On some contradictions during the development and testing of the T-64 corundum turrets

Turrets with corundum (ultra-porcelain) balls are, without a doubt, the hallmark of the Kharkov “sixty-fours” - the only serial Soviet танк With ceramics in the armor, after all. With ceramics, which, in combination with steel, provided high protection with a relatively small size (armor thickness).

However, during the development and testing phase, corundum-filled turrets generated considerable controversy regarding their survivability under fire and their production technology, compared to, for example, aluminum fillers. This was stated in the conclusion of VNII-100 technical report No. 630746 on topic NV-12-208-63, "Improving the protective properties of serial and new tanks against modern weapons through the use of shielded and combined protection systems."

The document has no practical value today, of course. However, historical From this point of view, it is a very interesting thing, which is why we are publishing it here.

Conclusion on the technical report of VNII-100 No. 630746 on the topic NV-12-208-63 "Increasing the protective properties of serial and new tanks against modern weapons by using shielded and combined protection systems"

The report presents the results of theoretical and experimental studies of composite armor with an ultra-porcelain filler, and defines the design relationships between the filler and the armor shell, which, in the opinion of the authors, can ensure satisfactory resistance and survivability of the composite armor during shell fire.

A technology for manufacturing composite armor, taking into account the feasibility of mass production, was developed and tested under factory conditions. Calculated labor costs for manufacturing a variant of the "432" turret with ultra-porcelain and aluminum fillers are presented.

A sectional, spaced armor system for tank hull sides was developed and tested against shaped charge (HEAT). The relationship between the distance from the spaced armor to the main armor and the armor thickness was studied and experimentally confirmed.
Recommendations are given for the use of combined armor with ultra-porcelain filler and shielded systems in serial and prospective tanks.

Based on the work performed, the VNII-100 Branch considers it necessary to make the following comments:

I. A comparison of the protective thickness and weight savings of combined "steel + ultra-porcelain" and "steel + aluminum + steel" armor (p. 17) showed that the weight savings of combined "steel + aluminum + steel" armor with an aluminum content of up to 65% of the total protective thickness is higher than that of armor with ultra-porcelain. Numerous firings of combined armor with aluminum using 115-mm shaped-charge projectiles showed that at an impact angle of 35° or higher, a barrier consisting of 50 mm of cast armor, 320 mm of A-00 aluminum alloy (58%), and 180 mm of medium-hardness cast armor is not penetrated.

The weight savings of such combined armor compared to medium-hardness steel armor is ~35%, and the protective thickness is only 6-7% greater than the protective thickness of equally resistant steel armor (520 mm).

According to the data provided by the report's authors and the results of firing 115mm HEAT projectiles at the turret and sectors with ultra-porcelain balls, the protective thickness against a 115mm HEAT projectile with an ultra-porcelain content of approximately 57-60% should be approximately 560 mm. To ensure the turret's survivability against 100mm caliber armor-piercing projectiles with an impact velocity of 850-900 m/s, the thickness of the front steel layer should be at least 60 mm along the normal, and the rear layer should be at least 40 mm to protect against 115mm HEAT projectiles. Therefore, the minimum thickness of the front and rear steel layers at an impact angle of 0° should be 100 mm, and at an impact angle of 45°, 142 mm.

With ideal placement of 88 mm diameter coated balls (40 mm diameter balls are not recommended due to incomplete filling of the interlayer steel), the remaining volume is filled with balls to 69–70%, resulting in an average specific gravity of the middle layers of ~4,5 g/cm³. In this case, the ultra-porcelain, with a specific gravity of 3,0 g/cm³, accounts for only 57% of the total protective thickness of the composite armor.

Therefore, it is not possible to take advantage of the weight advantage of a steel + ultra-porcelain barrier over a steel + aluminum + steel composite armor. Composite armor, with 318 mm of ultra-porcelain (57%) and 242 mm of steel in the path of a shaped-charge jet, can, at best, provide a weight advantage of approximately 30%.

Given that up to 17 coil springs are installed between the balls, and the ultra-porcelain content in the upper sections of the turret is less than 57%, and given that the turret top is made of cast armor up to 60 mm thick, the weight savings will be significantly less than 30%. This conclusion is supported by the turret weight characteristics.

