World of Tanks History Section: Flying Elephant

Englishman William Tritton must have had a well developed sense of humour to call his creation a "Flying Elephant".

The reason for its creation were the deficiencies of the Mark I tanks, discovered after their use in battle. Despite the panic that they caused at the Somme in September of 1916, the first British tanks were far from technical perfection. Additionally, once the Germans recovered from the initial shock, they discovered that the tanks can be penetrated not only by cannon fire, but by large caliber bullets.

Tritton had a choice: correct the deficiencies of the Mark I or create a brand new vehicle. He chose the second path. By December, a new tank project was ready and presented to the military.

The tank was very modern for its time. It would have had real anti-shell armour: 76 mm in the front, 51 on the sides and rear. Furthermore, Tritton developed a brand new suspension for his "Flying Elepant", which included two additional tracks underneath the tank. These tracks would increase the vehicle's performance on soft terrain. The tracks were positioned on the side of the tank, and not hugging the entire hull like on the rhombus tanks, and were covered in armour.

The tank would have been armed with a 57 mm gun, located in the front. A similar approach was later taken with assault guns. Aside from the main gun, the tank would have 4-6 7.7 mm Lewis machineguns, placed on the sides and the rear.

Foreign historians insist that the Flying Elephant had two types of hulls developed for it, one with a hemispherical front, and the other with a curved vertical front, with the aforementioned gun installed in it.

The crew would consist of 8-10 men, which was the norm at the time. The military did not accept the vehicle. It was too heavy, complicated, and expensive. Many components would have had to be developed anew. Since Mark IV and Mark V tanks reached production by December of 1916, the Flying Elephant had no future.

Original article available here. 

BT-7M Cost

Disagreements between the client and supplier about the cost of an item are nothing new. The T-40 stirred up such a disagreement, let's see how well the more mature BT-7 design fares when the BT-7M is ordered:

RGVA

"ABTU opinion:
ABTU proposes that the BT-7M be sold for the price agreed upon by the Government by decree #592-198s issued on September 4th, 1939, until a new decree is issued for 1940 prices.

Prices:

1. BT-7M regular: 161400 roubles
2. BT-7M with radio: 165300 roubles
3. BT-7M with AA gun: 165400 roubles

Total sum of the agreement is 151177800 roubles, one hundred and fifty one million, one hundred and seventy seven thousand, eight hundred roubles.

Factory #183 opinion:

We propose the following prices:

1. BT-7M regular: due to the increased cost of rubber according to EKOSO and NKF directions, the cost increases by 2260 roubles. Design changes introduced after the price was agreed upon: 4340 more roubles. Total: 168000 roubles.
2. BT-7M with radio: Increased cost of rubber: 2260, design changes: 4640. Total: 172200
3. BT-7M with AA gun: Increased cost of rubber: 2260, design changes: 4340. Total: 172000

Based on these calculations, the sum of the contract for BT-7M tanks should be 157354000 roubles, one hundred and fifty seven million, three hundred and fifty four thousand roubles. The factory considers the increase in price justified, as in January of 1940, ABTU was instructed by the NKF to pay for rubber such that rubber prices remained constant, and must continue to do so. The changes in the list must be paid, as it was in 1939, which was subsequently approved by the government."

D-25 One Piece Shell

There are two common misconceptions I keep running into regarding the D-25 gun. One is that its rate of fire was slow because it used a two-piece shell, and the second is that the gun could only be reloaded at a 0 degree elevation angle. Conveniently enough, both are shattered with one document.

"Conclusions on the possibility of using a single piece 122 mm shell in the D-25 gun on IS-122 and ISU-122S guns.

Based on instructions from GBTU, the NIBT proving grounds tested the feasibility of using a one piece 122 mm shell for the D-25 and D-25S guns on the IS tank and ISU-122S SPG, and came to the following conclusions:

1. Loading the gun:
1. In the ISU-122S SPG, the gun can be loaded at any angle.
2. In the IS-122 tank, the gun can be loaded at the following angles:
1. Horizontal: 360 degrees
2. Vertical: -3 to +10 degrees
   It is impossible to load the gun when it is elevated more than 10 degrees due to insufficient space between the gun breech and turret ring.
2. The loading of the D-25 gun with a single piece shell is inconvenient and difficult due to a large size of the shell (1210-1400 mm long), heavy mass (about 40 kg) and limited movement space for the loader. Loading in the SPG is easier than loading in the tank.
3. The ammunition capacity on the tank is reduced to approximately 27 shells compared to the current 28. In the SPG, the ammunition capacity is increased to 34 shells compared to the current 30.

Based on these results, GBTU considers it unreasonable to switch to a single piece shell for the 122 mm D-25 gun in the IS-122 tank and ISU-122S SPG for the following reasons:

1. The rate of fire is not increased, as it is more difficult to load a single piece shell. It is impossible to load the tank gun at an angle of elevation of 10 degrees.
2. The ammunition capacity of the SPG increases by only 4 shells, and the ammunition capacity of the tank decreases by 1 shell."

