Saturday 30 March 2013

Oops (and a sneak preview)

Setting up a mass production of any part, especially during a war, is bound to have any few bugs. Fortunately, this one was quite reparable.

CAMD RF 38-11355-871

"The first 207 KV tanks produced with the new water cooling system were produced and shipped out to the front without screens on the pump. It will be difficult to use these tanks in the winter. We recommend that the required screens should be manufactured immediately and sent out with crews to locate these tanks. The numbers of the tanks and their addresses are attached."

Well, at least these tanks will be fine until winter. Kirov factory workers have done this sort of thing before, including catching up to a shipment of KV tanks and installing starters on them en route, due to a delayed shipment. 

Some well learned readers might know how KV-1 #11302 and #11306 were special. If not, you'll find out on Tuesday.


You may have noticed new tabs appear on top of the page. Those are newly introduced categories, in an effort to organize content in a more accessible way than the flat tag system. The categories are as follows:

World of Tanks History Section: list of articles translated from the Russian World of Tanks website.
Battles: list of articles describing battles or fragments of battles on all fronts of WWII and precursor conflicts.
What May Have Been: prototypes, proposals, requests for tender, etc.
Lend-Lease Impressions: a list of articles that deals with vehicles and equipment supplied to the USSR via Lend-Lease.
Through the Eyes of the Enemy: a list of articles that deals with vehicles, equipment, and documents captured or supplied through the pre-war KaMa program. This section also includes intelligence reports.
Self-Reflection: a list of articles dealing with vehicles and equipment mass-produced by the USSR.

Since most articles cover more than one topic, they will appear multiple times in several categories.

World of Tanks History Section: Rheinmetall Leichttraktor

At the end of WWI, Germany ended up on the losing side, tied by harsh sanctions. Reichswehr was heavily limited, losing 90% of its heavy armament, but never lost all of it. In 1919-21, Germany was engulfed in a revolutionary spirit. In order to prevent the fall of the Wiemar Republic, a commission of allied countries allowed Germany to have a small amount of armoured cars, up to 150 in total. The situation with tanks was more difficult. After quelling the Berlin uprising, Germany was forced to destroy its A7V and captures MkIV tanks, as well as prototypes of the K-Wagen "Kolossal" and light LK-I and LK-II.

In early 1919, Germany made an agreement with Hungary, in which they built 14 LK-II tanks. Another batch of LK-II tanks was build for Sweden. The deal was made by the Steffen & Heyman company. Sweden also received German specialists to help with assembly. The LK-IIs were accepted into service under the name Stridsvagn m/21. In the early 1930s, they underwent modernization, and remained in service until 1941. With this, tank building in Germany stopped for some time. However, the Germans not only retained their experience, but managed to obtain some novelties from their former adversaries.

Work on a light tank, designated VK 31 (called Kleintraktor, or small tractor, for secrecy), started two years after the heavy Grosstraktor. This project was launched by the Reichswehr, on March 28, 1928, by announcing a request for tender for a tracked combat vehicle up to 12 tons in weight. Prototypes were to be constructed by 1930 and cost less than 50 000 Reichsmarks. The winner would receive an order for at least 17 tanks.

The request was delivered to three companies: Daimler-Benz, Krupp, and Rheinmetall-Borsig in May of 1928. By that time, the weight requirement was lowered to 7.5 tons. Additional requirements included 14 mm of front and side armour and a crew of 4. The armament of the Light Tractor was to be a 37 mm semi-auto gun and a 7.92 mm Dreyse machine gun. The tank also had to have a radio to provide voice communication with a range of 2-3 km and a telegraph for 7 km. Chemical protection was also required, in case of a gas attack. Maximum highway speed was 25-30 kph (40 kph by some sources), and 20 kph off-road.

Daimler-Benz refused to participate, leaving Krupp and Rheinmetall-Borsig in the competition. Both companies developed a "Kleintraktor" (renamed "Leichttraktor", or light tractor) together, and their results were very similar. Not having much experience with tank suspensions, Rheinmetall engineers used the tracks from a tow tractor. Each side had 12 road wheels, two wheels per bogey, one tension idler, and two support idlers, a front directing, and a rear leading wheel. In order to protect this system, a side screen was retained, with three openings to clean the mud out of the suspension. The hull was a combination of welded and bolted, from armoured steel 4-10 mm thick. The layout was inherited from a tractor. The front, which had the transmission, also housed a Daimler-Benz M36 carburator engine, 36 hp in power. The middle part had the control compartment (the driver sat on the left side). The driver had a small rectangular turret with vision ports above his head.

Krupp engineers did not trust tractors, and built their own chassis. Krupp's vehicle was slightly longer and taller, which allowed two hatches on the side for entrance and evacuation. The Krupp tank had 6 small diameter road wheels per side, with a vertical spring suspension, grouped in two groups of three, with the front-most and rear-most wheels slightly larger than the others. There were also two idlers, a front directing, and a rear leading wheel. Rheinmetall was responsible for both turrets. All VK 31s had radio stations.

The Soviet Union took a large part in creating Germany's tank army. A treaty on the creation of a Soviet-German tank school in Kazan was signed in Moscow, in 1926. It was headed by the Reichswehr colonel Malbrandt, whose name led to the project being codenamed KaMa (Kazan-Malbrandt). All four light tank prototypes were shipped here, numbered 37 and 38 (Krupp), 39 and 40 (Rheinmetall). The Special Technical Commission (TEKO), created to exchange experience in the area of tank building, began its work.

By 1933, each prototype traveled from 1660 to 1865 km. Soviet specialists agreed that these vehicles are not of any interest to the RKKA. However, Soviet engineers were interested in the suspension and the turret layout (namely the coaxial machine gun), as well as the tanks' radios. German specialists were not in awe of their vehicle either. Further modernization and up-armouring was not possible without increasing weight, and reducing the already unimpressive mobility of the tanks.

All four Leichttraktors were shipped back to Germany in 1933, when KaMa was closed down. In 1934, the tanks were moved to Munster for the winter. From 1935 to the start of WWII, they were used as training vehicles in Pultos.

Original article available here.

Thursday 28 March 2013

GABTU's Answers to the Tiger

In 1943, Tigers were deployed in sufficient numbers to become a nuisance to the Red Army. The Head Armour and Tank Directorate (GABTU) issued a set of requirements to increase effectiveness against heavily armoured tanks.

CAMD RF 38-11355-1380

"On the subject of combating German heavy tanks, the State Committee of Defense has established that:
  1. NKV (comrade Ustinov), GAU KA (comrade Yakovlev), head of the TsAKB (comrade Grabin), director of factory #8 (comrade Fradkin), and the head engineer of factory #8 (comrade Sandler) must:
    1. Increase the penetration of the 85 mm tank gun, such that it penetrates 100-110 mm of armour at 2000 meters. Present a prototype to the Kirov factory by June 15th, 1943.
    2. Design and manufacture a 100 mm tank gun with a two piece shell that can penetrate 120-130 mm of armour at 2000 meters.
  2. The People's Commissariat of Munitions (comrade Vannikov) and GAU KA (comrade Yakovlev) must:
    1. Shortly, no later than June 1st, 1943, begin the manufacture of 57 mm HE shells.
    2. Shortly, no later than June 1st, 1943, design a new AP shell for the 76 mm F-34 gun that can penetrate the side of a Tiger tank at 600 meters.
    3. Shortly, no later than June 15th, 1943, develop a subcaliber round for the 76 mm F-34 gun, capable of penetrating the front of a Tiger tank at 500 meters.
  3. The People's Commissariat of Tank Manufacture (comrade Zaltsmann) must:
    1. Starting on May 15th, 1943, install a 57 mm tank gun (ZiS-4) on 2-3 out of 10 T-34 tanks.
    2. By June 1st, 1943, build 3 prototypes of a self propelled 57 mm gun on the T-70 chassis (SU-57). The prototypes will be tested by the GAU KA in ten days from their arrival, and the result will be delivered to the GSKO.
    3. By June 1943, develop a tank destroyer on the SU-152 chassis armed with a 122 mm gun model 1931, and manufacture an equal number of these new TDs as the SU-152.
    4. By July 1st, 1943, develop a tank destroyer on the T-34 chassis with an 85 mm tank gun (SU-85) with a rear fighting compartment, like the SU-76."
Quite a number of requirements! Let's go through them one by one.

