Serge

Different crystal phases of the steel, essentially the grade "P" armor is welded while still hot, the other grades are welded at much cooler temperatures. Likely implies that the grade P material is welded post-heat-treatment, while the grade Q and R metal is welded pre-heat-treatment. (This is not necessarily the case, but would be the most likely reason for welding at different phases).

I am not sure how it is done for Leopard 2 components, but I have seen entire cast or welded assemblies heated up and quenched at once in appropriately massive facilities. This image of a Panzer 68 hull being Quenched at Thun always comes to mind.
 
Welding plates post heat-treatment is very difficult without making the zone around the weld weak. It is usually preferred in metallurgy to weld before heat treatment and then do it all together.

You previously wrote I would speculate too much on the weight of the tanks, yet you are making even more speculations. Your sources are inconclusive and thus one should be careful with trying to make any statements based on them.
 
First of all, the British document states that the KE protection for the Abrams would reach a level of 320 to 340 mm protection against APFSDS rounds along the protected frontal arc. Given that the hull front has its minimum armor thickness of the frontal hull  is at 0° (while the side armor wasn't altered), it should not have a protection level of "350 mm KE minimum". In fact the M1A2 offered to Sweden has a protection level of 350 mm along the frontal arc of the hull - this tank has no DU armor, but that doesn't matter because only five Abrams tanks were ever created with DU armor protecting the hull. We know that the M1IP  and the M1A1 feature upgraded hull armor, which can be seen by looking at the location of the weight demonstrators. This leads to the conclusion that the M1 Abrams did not have 350 mm KE minimum for the hull, but rather 320 mm.
 
The table from the British documents lists a single value for armor protection for the Leopard 2, you are speculating what this value exactly means. First of all, "at [the] normal" can refer to the armor modules - as suggested by you - or to the tanks. Hitting a tank at normal means hitting the "front side" at perpendicular angle (the side of the tank not being affected by the shape of the armor). Against your assumption speaks the fact that the Centurion, Leopard 1 and T-62 are not listed with the respective armor thickness values they'd have when the armor was hit at the normal from within the 60° frontal arc (Leopard 1 for example would have some 50-70 mm thickness, the T-62 some ~150 mm). This implies that "at normal" means "hitting the tank directly from the front".
You are assuming that this values would refer to the turret armor; but there is no proof for this. The document doesn't say anything about the table being limited to the turret, in fact it lists the hull armor of the Centurion, the Leopard 1 and the T-62! So even if this would refer to "hitting the armor modules at normal", it still could be a value for the hull being hit at 0°.
 
Do I think that the Leopard 2 must have a protection level of 400 mm or greater at the turret when hit from a 30° angle? No, I don't think it has to. It might have a protection level in the high-300s; but I think we should find sources before making assumptions. We however know for fact that the Leopard 2 has a protection level of ~430 mm steel against KE rounds at the turret when hit directly from the front, because this value is derived from an official table by the manufacturer. So your "350 at 0" is already a false premise. You seem to be eager to "prove" that the Leopard 2 has worse frontal armor than the M1 Abrams; you are ignoring some facts, which speak for the Leopard 2 having better frontal armor (such as the greater armor weight and thickness alocated to the turret front) and you are basing everything on a single source, which leaves too much room for interpretation. As I previously stated, it seems to refer to the protection of the hull front - this would match the data from the Swedish leaks and the physical armor thickness (the hull armor of Leopard 2 and M1 Abrams has nearly identical thickness) and is supported  by the values of other tanks matching their hull armor thickness.
 
The data from the Swedish leak is inconclusive regarding the protection level of the Leopard 2, when attacked from various angles:  

As you can see, the surface area with a protection level of 400 mm or more is always larger when attacking the tank from angles other than 0°. The only question that remains is: Which places reach this protection level? The document doesn't tell anything about that, it also doesn't specify wether the area (100%) is limited to the crew compartment or not. If the latter is the case, it seems easily possible for the turret frontal section to also to be part of the protected area. Most likely the hull frontal armor reaches a protection level greater than 400 mm when hit at 20° or 30°, if the frontal hull armor is actually included in the relevant surface area.
 
