Lend Lease Impressions: AEC MkII Armoured Car

Armoured cars are usually not my thing, but the review of this one contains many notes about its tank components.

Overall photo of the MK-II (AEC) Armoured Car

Photo #1: 3/4 view from the right

Photo #2: view from the left

"Summary:

1. The AEC armoured car is built using production tank and automobile parts.
2. The side of the car does not correspond to its combat ability.
3. The design of the hull and turret, as well as the thickness of the armour, do not match modern requirements.
4. The design and combat performance of the AEC is not of interest to us.

Conclusions:

1. The AEC MkII armoured car is built using production tank and automobile parts.
2. The engine of the armoured car is a four-stroke AEC engine and does not differ from the one used in English Valentine III tanks.
3. The armament and turret are used from the English Valentine I and early Churchill tanks.
4. The transmission and suspension consists of components used in heavy trucks. Parts of this design include the front wheels (drive wheels) constantly being in gear and pneumatic brakes.
5. Using mass production components makes the design more complicated, and placement difficult (the engine is tilted in two axes), and led to an increase in dimensions, especially height.
6. The design of the hull is obsolete. The armour plates are horizontal, except in the front.
7. The mass of the armoured car is 12.2 tons, which is too high for its combat performance. This is explained by its large size and using heavy tank components.
8. The vehicle is armed with a 57 mm gun MkV and a BESA 7.92 mm machinegun. This assembly has no elevation mechanism. The elevation is changed with the gunner's shoulder. There is a brake for fixing the gun in a certain position.
   The downsides of this design include the lack of balance in the oscillating section of the gun and a poor telescopic sight. It is immobile and has a monotonous scale, which makes aiming difficult.
9. The ammunition rack is poorly designed. Shells get stuck in their slots and decrease rate of fire.
10. The armour of the vehicle (maximum 25.4 mm) is insufficient.
11. The unusual always on front wheels and controllable rear wheels does not decrease maneuverability due to a balance between the axles, but results in more complicated front wheels, as they both turn the car and are drive wheels.

Mobility trials results:

1. The maximum speed is 78 kph, which is good for a 12.2 ton armoured car.
2. Medium speeds:
1. Highway: [illegible] kph
2. Stone-gravel road: 30 kph
3. Dirt road: 13 kph
   are satisfactory.
   The relatively low speed across a dirt road is explained by the stiff suspension, as well as that the trials were held on a road previously traversed by tanks. The difference in width and necessity to brake before bumps led to the inability to use the full engine power of the vehicle.
3. Fuel consumption for 100 km:
1. Highway: 29 L
2. Stone-gravel road: 34.7 L
3. Dirt road: 48.5 L
   is low. These figures demonstrate the the engine is economic and that the gear ratios were picked well.
4. The range is high:
1. Highway: 600 km
2. Stone-gravel road: 500 km
3. Dirt road: 360 km
   due to the economical engine and relatively large fuel tank (175 L).
5. Temperature measurement showed that the temperature of the coolant stabilized at 75-80 C and oil pressure at 40-45 psi (3.1-3.2 kg/cm^2).
   The stable temperature shows that the engine power and transmission ratios were chosen well and that the oil and cooling systems work flawlessly.
6. The vehicle can climb 30 degree slopes, descend on 30 degree slopes, and tilt up to 22 degrees, which is enough for a wheeled vehicle.
7. The minimum turning radius is 16 meters, and is caused by the large length of the car.
8. Accelerating the car to 45 kph takes 250 meters. This is a good distance for a 12 ton car and shows that the engine is of good quality.
9. When driving at 64 kph, it takes 28 meters to brake. This demonstrates that the vehicle has reliable brakes, and is safe to use in a column or in a city.

