slower, and the vehicle turns right. Another important design feature of the H4/Z5 gearbox is the reverse gear. When reverse gear is selected, the main shaft(E) of the gearbox is locked and stopped. The main shaft is connected to the F1/F2 ring gear, so the ring gear is brought to a stop. F1/F2 sun wheel going reverse, driving the planetary carrier reverse. This design has advantages and disadvanteges. The advantage is that the gearbox doesn't need to insert a idler wheel between range gears to change the driving direction, thus ease the operation of gear changing. The disadvantage is that the reverse gear is very slow, due to the large reduction ratio. The reverse gear ratio of Z5 gearbox is approximately 22.894, makes the tank's reverse speed very slow. When the vehicle is stopped on a solid plain terrain, and neutral position is selected, the planetary carrier stay still. The sun wheels go reverse, bring the ring gear and main shaft rotates forward. Pull left steering lever, right sun wheel is stopped and forward-rotating ring gear bring the planetary carrier slowly forward, so the right track goes forward. The left sun wheel reverse double-time and faster than forward-rotating ring gear, bring the planetary carrier slowly reverse, thus the vehicle pivot in place.
  11. T-14 Armata uses double differential steering systems and is able to neutral steer. Some Russian prototype MBTs can also perform neutral steer, like T-80UM-1 Bars and T-80UM-2 Black Eagle. The first Russian tank with neutral steering is Object 770 experimental heavy tank.
  12. Yes, Soviet tanks started to have dual-flow transmission after WWII, like Объект 770 heavy tank, Объект 906 amphibious tank and so on. The МТ-ЛБ transmission is similar to АТ-Л artillery tractor's transmission, which is also dual-flow transmission.
  13. The neutral steer, or pivot steer, means the tank drive one track forward while the other track backward, to perform a turn-on-spot. The very first tank with neutral steer, believe it or not, is the German A7V in WWI. Here is the transmission of A7V. The transmission incorporate two independent gearbox, each connected to a 100-hp engine. The gearbox use clash gears to select speed, and bevel gear to select forward or reverse. It's easy to perform a neutral steer. Those tanks with electric transmission(St.Chamond, Porsche Tiger, etc.) can easily perform neutral steer, for their twin driving electric motors can rotate in opposite direction. And tanks with twin driving hydraulic motors(Panzer IV mit Hydrostatischem Antrieb) can neutral steer in a similar manner. As mentioned above, the simplest way to neutral steer is to have seperated gearboxes or sub-transmissions driving both tracks. US airborne tank M551 Sherridan and Ukraine T-84 Oplot are modern approach of this manner. Althought they neutral steer with tracks driving in different speed, thus they cannot pivot steer precisely on the central spot. The neutral steer capability is more common on dual-flow transmission. A dual-flow transmission, or “双流传动” in Chinese, means the power flow from engine into the transmission splitted into driving power flow and steering power flow, then they join together with mesh gears or planetaries. Control these power flows allows the driver to change speed and steer left or right. The dual-flow principle itself came up even earlier than the tank. The 1899 Vedovelli Priestley electric taxi equipped with double differential steering system, is capable of neutral steering. And the first tank with dual-flow transmission is the Schneider-Renault SRB, then evolved into the Char B1 heavy tank. The Char B1 tank's dual-flow principle is quite simple. The power splitted into two: the driving power flow into gearbox and drive the main differential; the steering power flow into the appareil Naëder, a hydrostatic pump-motor assembly, can rotate on different speed and direction. Char B1 can use appareil Naëder to control its hull howitzer precisly, this principle inspired the Swedish Strv 103 tank. And the US M1 Abrams tanks use a HSU(Hydrostatic Steering Unit) based on the same principle of appareil Naëder. (To be continued)
  14. Sad to find out there is little information about AMX M-4's ZF transmission. ZF's official website mentioned that they converted a Entwicklung-Series tank transmission to meet French 1000-hp AMX M-4 tank design. This ZF-type transmission was widely used among early post war French heavy tank programs.
  15. From a Japanese magazine PANZER screenshot, it says: This is a Type 61 tank with a sort of ad-hoc spaced armour, using for target practice in exercise. The armour plates surrounding the turret and side skirts make it looks like a WW2 German Panzer IV. The crew tried to pull out a practice round stucking in the side skirt, this round was fired from a recoilless rifle. According to the vegetation of the exercise range, the vehicle was painted in a 4-colour camouflage.
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