The Leopard 2's turret armor has a frontal armor thickness of about 860 mm at the left turret cheek; given that the turret front is sloped at 34° in the horizontal plane, it will have a greater armor thickness when hit at 30° angle than the hull armor at 0° - overall the armor thickness might be comparable to that of the Abrams of 0° (unfortunately nobody has published proper measurements of the Abrams, but supposedly the early production model had some 700 mm physical thickness when hit at 0°). You should keep in mind that the Leopard 2(AV) was designed to resist the 105 mm smoothbore gun firing APFSDS ammo (i.e. the same projectile as used on the 120 mm DM13 with lower velocity) from unknown range. This round has a slightly higher MV and a longer & thicker tungsten penetrator than the M735 APFSDS, which is claimed to penetrate more than 300 mm steel armor.
 
 
___
 
Moving back from the armor and more to the general topic:
 
Something regarding mobility:
According to the French topic, the Leclerc squeezes 1,143 effective hp out of its 1,500 hp engine. The M1 Abrams reaches a1,232 hp net output of its AGT-1500C gas turbine, also some older discussion suggest that it might have only ~1,000 hp at the sprokets. The Leopard 2 seems to be less efficient in this regard, managing to get only 1,070 hp to the sprockets according to W. Spielberger. Leopard 1 gets 630 out of 830 hp to the sprockets. Maybe that is why the German army wishes for a 1,200 kW engine on future Leopard 2 models; however the published acceleration data suggests that the Leopard 2 beats the Abrams to 32 km/h. 
 
Regarding FCS:
In 1987 the Saudi Arabian Kingdom tested the AMX-40, the Challenger 1, the M1A1 Abrams and the EE-T2 Osorio tank. The EE-T2 Osorio was fitted with a French 120 mm smoothbore gun from GIAT and a fire control system developed by the British company Macroni. It included a 16 bit microcontroller and a SAGEM MVS 580 optic with integrated thermal imager for the commander (the same sight was later fitted to the Challenger 2E, which underwent trials in Greece). According to claims made by a Brazilian source, the Osorio was the only tank capable of hitting a stationary target in 4,000 metres distance. Against moving targets (at distances of 1,500, 2,000 and 2,500 metres), the Osorio supposedly hit eight with twelve shots. The Abrams hit 5 with twelve shots, while both of the other tanks managed to hit only a single target. The fuel consumption of the German engine was 200 g/kWh, which allowed it to travel a distance of 400 kilometres, further than any of the other three tanks.
 

In 1992 the M1A2 Abrams and the Challenger 2 were tested in Kuwait. During the tests numerous results were leaked by American representatives in order to prove that the Challenger 2 was the worse tank. In a statement made to Jane's Defence Weekly, British sources suggested that General Dynamics didn't tell the whole truth. Both tanks failed to climb a 50% slope, because it consisted of loose sand and chalk. The Challenger 2 had to be towed after driving 80 km on flat ground. Maximum speed achieved by the British tank was 50 km/h, while the Abrams managed to reach 65 km/h. The brakes of the Challenger 2 worked too slow in the opinion of the Kuwaiti officials, needing between 50 to 70 metres to come to an halt.
 
When trying to hit a T-55 tank at a distance of 4,000 metres, the M1A2 managed to hit one out of two shots (apparently it used APFSDS rounds); the Challenger 2 fired six HESH rounds at the same target, all missed. Firing at unarmored targets at distances smaller than 4,000 metres was easy for the Abrams. It hit 10 out of 10 targets, while the Challenger 2 hit only 7. Shooting on armored targets, the Challenger 2 hit four out of four shots, while the Abrams hit nine out of nine. General Dynamics' tank was also better at firing on the move; the Abrams hit three targets at a distance of 2,000 metres with three shots, while the Challenger 2 hit one out of three. In hunter-killer operations, the Abrams required 32 seconds to destroy four targets with fourt shoots; the Challenger 2 hit 3 targets out of four in 66 seconds. Accuracy when firing during night and fuel consumption had still to be measured, but Vickers believed to have an advantage there (at least in fuel consumption).
 
http://btvt.info/1inservice/abrams_vs_chelly.htm
 

 
Challenger 2 ARV towing an Abrams, which failed to climb a dune.