Gunnery trials results:

1. The average deviation of the gun at 1000 meters is 0.19 horizontally and 0.18 vertically, and matches norms for the domestic 57 mm ZiS-2 gun (0.18 and 0.20 respectively).
2. The gun hits targets at 700 meters directly 100% of the time.
3. The odds of hitting the target from short stops at 400-700 meters decrease to 85%, and further decrease to 8% when shooting on the move.
   The decrease in chance to hit from movement or short stops is explained by large oscillations of the wheels during motion and their slow damping, as well as the poor telescopic sight.
4. Practical rate of fire:
1. Stationary: 5.2 RPM
2. From short stops, including movement between stops: 2.5 RPM
3. On the move: 4.6 RPM
   Which is insufficient for a 57 mm gun.
   The reasons for low rate of fire include
1. Poor ammunition rack design with jamming shells.
2. Poorly balanced oscillating part of the gun.
3. Poor telescopic sight.
4. Large and long oscillations of the hull and the high mass of the gun system make aiming difficult.
5. The gas concentration with a working engine and fans is 0.64 mg/L, and is within acceptable limits."

CAMD RF 38-11358-405

Japanese Heavy Tanks

"Note: on Japanese heavy tank cooling systems

The Type 2604 tank has two 12-cylinder liquid cooled BMW engines. The cooling system includes three sections of cooling pipe radiators for each engine, and one section of an oil radiator, cooled with two intake fans that draw their power from the main reductor. The air is sucked in through grilles located above the engine compartment , goes through a section of radiators in the air-tight hull, and is released through a grille in the rear of the tank. For engine maintenance, each of the radiator sections opens upwards if the engine compartment cover is removed.

Advantages of this layout include protection from incendiary fluid. A disadvantage is the inefficient use of space.

The Type 2605 layout differs from the Type 2604. It is 35% smaller, but retains the same type of engine, resulting in a very cramped cooler design. Four radiator blocks are shifted towards the rear, and, along with the separate oil cooler, are cooled with one many-bladed fan, connected to the main reductor by a crankshaft, passing between engines. Air is gathered through vertical grilles in the engine compartment, passes through vertical radiators, and is released behind the tank. If the fan breaks, the air will be partially circulated with exhaust fumes, achieved by a nozzle collector on each engine. 

Advantages of this design include an efficient use of the space available, and the simplicity of design and adjustment of the large (950 mm diameter) fan.  Disadvantages include a lack of air flow over the engine components, leading to overheating of the generator and main reductor, and a small amount of radiator sections (only 4).

The wooden O-I model uses a liquid cooled Daimler-Benz 12-cylinder diesel engine instead of two BMW gasoline engines. The model has two six-section radiators with an air flow achieved by exhaust fumes. The air is gathered by the engine compartment cover. An auxiliary fan helps guides airflow over the engine and helps in clearing out the fighting compartment, driven by the fuel pump motor.

Advantages of this layout include simplicity of design and good ventilation of the tank turret, but only while the engine is running. A disadvantage of this layout is that service of the engine requires removing the airtight radiator sections.

Standards

"To the director of Voroshilov factory #174 (Leningrad)

Copy: NKSM Glavspetsmash Chief Engineer

Reply to your letter #4/85-76; 247

No conclusions on the "standards" produced by BBSV-2 will be given by BTU. The "machine gun ammunition rack" and "F-1 hand grenade ammunition rack" are untested and exist nowhere except on paper in BBSV-2. In the future, I deem it sensible to cease such correspondence.

Chief of the BTU 2nd Department, Military Engineer 1st grade, Afonin
Deputy Chief of the 4th Section of the 4th Department, Major Gorohov

February 3rd, 1941"

Matilda vs Panther at Tartu

From L.V. Gorchakov's collection.

"Report on the combat actions of the 16th Independent Tank Order of the Red Banner Don Brigade from September 1st, 1944 to September 30th, 1944

1. The enemy, taking heavy losses in battles in the vicinity of Tartu was forced by our advancing forces to retreat North-East and North-West of Tartu, fortifying for a defense with elements of the 11th ID, 96th ID, 32 ID, 185 ID, 37th ID, 46th IR, 20th PD, and the Schmitken tank brigade on the Pyvvatu, Bol, [illegible], Paidla, Tila, and marker 44.6 line, simultaneously counterattacking with up to two regiments of infantry and with support of artillery and up to 50 tanks from the regions of [illegible], Zoraku and Marama, striving to take the city of Tartu.