The aluminum-filled turret contains 840 kg of aluminum (specific gravity 2,65 g/cm³), while, according to KBTM data, only 740 kg of ultra-porcelain (specific gravity 3,0 g/cm³) could be placed in the ultra-porcelain turret. Thus, with an aluminum turret thickness of 600-560 mm along the flow path and an ultra-porcelain turret thickness of 550-570 mm, the ultra-porcelain turret is 400 kg heavier. It should be noted that ultra-porcelain balls were placed not only in the frontal and side sections, but also in the transition zone up to sections II and 17, which reduces the protective characteristics of the aluminum turret against penetrating radiation from a nuclear explosion by 20-25% in this zone compared to the aluminum turret, in which the aluminum is located only up to sections 9 and 19.

When a turret is constructed with 530 mm of ultra-porcelain filler along the HEAT stream, the turret's weight will exceed that of a turret with 560-600 mm of aluminum filler by 200-250 kg. However, reducing the protective thickness to 530 mm will result in an increased penetration rate for 115 mm HEAT rounds. Three penetrations were achieved out of 12 shots fired at a turret with a thickness of 550-570 mm. Therefore, even at 560 mm, the turret cannot be considered fully protected against a 115 mm HEAT round.

References to the results of beam tests, where penetrations were obtained at a thickness of 505–510 mm, while no such penetrations occurred at a thickness of 510–550 mm, are not convincing, since the performers do not provide the weight characteristics of these beams. Moreover, with a protective thickness of 510 mm, a sub-caliber projectile from the U-5TS cannon at an impact velocity of 1576 m/s formed a one-sided cut of the plug on the rear side with an extension of up to 5 mm. (Report of Military Unit 68054 No. 1757 dated December 4, 1963)

2. The section "Theoretical Analysis of the Resistance of Combined Armor with Ultra-Porcelain to the Penetration of Armor-Piercing Discarding Subcaliber and HEAT Projectiles" examines the issue of increasing the resistance of ultra-porcelain spheres encased in armor steel by compressing the ultra-porcelain spheres with the cooling steel. Based on calculations, it is concluded that the cooling metal shell compresses the spheres with a force of several thousand kg/cm².

Enclosing a brittle material in a tough, strong shell increases the resistance of both non-metallic and high-hardness steels due to the shell absorbing part of the load when a cumulative jet or projectile is introduced.

However, the calculation method does not take into account two important elements: the presence of a low-strength porous coating of ground chamotte and liquid glass 4–5 mm thick on the surface of the ball and the discontinuity of the metal shell—the skeleton—as a result of which the actual compression forces can be several tens of times less than those given by the authors of the report.

The report indicates that the survivability of the tower with ultra-porcelain is higher than that of the tower with aluminum.

When shelling the towers with aluminum, all reports from military unit 68054 indicated that the survivability of these towers was satisfactory.

A drawback of an aluminum turret is a slight bulge in the upper portion of the aluminum when an armor-piercing shell strikes the middle and upper portions of the turret. This drawback, which is not entirely justifiably considered a sign of reduced survivability, can be overcome by creating steel bridges between the turret canopy and the base and using a stronger aluminum alloy.

During the shelling of the turret with ultra-porcelain No. IA, four shots of sub-caliber shells were fired from the U-5TS cannon. A sub-caliber shell (shot No. 21) struck near target No. 9, causing a through-and-through armor breach measuring 350 x 150 mm. Similar hits (coincidences) occurred repeatedly on turrets (and sectors) with aluminum armor. However, no breaches, holes, or damage to the armor were observed (see military unit 68054 report No. 2499).

Features of the technology for casting towers with ultra-porcelain filler. The technology for placing ultra-porcelain balls in the casting involves installing spiral springs along the mold walls and the core. The size of these springs determines the thickness of the steel layers, and then filling (backfilling) the ultra-porcelain balls into the mold cavity. This method cannot be considered reliable, as the pouring and solidification of the liquid metal inevitably causes melting and deformation of the springs, made of 5 mm diameter wire made of grade ST 3 steel, which can cause the balls to shift within the mold cavity.

The presence of a large amount of metal reinforcement in the base metal of the tower should degrade the quality of the load-bearing steel layers and reduce their durability.

In addition, due to the small distance between the balls, in significant areas the gaps between the balls may not be filled with steel, which leads to a deterioration in the cumulative resistance.