The British military believed that its ammo was incapable of defeating the T-80 during the Cold War,  but it was enough to deal with the T-64. Given that this document is from 1986, Stillbrew armor might not have been adopted on the Chieftain yet, hence the statement about the Chieftain's armor being defeated by all modern Soviet tank guns (which I suppose means 100 mm, 115 mm and 125 mm guns).
 
The Challenger 1's frontal turret armor is claimed to be comparable to Soviet tanks with ERA. That would most likely be the T-64BV, T-72AV and T-80BV, given the fact that NATO learned about the T-72B in ~1988 (at least the official NATO codename for it was "Soviet Medium Tank 1988") and T-80U in 1989 (US/NATO codename M1989). This would suggest that the Challenger 1's frontal armor might be 450-500 mm vs KE and ~1,000 mm vs shaped charge warheads.
 
andrei-bt.livejournal.com/788654.html

British Army Warrior infantry fighting vehicle fitted with Soucy Defense composite rubber tracks during trials in the UK. Source: Soucy Defense/Defence Photography A British Army Warrior infantry fighting vehicle (IFV) fitted with Soucy Defense composite rubber tracks (CRT) has completed a 5,000 km trial, Jane’s has learned.

http://milnavigator.com.ua/українські-танки-отримають-новий-дин/
 
Credit on the finding to Stayh78 from waronline.org forum.
Translation for each page directly above it.
 
 

Fully agree. 
 
If the BMPT’s task is to support T90 squadrons, it’s not a problem. 
It would have been a problem if it was suppose to support a more mobile tank. 
 
The limited travers of AG17 is a point to improve. But the current design offers the best protection and is very affordable. 
 
Russian companies are always producing missiles with different warheads. So, it can already provide what you call for. 
 
Manpads are specific.
If you want to improve the AD capability, you must transfert your BMPT to the AD artillery C2. 
 
An other option could be to adopte ISTAR kit to be mounted in place of the Attaka launchers with dedicated operators in place of both bow gunners.
Mixted with classical BMPTs, units can provide both close in fire support and close in EW support. 
 
Yes. 

Hi im new to this forum and i found the debate on the BMPT very interesting. I think that in this debate there are two levels or aspects that should be discussed separatedly. From now on i will refer to BMPT concept as Tank Support Fighting Vehicle (TSFV).

Firstly, the theoretical need for such a dedicated vehicle and the economical and logistical cost of it. So far, two armies have recognized the need for a specialized tank support vehicle which are Russia and Israel based on their experiences in Afghanistan, Chechnya, Lebanon and Gaza in asymmetrical type warfare. In that sense a TSFV should provide defense primarily against enemy infantry in the same way a SPAAG provides air defense, i like to think about it as a "bodyguard" for tanks. It has been said that Infantry and their IFVs can fulfill this role very efficiently, which is true (BTW, in the conflicts aforementioned, tanks  suffered casualties when they were in poor and often non existent coordination with infantry), by definition infantry is one of the most multipurpose units for ground warfare.  However, mechanized infantry also has its limitations: in case of an ambush the moment  infantry dismounts they instantly become easier targets to enemy than tanks, in case the infantry doesn't dismount and chooses to fight from within their IFV  they can´t be nowhere near as effective with their weapons and also IFVs have lesser protection levels than tanks. In both  theoretical cases, we would end up with 3-4 tank crewmen, 7-9 infantry dismounts  plus 3 IFV crewmen in danger for a total of  13-16 possible cassualties.  If you replace the IFV with a TSFV you get not only less people involved but also better protected and with superior firepower. From that perspective and for that specific mission, a TSFV makes sense and is preferable over mechanized infantry.  

