Peer review T84 vs. T90

Dr Zaius

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The following is from the TacOps ML and I though people here might be interested to follow this discussion.
MajorH said:
The suggestion below argues for changing the armor values in TacOps for the T90 and T84 tanks.

Summary:
Big increase in T90 frontal armor vs chemical energy (HEAT).
Very big increase in Ukranian T84 frontal armor vs chemical energy (HEAT), which makes it slightly better than T90.

Current Values:

T90 - KE Front 810, Side 190, Rear 100
T90 - CE Front 1120, Side 205, Rear 100
T84 - KE Front 525, Side 180, Rear 100
T84 - CE Front 950, Side 195, Rear 100
Suggested Values:

T90 - KE Front 810, Side 200, Rear 100
T90 - CE Front 1250, Side 220, Rear 100
T84 - KE Front 846, Side 200, Rear 100
T84 - CE Front 1270, Side 220, Rear 100
Comments?

Best regards Major H.
 

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And Martin's reply:

Martin Cracauer said:


I am still very skeptical about active defense against KE projectiles, even if you are willing to use radar.

This is topic of a tanknet conversation here (my nickname is Redwolf):

http://63.99.108.76/ubb/Forum13/HTML/002924.html

Reasons:

1) timing

The system that Sir Kozakh Dragonfire claims is on the BMP-3 and some T-90 starts tracking the projectile when it is 50 meters away. A 1660 m/sec dart needs 30 milliseconds to travel 50 meters. In that time the radar has to be trimmed to the threat, the path of the projectile has to be computed, the countermeasure has to be launched, it has to fly to its detonation point, it has to explode and the debris have to reach the point where they meet the dart.

The radar alone is a huge problem. The most modern radar systems need

1 millisecond to be trained into a particular direction, but they have a limited angle and you have to figure out where to train it to. 30 msec is a very short time, an ATGM leaves you a lot more time.

2) energy and impule

You would have to throw a massive object into the dart which is 6.8 kg and moving at 1660 m/sec. It has very impressive impulse and kinetic energy (that's the point :). You can destroy a HEAT warhead, but you cannot destroy a DU dart and I don't think you can change its course with anything practial either. At best you can make it tumble so that it doesn't hit head-on and becomes more sensitive to the natural angle the passive armor has.

Martin

 

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Alexsey's reply:

Alexsey Kirsenko said:
ERA is and acronym for "Explosive Reactive Armor", also known as dynamic defence. It's effect is ABSOLUTELY DIFFERENT from the active armor's.
What you are talking about is an active armor, and I never told that it protects from KE rounds. In the topic "Changing vehicle specs" in official TacOps forum on Battlefront I have written about an active armor on Russian tanks.

 

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Martin replied:

Martin Cracauer said:
I understand this, but how is ERA going to do anything about a KE dart (anything else than the obvious resistance of the material it is made of - which will be very low)? ERA needs a HEAT round to "tip it off"

With the fuse mounted some distance in front of the round, that is how it works. The HEAT round is friendly enough to announce in advance that it will impact momentarily and the ERA says "thank you, I'll meet you in time". The KE dart is in the armor before the ERA can explode.

And even if it exploded in time, how is a pure explosion (nothing but air pressure/shockwave) going to affect a solid dart when the explosion is in front?

I don't want to be nag about this, but it is not realistic if you consider the physical characteristics of the moving dart. That thing is very hard to irritate, especially with air.

And I have never seen hard numbers from the trial, as in "the dart penetrated x56mm into the naked steel armor" and "x12mm when ERA was in front". All I see is very generic claims like "20% less" or "200mm resistance more" claims, but never any mention of firing gun, dart in use or even the specific penetration values into the target.

It is actually hard to establish a claim like "20% more penetration"

for a kinetic energy shot. If the target is 200mm thick and is penetrated you cannot say how much it would penetrate if the armor was thicker. If you just shoot into thick enough steel that is fine to establish HEAT penetration, but a KE shot's penetration depends on the characteristics of the plate. It may penetrate 200mm in a 200mm plate but only 180mm in a 300mm plate. The only way to really establish "20% more" is two shots at plates which are of 20% different thickness.

Martin

 

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Alexsey replied:

Alexsey Kirsenko said:
Here is how ERA effects APFSDS round.

1. APFSDS round penetrates the outer layer of ERA with ease.

2. Explosive charge makes both frontal and rear plates move.

3. When APFSDS touches the rear plate, frontal plate cuts the first 5-6 cm. of the rod. Additionally to the loss of mass, APFSDS round now has a blunt point, which severaly affects it's penetration capabilities.

4. The secondary effect of APFSDS is the yaw introduced by the first plate before contact with rear plate is established. The total is about 2-3* yaw, and it continiously grows in dense steel.



The test trials were made in Germany in 1996. The tank carrying ERA was T-72. The ERA was Kontakt-5, standard-type ERA on all modern Russian and Ukrainian tanks. The round was M829 APFSDS, fired from 120 mm. Abrams tank. Result - ERA on frontal glacis of T-72 stopped the round.

 

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MKRobel1 replied:

MKRobel1 said:
The penetrator of an APFSDS round is not sharp. The sharp portion you see is the wind screen. Behind the wind screen is a wobble cap. When the round hits the armor at an angle, the wind screen is deflected up, rotating on the wobble cap, which forces the penetrator down into the armor. The actual penetrator is rather blunt.

Having said that, I don't really think it makes a lot of difference in TacOps play.

I don;t really have any problem with the armor thickness proposed by the major. Players who want a real challenge can use the systems and those that don't can substitute other platforms. Myself, I like to play against the hardest platforms available for the same reason that the Romans used double weight training shields and swords. Roman Battles were bloody training, Roman Traing were bloodless (well sort of ) battles.

Tactics will compensate somewhat for technological capabilities, and there is always a seesaw in the gun armor battle.

Mike
 

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Then this reply:

Alexsey Kirsenko said:

First, the loss of 5-6 cm. for an M829A1 represents the loss of about 8% of the round mass.

Second, the blunt penetration point is very inefficient during the first phase of the penetration. The sharp ballistic point is made to compensate this.

Third, blunt point suffers structural damage and mass loss as the shock wave travels down the length of the round.

Forth, don't forget about the yaw introduced by the first plate of ERA.

The result of this is that M829A1 round can't penetrate the glacis armor of T-72 with ERA.

T-80 and it's succesor, the T-84 has a better armor compared to T-72.

About the armoring in the game. The only thing I want is the realistic TTC of the game's units. Besides, I love T-84 :)

 

Dr Zaius

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Alexsay also provided us with this link to the Kharkiv Morozov Machine Building Design Bureau and Malyshev plant: http://www.morozov.com.ua/eng/index.php

And here is the link to the T80UD MBT: http://www.morozov.com.ua/eng/body/t80ud.php?menu=m1.php

An interesting discussion. Good thing the Republican Guards didn't equip their divisions with these! That could have made things somewhat more interesting. They probably would not have been able to maintain them though.

Here are some additional links that may be of interest:

http://www.army-technology.com/contractors/ammunition/apfsds.htm
http://members.aol.com/panzersgt/theory/Ammo.html
http://www.fas.org/man/dod-101/sys/land/row/t-90.htm
 
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