Factory #8 is tasked with developing new 85 and 100 mm guns. The experimental high power 85 mm gun in a penetration table from 1944 penetrates 89 mm at 2000 m. Not quite there. The existing 85 mm gun was quite effective against Tigers, so it's understandable that the high power gun was not deployed. As for the 100 mm gun, the D-10 is capable of penetrating 125 mm of armour at 2000 meters. This requirement was met.

57 mm HE shells? Against a Tiger? Well, of course not. The 57 mm HE shells were meant to make the T-34-57 (which the Soviets had since 1941, but didn't really see an opponent worthy of their high penetration guns) into a platform as versatile as the T-34-76, useful against both infantry and tanks. Since T-34-57s were built in very small numbers, it's safe to assume that even if Vannikov and Yakovlev were successful, their efforts were in vain. 

As for effectiveness against a Tiger from the side at 600 meters, the engineers only managed to ensure effectiveness at 500 meters. Many efforts to develop a viable subcaliber 76 mm shell were made, but the same penetration table only gives 92 mm of "guaranteed" penetration. I guess that number would be around 100 for "initial" penetration, so that's another checkmark. 

As I mentioned before, there was a very small numbers of T-34-57s developed, and even fewer saw combat, so the 20-30% figure was not achieved. However, since T-34-85s rolled off the assembly lines, 100% of T-34s were able to face a Tiger at long range, instead of 30%.

A SU-76 with a semi-automatic 57 mm gun was requested, and may have even been tested, but not deployed. The SU-76 was effective against infantry first, and tanks second, and a 57 mm gun would jeopardize that. The SU-57 index ended up assigned to an American Lend-Lease halftrack that mounted a 57 mm gun.

A SU-152 with an A-19 gun was never fielded, but the ISU-122 was the same thing, but on the ISU-152 chassis.

The SU-85 was, of course, mass produced, but not with a rear fighting compartment. Engineers chose the more proven design of the SU-122, with a front fighting compartment. The same design was used for the SU-100, with the aforementioned 100 mm gun. 

Tuesday 26 March 2013

World of Tanks History Section: Jagdpanzer 38(t) Hetzer

In November 1943, Allied aviation bombed the Alkett factories in Marienfeld. These factories were one of the most important producers of self propelled guns in Germany. The Wehrmacht's demand for vehicles of this type was in danger of going unfulfilled. This was partially covered by Krupp producing a vehicle with the StuG casemate and PzIV chassis, but he alone could not satisfy the demand. Additionally, these tanks were expensive, and their chassis was used by other tanks that were also needed.

The Germans decided to set up additional manufacturing in Czechoslovakia, which was nearly unbombed. The VMM factories in Prague already repaired German SPGs, so retooling them for building StuGs didn't seem like such a bad idea. However, when specialists analyzed the situation, it was clear that such a swap would not be possible in a short amount of time.

In 1943, Heinz Guderian, chief inspector of the tank forces, proposed that a light tank destroyer with at least a 75 mm gun be developed. Germany already had vehicles like these, the Marder and the Bison, but they were more self propelled carriages for the guns, with not much armour or survivability. The Wehrmacht needed a full fledged TD, with a proper armoured hull.

Something like this was proposed by VMM engineers in October of 1943, but it did not cause much interest back then. Now, they had the opportunity to blow off the dust and finish what they started. The order came in to VMM late November of 1943. On December 17th, the commission from the Armament Directorate received project documents and two wooden models with different armament and suspensions. The commission chose "Solomon's solution" and ordered a combination of the best parts of the two projects be made. The new TD received the chassis from the PzKpfw 38(t) light tank, 75 mm gun PaK 39 L/48, and a closed casemate with sloped armour plates. Starting on December 4th, 1944, the TD was nicknamed Hetzer (hunter).

The Hetzer was the first Czech vehicle with welded armour. This halved the time needed to make it. The armour thickness varied greatly. The front was 60 mm, but the sides and rear were only 20 mm. The Hetzer's armour protected it from bullets, shrapnel, and AT guns up to 45 mm in caliber. The hull was air-tight. The crew climbed in through hatches on top. According to memoirs, the ventilation was poor, and it very hot inside the tank during the summer.

Many claim that Soviet tanks were "blind", but the Hetzer was no beter. On first Hetzers, the observation devices could only be used when the hatches were open. If the hatches were closed, it was not possible to look right. This problem was tackled by adding more observation devices for the commander, but the deadzone on the right was never fully removed.

The Hetzer was very compact, only 4.8 meters in length (not counting the gun) and 2.1 meters in height. The 75 mm gun only fit in such a small hull due to a special universal joint developed by K. Stolberg. Ironically, this joint was developed in 1942. The Germans claimed that it could never work. However, after finding it in Soviet TDs (SU-76I, SU-85, SU-152), this solution was used on the Hetzer, JagdPzIV and Jagdpanther.

The Hetzer was a very agile vehicle. It accelerated to 40 kph with no problems. A well trained driver on a well maintained Hetzer could reach even higher speeds. Soviet test crews accelerated a captured Hetzer to 50 kph. The gas tank lasted for 190 km.

The Hetzer was mass produced in April of 1944. The design was modernized almost immediately. The tracks were widened to improve cross-country performance. The engine was improved by increasing its RPM. In order to simplify removing the engine and transmission, the Hetzer was modified to mount a 2-ton crane. Attempts to improve visibility were mentioned earlier. Command, engineering, and flamethrower modifications of the Hetzer were produced. The flamethrower modifications were used in the Ardennes forest on the Western front and at lake Balaton in the East. The combat performance was deemed unsatisfactory. The engineering modification attempted to mount a 150 mm gun. 24 large caliber Hetzers were made.

The Hetzer resembled Soviet tanks with its simplicity and effectiveness. No aces fought in these vehicles. Crews were formed from personnel with very basic combat and technical training. Hetzers were placed in infantry AT squads, grenadier and cavalry units. The crew reviews were largely positive. The Hetzer was praised for its small size, agility, simplicity, and reliability. The gun also performed well. Soviet soldiers commented on its small silhouette  and its ability to suddenly appear, and disappear. The Hetzer's shape earned it a number of nicknames: "flea", "chisel", "ax", "coffin", and, for some reason, "whistle".

The Hetzers stayed in production until May of 1945. During WWII, it was used by the Hungarians, as well as the Germans. During the Warsaw uprising on October 2nd, 1944, Krajow's army captured one Hetzer, and used it against the Germans. During the Prague uprising in 1945, these vehicles were used by the Czechs as well.

Summing up all the information on this project, the Hetzer was a pretty good vehicle. It was used after WWII as well as during. Until 1970, the Swiss army used Hetzers under the index G-13. Most Hetzers that exist today are Swiss G-13s that were cosmetically modified to more closely resemble its German ancestor.

There are 9 authentic Hetzers left worldwide.

Original article available here.

Note: historical scholarship indicates that "Hetzer" is a post-war name. In various documents from 1944 and 1945, the TD in question is referred to as "G-13" or "Jagdpanzer 38(t)". 

Sunday 24 March 2013

Soviet 85 mm Guns vs Tigers

When the Germans encountered the thick armour of Matildas at Arras, they lowered their 88 mm FlaK guns and used them to engage the British tanks. When faced with the Tiger's thick armour, the Soviets did the same. The AA gun chosen for this task was the 85 mm anti-aircraft gun model 1939. Let's see how well it worked against a Tiger.

"Target: side. Distance: 800 m. Result: penetration, breach size 350 mm by 230 mm.
Target: side. Distance: 1450 m. Result: penetration, breach entrance diameter 110 mm, exit diameter 380 mm. A fragment 700 mm by 92 mm by 82 mm was knocked off. Cracks 220 mm, 200 mm, and 180 mm in length developed."

Some pretty catastrophic spalling going on here. Recall that the T-34-76 had to close in to 500 meters to even have a chance of damaging a Tiger tank, even from the side. 