Secondly, about the specific BMPT to be adopted for Russian army. In general, i like it but i think that its far from perfect, i´ll make a list of the things i would change and/or improve:
 
- To navigate either urban or mountainous  terrain you need high maneuverability as well to be able to escape ambushes. This means to be able to NEUTRAL TURN and GOOD REVERSE SPEED, which are two things that T-72/90 can´t do. So BMPT should have had a different transmission system to allow this.

- APS with 360 degree protection. ARENA APS (or a modernized variant) could have been perfect for this and its already available. Can´t believe the russians didn´t equip the BMPT with it. 

- Sensors to locate enemy snipers and ATGM teams. Its not a new technology and could be integrated into the APS.
 
- Better stations for bow gunners. I think that having bigger crews is a good idea, 5 pairs of eyes see a much more than 3 provided the have the correct tools and the right crew layout. In this case, the  bow gunners hatches should have have been rotatable (like old school commanders cuppola) and/or the grenade launchers should have been mounted differently on fully rotatable RCWS. I can imagine several simple solutions to this. Currently the bow gunners and grenade launchers in the BMPT are mostly wasted potential. 

- At last i would have made a slight modifications to the ATGM mounts: perhaps some sort of hard point mounts (like on the wings of attack helicopters and airplanes) to mount not only ATGMs but also MANPADS, rocket pods, flamethrowers, recoiless guns, etc depending on the mission. This way you can give the vehicle much greater flexibility and utility in any scenario outside its specific purpose of providing defense against enemy infantry using guerrilla type tactics. 

About the discussion of main armament: I think that 30mm autocannons are currently the best compromise. Firstly you have logistics commonality with the rest of the armored fleet. Secondly, you can fire up to four types of ammunition. Thirdly, you can carry much more ammo than, lets say a 57mm autocannon. Fourth and very important: the 30mm autocannons don´t protrude much from the vehicle which is a VERY important aspect for urban warfare often overlooked, actually one of the reasons the israelis kept the 120mm L44 gun is because it almost doesn´t protrude much from the Merkava and doesnt hinder as much its ability to take sharp corners in dense cities (or traverse its turret to actually use the gun). 

TLDR: I think that the concept behind the BMPT has solid foundations but the actual BMPT to be adopted, while overall good, can be improved a lot.

Sorry for my english, its clear that it isn´t my mother language.  

+1 for creativity.
-2 for cutting down trees.
-3 for ruining a road.
+4 for Soviet logs.

Here some scans from the Satory VI (1977) catalog :
https://imgur.com/a/zfjSNwm

Early Chrysler XM-1 validation phase model with a coaxial Bushmaster weapon system :
 

Both commander and gunner’s seats are identical.
The only difference is the commander adjustment’s got a rear stopper to reduce the setting by 3 cm. Why ? To avoid to pierce fuel tanks. Without the stopper, the seat can protrude from the turret basket. 
My goal is to protect the crew from shrapnel. So, I would have manufactured seats with ballistic materials. 
 
We have to remain that in France, people above 185cm were not permitted to become tankist, but tank commanders.
So my knees suffered a little bit against the gunner’s seat. 
 
Look at any tank at war. You never have enough place.
The only external storage you have (on the RC standard, not the RCR), is a basket designed to carry 4 of the old butyl waterproof tank crew pack. During the Gulf war, crewmen stored MREs between the hull and the add-on armor.
In the French troop, you have a truck per troop to carry burden. But, in the real life you must be as autonomous as possible. 
My solution would have been a mixt between the TML-105 storage for the front and the sides and a Merkava like rear basket. 

 
SEPAR is too much heavy. 
I’m just thinking about internal layer on some dedicated places. AMX-10RC can’t be burdened. It’s very dangerous considering its steering system.
In 2002, Australian SAS LRPV received 4cm thick anti-mine composite floor plates. This kind of solution would have been acceptable. 

