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What about mounting a gas turbine engine in the front of the tank?

 

One of the problems of front-mounted engines is that they are underneath the glacis plate of the tank when you want to service them.  Modern turbines should require less frequent maintenance, so this would be less onerous.  Furthermore, gas turbines are quite small for the power they produce, so the dimensions of the front of the tank will be less stretched (which is a problem, e.g. in the merkava) to accommodate the turbine.

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The specs required a highly mobile tank capable to destroy any Warsaw pact (PAVA) tanks at long range with a high hit probability on first shot. This led to the crafting of highly precise system. To

Well it's just a certain nuance. Obviously there is a stabilisation system but it is limited to the stabilisation of the line of sight (within the sights). The turret itself has no stabilisation s

*Warning, Walter engine sperg ahead*     The engine in the Merkava 4 is actually the most compact engine in the market, the MTU 883.  All the other Merkava models use a version of the AVDS-1790 eng

What about mounting a gas turbine engine in the front of the tank?

 

One of the problems of front-mounted engines is that they are underneath the glacis plate of the tank when you want to service them.  Modern turbines should require less frequent maintenance, so this would be less onerous.  Furthermore, gas turbines are quite small for the power they produce, so the dimensions of the front of the tank will be less stretched (which is a problem, e.g. in the merkava) to accommodate the turbine.

So.. Object 299? (Only without 152 mm Abrams smasher)

 

9.jpg

 

DJS6h.jpg

 

UHxSM.jpg

 

I am more interested in placing engines/generators in vehicle sponsons/parts above tracks.  

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You'd have to have a hell of an engine to fit into a sponson and have enough power to drive an MBT.

 

Getting power to the drive sprockets would be interesting too.

IIRC not long time ago some company (BAE?) showed a prototype of their heavy IFV with 2 generators in sponsons and electrical transmission.  

 

Oh, i found it.

 

http://defense-update.com/20141014_from_gcv_to_vision2025.html

 

gcv_hed_design.jpg

 

gcv_hed_layout.jpg

 

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Electrical motors (and presumably generators) are becoming efficient enough that they're probably competitive for IFVs and APCs.

Article speaks about 70 tons and 40 tons versions, which is MBT levels of weight. 2 engines are needed for 70 tons version, while 49 tons model will need only 1, according to article.

 

Although engines in sponsons would become more vulnerable for mines, plenty of photos of tanks after mines explosions can be found in Ukrainian tanks thread.

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Oh, is this that silly IFV that's heavier than an abrams?

 

The biggest problem with sponsons is, as Xlucine mentioned, they're not very volumetrically efficient.  They add more surface area, and therefore more weight of armor, relative to the volume they add than simply making the hull bigger.  Also, they limit the vertical travel of the road wheels.

 

On an IFV, which is going to have a taller hull than an MBT anyway, sponsons aren't as much of a penalty.  Most MBTs designed in the second half of the Cold War lacked sponsons though, look at an abrams hull:

 

abrams-tank-hull-920-3.jpg

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What about MBTs with crew located in the hull? There was a picture of Object 195 compared to T-90A. That thing could have pretty big sponsons. Also, look at Object 299 based heavy APC/IFV - it also have enough space to use sponsons for something more than storing crew's stuff.

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Crew in hull has been tried many times, but I don't recall seeing any reason on why it was abandoned.

 

I think I see what you are proposing; reduce the "turret" to just the gun mount, sensors and armor.  The crew, ammo, etc all get shoved into the hull.  This will make the hull bigger, but the tradeoff is that the hull doesn't get hit as often as the turret, so the overall survivability of the tank is better.

 

It would be a rather strange looking tank.  Sort of like a merkava but with a Stryker MGS turret on top.

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Crew in hull has been tried many times, but I don't recall seeing any reason on why it was abandoned.

 

I think I see what you are proposing; reduce the "turret" to just the gun mount, sensors and armor.  The crew, ammo, etc all get shoved into the hull.  This will make the hull bigger, but the tradeoff is that the hull doesn't get hit as often as the turret, so the overall survivability of the tank is better.

 

It would be a rather strange looking tank.  Sort of like a merkava but with a Stryker MGS turret on top.