"Target: side. Distance: 1450 meters. Result: penetration, breach diameter 115 mm.
Target: lower front. Distance: 1000 meters. Result: penetration. Entrance diameter 150 mm, exit diameter 160 mm. An armour fragment 230 mm in diameter broke off on the inside. Three cracks, 300 mm long, developed. The welding seam is destroyed." 

More catastrophic spalling, this time in the front. More welding seams giving in under pressure. The testers then got optimistic, and moved out to 1500 meters.

"Target: upper front. Distance: 1500 meters. Result: dent 30 mm deep, 120 mm in diameter. Bump on the inside.
Target: lower front. Distance: 1500 meters. Result: the plate cracked from previous impacts by the 85 mm gun. Two pieces broke off: 500 mm by 240 mm and 800 mm by 200 mm."

The Tiger's overhardened armour cracks and falls apart after two hits to the lower front plate. A bit disappointing for a tank that has been made out to be invincible. 

"Conclusion: the armour piercing shell can penetrate the side of the Tiger tank, 82 mm thick, from 1500 meters, and the front, 100 mm thick, from 1000 meters."

These are certainly some excellent results. They appear to be confirmed in practice, since a Red Army document on tactics of Tiger combat notes that it can be penetrated from the front at 1000 meters, and from the side at 1450 meters. It is not surprising that an 85 mm gun with similar ballistics was placed first in the SU-85, then in a T-34, to make a dangerous enemy for any German tank.

Now, let's take a look at tests against the Tiger II. The D-5 gun is used in these, mounted on the SU-85 tank destroyer.

"Shot # 22. Target: upper front plate. Distance: 300 m. Result: dent, 200 mm by 125 mm, 50 mm deep (including remains of the shell that welded itself to the armour). A fragment broke off the other side of the armour, 300 mm by 250 mm, 85 mm thick."

As with a lot of shots at the Tiger II, even when the shell does not penetrate, the spalling takes care of the crew and internal components anyway.

For shots from the side, the data is presented in a different report (from which there is only a table in the summary report). From that table, the following conclusions are made:

"The AP shell from the domestic gun D-5-S penetrates: 
  • the side of the hull from 1350 meters
  • the over-track hull from 800 meters
  • turret side from 800-1000 meters"
A T-34-85 fought several Tiger IIs from the s.Pz.Abt 501 at Ogledow. There were supposed to be 45 of these new tanks, but only 8 made the 45 km march. Oskin's T-34-85 destroyed 3 of the Tiger IIs in that battle. One of the tanks that was captured at Ogledow intact was the one that served as a test subject in the Tiger II penetration report. 

Friday 22 March 2013

Artillery T-34

Previously, I wrote about an 85 mm gun installed in a T-34-76, but it turns out that 85 mm wasn't the largest caliber intended for the tank. The Directorate of Mortar Armament wanted to install 120 and 240 mm guns!

CAMD RF 38-11355-190

"NII #13 sent you a schematic of a 120 mm mortar to be installed in a T-34 tank. In the same letter, the Institute requests a T-34 tank to test the mortar in. Additionally, the Special Construction Bureau of the Uhtomsk factory requests blueprints of the T-34 and a T-34 tank to develop and test a 240 mm mortar for it.

Please respond with the decisions made and orders issued regarding these letters."

Yuri Pasholok further writes that the 120 mm mortar was to be placed in place of the F-34, using the same recoil mechanisms. 

Another project involves a 152 mm mortar in the T-34.

CAMD RF 38-11355-190

"1. The 152 mm mortar in a T-34 is intended to combat enemy infantry, positioned behind cover, hardpoints, or ground-wood fortifications of the enemy. 

2. Combat and tactical characteristics of the 152 mm mortar installed in a T-34:
a) maximum range: 1200 meters
b) minimum range: at most 300 meters
c) rate of fire: 2-3 RPM
d) number of charges: 1

3. The ammo rack must fit at least 25 shells.

4. The accuracy must provide the following groupings at 500-600 meters:
1) 1/100 forward and backward
2) 1/200 side to side

5. The artillery system must provide:
a) convenience during loading, aiming, firing, and unloading.
b) convenience during disassembly, assembly, and cleaning.

6. A maintenance kit must be developed for this system, as well as cases for it.

7. The aiming sight must be from an existing tank artillery system.

8. The sight must provide:
a) safety and convenience for the gunner.
b) reliability of its attachment and calibration during firing.
c) ability to aim the mortar in full rotation. 
d) the ability to check your line of fire in field conditions without complicated devices.

9. In development of this system, use the following:
a) barrel with a breach and firing mechanism from the 152 mortar model 1931. The propellant charge must be recalculated to provide (with one charge) firing distances from 300 to 1200 meters.

b) anti-recoil mechanisms, and mechanisms of horizontal and vertical aiming currently used on the T-34.

c) use the existing shell from the 152 mm mortar.

10. The artillery system must be serviced by no more than two crew members."

The model 1931 mortar was previously used in the SU-5 SPG, but the T-26 chassis was deemed too weak for a gun of that caliber. It seems that the T-34 chassis was an answer to the artillery engineers' needs, but the only mass produced artillery piece to ever arise from that was the SU-122, an M-30 howitzer in a turretless hull. 

Thursday 21 March 2013

World of Tanks History Section: StuG III

Along with millions of people, WWI killed old war tactics. In the most cruel war to date, the best engineers in the world created new weapons, for a new war. One of the questions that had to be addressed was the relationship between artillery and infantry.

When advancing, infantry takes heavy losses. They need artillery to crush the enemy's defenses. Towed guns cannot keep up, as they are not mobile enough. WWI saw the first self propelled guns: cannons on tractor chassis, in trucks, or on tracks, moved by electrical actuators. The agility of the latter kind was questionable, but good enough for the war that was being fought.

In 1935, Erich von Manstein sent a memo to General Beck, describing the necessity of creating self propelled guns, protected by armour, and capable of knocking out enemy hardpoints. These guns should also be capable of dealing with enemy tanks. These guns were not meant to fight alone, or in mass formations, but in platoons. This memo was the start of a new type of mechanized forces: assault guns.

There was no consensus about what to do with this idea. Opposition (including Heinz Guderian) insisted that tanks can support infantry just fine. The German PzIV tank had a gun just for that purpose. Unlike an SPG, it had a turret, allowing it to shoot in all directions. After considering all pros and cons, the Germans high command decided to develop an armoured vehicle for infantry support. The vehicle was the responsibility of Daimler-Benz, and Krupp was going to make the 75 mm gun.

In July of 1937, five experimental vehicles left the factories. They had a modified PzIII chassis, with a 75 mm gun in a closed, low profile casemate. There were no machine guns on this first iteration. The vehicle had a low profile and good armour, but a poor engine, allowing it to only reach 25 kph. However, that was enough at the time.

The first vehicles were not meant for combat use. The hulls were made from mild steel. After tests at Kummersdorf, these vehicles were transferred to an artillery school, where they were used until 1941.

In 1940, after several modifications, Daimler-Benz released the first batch of new vehicles. These tanks had a new engine, 50 mm of front armour, and an improved suspension. They were named "7.5 cm Sturmgeschutz III Ausf A", or StuG III for short. In just over a month, these tanks would fight in France. At the end of the campaign, they received the highest of praises from their commanders and crews.

Convinced of the StuG's effectiveness, the Wehrmacht ordered to move the production from DB's overloaded factories to Alkett. Production was increased to 30 vehicles per month. In 1940, 184 StuGs were produced, and 584 in 1941.

The StuG III became the most numerous assault gun in WWII. 10 500 were produced. Aside from being very effective in combat, the StuG was also cheaper than the PzIII, let alone the PzIV. The PzIII cost around 105 000 marks, while the StuG cost only 82 500.

In 1942, the StuG got a new long barreled 75 mm gun. This modification turned an effective assault gun into an effective tank destroyer. The StuG became the main anti-tank weapon of the German army, surrendering the role of infantry support to the StuH 42, developed on the same chassis with a more powerful howitzer.

