M1 is not protected against old rpg7, then what?
The M1 is protected against the RPG-7 in the area were composite armour is applied to the vehicle's surface. Since the M1 is however designed for conventional warfare, composite armour is only used in the frontal sector.
Merkava 4 with very thick side armor is not protected against rpg 29.
No. This has been discussed in various different forums (including this one) mutliple times. The Isreali Defence Force uses currently all types of Merkava tanks - inlcuding the old Merkava I, II and III - which don't have thick side armour. These tanks are vulnerable to old RPGs, anti-tank missiles and IEDs and these tanks make up the majority of Isreal's combat losses.
There is currently not a single evidence that a RPG-29 destroyed a Merkava
IV. Besides the Merkava IV is - compared to newer tanks like the Leopard 2A7, Leclerc Azur or the Challenger II with TESH - less armoured (in terms of weight and armour thickness).
So what? In reality tank can be defeated by all rpgs
In the non-armoured sectors, yes. But on the latest tanks the armour coverage has been increased drastically, making only the rear vulnerable.
Because rpg 29 is old then it must be worthless? Is this your logic to claim protection against it without hard proof?
The RPG-29 is not worthless, it is outdated. It could not penetrate the frontal armour of tanks made prior it entered service and it does not have the penetration power to guarantee the penetration of thinner but much more modern armour.
Ok, how old is .50 caliber? Is there any body armor protected against it? Oh with your and Damian and super fancy nano material, body armor should be protected against .50 or it can not provide protection against anything? Right?
This is a very stupid analogy. There never has been any attempt to protect infantry against the 12.7 mm caliber. There never was a requirement for infantry to be protected against HMG rounds, and even if the armour would provide sufficient protection to resist a direct hit from a 12.7 mm round, the kinetic energy would lead to very likely lethal wounds.
But if you look at body armour, why don't you look at the increase which was made. Today's body armour is capable of resisting armour-piercing rounds from battle rifles and bolt-action rifles, something what wasn't be granted during the 1980s and early 1990s... at the same time current generation armour is lighter.
25cm composite armor + 10cm RHA + airspace is enough against 600mm.
This is strongly depending on the type of armour used. The following image is taken from a random Krauss-Maffei Wegmann patent:
(It obviously shows multiple layers of bulging-plates armour (NERA).)
If we now take a look at the scientific report "Disturbance of Shaped Charge Jets by Bulging Armour" by Manfred Held (the inventor of ERA), we see that
a single layer made of 2 mm mild steel, 20 mm Dyneema and 4 mm mild steel at 60° angle (so line-of-sight thickness is 52 mm) reduced the penetration into mild steel of a 115 mm shaped charge by around 400 mm at a standoff of 15 calibers.
While the standoff is much greater, the targets and armour are only made of mild steel (reducing the protection capability) and the 115 mm warhead is much more powerfull than the 105 mm warhead of the RPG-29 (residual penetration into mild steel after the reduction of "around 400 mm" was 590 mm and 610 mm).
By these considerations 3 similar layers should be easily enough to deal with a 105 mm warhead capable of penetrating 600 mm steel armour.
Furthermore the protection can be increased by optimizing material and layering. In "Shaped Charge Jet Interaction with Highly Effective Passive Sandwich Systems - Experiments and Analysis" two NERA layers (10.5 mm steel + 7-8 mm interlayer material + 10.5 mm steel) at 65° angle spaced 71 mm apart were tested against a 136 mm (!) shaped charge warhead capable of penetrating 950 mm RHA. Penetration into the witness block placed 6 calibers behind the armour array was between 14 mm and 107 mm, depending on material.
In "MULTIPLE CROSS-WISE ORIENTATED NERA-PANELS AGAINST SHAPED CHARGE WARHEADS" NERA plates made of 3 mm steel - 5 mm rubber - 3 mm steel at 60° angle are tested against a 84 mm shaped charge warhead capable of penetrating 450 mm RHA. Depending on the exact configuration the penetration power is reduced to 40 mm RHA at 590 mm standoff
It is clearly possible to provide sufficient protection to survive a hit of a RPG-29 with the available space.
If the armour is not NERA - as I personally believe - it could be ceramic armour. 3 parts AD-92 (which is already outdated) with 1 part steel will provide 1.65 times the protection as steel armour of the same thickness against HEAT rounds. 1 part AD-92 with 1 part steel provides 1.79 times the protection as steel armour of the same thickness.
This would mean that the 300 mm thick side armour would provide 495 - 537 mm protection against HEAT, with the 625 mm air and the 100 mm RHA doing the rest.
Why 25cm? leo2a7 is under 4m wide, 3.5m without skirt so you do the math.
Instead of randomly making a statement after looking at two values, you should at first take a closer look at the vehicle. The Leopard 2 in it's bais configuration is 3,700 mm wide
including the armoured side skirts - these are 150 mm thick (both by scale drawings from Spielberger and by assertion from former German soldiers). If the Leopard 2A7 is 4,000 mm wide (as claimed on the Krauss-Maffei Wegmann website, but the value is probably rounded) - then there is an extra 300 mm of armour, or half the amount on both sides (which then happens to be 150 mm + 150 mm = 30 cm). The value 25 cm was a rough estimate from looking at the vehicle.
RPG 29 is not special because it is the best in it class.
No, it is not. It is very cheap and reloadable, which is the reason why it is very widespread. PzFst-3, RPG-28, etc. all can penetrate more armour, but are more expensive.
There is AT4 120mm back in the 90s can penetrate even front armor.
AT-4 cannot penetrate the frontal armour of 1990s tanks.