I propose a new topic to regroup information about French AFVs.
 
Days after days, information is overwhelmed under the inflow of photos about anything and everything.
It can be interesting to try to have dedicated topics to ease the quality of exchanges. 
 
So, if you have already posted interesting photos, documentations and view about French AFVs, you can quote them here. 

AMX-30 M693 20mm autocannon superelevation (-8° to +40°) :
 

Might as well repost this from the AW forum.
(Thanks @Laviduce for taking the time to incorporate the label in English directly)
The translations I did back then were quite literal since I'm not really a mechanics guy, so it may sound awkward.
Scans comes mainly from 2 books I have.
 
 
V8X Hyperbar and the ESM500 gearbox:
 
 
Principle scheme of the engine:
 
1) Autoadaptation valve of the turbine
2) Discharge valve
3) Turbine
4) Compressor
5) Air intake regulation valve (secondary combustion chamber)
6) Secondary combustion chamber
7) Cooling unit of air intake
8 Ignition
 
 
Kinematic chain:
Didn't tried to translate that one since I'm not too good are reading this kind of diagram.
Ask if you need me translate something in particular.
 

Yes.
The Leclerc MBT barrel is very rearward compared the manualy loaded turret. This way, artillery is naturally balanced. 
 
Yes.
Leclerc MBT was the first tank designed to achieve fire on the move at hight speed. Firing off road at 40km/h to a mobile target is basic.
Maybe Type-10 and K2 are better today. Maybe. 
 
Yes. 
Aluminium tracks can’t last as long as classical steel ones. They were found too much expensive to support for peace time. 
 
You have such a mechanical link. I don’t know the exact purpose. 
 
I was AMX-10RC tank commander. I never served with Leclerc MBT. So, I can’t help for very detailed data. 
In France, you have Leclerc, Darklabor, Totochez, Rescator. They are not bullshiting. 

Generaly speaking, I never answer to such a question because it’s the start of unrealistic discussions of technology fanboys unknowing real. But, I can say :
- never forget AMX-10RC is a very 80’s light tank. So, any improvement must be cheap provide. 
- the world famous Serge AFV belief is : an AFV chassis push, carry and tow. 
- having a good AFV is good, but without its environment, it’s useless. 
 
FCS, sights, weapons were good.
 
So, I would have :
- modified the seats to have something more confortable and armored. Maybe an harness to sleep ;
- introduced a new TC hatch with an umbrella opening (my priority) ;
- rearrange external storage to increase them ;
- suppress river crossing (both useless and dangerous) to have more storage ;
- add spall liner and mine proof plates under pilot seat and turret floor. 
 
Considering chassis, I would have add :
- 2 rear fuel drop barrels like the Leclerc ones. Fuel drums are compulsory ;
- front tools connector to push mine rollers...
 
Considering it’s environment, I would have :
- add a fourth 10RC per troop (In France, reccon tanks troops are 3 tanks troops. Leclerc : 4 MBT troops) ;
- adopted AMX-10RTT as command post and ARVs instead of VAB and ARV based on trucks.

 
With diminution of 10RC number, I would have transformed some of them in general purpose vehicles able to carry dedicated teams for special tasks such as EW....
When dimounting the barrel and ammo racks, you have plenty of room. 
 

You can have thickness to have vacuum for air intake to cool the plate avoiding problems with the thermal sight and improving thermal signature. 

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 system.
A stabilisation system uses a set of gyroscopes located at specific points (hull, turret, armament).
The angular informations gathered by the different gyros is computed by the FCS which gives a set of corrections to the elevation and traverse mechanism (the most early stab systems where the armament remains to the same position no mater how the tank behaves). In addition the FCS adds on top of this another set of corrections related to the ideal LOF (later stab systems that introduces the concept of correction of the position of the tank).