Like all German tanks released over a long period of time, the StuG underwent many modifications and modernizations in order to increase its combat effectiveness. Eight revisions of the StuG III were manufactured.

As the Germans faced more and more perfected vehicles, the StuG was improved in turn. The short barreled 75 mm gun was ineffective against T-34s, let alone KV-1 and KV-2s. This was the cause of the aforementioned gun upgrade. Later, an even more powerful gun was needed.

Along with new main guns, the StuG also got a machine gun. The StuG's enemy was not always a tank, and an infantry escort was not always available. The assault gun was extremely vulnerable to infantry in close quarters. Starting with Ausf E, the StuG had a machine gun on the roof, protected by an armoured shield. It had a limited traverse, but it was better than nothing. The Ausf F had a remote controlled machine gun that could rotate fully, which saved the lives of many German tankers.

Some of the StuG's modernizations had unfortunate side effects. While trying to make the vehicle as protected as possible, German engineers increased the thickness of the armour and added anti-HEAT screens, increasing the mass of the vehicle and making it slower and more sluggish.

The biography of the StuG has many glorious pages. Near Stalingrad, Kurt Pfrendtner's StuG destroyed 9 tanks in 20 minutes. In the battles for Demyansk, Horst Naumann's crew destroyed 12 vehicles in 3 days. The most famous StuG ace was Walther Knipp. From July 1943 to January 1944, his division destroyed 129 Soviet tanks. Finnish aces Berie Brotel and Erkki Halonen also fought in StuGs.

After the end of WWII, the StuG remained in the Romanian, Spanish, Egyptian, and Syrian armies, further proving the effectiveness of this fantastic vehicle.

Original article available here.

Wednesday 20 March 2013

BL-8 High Power 152 mm Gun

As we already determined, the 152 mm ML-20 howitzer was very effective against German tanks. However, after the Ferdinand's arrival on the battlefield, the Red Army started looking into guns with exceptionally high penetration. The most powerful gun they had at the time was the 152 mm BR-2 Model 1935. This gun was already tested in the experimental SU-14. A gun with identical ballistics, the BL-7 (OBM-43), was developed by the Special Design Bureau # 172. After refinements, the gun was indexed BL-8, and installed in the ISU-152 SPG, designated ISU-152-1. Let's take a closer look at the gun.



This was quite a massive gun. The long barrel accelerated 43 kg 152 mm shells to about 900 meters per second. As for its destructive power, I will let these photographs speak for themselves. (Source: CAMD RF 38-11369-304). 

150 mm plate. Shots 1-4 were fired at a 30 degree angle. Shots 5 and 6 at 0 degrees.

180 mm plate. Shots 9-12 fired at 0 degrees. Photo #5 shows the front of the plate, photo #6 shows the rear. 

 203 mm plate. Shots 13-16 fired at 0 degrees. Photo #9 shows the front of the plate, photo #10 shows the rear.

As devastating as the BL-8 was, the design did not satisfy the RKKA. Work on a powerful gun continued, and the BL-8 was further improved to become the BL-10 (the BL-9 index was taken by a 122 mm gun). The BL-10 was mounted on the ISU-152-2, also called the ISU-152BM or ISU-152-10. By that time, the war was coming to an end, the Germanic gigantism proved to be containable with the D-25 gun, and work on a high power gun of a large caliber ceased.

ISU-152 with a BL-9 (OBM-50) on top and a BL-10 (OBM-53) gun on the bottom. 
CAMD RF 81-12038-268

A number of these guns were produced throughout the development process. You can currently find a BL-7 gun marked #4 in the Armed Forces Museum in Kazakhstan.

Tuesday 19 March 2013

World of Tanks History Section: ISU-152

At the start of the Great Patriotic War, the KV tank was a menacing opponent for the Wehrmacht's armoured forces. However, it lacked modernization potential, and was scheduled to be removed from production in 1943. It was meant to be replaced by the IS. There was one problem, however. The KV chassis served as a basis for the SU-152 heavy SPG, desperately needed by the army. In July of 1943, the construction bureau of the Chelyabinsk factory, led by Joseph Kotin, began work on a new SPG.

The new vehicle was based on the IS. The technical requirements for this project were: 100 mm of front armour, the same 152 mm gun, addition of a machine gun, improved optics, and improved ventilation. The designers were given until July of 1943, but finished much earlier. Mere weeks were spent on creating the blueprints. At the beginning of July, a prototype started construction, designated IS-152.

Various historians place the demonstration of the prototype vehicles on either July 31st or August 31st of 1943, on the Ivanovskaya Square in the Kremlin. Stalin, Beria, Molotov, Voroshilov, all came to familiarize themselves with this new vehicle. In order to guarantee the security of these important persons, all crew members were replaced with NKVD staff, excluding the driver. Stalin, very interested in the new SPG, decided to examine it closely. Looking inside the IS-152, Stalin asked if the problem with poor ventilation was solved. Obviously, the NKVD crewmen could not answer the question, since they were not very well learned in armoured vehicles. The driver piped up in time to report to Stalin that there is an additional fan installed to clear the crew compartment of gases. Satisfied, Stalin cleared the new vehicle, and it was accepted by the State Committee of Defense in November of 1943.

By that time, the first prototype of the SPG, given the name "Object 241", was undergoing field and factory testing. This vehicle became the template for the production SPG. The new vehicle saw combat under the name ISU-152. The design of the tank combines the existing solutions from the IS and SU-152 SPG.

The tank gave the ISU-152 its suspension: the same six paired road wheels, the same rear drive wheel, the torsion bars. The SU-152 gave its ML-20S model 1937/43 howitzer. The 152 mm gun was equipped with AP and HE rounds. When necessary, the SPG could be equipped with concrete piercing shells, for the destruction of fortifications. The single loader of the ISU-152 had a hard time moving around 40 kilogram shells.

The SPG had a diesel V-2-IS engine, with 520 hp. With it, the vehicle achieved road speeds of up to 35 kph and 10-15 kph off-road. It didn't need to set any speed records; the vehicle was not made for rapid marches.

The production of the ISU-152 started in November of 1943. The new SPG was very similar to its predecessor, and production speed was high enough that only one month was required to form the first heavy SPG regiment of ISU-152s. By the spring of 1944, the ability to produce the hull surpassed the ability to produce the gun. Surplus hulls were armed with a 122 mm gun. This gave birth to another heavy SPG, the ISU-122.

First seeing combat in the spring of 1944, the ISU-152 proved itself to be an effective and universal weapon. They were used as an assault gun, supporting tanks and infantry, and as tank destroyers. There were also instances of the ISU-152 firing indirectly from rear positions, but this was not widely done for two reasons. The gun elevation angle was not large, and the SPG could only fire in a very flat arc. Secondly, it had a small ammo rack, only 21 shells. Extra shells had to be placed near the SPG, and then, once the ammo rack ran dry, replenish it, which took about an hour. Alternatively, the shells could be handed to the loader one by one, further reducing the ISU-152's already non-exceptional rate of fire, resulting in lower effectiveness.

The separate loading process of the gun was a large weakness, due to which the ISU-152 could not be a very effective tank destroyer. However, it still earned the reputation of a feared opponent. In the Red Army, it was nicknamed Zveroboy (beast-slayer, hunter). The Germans called it Dosenöffner (can opener).

An example of the ISU-152's effectiveness can be seen in the battle of Katukov's 1st Guards Army near Nizhnuv Place in the Transcarpatians. The Germans, with 40 Panther tanks, penetrated the Soviet defenses and threatened the city of Chernovtsy, encircling Katukov's forces. In order to prevent this, a regiment of ISU-152s, deployed on a hill in the most likely direction of attack, spent several hours fighting the advancing Germans. In the end, the Germans retreated, leaving behind 30 tanks.

The SPGs also behaved very well in city battles. Powerful HE-fragmentation shells allowed liquidation of a dug-in enemy with only one shot. In order to protect the vehicle from Panzerfausts, ISU-152s were often used as a part of assault groups, with an infantry escort.

