Why did NATO tanks use smoothbore guns and composite armor so much later than the Russians?

[F.T]

[mpow66m]

Why is a Smooth Bore cannon more accurate then Rifled when the exact opposite is true with a rifle?

[Ssnake]

11 minutes ago, mpow66m said:

Why is a smoothbore cannon more accurate then rifled when the exact opposite is true with a rifle?

They aren't.

But they have no spin induced drift (which can be compensated for), but the round-to-round dispersion is bigger. What has changed are the introduction of computerized fire control systems that have substantially reduced human error and which take into account more environmental variables, all of which helps with accuracy. Add to that primary-stabilized optics with guns firing only while inside the coincidence window, and you get decent accuracy even from a smoothbore.

[Ssnake]

5 hours ago, F.T said:

Why did NATO tanks use smoothbore guns and composite armor so much later than the Russians?

Please expand, what's "so much later" to you, and where do you see the date of introduction of composite armor in NATO, and Warsaw Pact tanks respectively?

[Hedgehog]

1 hour ago, Ssnake said:

Please expand, what's "so much later" to you, and where do you see the date of introduction of composite armor in NATO, and Warsaw Pact tanks respectively?

Might be that T-64 has Composite armour

And T62 has a smoothbore gun

both have a late 60s in service date

 

leo 2 didn't enter service until 1979

So that's about a decade.

Unless theres another type that entered NATO service we've missed.

[Ssnake]

Sure. But not all Soviet tanks that came after the T-64 had composite armor, which suggests to me that a formula that offered clear advantages was not yet found, at least not in the West. I wouldn't rule out that the Soviet engineers simply had a temporary lead in composite armor design. But note that the T-72A did NOT come with composite armor, and the base T-72B had only rather simplistic inserts for the turret front.

During that time, Western focus, at least for lighly armored vehicles, seems to have been on aluminum alloys (M113). In fact, only the British research with the Dorchester armor was the actual breakthrough that made it possible again to offer protection against large caliber HEAT and APDS rounds, and that wasn't developed before 1972.

 

Likewise, the L7 was considered quite adequate well into the 1980s. Yes, the Bundeswehr was concerned about the limited growth potential of the 105mm caliber and therefore wanted a bigger caliber right away. Again, only when Rheinmetall actually developed the material science and production know-how to produce a rather lightweight smoothbore cannon of 120mm caliber with heretofore unmatched peak chamber pressure rating it was clear that smoothbore was the way to go (note that even then the British tried to push their rifled 120mm cannon so they could keep the war stocks of HESH rounds of the Conqueror and Chieftain legacy; the smoothbore advantage was clear in the anti-tank/APFSDS role, but if you considered infantry fire support as another important doctrinal role, the advantage is less clear-cut).

True, the 115mm smoothbore gun of the T-62 offered an unmatched muzzle velocity 15 years earlier, but only because it used a low mass steel sabot round rather than uranium or tungsten, which would have almost tripled the mass for the same volume ... and uranium offers superior performance at lower impact velocities, ideally 1100 +/-200m/s, so at least from an American perspective going for highest muzzle velocities was not necessarily the highest imperative.

[F.T]

12 hours ago, Ssnake said:

Please expand, what's "so much later" to you, and where do you see the date of introduction of composite armor in NATO, and Warsaw Pact tanks respectively?

NATO tanks were not updated until the 1980s.

[Grenny]

1 hour ago, F.T said:

NATO tanks were not updated until the 1980s.

What?

Define "where not updated"...otherwise you're just way off.

[F.T]

The Leopard 2 appeared in the late 1970s and the M1 in the early 1980s. The T72 and T80 have been around since the 70's, although their fire control system is relatively backward, but they have composite armor and smoothbore guns.

Edited May 31, 2022 by F.T

[Ssnake]

Leopard and M1 were developed precisely because the Soviets had become dangerously ahead in conventional strength, and, at the same time, the nuclear strategy was evolving as theorists recognized that the threat to escalate to mutual annihilation was hollow as long as the other side's aggression was a non-existential threat.