On the Leclerc, the sight being how it is, the number of variables is kept as minimum as possible. You only compute the angular variation between the current LOS and the ideal LOF. The set of values is then dispatched to the "guidance system" (asservissements) which monitors the actual movement of the turret (traverse and elevation) and assess the need to power the electric motors or revert them into generators to brake the movement.
In itself the tank knows on its own the position of the differents elements (hull, turret and armament) with the closed loop elevation and traverse. The sight give the angle of the whole.

Hope it is clear. It's not a whole lot but we make this distinction.

Topic to post photo and video of various AFV seen through a thermal camera.
I know that we won't be able to make any comparisons on the thermal signature of various tank without knowing which camera took the image and that the same areas (tracks, engine, sometimes exhaust) will always be the ones to show up but anyway:
 
Just to see them under a different light than usual (pardon the terrible pun^^)
 
Leclerc during a deployment test of the GALIX smoke dispenser:
 
The picture on the bottom right was made using the castor sight (AMX 10 RC, AMX 30 B2)
 
Akatsiya :
 

 
T-72:
 


 
A T-62 I think between 2 APC:
 

 
Stryker:
 

 
Jackal:
 

 
HMMWV:
 

 
Cougar 4x4:
 

 
LAV:
 

Generaly speaking, I never answer to such a question because it’s the start of unrealistic discussions of technology fanboys unknowing real. But, I can say :
- never forget AMX-10RC is a very 80’s light tank. So, any improvement must be cheap provide. 
- the world famous Serge AFV belief is : an AFV chassis push, carry and tow. 
- having a good AFV is good, but without its environment, it’s useless. 
 
FCS, sights, weapons were good.
 
So, I would have :
- modified the seats to have something more confortable and armored. Maybe an harness to sleep ;
- introduced a new TC hatch with an umbrella opening (my priority) ;
- rearrange external storage to increase them ;
- suppress river crossing (both useless and dangerous) to have more storage ;
- add spall liner and mine proof plates under pilot seat and turret floor. 
 
Considering chassis, I would have add :
- 2 rear fuel drop barrels like the Leclerc ones. Fuel drums are compulsory ;
- front tools connector to push mine rollers...
 
Considering it’s environment, I would have :
- add a fourth 10RC per troop (In France, reccon tanks troops are 3 tanks troops. Leclerc : 4 MBT troops) ;
- adopted AMX-10RTT as command post and ARVs instead of VAB and ARV based on trucks.

 
With diminution of 10RC number, I would have transformed some of them in general purpose vehicles able to carry dedicated teams for special tasks such as EW....
When dimounting the barrel and ammo racks, you have plenty of room. 
 

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 be honnest with you there is no stabilisation on the Leclerc. The gun is slave to the ballistic computer which computes the ideal LOF from the stabilised LOS.
When reloading, the gun goes to the reloading elevation. Meanwhile the LOS is still stabilised to the direction of observation (in the limits of the mirrors amplitude). Unless you release the palm switches, the mirrors go to their mechanical neutral positions.

The gunner sight is mechanically mounted to the main armament. When the gun goes up and down; the sight bows up and down.
Since the both move along with the exact same angle, boresighting can be done automatically with a deviation measurement laser (AMX 10 RC being the first french AFV to be equiped with such device).
Crews do some alignments (what we call "harmonisation" where we keep the parallax in check), but that's not the bullshit stated by Sergei Suvorov where crews were forced to boresight everytime they move their tanks...
 
At the time engineers were open minded on what could replace the classical tank. Once they defined that their platform was still an AFV, they assessed every kind of compromise to take what was the most favorable and compatible to their specs guideline.
 
 
Fun fact regarding the tracks. They spent quite some time to switch to steel tracks. They initially used the same arrangement as the aluminum alloy tracks (the shape of the rubber trackpads were supposed to reduce the stomping effect). Surprise, surprise, the vibrations at high speed were strong enough to be a handicap. This explains why we transition from V2 (alloy) to V5 (steel). Apparently V4 was also a disappointment.

Even with V5 or DST 840 the vibration is quite awkward compared to V2.