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    Domus Acipenseris

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    • By Monochromelody
      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. 
    • By Beer
      There is a website which holds records about known aircraft crash sites in Czechia since 1918. Unfortunately it's all in Czech but with a decent translator you can dig a lot out of it (base data even without). It contains information about known circumstances of each crash site, its location and if possible also an information about artifacts found on the crash site. It can be particularly interesting for everyone interested in WW2 air war or for someone whose relatives were airmen who died somewhere over Czechoslovakia. 
       
      This is the link to the website.
       
      Particularly interesting sections are these:
      WW2 per type
      WW2 per date
       
      Unfortunately there is only one-way link between the map and the database and that is from the map to the database. 
       
      Of course not everything is in and with the time it's getting more and more difficult to search for what happened so long time a go... 
       
      One example of what you can find is this. Capt. Robert B. Holmes from 82th Fighter Squadron 78. Fighter Group 8. AF was shot down by FlaK on 16th April 1945 during an attack on Prague Ruzyně (Václav Havel Airport today) airport. He died in the cockpit of the plane and was burried in a near Ruzyně cemetery. His body was later moved by the US officials to a French US military cemetery and later back to USA per wish of the family. The fragments of his Mustang were found in a forest and neighbouring fields in the period of 2007 to 2012 including some rather large parts such as a piece of the wing with the US star still well visible on it. The people behind this website were later contacted by a man whose father was one of the first responders on the crash site (he was working on the field nearby). This family built a small memorial dedicated to Capt. Holmes on the crash site and they keep taking care of it. 
       
      There are some interesting records even after the WW2. For example this one. Two F-84F of the Luftwaffe crashed into a forest behind Czechoslovak frontier in 1959 due to navigation error in bad weather (both pilots managed to eject after first impact with the treetops). Long article (in Czech only) about this particularly interesting incident can be found here.  
       
       
      Is there something similar for other countries? 
    • By Akula_941
      Anti-air bobcat design to take away driver's hearing in maximum efficiency

      SH11  155mm SPG


    • By Belesarius
      http://www.popsci.com/china-builds-worlds-fastest-tank-gun-then-tries-hide-it
       
      New high velocity 125mm tank gun reportedly starting testing for the Chinese military.  Not surprised that the data disappeared off the university website at all.
       
      Edit: 125mm/60? oO
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