Yeah, and it is called Object 299. Those are not new ideas, there are smarter people that wanted to do that. If USSR did not had such shity elites in 1970-80s, we could already see them in use.

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Yeah, and it is called Object 299. Those are not new ideas, there are smarter people that wanted to do that. If USSR did not had such shity elites in 1970-80s, we could already see them in use.

 

Soviet Obj. 299, Jordanian Falcon, British COMRES, various American projects...

 

Except for the stryker MGS, none of them has entered service.  I wonder if there is a problem with the concept.

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     There is plenty of unmanned turrets around in service, BTR-82A for example, BMPT, Ukrainian BTRs with Shkval turrets. Note that they are not RCWS with secondary weapons, but a turrets with primary guns and missiles.  

 

RVt2n.jpg

 

     Problems with Soviet designs is obvious, for others (and Soviets before 1990) main problems was required level of tech for targeting systems, price, required amount of cooperation between different companies/factories to produce such vehicles, reliability concerns, needed amount of changes to crew working stations, concerns about increased chances to "oneshot" all crew members, visibility for crew looking from hull, distrust to the reliability of complex systems and questions about how it would be serviced, field repair, and etc. etc..

     I do think that another, really big question for those countries was "is this actually worth all that work?". For Soviets anwser could be "yes", while for US, a "naval-air" type of force it wasn't as needed as for "land force" USSR. 

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I'd say it's likely both. The US spent most of its time trying to use aerospace and maritime power to hold a coalition together and land power was a third place to be used to stiffen the minor land powers they'd convinced to stand in the way of the traditional Napoleonic threat of a single power gaining control of all Europe and being in a place to really oppose the US. For the rest I'd consider the problems of smaller countries with smaller talent pools making all their own stuff. The only real change came in the 80's when the US really went all in on all aspects of its military, and at the risk of giving those in charge too much credit (I think the timing was somewhat accidental and pretty much perfect), cashing in the economic lead they'd built up against an economically worn down USSR to make a military threat the USSR would have to bankrupt itself to counter without switching to a credible threat doctrine or something similarly intolerable.

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      USSR/Russia is "land" power, because majority (if not all) wars were happening between countries with land border with Russia or came to Russia through land. This is different from US, they don't really have anything that can wage serious war with it in North America. Thats why tanks for USSR/Russia are more important, in minds of engineers, army, politicians. They have a way to rationalize a need to continue work.

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Frontal engines sucks, frontal engine tank layout is wrong. Discuss.

 

 

 

Merkava seems to suffer unusually from the frontal engine layout.  It has a very tall hull, but there doesn't seem to be a good reason for this.  If you look at the Swiss design proposed to replace Pz. 68, you can see that it's much, much lower than the merkava despite also having a frontal engine.

 

Also, many tanks such as T-72 do not have a raised engine deck the way a Leo 2 or Abrams does.

 

Hell, Object 416 was shorter than just about any other tank ever, and it had a frontal engine and transmission.

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       First, frontal engine and frontal transmission screw up weight distribution. In Object 416 it was "balanced" by removing driver from his usual position, increasing turret size, and moving this big turret to the rear part of hull. Still, frontal armor was not better than T-54's, even if 416's UFP had smaller overal sizes and area than T-54's UFP. 

       Merkava tanks have weaker UFP compared to contemporary Soviet MBTs (until Merkava Siman 4, although 90s left their durty hands on Russian tank industry. At least, Armata is coming). Merkava 1 was accepted for service and produced around same time as T-72A and T-80 (1976, accepted for service 3 years earlier than Merkava 1). Merkava SIman 2 was produced around same time as T-72B and T-80U. Merkava 3 was something less underarmored, compared to Soviet vehicles, or 'Murica Abramovichs. Basically, all Merkavas had lower protection against APFSDS than Commies tanks and Best Democracy forces MBTs, while being heavier and bigger.

 

      Second, such layout makes engine and transmission more vulnerable to incoming fire. Instead of using... actual god damn armor to act as "armor", engine and transmission partially plays that role. Thanks to weight of engine/trany module, designers had problems placing enough armor on UFP (and we don't speak about pretty big LFP), which leave engine as substitute for lacking armor. And question of crew survivabilty "being better because engine will catch all cr@p" is not so obvious, if you look at complex problem of tank not able to move and fires in engine compartment after even non-penetrating hits.

