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In the "Theoretical Study of a Diesel-Filled Airtight Structure Unit Subjected to Shaped Charge Jet Impact" study done by Zhen-Yu Gao et al, there is no mention of the fuel starting to burn or there being a danger of fire.

There is a document on DTIC from 1987, where the probability of fuel fires after armor penetration was being investigated on the M2 Bradley, M113 and M1A1 Abrams tank (with diesel fuel, JP-08 was introduced in the Army later). The document is a technical report from the Ballistic Research Laboratory written by Antony E. Finnerty.

 

It is noted that the automatic fire suppression system (AFSS) of the M1A1 is not capable of supressing engine fires.

 

Depending on hit location and how much fuel is left inside the fuel tanks, the probability of incinerating the diesel stored in the Abrams with the first hit by a shaped charge is between 10% and 50%; the probabiltiy of a fire in the frontal fuel tanks was only 15% at 8°C ambient temperature and 25% at 24°C ambient temperature. These values are based on Soviet 125 mm HEAT rounds and might not be valid for more modern, larger calibre, HEAT warheads with tandem charges.

 

The probability of a fuel fire after penetration by a 125 mm APFSDS projectile is between 50% and 60% (at 8°C and 24°C ambient temperature respectively). Again this represents Soviet technology from the 1980s and might not be valid for modern APFSDS rounds.

 

That doesn't matter all that much. Steel armour perpendicular to the hydrodynamic jet will barely have an effect on the total penetration capabilities. For every 1 cm of penetration in steel, the hydrodynamic jet loses 0.94 cm of length. And if he includes the steel walls in the calculation for relative effectiveness vs RHA and still gets a factor of three, doesn't that mean the fuel is even more effective than calculated, since the steel walls will have a relative effectiveness of ~1?

The efficiency is determined by using a sample shaped charge against steel armor as reference (reference penetration is Pref), then using the same type of sample charge against the fuel tank (to determine the penetration into fuel Pfuel). The efficiency then is calculated using these factors.

 

If the fuel tank includes 25 mm front and 20 mm back plates of steel, and this is included in Pfuel, the efficiency will be exaggerated depending on the reference penetration of the sample charge. Let's say (just for this argument) that the reference shaped charge penetrates 180 mm, but it can be stopped by 25 mm steel + 680 mm of fuel + 20 mm steel. Then 680 mm of fuel provides as much protection as 135 mm steel. Now if somebody forgets the fact that there is a 25 mm coverplate and a 20 mm back plate, the efficiency of fuel will be exaggerated by 33%.

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The efficiency is determined by using a sample shaped charge against steel armor as reference (reference penetration is Pref), then using the same type of sample charge against the fuel tank (to determine the penetration into fuel Pfuel). The efficiency then is calculated using these factors.

 

If the fuel tank includes 25 mm front and 20 mm back plates of steel, and this is included in Pfuel, the efficiency will be exaggerated depending on the reference penetration of the sample charge. Let's say (just for this argument) that the reference shaped charge penetrates 180 mm, but it can be stopped by 25 mm steel + 680 mm of fuel + 20 mm steel. Then 680 mm of fuel provides as much protection as 135 mm steel. Now if somebody forgets the fact that there is a 25 mm coverplate and a 20 mm back plate, the efficiency of fuel will be exaggerated by 33%.

 

That explains how included steel could exaggerate the thickness efficiency of diesel, but not how it could exaggerate the mass efficiency, which was your original objection:

 

 

 

I don't know your source, but a few years ago there was a discussion on the TankNet forums, where somebody claimed that fuel hat a ME of 3 vs HEAT. After he posted a link to a research paper, it became clear that this included the (relatively thick) steel walls of the fuel tanks.

 

 

 

 

There is a document on DTIC from 1987, where the probability of fuel fires after armor penetration was being investigated on the M2 Bradley, M113 and M1A1 Abrams tank (with diesel fuel, JP-08 was introduced in the Army later). The document is a technical report from the Ballistic Research Laboratory written by Antony E. Finnerty.

 

It is noted that the automatic fire suppression system (AFSS) of the M1A1 is not capable of supressing engine fires.

 

 

 

Linky?

 

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There is a document on DTIC from 1987, where the probability of fuel fires after armor penetration was being investigated on the M2 Bradley, M113 and M1A1 Abrams tank (with diesel fuel, JP-08 was introduced in the Army later). The document is a technical report from the Ballistic Research Laboratory written by Antony E. Finnerty.