With all of its advantages, the ISU-152 had some disadvantages. The extra vent that Stalin was so interested in did not completely solve the problem of gas concentration. At peak rate of fire, it was hard to breathe inside the vehicle.

The loader's work was very difficult, with him having to move heavy shells by hand, in a relatively cramped space. The panoramic sight was inconveniently placed, making it difficult to aim at targets past 900 meters. The internal gas tanks increased the risk of the crew going up in flames along with the tank, or blowing up the gunpowder gases in case of a fire. Thankfully, according to documentation, it was very easy to put out fires on the ISU-152.

Even all those disadvantages did not overcome the positive qualities of the SPG. The ISU-152 remained a part of the Soviet Army for a very long time. The last time it saw battle was during the Hungarian Uprising in 1956. The commanders of the first stage of the operation did not show their best side, and about 10 ISU-152s were lost to incendiary bottles. The exact figures are still unknown. After that, the ISU-152 saw no more combat, but was used in training.

The last ISU-152s were decommissioned by the Soviet Army in 1972.

Original article available here.

Sunday 17 March 2013

IS-2 vs Ferdinand

My previous article talked about the effects of the IS-2's gun on various German tanks. However, a popular character, the Ferdinand, is missing. This article is going to remedy that.

"Photo #35. Front of the assault gun "Ferdinand" hit by a 122 mm shell. The first armour plate, 100 mm in thickness was penetrated. The shell ricocheted from the second plate. Distance: 1400 meters.

Photo #36. Turret of the assault gun "Ferdinand" hit by 122 mm shells.
1. Dent 100 mm deep, a bump formed on the other side. Armour thickness here is 200 mm.
2. Penetration, the shell is stuck. Armour thickness here is 150-180 mm. Distance: 1400 meters."

The Ferdinand is a formidable opponent, even for the powerful D-25 gun. However, we see the flaw in Soviet penetration metrics. The shell that penetrated the Ferdinand penetrated the armour, and produced spalling that would have killed the crew. And yet, the shell itself is stuck in the armour. This does not count as a penetration by Soviet standards. If you look at the table of penetrations, the IS-2, theoretically, cannot penetrate this much armour.

Let's see how these test results apply to real life. An IS-2 from the 71st Guards Heavy Tank Regiment of the 3rd Guards Tank Army encountered a Ferdinand belonging to the s.Pz.Jg.Abt 653 on July 22nd, 1944, near the city of Magerov. From the report:

"At 13:30, the regiment received a new objective: the 53rd Guards Tank Brigade was to move toward Nogortse, Veryny, Turnnko, Dobrosin, Magerov, Shezehts, Yavorov, and must be ready to deflect a counter-attack from the Zhulkev and Nemirov direction.

In the region of Nogortse and Turnnko, about 15-20 km in the march, the terrain became extraordinarily difficult for heavy tanks, due to a large amount of swamps, lowlands, and completely destroyed roads. Due to this, the regiment crossed this section all night, and only made it to the highway at Dobrosin in the morning.
Moving forward, elements of the brigade were ambushed next to Magerov. Without engaging, the attacking forces were ordered to go around Magerov from the North-East, and regroup at their original destination 3 km away from Magerov. At the same time, a platoon from Ryzhinkiy's tank company, acting with the 53rd Tank Brigade, was ordered to destroy the ambush, and clear the road to Nemirov.

Lieutenant Slunayev's tank, under the cover of another tank, moved to the crossroads north of Shestaki, and observed the enemy ambush for 10-15 minutes. It was thoroughly camouflaged on the clearing in the forest south of Borki. After detecting all threats, Slunayev's tank opened fire from 1000 meters, and destroyed it in several shots. As a result, a Ferdinand SPG and an APC were burned, along with 2 guns. The path to Magerov was open."

Friday 15 March 2013

PaK 41 Squeezebore Gun

In August 1942, Soviet successes in the Rzhev direction led to the capture of a number of trophies, including a PaK 41 squeezebore gun. On October 29th, it was tested in the Gorohovets artillery proving grounds. Only 3 shells were captured, however, so the results are somewhat limited.

CAMD RF 81-12038-54

"Due to a lack of homogenous armour plates 120 mm thick at the Gorohovets artillery proving grounds, it was decided to shoot at two plates: 45 mm and 100 mm angled at 30 degrees from normal. Both plates were mounted on a wooden frame and attached with metal bolts. 100 mm plate [illegible], the 45 mm plate was placed as close as possible. Due to deformations of the 100 mm plate from previous tests, the space between the centers of the plates was about 30 mm. The plates were square, 1.2 meters per side. Shots were fired directly. The gun elevation was set with a quadrant.

The first shot was fired at  200 meters. The shot missed, and it was decided to shoot from 100 meters. The second shot hit the wooden frame. 

The third shot was fired from 75 meters. On impact with the armour plates, the ballistic cap was deformed, and the core shattered into small pieces. The jacket was deformed and got stuck between the 45 mm plate and the 100 mm plate."

Wednesday 13 March 2013

World of Tanks History Section: T-26

In 1929, the Red Army decided that the current armament of the RKKA does not meet the requirements of modern war. An independent solution of this problem was not possible at the time. Soviet engineers lacked experience, and the manufacturing base was weak. The only solution was to rely on foreign expertise.

In 1930, a delegation from the Directorate of Mechanization and Motorization of the RKKA, led by Innokentiy Halepskiy, bought a number of vehicles abroad, including tanks. One of these tanks was the British Vickers Mark E, more commonly known as "6-ton Vickers".

The British army was not interested in any modification of this tank. Not because the tank was bad. Military minds of Foggy Albion, let's just say, had an excessively creative approach to tank design. The 6-ton Vickers did not fit in their doctrine. The developers had to focus on marketing this tank externally.

The USSR purchased the two turret variant, armed with machine guns. These were named V-26, and did not cause much excitement in tank specialists. However, on January 8th, 1931, RKKA high command was introduced to the Vickers. They were in awe of the agility of this new tank, the ease with which they nearly flew across the proving grounds, leaped over trenches, and spun in place. The next day, Voroshilov ordered an immediate inquiry into the possibility of producing the V-26 domestically. A commission, led by S. Ginzburg, reported that the optimal solution would be to produce a "hybrid" vehicle, with some parts from the original replaced with those currently being developed for the T-19 tank. However, initial production started with no changes. Intelligence reported that Poland was ready to mass produce the 6-ton Vickers for its own army. These reports did not exactly correspond to reality, but orders are orders. The Vickers started production under the index T-26.

Manufacturing the T-26 was the job of the Bolshevik factory in Leningrad. The factory was loaded with other orders, but there was no other choice. The Stalingrad and Chelyabinsk factories were still being built. The head of production, and all further modernization, was the same S. Ginzburg.

Following the best traditions of the administrative bureaucracy, the initial order was for an incredibly unrealistic 500 T-26es by the end of 1931. Almost immediately, the order was reduced to 300, which was equally optimistic. The first half of 1931 was spend converting all blueprints to metric, prepare the manufacturing base, and create pre-production samples. This first stage was strictly closed to any changes, even if they clearly improved the design.

Soviet engineers successfully copied elements of the design. The ability of the elements once assembled, however, was limited. The 10 tanks that managed to leave the production line by summer were, at most, functional models. Their engines constantly broke down in the most creative and varying ways imaginable. The acceptable mode of operation allowed for 65% of engine parts to be discarded. Engines had mismatching dimensions, crumbling valves, the driveshaft was insufficiently hardened. Armoured hulls, released by the Izhor factory, had cracks in them. 10 mm of armour could be penetrated by a regular rifle bullet at 100-150 meters, which was considered impossible. Only by 1934, did the quality of the released vehicles drastically improve.

At first, the T-26 was produced with two turrets, located next to each other. This allowed the two gunners to fire in different directions at once, and was considered a good solution for an infantry support tank. As an alternative to a machine gun, is was possible to place a 37 mm cannon in one of the turrets.

In 1933, the T-26 underwent a change. Instead of two turrets, the tank got one, that could rotate in a full circle. The turret received a new 45 mm gun, which was superior to the 37 mm gun. Initially, all new tanks were to receive this upgrade, but due to deficits, both variants were produced until the end of 1933. The new gun and turret increased the weight of the tank, and a new engine and suspension had to be developed. The engineers did not reach great success here, and the tank became slower and more sluggish.