 

I can but repeat myself, however, in saying that early on composite armor did not offer clear advantages over cheaper, simpler, and lighter alternatives such as numerous air-gapped mild steel sheet assemblies to degrade HEAT attacks), nor was it clear that smoothbore guns were the best option once that you thought beyond the "anti-armor with non-Uranium kinetic energy projectiles" application case.

 

And then, in 1971, the British researchers came up with a lab sample of the Dorchester armor that still had to be scaled up in production technique from lab sample to serial production.

[F.T]

43 minutes ago, Ssnake said:

Leopard and M1 were developed precisely because the Soviets had become dangerously ahead in conventional strength, and, at the same time, the nuclear strategy was evolving as theorists recognized that the threat to escalate to mutual annihilation was hollow as long as the other side's aggression was a non-existential threat.

 

I can but repeat myself, however, in saying that early on composite armor did not offer clear advantages over cheaper, simpler, and lighter alternatives such as numerous air-gapped mild steel sheet assemblies to degrade HEAT attacks), nor was it clear that smoothbore guns were the best option once that you thought beyond the "anti-armor with non-Uranium kinetic energy projectiles" application case.

 

And then, in 1971, the British researchers came up with a lab sample of the Dorchester armor that still had to be scaled up in production technique from lab sample to serial production.

Ok, got it.

[Da history dude]

But why would the advantages not be clear in that point in time?

[zerocrack01]

12 minutes ago, Da history dude said:

But why would the advantages not be clear in that point in time?

In retrospective it always does seems clear

[Ssnake]

Scaling lab samples to (affordable) industrial production is a step where a lot of products fail. Yes, there's more gold dissolved in the world's ocean than we have in global gold reserves. It's just that you can extract it in an economic fashion, even though it has been demonstrated at the lab level.

It's not just about the best possible armor. It's about the best possible armor that fits the monetary, and the weight budgets; one that can withstand multiple hits, and that is sufficiently easy to replace/repair after a hit.

 

The next unknown is to which degree ammunition design changes can scale performance.

Shaped charges:

-- There is a linear scaling effect for HEAT with caliber. Double the caliber for a given design, and you get twice the penetration limit. That's a really terrible way to improve.

--  The other is to vary the liner materials; gold has been proven to be the best possible liner material due to its high density and extreme ductility. But obviously, it's not ideal from a cost perspective, so copper it is for 99% of all HEAT warheads.

--  Fluted cone designs have been tried, and while they offer a slight advantage, they are more costly to produce, so usually that's only done if there are no other options left.

--  The last bit that's left is precision manufacturing. Whether you get 3x the cone diameter in penetration from a HEAT warhead, or 6x the CD, is largely down to your ability to control the shape of the wavefront of the detonation that collapses the cone and forms the HEAT jet.

 

Kinetic energy:

In the early 1960s it was clear that subcaliber APDS rounds would offer the best growth potential. It was much less clear to which degree they could be successfully elongated. Just compare how German 120mm APFSDS rounds evoled from DM13 (1979) over time:

 

While elongated designs perforate deeper, they inflict less damage once through. But the biggest challenge is to create a sabot that is stiff enough to prevent oscillations from the gun fire so that the projectile doesn't break up after leaving the muzzle behind - and to ensure clean separation of projectile and sabot so that the projectile can fly undisturbed. Of course, you must not exceed certain outer dimensions of the cartridge, you want the mass of the sabot petals to be as small as possible (but carbon fiber composites are tricky because they can change their shape/diameter in moist air), ...

 

So, at the time when the armor was designed, it was not clear how far we, and how far the Soviets would come over the projected lifespan of these tanks (which were expected to be replaced by the mid 1990s anyway --- it's just that due to world events and an unexpectedly well-balanced design of the Leopard 2 and M1, we got away with keeping these machines in operation for three decades longer; this shall serve as a reminder that predicting the future very often replaces uncertainty with prediction error.