 

Making such a statement without linking is considered a permabannble offense on this forum.

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TbhGq66.png

My problem with this image is it does not take into account any side armor.

Take a Leopard 2 for example. It may not have armor cavities directly over its bustle, but the armor over the crew compartment still provides cover for its ready rack from a sizable frontal angle.

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I forgot the link :wacko:

Here is it.

As for the mass efficiency and the thickness efficiency; in the original discussion on TankNet the ME was calculated from the TE. You just need to take into account the areal density for this.

Ramlaen, on the Leclerc, Leopard 2 and similar designed tanks, the side skirts are meant to cover only the crew compartment (i.e. driver's place + turret ring section) along the 30° arc. The ammo would need to be stored behind the turret ring. While it is possible to extend the skirt armor, this would lead to an increase in weight or a decrease in frontal arc protection for the crew compartment (compare Leopard 2 and Leclerc with ~150 mm thick skirts to M1 Abrams with ~70 mm skirts). Each tank design is a trade-off between benefits and disadvantages.

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Ramlaen, on the Leclerc, Leopard 2 and similar designed tanks, the side skirts are meant to cover only the crew compartment (i.e. driver's place + turret ring section) along the 30° arc. The ammo would need to be stored behind the turret ring. While it is possible to extend the skirt armor, this would lead to an increase in weight or a decrease in frontal arc protection for the crew compartment (compare Leopard 2 and Leclerc with ~150 mm thick skirts to M1 Abrams with ~70 mm skirts). Each tank design is a trade-off between benefits and disadvantages.

What? I wasn't talking about hulls. The Leopard 2's bustle ammo rack is protected from frontal angles by the crew compartment armor.

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For the record, I'm dubious about the effectiveness of wet ammo stowage.  Sure, wet ammo rack Shermans burned far less frequently than their dry rack counterparts.  Wet rack Shermans also moved the ammo out of the easily-penetrated hull sponsons and onto the hull floor, where they were less likely to get hit in the first place. 

The chemistry just doesn't make much sense.  Gun ammunition and explosives contain both fuel and oxidizer, so pouring water over burning nitrocellulose won't snuff it out like it would a regular fire.  In a few edge cases, if the water gets to the spark very early the heat energy could dissipate into the water quickly enough that the temperature inside the propellant would drop, and the combustion could no longer proceed.  Maybe maybe maybe the water could get into a hole fast enough to waterlog the propellant, which would render it more or less inert, but flame propagation in nitrocellulose-based propellants is scary fast and I would be shocked if water managed to outrun it.  I would think in most cases, however, that the wet ammo stowage just slows down the fire by absorbing some of its energy for a time.  This is not without value, as it could allow precious extra seconds for the crew to GTFO.

 

I recall some study of knocked-out tanks from the Iran-Iraq War, including T-62s and Chieftains, which concluded that the wet ammo stowage on Chieftains did not make them less prone to fire.

The May 1951 version of TM 9-729 for the M24 Chaffee notes that "The use of any fluids (water, antifreeze compound, or ammudamp) in ammunition box cans has been discontinued. All ammudamp cans will be completely drained of ammudamp fluid." So it seems that the US discontinued wet stowage even in tanks already using it not long after WW2.

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The May 1951 version of TM 9-729 for the M24 Chaffee notes that "The use of any fluids (water, antifreeze compound, or ammudamp) in ammunition box cans has been discontinued. All ammudamp cans will be completely drained of ammudamp fluid." So it seems that the US discontinued wet stowage even in tanks already using it not long after WW2.

That is quite interesting.  Didn't know that.

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It is noted that the automatic fire suppression system (AFSS) of the M1A1 is not capable of supressing engine fires.
Ah that is correct. But that's because the engine bay doesn't have an AFSS.

 

As for the AFSS in the crew compartment:

987492d222.png

Which follows on to this:

8871ef0c2e.png      c31bc4cec3.png

tl;dr:

- Where there's an AFSS the chance of a sustained fire is zero.

- Sustained fires can only happen in locations where there is no AFSS and where there the fuel is actually in a form in which it can form a sustained fire.

 

And with that in mind the only place where sustained fires can happen are the REFC, LEFC and EHY. All of which are in the engine bay.