To reduce liquid metal consumption, labor intensity, and metal consumption during machining of the tower's lower end, a previously untested option has been proposed: casting the tower with ultra-porcelain spheres roof-up. It is believed that the casting quality will be satisfactory.

The thickness of the normal sections in the lower part of the towers is 1,5–2,0 times greater than in the upper part, and therefore, despite the significant amount of metal reinforcement and ceramic balls in the mold cavity, it is extremely difficult to avoid casting defects (shrinkage cavities, looseness, etc.) both when pouring the mold from above and by siphon.

The authors' assertion that an aluminum tower cannot be cast roof-up is unfounded, as despite some difficulties in installing the cores that form the cavity for the aluminum core, directional solidification can be achieved by installing external coolers, selecting molding sand, and adjusting the thickness of certain sections. Therefore, it is easier to cast an aluminum tower roof-up than an ultra-porcelain tower.

Regarding the labor intensity of manufacturing towers with ultra-porcelain and aluminum fillers, only a rough comparison can be made, as ultra-porcelain towers are not in mass production. Rough calculations conducted by the VNII-100 branch at the Zhdanov Heavy Engineering Plant showed that by eliminating the process of measuring aluminum cavities and replacing aluminum master alloys with salts, the labor intensity of manufacturing an aluminum tower would be approximately 60 standard hours less than that of manufacturing an ultra-porcelain tower.

The VNII-100 branch believes that, to reach a sound conclusion on the feasibility of using turrets with ultra-porcelain filling, VNII-100 should be tasked with completing the design development of a turret for the 125mm D-81 system, which is currently underway jointly with the Malyshev Plant Design Bureau. The branch should also discuss the calculated weight and protection characteristics of the turrets with the VNII-100 branch and the 12th Directorate. Three turrets should be manufactured using these drawings for subsequent comparison of the actual weight characteristics and resistance to the weight and resistance of turrets with aluminum filling for the same system.

The VNII-100 branch will also present three towers for these tests, manufactured with the elimination or reduction of design flaws identified during state tests.

Comments

[Konnick]

For some reason, they didn't test the Armata with shelling... did they believe the word "the most invulnerable"?
The T-64 weighs 36 tons.... The Armata weighs 60 tons and is one and a half times larger in dimensions.
The conclusion is that if, using the T-64's armor technology, a tank with the same weight and dimensions as the Armata was made, its protection would be better than that of the Armata.

[Bad_gr]

Quote: Konnick

For some reason, the Armata was not tested by shelling...

Where did you get the information that they didn't test it? The more advanced and expensive Object 195 (T-95) had one completely destroyed, but the T-14 didn't?

Quote: Konnick

The conclusion is that if, using the T-64's armor technology, a tank with the same weight and dimensions as the Armata was made, its protection would be better than that of the Armata.

A highly questionable statement. The T-14 tank's exact weight is unknown, but 55 tons is commonly assumed. Its turret is likely lighter than the T-80's, as the main armor only covers the gun and sight, with the rest being protected by a spall shield (locators and sensors cannot be covered by the main armor). The tank is larger, but not by half; its dimensions have become comparable to those of the Abrams and Leopard.

[Alexandra]

Quote: Bad_gr

The tank is larger, but not one and a half times larger; its dimensions have become comparable to those of the Abrams and Leopard.

The Abrams has a very heavy turret. It's believed that the M1 tank's turret weighed approximately 19 tons, the M1A1 - 21 tons, the M1A1HA - 22-23 tons, the M1A2 - 24,4 tons, the M1A2 SEP v2 - ~25-26 tons, and the M1A2C - 28,6 tons.

It is believed that the T-72 tank turret weighed about 9 tons, T-72A - 10 tons, T-72B - 11,5 tons, T-72B3M - 13,5 tons, T-90 - 12 tons, T-90A - ~13,5 tons, T-90 14,5-15,5 tons.

It's clear that the T-14's turret is lightweight because it's unmanned. It's believed to weigh as much as the first T-72's turret, ~8-9 tons.

Due to this, the T-14 is approximately 18-20 tons lighter than the M1A2C.

[Sergey Tkach]

There was a recent article about the combined armor of a South Korean tank (using wood), also an interesting option.

[Alexandra]

Thus, with the thickness of the tower with aluminum being 600-560 mm along the flow path and the tower with ultra-porcelain being 550-570 mm, the tower with ultra-porcelain turns out to be 400 kg heavier.