 

     Merkava 4 hull big size can be attributed to 1500 HP engine, but why previous vehicles were on bigger side is unknown to me.

 

      Israeli designers had only one serious justification for their weird decision - rear door, which is pretty big and rear compartment for ammo or something else. 

 

 

      So, each time you hear that frontal engine is for better crew protection - don't believe it. Frontal engines forces to decrease frontal armor, to cut UFP, which usually is designed to stop APFSDS, and not just some random RPGs (Merk's 4 gen side armor can deal with them not so badly). Less frontal armor will mean higher chance of penetration and/or fragmentation, which leads to higher chance of losing engine or trany, which leads to immobilized vehicle. I do think that tanks with frontal engine have higher chance to be mobility killed compared to rear engine designs, which can lead to higher chances of situations when crew is cut from other forces and can't just drive to them. 

 

And still i like this vehicle, with all problems behind design.

Trophy_APS_-_operational.jpg?uselang=ru

Run, Merkava, your armor is not so good as they told me!  :(

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     Merkava 4 hull big size can be attributed to 1500 HP engine, but why previous vehicles were on bigger side is unknown to me.

 

*Warning, Walter engine sperg ahead*

 

 

The engine in the Merkava 4 is actually the most compact engine in the market, the MTU 883.  All the other Merkava models use a version of the AVDS-1790 engine, which is quite a bit bigger.  This is why there is that characteristic bulge on the front of the Merkava 1,2, and 3 hull.  That said, the complete powerpack for the earlier Merks are not all that much heavier or bigger than Merkava 4, but the smaller size of the MTU engine allows the the powerpack to be arrainged more efficiently so that the front hull does not have that bulge.  

 

Now, you might be asking how is it that the Merk 4 powerpack is as heavy as the powerpack for the Merk 1-3 when I just said that the MT883 is a much smaller engine than AVDS-1790?  It has to do with cooling.  AVDS-1790 is aircooled.  All the cooling it requires are provided by the two big fans mounted on the top of the engine.  These fans are included in published size dimensions for the engine, which also include all the other engine accessories like the alternator etc.  That means that the powerpack for a Merk 1-3 is literally an AVDS-1790 and a transmission.  There is nothing else required.  The powerpack for the Merk 4 includes the MT-883, the transmission AND the liquid cooling system for the engine and the engine accessories.  Cooling systems add quite a bit of extra bulk to a powerpack. The advantage the MT-883 has is that these components can be arranged in different configurations for different vehicles for a better fit.  With the AVDS-1790, it's just an  engine and a transmission and their is not much you can do to change the dimensions to suit a particular vehicle.  

 

For example, here is the "europack", which is the MT-883 in a transverse mounting for rear engine tanks. (I love how it's labeled "compact cooling system" and its as big as the engine)

 

altay-tank-engine-assembly.jpg

 

Of course, this powerpack is unsuitable for the Merkava 4 since it would leave no room for the driver.  Therefore, they go with a different layout which looks like this:

 

GD883_proE.gif

As you can see, the engine is mounted North-South in this configuration and the entire powerpack slopes down so it can fit within the armor profile of the Merkava 4.  

 

Here is a picture of an AVDS-1790 powerpack (this is from an M88 Hercules, I can't find a good image of a Merk 1-3 powerpack.)  As you can see, no bulky cooling system, just an engine and transmission.  Also, there is really only one option on how to configure and mount this engine. 

 

232745-3.jpg

 

Here is a picture of an AVDS-1790 sitting all nice and pretty in a shipping container.  You can see the big cooling fans on the top of the engine.  

 

AVDS1790Foto-1.jpg

 

In a rear mount situation, that MT-883 europack system is going to fit in a much shorter engine compartment than an AVDS-1790.  That's the advantage of a transverse mounted engine versus a more traditional north-south arraignment.  The only problem is that with a transverse mounting like the Europack, it takes up the entire width of the engine compartment, while a north south mounted engine usually leaves a bit of space along each side.  What typically goes into that space along the sides?  Fuel tanks.  That's why Soviet vehicles with transverse mounted engines have such limited fuel storage and rely on external fuel tanks.  Of course, it allows the vehicle to be shorter and lighter so they see it as a good trade off.  