 

Furthermore, all this is based on calculated probabilities, with the actual calculation not mentioned in the paper:

c78564384b.png

 

Also, only steel/aluminium armours were considered in the paper, for as far as I can see. While currently we obviously have NERA and ERA which will result in different terminal ballistics.

 

Reading further on in the paper, there is some data that's outright wrong, based on actual tests I've attended. But for (hopefully) obvious reasons I can't discuss the tests nor the results of the tests. And the more I read this paper, the more I'm raising my eyebrows. Here are a few quotes:

Considerable personal judgment was required
Only one useful model of sustained fuel fires caused by munition attacks has emerged. This is the Dehn Model.
Unfortunately, at this time we cannot use the mathematical form of the Dehn Model. We simply do not know the correct values of the parameters and variables which go into the model.
(!!!)
At this point In time, we do not have sufficient data to implement even the simplified form of the Dehn Model.
(!!)
It is also necessary to use personal judgment as to the applicability of much of the data

 

...these aren't things I want to read in a report.

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Come on, were are talking about something that is capable of penetrating the Abrams' hull armor; so essentially a tank round or some sort of modern anti-tank weaponry (RPG, ATGM, EFP). There shouldn't be much doubt about the JP-8 being incinerated in such a case. Btw. diesel has a higher flash point than JP-8 and is often set on fire during combat.

 

 

I missed this when I first went through it, but this old canard is beloved of the Military Reform crowd (when they were busy bashing on supposed survivability shortcomings of the M1) and is just as wrong now as it was in the 1980s.

 

flash point is not a general indicator of flammability.  It refers to something very specific; it is the lowest temperature at which fumes of a liquid will ignite if exposed to an ignition source.  JP-8 has a lower flash point than some diesel fuel, but because JP-8 has much more precisely formulated than diesel fuel is.  The flash point of commercially available diesel fuel is a wide range that straddles the flash point of JP-8.  JP-8 and diesel just aren't that different; they're very slightly different average molecular weights of hydrocarbon, and JP-8 has a number of additives which mainly improve shelf life.  Look at a destructive distillation diagram for petroleum cracking; jet fuel is based on C10 to C16 while diesel is C14 to C20.  They're just not that different.

Moreover, flash point is not generally indicative of flammability.  It is a component of flammability, but it refers to a specific circumstance under which ignition can occur; namely when there are fumes present and the fumes are exposed to an ignition source.

 

And the fumes are exposed to oxygen.

 

The fact that diesel fuel usually ends up burning when military vehicles are hit does not prove that the fuel was the source of the fire.  There's plenty of other shit on a tank that burns, like lubricants, hydraulic fluid (which was enough of a fire hazard that it was re-formulated after the great 1973 Arab-Israeli rematch), and of course the ammo.

 

I don't see how you jump from the idea that anything that can penetrate an MBT will automatically vaporize and ignite JP-8, especially when the availability of oxygen is in question.

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From Otvaga:

 

cixhM0iHW6I.jpg

 

rVwdWP1h7lY.jpg

 

Looks like the MBT-80 designs were better protected than the XM1, at least when it comes to protection against APFSDS ammunition. The XM1 has better protection against HEAT ammunition, but that doesn't really matter. The MBT-80 had much better turret armor than the XM1, so it was much less likely to be destroyed in hull down configuration (11 to 28% chance on the MBT-80, 17 to 58% (!) chance on the XM1).

 

f.jpg

 

5pq3om.jpg

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2 hours ago, SH_MM said:

From Otvaga:

 

cixhM0iHW6I.jpg

 

rVwdWP1h7lY.jpg

 

Looks like the MBT-80 designs were better protected than the XM1, at least when it comes to protection against APFSDS ammunition. The XM1 has better protection against HEAT ammunition, but that doesn't really matter. The MBT-80 had much better turret armor than the XM1, so it was much less likely to be destroyed in hull down configuration (11 to 28% chance on the MBT-80, 17 to 58% (!) chance on the XM1).

 

f.jpg

 

5pq3om.jpg

 

Could the reason the XM1 proved more resilient to CE when fully exposed be because off the front mounted fuel tanks and composite side skirt?

Or could it be because the XM1 had almost all it's ammunition in the turret, while the MBT-80 had all of the propellant in the hull, assuming the layout is similar to the Challenger 1?