By the beginning of 1936, tank builders finally crossed out the half-track concept. The newly developed T-46 was too complicated and expensive. Work to modernize the T-26 had to be restarted. Bolted armour was replaced with welded, increasing its durability. The gun mantlet was altered, the fuel system was improved. The suspension was redesigned yet again. Due to new technology of electrical hardening, exceptional strength of the track links was achieved.

All of these modernizations could not hide the fact that, by the end of the 1930s, the T-26 no longer excelled in its category. Other countries had equal, or superior, tanks. An attempt was made to arm the tank with a 76 mm gun, but the project did not live long due to a manufacturing defect.

The first T-26es saw battle in the Spanish Civil War. Tanks supplied to the Republicans by the Soviet Union were used in nearly every operation, and performed admirably. A contribution to the T-26's status of a dangerous enemy was the fact that the German and Italian tanks that opposed it were only armed with machine guns. At the same time, the thin armour of the T-26 made it an easy target for AT guns. After evaluating the performance of the T-26, Soviet engineers installed additional armour screens.

Soviet tankers used the T-26 in the battle for lake Hasan. Due to incompetent commanders, many tanks were lost. During the assault on Zaozernaya hill, the tanks ran into a well prepared defensive line. Considering their weak armour, any frontal assault would lead to significant casualties. 85 tanks were destroyed, out of which, 9 burned. However, commanders reported a high survivability. A T-26 could withstand 5-6 Japanese shells. It's a shame that this quality had to be discovered in combat, and not on proving grounds.

In all conflicts the T-26 saw, its poor reliability shined through. Many vehicles were lost without participating in battle. During the Winter War, the Red Army lost 3178 tanks, 1275 of which were breakdowns. This war was difficult for all tanks. The terrain in most combat zones was poorly suited for armoured vehicles.

By June 22nd, 1941, 10 thousand T-26es of various types were in service. Its use in the first part of the war could only be described as a failure. The primary cause of low effectiveness of the T-26 was its obsolescence. The tank ceased to be exceptional in the 1930s. By 1941, it was weak. Its armour protected only from bullets. The weak engine did not provide a very high maneuverability. The poor reliability was another cause. A large number of vehicles was abandoned by their crews when there were not enough time or resources to repair them.

The second cause was the human factor. The level of commanders in the Red Army was quite low. Frequently, they had no idea how to use tanks correctly. Frontal assaults were deadly for the "cardboard" T-26. Instead of being used en masse, the tanks were subdivided up to individual vehicles. Coordination between units was lacking since there was no surplus of radios, and those that were available, were frequently poorly used. The situation with commanders' maps was a catastrophe. Frequently, hand-drawn diagrams were used. Even if the commander had a map, that didn't mean he knew how to use it. Reports and memoirs list many of these occurrences.

The combination of these two causes led to the destruction of most T-26es in the first 6 months of the Great Patriotic War.

The last operation T-26es were used in was the destruction of the Kwantung Army in 1945.

Original article available here.

Tuesday 12 March 2013

SU/ISU-152 vs the German Big Cats

Previously, I explored the effect of 122 mm shells on German steel. Let's kick it up a notch with 152 mm! The ML-20 howitzer, mounted on the KV-1S chassis (SU-152) and an IS chassis (ISU-152), was meant to handle concrete bunkers and enemy emplacements with its massive high explosive charge. Turns out, it was quite effective against tanks too. The 152 mm tank destroyers were nicknamed "Zveroboy" (beast-killer) by the Soviets and "Dosenöffner" (can opener) by the Germans. Let's see how well it could handle German beasts.

"Photo #37. Front of "Panther" tank. Direct hit by an AP shell from the 152 mm gun-howitzer. Breach in the armour 360 mm by 470 mm. Shell ricocheted. Distance: 1200 m"

The Panther's upper front plate is no match for the massive 152 mm shell. Despite ricocheting, the armour is breached anyway. Being in a tank that's hit by a shell that big, even if it doesn't penetrate, is no picnic.

"Photo # 38. Turret of "Panther" tank. Direct hit from HE-fragmentation shell from the 152 mm gun-howitzer. Penetration, breach size 350 mm by 370 mm. The explosion of the shell forms breaches in the turret platform and the opposite side. Distance: 1200 m. Angle between the path of the shell and the hull is 60 degrees."

As you can see, HE shells of that caliber are quite effective against tanks, as well as bunkers. In practice, AP shells for the ML-20 were infrequently used, as HE was more versatile.

Next up is the Ferdinand. Not quite a "cat", but still a beast by one of its names (Elefant).

"Photo # 39. Side of the "Ferdinand" assault gun. Penetration of a concrete piercing shell from the 152 mm gun-howitzer. Breach size is 220 mm by 230 mm. Distance: 1000 m."

"Photo #40. Front of the "Ferdinand" assault gun. Direct hit with an armour piercing shell from the 152 mm gun-howitzer. A piece 500 mm by 1000 mm from the front armour plate broke off. Distance: 1200 m."

Even the Ferdinand cannot withstand the firepower of the ML-20! Instead of leaving a hole in the armour, like a normal shell, the 152 mm AP just takes half of the plate with it on its journey into the enemy tank.

Photo #41 shows the Ferdinand before meeting the ML-20. Photo #42 shows the Ferdinand after. As you can see, it's rather lacking in structural integrity, after only two hits.

Sadly, I do not have any photos of tests against the Tiger, but I do have photos of tests against its successor, the Tiger II. The source is the same test as the D-25's article, CAMD RF 38-11377-129.

"Shot #8. Target: upper front plate. Shell: 152 mm AP. Distance: 100 m.
Result: dent 190 mm by 270 mm, 60 mm deep. On the inside, a bump 10 mm high. Cracks formed, 500 mm and 400 mm in length. The welding seam between the left hull and upper front plate burst."

Seems that 152 mm AP is not as effective as 122 mm AP was. Again, the poor welding seams make an appearance.

"Shot #9. Target: lower front plate. Shell: 152 mm AP. Distance: 100 m.
Result: Penetration. Entrance hole: 260 mm by 175 mm. Exit hole: 85 mm by 160 mm. Narrowest part of the breach is 130 mm by 80 mm. A 320 mm by 190 mm section of armour was blown off on the inside. The break is clean, crystalline. Cracks running all the way through the armour, 300 mm, 280 mm, and 400 mm in length. Left hull weld seam burst on its perimeter. The majority of the shell remains outside the tank."

This is some pretty massive damage. Poor quality armour shows up again, as evidenced by the clean separation of armour pieces. This penetration is amazing enough to deserve a picture in this article.

CAMD RF 38-11377-129

Photo #14 shows the penetration on the outside. Photo #15 shows the penetration from the inside. By the way, since the majority of the shell was left in front of the armour, this doesn't count as a penetration by Soviet metrics. This shows how penetration tables can be misleading, and why practical testing should always be done when possible.

"Shot ##10-11. Target: machine gun ball. Shell: 152 mm AP. Distance: 100 m.
Result: Penetration though the machine gun ball. The bolts fixing the ball in place are torn off. A crack through the armour plate, 210 mm long, formed. The left armoured bulkhead was torn off."

Looks like aiming at weak points is just as effective in real life as it is in video games. 

Shooting at the side of the turret was even less fortunate for the Tiger II. Notice the size of the breach compared to the side of the turret. That is the exit breach. The AP shell penetrated both sides of the turret.

In conclusion, the ML-20 is a potent weapon against even the toughest German tanks. The name of "beast-killer" is certainly deserved!

Monday 11 March 2013

World of Tanks History Section: British Tank Building

On July 28th, 1914, the cannonade of a new war rolled through Europe. Nobody thought that the conflict would be a global war of attrition. All participants assumed they could quickly crush their opponents in a few months of decisive offensives. New countries joined the fight, armies took colossal casualties, and Europe was crisscrossed with trenches from the north shores to the south. Offensives were ineffective. Tens, sometimes hundreds, of thousands of lives were given for mere kilometers. In order to break the stalemate, all participants developed new, deadlier weapons. Flamethrowers, poison gases, airplanes. The British invented the tank.