2. The 2nd tank battalion was equipped with new tanks on August 30th, 1944. The brigade received orders from the commander of the North Combat Sector: by 15:00 on August 30th, march from Unipiha to the North-East outskirts of Tartu in order to deflect potential tank counterattacks in the directions of Anne-Tartu, Vadula-Tartu and [illegible]-Tartu.

At 8:00 on August 30th, the Brigade, composed of 18 Matildas, 2 SU-85, one T-34, an evac unit and an AA battery set out on the route of Unipiha-Tartu. Having completed the 25 km march by 14:00, the brigade reached the North-Eastern outskirts of Tartu, placing its tanks in AT ambushes.

The 1st and 3rd battalions were left in Unipiha without functional vehicles, awaiting evacuation and restoration.

According to the orders, the following was done:

1. The objective was delivered and explained to all personnel.
2. Observation of tank ambushes and approaches to enemy lines was performed.
3. Cooperation with infantry and artillery was outlined.
4. Anti-tank ambushes were set up on main directions: Kazake, height 62.1, Orova-Tila, Vakhi, and Myuta, composed of three tanks and a unit of mechanized infantry each. Reserves: the commander kept a reserve of 5 tanks and 80 men in the region of the wine factory with the goal of reinforcements of AT ambushes at threatened directions.
5. Tank ambushes in the regions of Letsi and Varevy were prepared to deflect the enemy's counterattack at the river crossings.

Throughout September 1st and 2nd, the 2nd battalion, infantry, and AA battery securely covered Tartu. The enemy did not show activity, but opened artillery fire in the direction of our units. According to the orders of the 67th Army Armoured and Mechanized Forces commander, 8 tanks were removed from ambushes on the night of September 4th and transferred to Unipiha. Others were left in ambush. At 13:00 on September 4th, the enemy attacked with up to two regiments of infantry and 30 Panther tanks, supported with artillery. Enemy tanks moved out from [illegible], Vazula, Lane, Marama and reached Orova, Tila, and Myuta by 15:00.

9 Matilda tanks from the 2nd battalion deflected the attack from anti-tank positions at Kazake, height 62.1, Tila, Myuta, with support from infantry and artillery. The enemy, at the cost of heavy losses, pushed us back from [illegible], Tila, Vakhi, Myuta, having cut off five out out tanks form infantry at Tila and Vakhi. Further advances of enemy tanks and infantry was prevented by artillery fire. 7 Panther tanks were knocked out, as well as 5 APCs, and up to 200 soldiers and officers were killed.

Our losses: 5 tanks destroyed or disabled, 10 men killed or wounded.

At the same time, the enemy attempted to ferry infantry across lake Vyrtserv. Three tanks in ambush at Verevi opened heavy fire and did not allow the enemy to land. Since a landing was impossible, the enemy turned back, having lost one motorboat, two rowboats. Up to 75 soldiers and officers were killed or drowned.

Due to the developing situation, tanks from Unipiha were transferred over to the anti-tank regions at Radi, Cemetery, and Klaoze with the objective to not let enemy tanks and infantry through to the city. At this time, defenses East, North-East, and North of Tartu were reinforced by elements of the 1047th SPG regiment, 379th Guards SPG regiment, 332nd Guards SPG regiment and 351st Guards SPG regiment transferred over from other parts of the front.

The enemy transferred over two more regiments of infantry and up to 25 Panther tanks from Valga by 18:00 on September 5th, 1944, and with up to two regiments of infantry and 30 Panther tanks and 10 APCs, with artillery support, attacked from Pyvvatu, Tila, Vakhi, and Myuga, with the goal of capturing the city of Tartu.

The 2nd battalion and AA battery opened fire from the anti-tank regions at Kazake, Radi, and Klaoze, along with reinforcing tank units, in cooperation with infantry and artillery. With heavy losses, the enemy was forced to retreat to his starting positions, leaving up to 175 soldiers and officers, 9 tanks, and 5 APCs on the battlefield. From September 6th to 10th, the enemy did not attempt any engagements. limiting himself to periodic artillery fire.

The 2nd battalion and AA battery continued to hold their line at Kazake, height 62.1, Radi, Klaoze and Verevi, carefully observing the enemy.

According to orders from the commander of the North Combat Sector, the tanks still remaining in ambush were removed on the night from September 10th and September 11th and were relocated to Memmatsi by 5:00 on September 11th, 1944."