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MBT-80 had that stupid hull design with the giant cutout in the glacis for the driver:

 

LUbrT7I.jpg

 

 

As for the MBT-80 having better turret armor than the XM1, I don't think that means a lot.  This is the XM1:

 

9wVzzD7.jpg

 

As you can see, the armor package installed on the XM1 doesn't particularly resemble the armor package of the production M1.  It might not even have composites at all.  Likewise, neither MBT-80 turret was representative of a production tank.  The one with the big, sloped slabs near the front of the turret is simply an FV4211 turret with additional weights attached to it to simulate the mass and moment of inertia of the final armor package.  The other one in the picture above is simply a test rig.

 

So when a test document or archival document or whatever (where did you get those numbers, @SH_MM ?) comes forward saying that the XM1 has inferior HEAT protection to the MBT-80, it's not really clear what they're comparing.  Are they comparing the calculated protection of the prototype turrets against each other?  That would just be silly in the case of the MBT-80, neither test turret actually had composite armor installed.  Are they comparing the calculated protection of the production turrets against each other?  That would be more interesting, but how close was the MBT-80 to production at the time the statements were made?  As I recall, fairly late in the MBT-80 program they were still screwing around with concepts like asymmetrical gun mounts.  And what production M1 turret were they comparing to the MBT-80?

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12 hours ago, Collimatrix said:

As for the MBT-80 having better turret armor than the XM1, I don't think that means a lot.  This is the XM1:

 

9wVzzD7.jpg

 

As you can see, the armor package installed on the XM1 doesn't particularly resemble the armor package of the production M1.  It might not even have composites at all. 

 

Except for the original validation prototypes, all manufactured XM1 prototypes either featured Burlington ("Chobham") armor or weight simulators representing Chobham armor. The armor technology was given to the United States by the UK in 1973. The photo you posted shows an XM1 validation prototype from Chrysler with Chobham armor, which was made after Chrysler completed a redesign of their tank to adopt the new type of armor in 1974.

 

In 1976, after both designs from Chrysler and General Motors were trialed (including ballistic tests), the tanks were redesigned for the FSED (full scale engineering development) stage. The photo below shows a model of the Chrysler FSED prototype, which is pretty much identical (except for a few minor modifications) to the initial production M1 Abrams tank.

 

bCIJJ1u.png

 

12 hours ago, Collimatrix said:

Likewise, neither MBT-80 turret was representative of a production tank.  The one with the big, sloped slabs near the front of the turret is simply an FV4211 turret with additional weights attached to it to simulate the mass and moment of inertia of the final armor package.  The other one in the picture above is simply a test rig.

 

So when a test document or archival document or whatever (where did you get those numbers, @SH_MM ?) comes forward saying that the XM1 has inferior HEAT protection to the MBT-80, it's not really clear what they're comparing.  Are they comparing the calculated protection of the prototype turrets against each other?  That would just be silly in the case of the MBT-80, neither test turret actually had composite armor installed.  Are they comparing the calculated protection of the production turrets against each other?  That would be more interesting, but how close was the MBT-80 to production at the time the statements were made?  As I recall, fairly late in the MBT-80 program they were still screwing around with concepts like asymmetrical gun mounts.  And what production M1 turret were they comparing to the MBT-80?

 

The two excerpts posted earlier are taken from a 1978 report (WO 194/2767) from the British military (afaik FVRDE). Obviously the MBT-80 tanks were pure paper designs, given that there are no prototypes/testrigs (known to the public), which have been fitted with a V16 engine or a gas turbine. However I don't see a reason to assume that the British report used the old 1974 design of the XM1 Abrams (rather than the improved design from 1976) as reference. I also don't see much reason to dispute the credibility of the report, given that the XM1 is fitted with a type of Chobham armor and the UK had started researching Chobham armor two decades before this report.

 

There wasn't a MBT-80 production design, the program was canceled before it lead to any results. However the XM1 FSED prototype from Chrysler is the same design that went into LRIP and final production, aside of fixing a few errors and improving reliability.