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Chieftain and chally have longitudinal engines, but no fuel stowed either side of them - that space is for the air cleaner and generator. Fuel stowage is all in the sponsons - because those run the entire length of chally, it gets an extra 150 gallons of it (~210 Vs ~360). AVDS-1790 normally has air cleaners outside the hull, of course, and no generator

 

 

Frontal engines sucks, frontal engine tank layout is wrong. Discuss.

 

You are correct. A good example:

Smile_trollface-3.gif

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Chieftain and chally have longitudinal engines, but no fuel stowed either side of them - that space is for the air cleaner and generator. Fuel stowage is all in the sponsons - because those run the entire length of chally, it gets an extra 150 gallons of it (~210 Vs ~360). AVDS-1790 normally has air cleaners outside the hull, of course, and no generator

 

 

The M1 has the fuel tanks in the rear sponsons as well.  Actually, from this diagram it looks like the right side sponson.  This picture is nice because it shows all the crap that has to go into the engine compartment in order for the "small" turbine engine to operate.  

 

abrams%2Bfuel.jpg

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                                                                    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!
    • By Collimatrix
      Shortly after Jeeps_Guns_Tanks started his substantial foray into documenting the development and variants of the M4, I joked on teamspeak with Wargaming's The_Warhawk that the next thing he ought to do was a similar post on the T-72.
       
      Haha.  I joke.  I am funny man.
       
      The production history of the T-72 is enormously complicated.  Tens of thousands were produced; it is probably the fourth most produced tank ever after the T-54/55, T-34 and M4 sherman.
       
      For being such an ubiquitous vehicle, it's frustrating to find information in English-language sources on the T-72.  Part of this is residual bad information from the Cold War era when all NATO had to go on were blurry photos from May Day parades:
       

       
      As with Soviet aircraft, NATO could only assign designations to obviously externally different versions of the vehicle.  However, they were not necessarily aware of internal changes, nor were they aware which changes were post-production modifications and which ones were new factory variants of the vehicle.  The NATO designations do not, therefore, necessarily line up with the Soviet designations.  Between different models of T-72 there are large differences in armor protection and fire control systems.  This is why anyone arguing T-72 vs. X has completely missed the point; you need to specify which variant of T-72.  There are large differences between them!
       
      Another issue, and one which remains contentious to this day, is the relation between the T-64, T-72 and T-80 in the Soviet Army lineup.  This article helps explain the political wrangling which led to the logistically bizarre situation of three very similar tanks being in frontline service simultaneously, but the article is extremely biased as it comes from a high-ranking member of the Ural plant that designed and built the T-72.  Soviet tank experts still disagree on this; read this if you have some popcorn handy.  Talking points from the Kharkov side seem to be that T-64 was a more refined, advanced design and that T-72 was cheap filler, while Ural fans tend to hold that T-64 was an unreliable mechanical prima donna and T-72 a mechanically sound, mass-producible design.
       
      So, if anyone would like to help make sense of this vehicle, feel free to post away.  I am particularly interested in:
       
      -What armor arrays the different T-72 variants use.  Diagrams, dates of introduction, and whether the array is factory-produced or a field upgrade of existing armor are pertinent questions.
       
      -Details of the fire control system.  One of the Kharkov talking points is that for most of the time in service, T-64 had a more advanced fire control system than contemporary T-72 variants.  Is this true?  What were the various fire control systems in the T-64 and T-72, and what were there dates of introduction?  I am particularly curious when Soviet tanks got gun-follows-sight FCS.
       
      -Export variants and variants produced outside the Soviet Union.  How do they stack up?  Exactly what variant(s) of T-72 were the Iraqis using in 1991?

      -WTF is up with the T-72's transmission?  How does it steer and why is its reverse speed so pathetically low?
       
       
    • By Sturgeon
      This is the place for flame wars about rifle-caliber MGs versus autocannons for tank coaxial weaponry. First, we have Ensign's blog post about tank machine guns:
       


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