German Prospects

I showed German production plans before, but those aren't as interesting as the prototypes they had in store.

"Report to the Fuhrer, April 7th, 1944 Top Secret

1. Planning to deliver trucks for 11 (eleven) motorized units (see attachment).
2. The Inspector General of the tank forces requested the following armoured vehicle improvements:
1. Super-heavy anti-tank gun
1. 15 cm: L/63 (length of barrel in calibers)
2. 17 cm: L/53
   Penetrating power: 200 mm at 4000 m.
   Shell weight:
   for 17 cm: 72 kg
   for 15 cm: 45 kg
2. 21 cm SPG: assault gun on the Panther chassis
3. Modernized PzIV: sloped armour, more powerful engine (fall 1945), 7.5 cm L/70 tank gun.
3. Bergepanzer III cannot be removed from production and rebuilt as an assault gun (SPG).
   The 240 PzIII tanks currently bring repaired in the rear should be rebuilt as recover vehicles. There is difficulty when converting them into SPGs due to increasing the front armour from 50 mm to 80 mm."

CAMD RF 500-12462-94

Guess the Tank

"To the BTU GABTU Chief, military engineer 1st grade, comrade Korobkov

I ask for your conclusions on the description of a Krupp tank, given by a captured soldier from the 11th TD.

Question: What types of tanks exist in your division?
Answer: My division uses the Krupp tank. Weight: 52 tons. Speed: 40-50 kph. Fuel capacity: 500 liters. Fuel efficiency: 60-70 liters for 100 km on the highway, 120-130 off-road. The average range is 420-450 km. The engine power is 300 hp. The tank moves only on tracks. Armament: 1 54 mm gun, 1 7.9 mm machinegun. The crew consists of a commander, driver, loader, and radio operator. The tank is equipped with a radio transmitter and receiver. It can cross a 140-150 cm tall wall, a 5 meter wide trench, or fort a 180 cm deep river. The tank is 5 meters long, 2 meters wide, and 180 cm tall. The turret armour is 5 cm thick. The rest of the armour is 3.7 cm thick.

The tank has a semi-automatic 54 mm gun. The rate of fire is unknown. The machinegun has a caliber of 7.9 mm. The tank holds 75 shells and 1320 bullets. The tank carries spare track parts.

The range of the tank is 420-450 km. A truck can go 350-400, a motorcycle can go 300. On a dirt road, that range is halved.

If swift concentration of forces is required, the division moves quickly, with small breaks for food. Maximum speed is 500 km per day in 14-15 hours.

GABTU HQ Chief Assistant, Lieutenant-Colonel Kudryashov
September 1st, 1941"
CAMD RF 38-11355-117

Tank on Tank Action

Lots of casual visitors to the field of military history look upon "kill ratios" as something that defines the effectiveness of a tank, forgetting that the modern battlefield is populated by things other than tanks, or even anti-tank guns.

Heavy Tanks and Lightening

"To the Deputy People's Commissar of Defense, Lieutenant-General of the Tank Forces, comrade Fedorenko

Report.

On the issue of design and production of experimental heavy tanks, I report that:

The current heavy KV tank fielded by the Red Army demonstrates superiority in battle over fascist tanks with its powerful armour and armament. It can be successfully used to destroy the enemy defences, crushing them with its tracks and gun. The Patriotic war, combining in its nature a positional war with a maneuver war requires much of a heavy tank, and the KV does not fully meet those requirements. The KV lacks mobility for the following reasons:

1. A low maximum speed limits its ability to move between flanks to counter-attack.
2. Insufficient visibility from the tank makes orienting on the battlefield difficult.
3. The tank's mobility is decreased by its number of gears: five forward gears is not enough for a heavy tank.
4. The force required to shift gears is large. Momentum acquired on lower gears is wasted, and the tank must slowly accelerate in a higher gear.
5. The brake ribbons are insufficiently reliable and lead to the tank stopping on the battlefield and requiring repairs.

The usage characteristics of the KV are limited by:

1. The requirement for robust bridges or other means of crossing ravines or water hazards.
2. The requirement for powerful tractors for rapid evacuation from the battlefield, dragging out of ravines, traps, etc, or the use of more of these expensive vehicles.
3. The requirement of units to have powerful repair tools.