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Here is something for this topic:

 

A Greek blog entry on their testing of the Challenger 2E, Leclerc, Leopard 2 Improved, M1A2 Abrams, T-80U and T-84 tanks. The scores from the evaluation are the following:

  1. Leopard 2 Improved - 78.3
  2. M1A2 Abrams - 72.95
  3. Leclerc - 71.92
  4. Challenger 2E - 69.89
  5. Т-80U - 59.2
  6. Т-84 - 56.3

The google translate output is quite interessting, if correct. Supposedly the Challenger 2E was found to be worse armored (!) than the M1A2 Abrams and Leopard 2 Improved despite being heavier. So much about mighty "Chobham Mk. 2 Dorchester" being the best armor. Even the ten tons lighter Leclerc tank had nearly the same level of protection as the Challenger 2E. The use of the EuroPowerPack in the Challenger 2E is believed by the blog author to not have enhanced the mobility, because there have been issues with power delivery and despite switching the powerpack, nothing else was changed to properly optimize the tank for the different engine (?).

The T-80U had issues with the semi-automatic transmission and general reliability, including the weapon systems (guided missiles) and FCS.The T-84 has a weird internal layout and bad controlls, essentially requiring the driver to have "three hands" to work with the steering wheel and operate his other controls. Operating the T-84 was so tiring, that the Greek crew had to be replaced by the Ukranian crew in some tests. Leclerc, Leopard 2 and M1 Abrams had no issues with driving up and down a 60% slope, the other tanks however had some problems.

 

Btw: the Italian C1 Ariete and the Israeli Merkava III tanks were considered, but the manufacturing companies/officials didn't want them to participate in a competition (maybe because they were afraid of these relatively new vehicles underperforming and causing big political backlash).

 

20170514_185634.jpg

 

20170514_185259+-+Copy.jpg

Note that the Leclerc is fitted with additional armor.

20170514_185326.jpg

The Challenger 2E lost most of it's track's pads when trying to climb a wall. Does anybody know if the Challenger 2E used the same tracks (by Cook Defence) as the British Army model? Did the greater powerpack cause these issues?

 

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2 hours ago, SH_MM said:

Here is something for this topic:

 

A Greek blog entry on their testing of the Challenger 2E, Leclerc, Leopard 2 Improved, M1A2 Abrams, T-80U and T-84 tanks. The scores from the evaluation are the following:

  1. Leopard 2 Improved - 78.3
  2. M1A2 Abrams - 72.95
  3. Leclerc - 71.92
  4. Challenger 2E - 69.89
  5. Т-80U - 59.2
  6. Т-84 - 56.3

The google translate output is quite interessting, if correct. Supposedly the Challenger 2E was found to be worse armored (!) than the M1A2 Abrams and Leopard 2 Improved despite being heavier. So much about mighty "Chobham Mk. 2 Dorchester" being the best armor. Even the ten tons lighter Leclerc tank had nearly the same level of protection as the Challenger 2E.

 

I find it hard to believe the Leclerc was deemed better armored than a significantly heavier Challenger 2, especially when both were very modern at the time.

Maybe they meant it was better protected, as opposed to better armored? No need to mention that protection and armor are not the same thing.

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machine translating the conclusion section

 