All this petty squabbling with "400 kg lighter", "400 kg heavier", just to stay within the combat weight of 38-40 tons, from today's perspective, looks like a "mouse" fuss.

Because of this desire to keep the mass of tanks like the T-64 below 40 tons, a whole generation of Soviet tanks was born with a "neckline" on the upper hull plate, a lower hull plate that could be penetrated by anything, supposedly "covered by a screen of terrain," and a lower third of the hull side made of 20 mm armor that could be penetrated by large fragments of artillery shells.

There was no scientific justification for why the combat weight had to be less than 40 tons, or why it had to be less than 40 tons. It was simply "how the tank designer saw it."

[Melior]

This was a military requirement to be able to transport tanks on transport planes, so they fought seriously for every kilogram.

[Alexandra]

T-64 - 36 tons, 1963
T-64A - 38,5 tons, 1969
T-64B - 39 tons, 1976
T-72 (basic version) 41 tons, 1973
T-72A 41,5 tons, 1979
T-80 (basic version) 42 tons, 1976
T-80B 42,5 tons, 1978

For some reason, they fought for every kilogram only in the design bureau of the Kharkov plant.

PS An-22 60 tons, 1965. Total production in 1965-1973 was 40 aircraft. An-22A 80 tons, 1973. Total production in 1973-1976 was 28 aircraft.

Il-76 28 tons, 1973. Il-76M 42 tons, 1978. Il-76MD 48 tons, 1981.

[Ulysses]

"Why did the combat weight have to be less than 40 tons? Why less than 40 tons?" One of the reasons was the vehicle bridges.

[Alexandra]

The NG-60 standard for bridges (tracked vehicles weighing 60 tons) was introduced in the USSR in 1953 with the adoption of the “Standards for moving vertical loads for calculating artificial structures on highways” (N-106-53).

The T-10 heavy tank of various modifications (mainly the T-10M) with a combat weight of 50-51,5 tons was mass-produced from 1953 to 1966.

[Melior]

It's just that in the 60s, the concept changed: they abandoned the division of tanks into medium and heavy, and introduced the concept of a "main battle tank," which had the same firepower and protection requirements as a heavy tank, and the same weight as a medium tank. That's how we got what we got...

[Alexandra]

The concept may have changed, but Alexander Alexandrovich Morozov's desire to "fight for every kilogram" remained. The results of this pursuit of kilograms affected the entire generation of MBTs. The same "neckline" on the upper hull plate was only corrected on the Object 187, developed by the Ural Design Bureau of Transport Engineering in 1987. Unfortunately, the development and mass production of the new tank were not completed before the collapse of the USSR.

[Bad_gr]

Quote: AlexanderA

Unfortunately, they did not manage to complete the development and launch the new tank into serial production before the collapse of the USSR.

Object 187 was proposed to replace the T-90 tank, but its cost was not much lower than the T-80 tank, so they chose a cheaper option (according to Grachev) Object 188 (based on the T-72).

[Alexandra]

It is clear that the development of serial production of Object 187 would have cost significantly more than the development of serial production of the "17th modification of the Soviet T-72" (C) Commander-in-Chief of the Ground Forces from January 2010 to April 2012, Colonel General A.N. Postnikov.

During the catastrophic underfunding of the defense industry in the early 1990s, the launch of Object 187 into production was unrealistic. When it became a reality, money was spent on Object 195, Object 640, and so on, and later, on Object 148 of the T-14 "Armata."

This is a common situation. We haven't been able to switch from the rimless 7,62mm rifle cartridge to a more suitable rimless cartridge for automatic weapons since the 1920s, for about 100 years. And here, it's only been 1973.

After all, the Abrams, which the US Army has been unable to get rid of for almost a couple of decades now (the Future Combat Systems (FCS) program was closed in 2009), went into production in 1980.

[SUKRAM]

this may sound stupid to many, but what if the armor used fluids
there are substances that are called ..non Newtonian fluids
for example, if you put your hand into custard it will sink into it
stomp on it hard, and your hand will not go into it
so will it stop a bullet or a heat / hesh / tungsten round

has sort this of armor been tested or even thought of i wonder
there must be a Russian version some where, but this will show the principle
https://youtu.be/Iz9KnPZWOgs?t=176
https://duckduckgo.com/?t=lm&q=walking+on+custard+experiment&ia=videos&iax=videos