Based on the above, the government must task the People's Commissariat of Tank Production to order the Kirov factory and factory #183 to produce two experimental prototypes of heavy tanks with the following characteristics"

1. Combat mass: 30 tons
2. Crew: 4 (3 in the turret)
3. Armour:
1. front and turret: 90 mm
2. side and rear: 75 mm
3. roof and bottom: 25 mm
4. Armament:
1. 76 mm gun: 1
2. DT machineguns: 2 (one coaxial and one in the hull)
3. SMGs: 2 (PPSh)
4. Flamethrower: 1 (attachable instead of the hull machinegun)
5. Gun range:
1. vertical: -5 to +25 degrees
2. horizontal: 360 degrees
6. Hull machinegun range:
1. vertical: -5 to +15 degrees
2. horizontal: +/- 10 degrees
7. Ammunition capacity:
1. Shells: 50
2. Machinegun rounds: 2520
3. PPSh rounds: 1000
4. Flamethrower fluid: 20 shots
8. Engine: V-2 or V-2K diesel, 500-600 hp
9. Maximum speed:
1. Highway: 60 kph
2. Off-road: 25 kph
10. Off-road range, non-stop: 10 hours
11. Transmission: planetary
12. View: 360 degrees, provided to the commander with an observation hatch in the turret roof, optical sights (with exit eyepiece 10-12 mm and field of vision no less than 60 degrees), and doubled observation devices (in the roof) for the driver.
13. Communications:
1. External: quartz radio station
2. Internal: TPU-3 with throat microphone
14. The side reductors must be protected by main armour.
15. The coolant system and air filters should provide 10 hours of uninterrupted movement off-road in 45 degree heat.
16. The engine must be able to start without external heating at a temperature of -45 degrees.

A tank produced in accordance with the above requirements will be fully equipped for modern war and will be an even more deadly weapon against fascist tanks.

BTU Chief, Major-General of Tank Forces Korobkov

Representing the BTU Military Commissar, Engineer-Lieutenant-Colonel Kovalev

June 1st, 1942"

CAMD RF 38-11355-935

Seems that the "medium tank with heavy armour" concept surfaced again, two years later. If you look at the characteristics of the A-44, it matches these requirements exactly!

As for the products of Kirov factory and factory #183, those were, of course, the KV-13 and T-43. Neither vehicle ended up in production, but the KV-13 influenced the IS series and the T-43's turret migrated to the T-34-85. 

Restoring a StuH 42

Not content to fall behind its a rival company's projects, Gaijin (maker of War Thunder) is also funding restorations of WWII vehicles.

It's not as long and detailed as the competitor, and there are no subtitles, but it's short enough to translate.

Edit: turns out there is an English video after all. The video has been updated.

Spare Track Links

"In order to increase the protection of the T-VI (Tiger) tank, the Germans place spare track links in front of the hull, on the vertical armour plate.

In order to check if this is an effective method, in March of 1944, a T-34 upper front hull segment (part number 34.29.304) with track links attached was tested at the NIBT proving grounds.

The shooting was done with an armour piercing 75 mm shell fired from a German gun (PaK 40) with the muzzle velocity of 770 m/s.

Trials showed that the front of the hull protected by track links can be penetrated by the German gun from 800 meters, but not from 900 meters. The unprotected part of the hull can be penetrated from 1000 meters, but not from 1100 meters. Therefore, the tracks increase protection by 200 meters.

I deem it sensible to alter the existing spare track transport method on the T-34 and SU-85. I ask you to order the People's Commissariat of Tank Production to move the spare track link holders to the front of the T-34 and SU-85 hull starting on April 15th, 1944."

CAMD RF 38-11355-2548

Of course, not only the Tigers had such protection. Many vehicles had track links attached to them to the front for extra armour, including tracks from other vehicles.

This StuG, for example, is clearly covered in T-34 track links.

Those that could not find nice and wide T-34 tracks had to make do with less.

Track links on T-34 tanks were also carried tucked behind infantry handrails, but it's also possible that these were not expected to improve protection.