Quote
Final assessment of tanks
 
The tanks participating in the competition were as follows:
Compared with other Leopard-2A5S front of the most well preserved and was the only one at the top of the tower which is listed in the manufacturer had thought seriously. The ideal result of firing tests showed that it was quite reliable and convenient and ergonomic for the crew.
M1A2 Abrams reservation was the second best. The Americans offered the Greeks a tank without a "Depleted Uranium" reserves (DU reserves are still prohibited). The tank was superb enough and was a special ergonomic for the crew. The car was reliable and there was only one major disadvantage on the tests - it was a gas turbine engine that thawed the fuel.
Leclerc- was that a few years earlier by the French, the United Arab Emirates proposed variant slightly differed, double impression: ideal for building and driveline (ie, German firms, RENK- and MTU-'s, the latest generation of diesel engine and speed transmission, so Called Europack), an excellent hydro-pneumatic suspension and weight of participants The best ratio of A-power. All of this made it particularly fast and flexible, and with all of this it was distinguished by the low fuel prices. In terms of armor, Leo-2A5S and M1A2 have always been distinguished in comparison with the previous two tanks, but it was probably very high at the level of its weight. The tower, with a completely automated charger, offered innovative innovation to the customers, but in practice the automated performance did not justify the expectations and was constantly crippled and spoiled. On the other hand, the tank was not distinguished by the crew's ergonomics (mainly due to the lack of existing space), for the same reason was the use of weapons, such as pulverizing machine guns. In the precision of the hand, well, but not the best.
Challenger-2E was a negative surprise. Despite the fact that the version presented in the competition was equipped with a similar type of Europack-type military equipment, it was often spoiled when switching to high speeds, which was responsible for the transmission of the motorway from the machine. The 1200-horsepower engine with the Challenger-2 engine was replaced by a 1500 horsepower engine and did not have a proper study of the kinetic circuit and adjusted to the engine that caused frequent outflow from the car. It was also a disadvantage of his annexed armor. The car was distinguished with a relatively weak armor compared to Leo-2A5S and M1A2, while Leclerc even 10 tons was almost never behind British tanks.
The car was not very precise, it was the only one that was equipped with a 120 millimeter stroke and was used in three parts (shells, sparkle and insulating capsules), while Ukrainians and Russians used both guns and rifles, Doing this with automatic charging). However, the car had a positive side: he served in the army with long military experience and was the only one who had a toilet in the tower and traditional British tea makers.
Russian Т-80У Soviet tankmsheneblobis School was a classic representative. Its main problem was the semiconductor speed of the prototype at the moment, which was often out of order. The machine showed low results in accuracy, as well as the crew's ergonomics. In addition, the two systems, which the manufacturer claims, compared with Western counterparts, the electrical-optical flaw system and a 6-kilometer laser-guided tank missile, was unreliable in practice and did not show any possible results.
Ukrainian Т-84- on the whole characterized by Russian tanks, but another significant disadvantage, he ortaktiani diesel engine, which predictably burn oil, and mechanical gear box was equipped with Russian car unlike the steering wheel instead of a lever ruled. That is why the Greeks were saying jokingly "I need three hands for him to manage" (to turn the driver-mechanic into a curve, let alone the third hand). It is also worth mentioning that the car was causing the crew of the crew - the Greek crew was replaced by Ukrainian crew due to fatigue in checking stock.
In January 1999, the General Staff of the Greek Army presented the results of the competition, according to the scores the following places were distributed:

         Leopard-2A5S - 78.3
         M1A2 Abrams - 72.95
         Leclerc - 71,92
         Challenger-2E - 69,89
         Т-80У - 59,2
         Т-84 - 56,3

 

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13 hours ago, SH_MM said:

The use of the EuroPowerPack in the Challenger 2E is believed by the blog author to not have enhanced the mobility, because there have been issues with power delivery and despite switching the powerpack, nothing else was changed to properly optimize the tank for the different engine (?).

 

 

I can definitely buy this part.  Technology of Tanks describes a little bit of the engine tweaking and optimization that went into the Leo 2.  Despite having a better power to weight ratio than the late-model Leo 1, the early Leo 2 had worse acceleration until modifications to allow better engine RPM increase were made.

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21 minutes ago, Volkswagen said:

When I open that blog post, it's in georgian. Am I the only one who has it so?

 

Oh, that is Georgian? I didn't pay too much attention to this and assumed it was Greek. My mistake resulted from using Chrome (Chrome has a built-in translator, which I use for most languages other than English).

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      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!
    • 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 Proyas
      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
    • By Mighty_Zuk
      I realized we don't have a topic for a proper discussion of what future AFVs should look like, in the style of a general AFVs discussion rather than country-specific threads.
       
      I spotted a revived potential need for future MBTs - a coaxial autocannon to replace the coaxial MG. The reason? An APS neutralizer. 
      Here's my short post on why I think it should happen:
       
      I didn't add it there, but I see lasers as a potential alternative. However, I don't think they're viable because of the power required to properly neutralize an APS's components, especially if these components are dispersed, or worse yet, effectively camouflaged. An autocannon will be able to disable not only the APS but other external components all at once. 
      Similar to the engagement method showcased by Russia where they fired 2 Kornet missiles (almost) simultaneously to defeat an APS, a hypothetical mode of operation could include firing a burst of 2 KETF shells at a target prior to firing a main gun shell.
       
      An additional alternative could be to use a single main gun ABM shell that would initiate outside the scope of the APS's engagement range (e.g engagement range is 30m so it initiates at 50m), but it would have 2 main issues that are a longer time to kill a target and a greater consumption of ammunition (up to a 3rd of ammo would have to be allocated to ABM munitions strictly for anti-armor operations).
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