The first tanks went into battle on September 15th, 1916, at the river Somme. Armoured monsters broke through the German defenses, but the effect was only tactical, not strategic. Overall, tanks failed to play a decisive role in WWI. Two decades went by before the full potential of armoured vehicles was discovered. Over these years, not only the tanks themselves evolved, but their use in combat. Surprisingly, the British, pioneers of tank building, had problems with both these aspects.

As always, the biggest problem was the human factor. The British Ministry of Defense had many opponents to armoured warfare. D. Brown wrote that military commanders treated the tank corps with hatred and jealousy. Claims that tanks were a waste of budget were common.

The pro-tank camp wasn't running too smoothly either. There was no single opinion about what tanks should do on the battlefield. Two viewpoints were common. One was that the tanks should advance with infantry, cover it with armour, and help it fight enemy infantry. Other tanks, field guns, and bunkers were the responsibility of artillery. The second camp was of the opinion that tanks had to act like cavalry. They would break through to the rear of the enemy, strike at their communications, warehouses, attack infantry that is matching and incapable of effectively fighting back.

At the end, the British decided to sit on two chairs at once. Tanks were divided into infantry and cruiser types. The first were slow and well armoured. The second were fast and thinly armoured. The armament was more or less the same. Although it was originally proposed that infantry tanks should just have machine guns, they were eventually upgraded to AT guns. The caliber of these guns was limited, and neither cruiser nor infantry tanks were equipped with HE shells.

Let us closely examine the two British tank families at the beginning of WWII.

Infantry tanks, at the beginning, had no AT guns. An example of such a tank is the Matilda I, which was built starting in 1937. It was a clumsy, but well armoured tank. In 1940, when the British first crossed paths with the Germans, it turned out that German AT guns were ineffective against it. Sadly, the advantage in defense was completely nullified by its poor offensive capability.

In 1939, the Matilda II entered production as the heaviest British tank of the start of the war. Its 60 mm armour could only be penetrated by 88mm AA guns and 76 mm guns on Marder II tank destroyers. Unlike its first modification, the Matilda II carried a 2-pounder gun. For the beginning of the war, this was enough. However, by the middle of 1942, the Matilda's gun stopped being a significant threat. A larger gun was not possible due to the small turret ring.

The best infantry tank of the early war was the Valentine. This vehicle first saw combat in North Africa. The Valentines were produced until 1944, even though it was deemed obsolete by 1942. It was hindered by its low speed and weak gun. Unlike the Matilda, the Valentine could be fitted with a 57 mm (6 pounder) gun. The cramped turret fit two crewmen, which reduced the crew's effectiveness. Around half of all Valentines built were shipped to the USSR under Lend-Lease.

As for cruiser tanks, at the start of WWII they were far from perfect, and distinguished themselves with poor reliability. Cruiser tanks were based on Walter Christie's vehicles.

The first cruiser tank was the Vickers Mk I, produced in small numbers since 1934. They were practically not used in the war, even though several remained on active duty until 1941. Most tanks were used for training purposes.

Vickers Mk II and Mk II were a little better than the first model, but were weakly armoured and lightly armed. Still, there were many non-combat losses, credited to the poor reliability of these tanks.

The Vickers Mk IV was supposed to solve this situation. The armour was increased to 30 mm by welding armour plates on to the turret and weak spots. This gave the turret a strange 6 sided shape, which the Covenanter inherited. The suspension was also improved. The Mk IV was much more combat capable than its predecessor, but was still broke down unacceptably often.

In 1940-1941, Britain suffered heavy losses on all fronts. In France, North Africa, Greece, British tanks were inferior to their opponents. Sometimes this was due to technological superiority, sometimes due to incompetent commanders. Britain had to take drastic measures.

The Tank Committee was reshuffled in 1941, after British defeats against Germany's forces. The committee was joined to the Ministry of Defense, and given control of all enterprises that dealt with manufacturing tanks or developing tank doctrine. This was vitally important, since the current state of affairs rendered the British army incapable of properly completing the objectives of a modern war.

Based on the experiences of 1940-1942, the British concluded that their tanks were ineffective against almost all vehicles of the enemy, aside from very old ones, like the PzI. Light tanks were placed on scout duties only, and, even there, they were slowly replaced by armoured cars.

Infantry tank experience in Europe did not go as poorly. As an example, one can look at the battle of Arras on May 21st, 1940. Matilda I and II tanks of the 4th Royal Tank Regiment attacked two regiments of the 7th tank division and a regiment of the SS "Death's Head" division. The Matilda's armour, 60-78 mm thick, could only be lightly dented by German 37 mm AT shells. The SS "retreated with signs of panic" or, in more colloquial terms, fled. The British were only stopped when the Germans calmed down and towed in 88 mm AA guns. Infantry tanks could be improved by heavier armour and better weapons.

Cruiser tanks had the most room for improvement. On one hand, the cruiser tanks that Britain had in its possession distinguished themselves with neither combat effectiveness, nor reliability. On the other hand, the army needed a proper universal tank that was capable of both accompanying infantry and completing independent objectives. Cruiser tanks were the obvious choice here, but something had to be done about their engines, with the service life of several hours and their flaky ventilation and suspension. Skipping forward a bit, the British only accomplished this by 1944.

Both cruiser and infantry tanks required improved weaponry. The main tank gun at the time was the 2 pounder (40 mm) gun. It was ineffective against tanks of the time and nearly worthless against infantry: HE shells were either absent, or of such poor quality that tankers discarded them for AP.

It was necessary to use a 57 mm (6 pound) gun. The British had a gun like this, and it was used on the Valentine since 1943. For a very long time, most British tanks were armed with the 57 mm gun that, while better than the 2 pounder, was still not powerful enough. A 75 mm gun was only adapted in 1944.

Despite their active participation in the war and a realistic view of a tank's requirements, the British created several very unfortunate vehicles. For example, the Covenanter. This Christie suspension cruiser tank was released with the 2 pounder gun, and was very unreliable. By the time its technical problems were ironed out, it was obsolete. Its heir, the Crusader, was considered to be very comfortable to drive and use, but was not loved by tankers. The reasons for this were the same: poor gun, thin armour, low reliability.

The Matilda was replaced by the Churchill, which will be the topic of another article. It was a very strange tank for its time. It was probably more suited for the battlefields of WWI. Like all infantry tanks, it was slow, and had a questionable weapon layout. The turret held a 2 pounder gun. The hull, a 76 mm howitzer. This was quickly seen as a poor choice, and the Churchill was modernized. The howitzer was removed, the main gun was replaced with a 57 mm, and later a 75 mm gun. There were also fire support tanks, with 95 mm howitzers. One of the Churchill's problems was its narrow hull. It was impossible to enlarge the turret ring, and the existing turret was not large enough for a bigger gun.

This problem was addressed by a new infantry tank, the Super Churchill, also known as the Black Prince. It was largely based on the Churchill tank, but with a wider hull. The larger turret managed to fit in a 17 pounder gun. By May of 1945, when 6 Black Princes were ready for testing, the vehicle's layout and armament were already obsolete. The tank never had a chance to see combat before all work on it stopped.

The Cromwell, on the other hand, was a breakthrough. Developed in 1941-1943, it was armed with a 57 mm or 75 mm gun, and, with the "Meteor" airplane engine, it was the fastest British tank at the time. The Cromwell was a decent tank, but by 1943, the Germans had Tigers and Panthers. The 75 mm gun was insufficient against them, and the small turret ring prevented a larger gun from being mounted.

A more powerful gun was mounted on the Cromwell's successor, the Comet. With a wider and longer turret, a 77 mm gun with a muzzle velocity of 787 m/s was installed. This was the most powerful cruiser tank of WWII. It was not as good as a Panther, but significantly better than the German PzIV, which remained Wehrmacht's most common tank.

A cruiser tank nicknamed "British Panther" was built after WWII. It was called the Centurion. It had an angled welded hull, a 17 or 20 pounder gun, and remained in use until 1970. Later versions of the tank (starting in the 1950s) were armed with the 105 mm rifled L7 gun. This tank served as a basis for the experimental FV4202, which, due to a redesigned hull shape (the driver was now lying down), was smaller, lighter, and more maneuverable. The tank had the same 105 mm gun. The FV4204 was not mass produced, since at that point, Main Battle Tanks were conceived. The British themselves, in 1945, agreed that the idea of splitting tanks into cruiser and infantry was a poor one.

The last heavy tanks of Britain were the Caernarvon and Conqueror. They were built as heavily armed tanks, meant to combat the tanks of the enemy. This narrow specialization, and a large amount of technical problems, led to only 180 of these tanks built in various modifications.

Caernarvon and Conqueror were meant to fight enemy tanks from large distances. Based on the Conqueror chassis, another heavy tank was being developed, the FV215b. At first, it was meant to have a 183 mm gun with a drum type autoloader, but the gun was incapable of rotation, and had to be installed without any kind of turret. One close call with an HE shell, and the crew was dead and the tank inoperable. At first, this was solved by welding a box on top of the tank. Later, a turret was built, but had to be placed in the rear of the hull. 120 mm and 130 mm weapons were tested as well. The tank was not mass produced.

To summarize, while the British were the first to put tanks on the battlefield, they did not stay in the lead for long. Perhaps, this was due to the United Kingdom's geographical location on an island, with a reduced priority given to land forces compared to ships and aviation. When the time came to fight on land, the British were incapable of catching up to Germany and the USSR, whose tanks were the main striking force.

Original article available here: part 1 and part 2.

Sunday 10 March 2013

IS-2 vs. the German Big Cats

I have written a great deal about the D-25's accuracy (combat and test) and penetration, but what happens when you combine the two, and have some captured Tigers and Panthers laying around? Let's find out!

"Photo # 33. "Panther" tank turret. Hits from armour piercing shells from the 122 mm gun.
1. Penetration. Breach 130 mm by 180 mm. Side armour plate of the turret is torn off.
2. Penetration. Breach 130 mm by 230 mm. Turret torn off the turret ring and displaced to the rear by 500 mm.
Distance: 1400 m.

Photo #34. Turret fragment torn off my penetration #1."

Now, for the Tiger.

CAMD RF 38-11377-12

These tests use the "Corps level 122 mm gun model 1931", more commonly known as the A-19, the precursor to the D-25. With the BR-471 shell, shooting at 1500 meters, the following was observed:

"Shot #1. The shell passed through a previously made opening in the front armour, went through the tank, and penetrated the rear. The entrance hole is 140 mm in diameter. The exit hole is 225 mm in diameter. Three cracks formed at the penetration point, 240 mm, 300 mm, and 220 mm in length. Three bolts holding armour screens were torn off.

Shot #2. The shell tore off a piece of armour off the turret 580 mm by 230 mm. The turret was torn off its turret ring, and displaced backwards by 540 mm. 

Shot 3. Shell ricocheted off the turret roof. A dent 25 mm deep formed. Cracks spanning the thickness of the armour formed, 330 mm, 230 mm, and 210 mm long."

Tiger tank after testing. The displaced turret can clearly be seen.

With this Tiger, you can see the armour crack as it is hit. This is really bad, since cracking armour is indicative of the plates being too brittle. While brittle plates are more likely to shatter a kinetic penetrator, they are also likely to shatter themselves, sending armour fragments into the crew and the tank's internal components. 

Now, let's take a look at the Tiger II. This report is much more detailed than the previous ones, so I won't be posting pictures. However, you can grab the report here, courtesy of litl-bro. Also, here's the picture of the Tiger II after the penetration trials, which adequately communicates what happened.

"Shot #1. Target: upper front plate. Shell: 122 mm HE-fragmentation.
Result: spalling across an area 300 mm by 300 mm. The welding seam between the upper front plate and the machine gun port burst on 3/4 of its circumference. Internal bolts holding the machine gun ball were torn off. The welding seam between the upper front plate and the right side burst, and the right side was displaced by 5 mm. The tank caught fire internally."

Here are those German welding seams, causing trouble again. If an enemy shell literally tears your tank apart without even penetrating it, that's bad news for you. The spalling and machine gun bolts flying around mean that the driver and radio operator would be dead. Let's read on.

"Shot #2. Target: upper front plate. Shell: 122 mm AP flat type. Propellant: reduced. Distance: 2700 m. Result: dent 165 mm by 260 mm, 60 mm deep. The shell ricocheted."

Well, looks like shooting at nearly 3 kilometers out with a reduced propellant charge won't do you any good. Let's consider a more realistic scenario.

"Shot #3. Target: upper front plate. Shell: 122 mm AP flat type. Distance: 500 m.
Result: dent 310 mm by 300 mm, 100 mm deep. On the rear side, a piece of armour 160 mm by 170 mm and 50 mm deep cracked off. The welding seam between the upper front plate and hull roof burst. All seams between the upper and lower front plates burst. The seam between the lower left hull and the left side of the hull burst. The driver's observation device was torn off."

Here, we see the perils of overly hard armour again. Even though the shell did not penetrate, the large chunk of armour that flew off the other end effectively carried out the shell's job, killing crew members and destroying tank components. The driver now has his observation device embedded in his skull, which doesn't increase his effectiveness any. More welding seams fail throughout the tank.

"Shot #4. Target: upper front plate. Shell: 122 mm AP pointed type. Distance: 600 m. 
Result: penetration, hole is 180 mm by 250 mm. A piece of armour is torn off the rear side, 580 mm by 500 mm, 80 mm in thickness. The shell struck close to the non-penetrating hit from shell #3. The shell remained in the tank."

This is some pretty massive damage. The piece of armour that fell off further indicates the rapidly decreasing quality of German armour as the war went on.

"Shot #5. Target: upper front plate. Shell: 122 mm AP pointed type. Distance: 700 m.
Result: dent 200 mm by 250 mm, 90 mm deep. A crack all the way through the armour, 150 mm long. The welding seam between the upper front plate and the lower front plate burst from the inside."

The perils of overhardened armour show themselves yet again.

"Shot #6. Target: lower front plate. Shell: 122 mm AP flat type. Propellant: reduced. Distance: 2500 m.
Result: dent 290 mm by 130 mm, 60 mm deep. The opposite side shows a cracked bump. The right welding seam burst on its entire perimeter.

Shot #7. Target: lower front plate. Shell: 122 mm AP flat type. Distance: 600 m.
Result: hit the point where the upper front plate and lower front plate meet. Dent 180 mm by 120 mm, 35 mm deep."

Ironically, the effects of the 122 mm gun on the lower front plate were not as effective. However, shots to the upper front plate from any reasonable distance harmed the tank greatly. Let's see what happens when you shoot at the turret.

"Shot #34. Target: turret front. Shell: 122 mm AP pointed type. Propellant: reduced. Distance: 2500 m.
Result: A piece 700 mm by 220 mm was torn off the turret front. The shell penetrated completely. The roof of the turret is missing a piece 460 mm by 300 mm. The rear of the turret has two cracks through its entire thickness, through the welding seam of the roof and left turret side, 1100 mm in length, and on the turret roof, 1350 mm in length."

For a change of pace, this time the turret didn't fall off. However, it might as well have. It's missing massive chunks of armour, and is cracked significantly. Another demonstration of overly brittle armour.

Now, the testers are getting a bit overconfident.

"Shot #35. Target: turret front. Shell: 122 mm AP flat type. Propellant: reduced. Distance: 3400 m.
Result: a dent 200 mm by 230 mm, 90 mm deep. The rear side of the armour had a bump with cracks. The welding seam between the turret front and the bracing strut has a 200 mm crack."

Again, shooting at ridiculous distances using a reduced propellant charge doesn't do you any good. However, it has been demonstrated that the IS-2 can take out a Tiger II at over 2500 m by penetrating the turret, and does not even have to penetrate the upper glacis plate to incapacitate the tank and its crew.

Edit: The effects of the D-25 on the Ferdinand are explored in a separate article.