CAMD RF 38-11368-696

Reliability and Repairs

"Between February 22nd, 1943, and March 14th, 1943, 527 tanks were lost in offensive operations by several tank units that operated around the 10th Army. These losses are distributed as follows:

Losses	KV	T-34	Matilda	Valentine	M3 Stuart	M3 Lee	T-60
On marches	14 (14.3%)	44 (29.7%)	16 (41%)	11 (13.3%)	8 (16.6%)	3 (23%)	26 (12.3%)
In battle	84 (85.7%)	104 (70.3%)	23 (58.9%)	72 (86.7%)	40 (83.4%)	10 (77%)	182 (87.4%)

The amount of tanks lost in battle includes the amount of tanks lost in battle due to technical problems, but it was not possible to establish that number.

Out of the losses, most vehicles were repaired by the repair bases or the tank unit's maintenance company, but a significant amount of the losses were permanent.

	KV	T-34	Matilda	Valentine	M3 Stuart	T-60	T-70
Total losses	98	148	39	83	48	208	8
Repaired at repair base	82 83.6%	102 68.9%	22 56.3%	52 62.5%	21 43.7%	125 60%	1 12.5%
Sent for major repairs	4 4.2%	16 10.8%	11 28.2%	15 18.2%	8 16.6%	25 28%	3 37.5%
Irreparable	12 12.2%	30 20.3%	6 15.5%	16 19.3%	19 39.7%	58 12%	4 50%

"

CAMD RF 38-11355-1466

Of course, the losses are given in the Soviet style, where a single tank can be considered lost several times. For instance, the document gives an example where the 26-tank 117th Tank Brigade lost 25 tanks during marches and combat (3 on marches, 11 knocked out, 11 burned up) and still managed to have 4 tanks come back undamaged between March 18th and March 21st.

The tables paint an interesting picture. The meek T-60 is reliability star, with the traditionally "unreliable" KV keeping close. The KV also largely took insignificant damage, with a very small number of tanks lost irreparably or in bad enough condition to be sent back to the factory for major repairs. Few T-60s are irreparable, but very many have to be sent back for major repairs. 

The T-34 isn't exactly a top performer, with almost 30% of the vehicles lost on the road, but the damage is slight. It is only second to the KV in terms of vehicles repaired in the field and percent of vehicles sent back to the factory. 

The Americans are doing okay on the reliability front. The M3 Lee is a little better than the T-34 in terms of vehicles lost on the road (for some reason there is no data on repairing them), and the Stuart is up there with the best of them in terms of marches. However, it seems very difficult to repair, with the worst numbers for irreparable losses and field repairs aside from the T-70 with its very low sample size.

The contributions of the British are all over the place. The Matilda is faring poorly, with a record number of vehicles breaking during marches and a very high percentage of vehicles that need to be serviced at the factory (although the number of complete losses is low). The Valentine is the complete opposite, with a very low number of breakdowns and very high number of field repairs.

For completeness' sake, let's look at similar numbers for some German tanks.

ORO-T-117

This report covers fighting on the Western Front, 1944 through 1945. Elsewhere, it mentioned that "the majority of Mark III and Mark IV chassis tanks do not have turrets", making it likely that these numbers are more representative of the StuG III and IV. These are some bleak numbers. Out of tanks operated by the Red Army, only the Matilda broke down more. A burned up tank is a total loss, so that's at least 20% of all tanks rendered entirely irreparable. This is about the same rate as a T-34, but the PzIV value doesn't include tanks captured by the enemy (in which case it would be 100% complete loss), or tanks that were rendered irreparable by gunfire and did not brew up. 

World of Tanks History Section: Tanks in the Kiev Operation

In September of 1943, elements of the Voronezh Front (soon to be renamed 1st Ukrainian) were marching towards the Dnieper. The advance guard of the Front consisted of elements of the 3rd Guards Tank Army. The tankers were tasked with pursuing the retreating enemy and capturing a foothold on the right bank of the river for another offensive. Capturing a bridge would be ideal, but Rybalko's army was unlucky. The Germans blew up the bridge in Kanev just as the first T-34 touched it. The army's pontoon bridges at the time were migrating somewhere around Kursk.

Bukrin Foothold

Crossings had to be built with whatever was on hand, and the enemy made sure that there wasn't a lot. Engineering units had to carry out feats of creativity. For instance, sappers of the 69th Motorized Infantry Brigade noticed a sunken barge on the German shore, swam across during the night, poured out the water with buckets, and dragged it away from under the Germans' noses. The 69th Brigade started crossing the river on the night of September 22nd, capturing the first scrap of the Bukrin foothold. Soon they were joined by elements of the 6th and 7th Guards Tank Corps.

Initially, the enemy did not have many forces here, but as early as September 21st, the Germans started hurriedly transferring elements of the 24th Tank Corps. The Bukrin foothold was not a random choice. The Dnieper curved eastward, allowing the attackers to bombard a section of the right shore from three directions. The German artillery could only strike from one.

However, this had a downside. Incapable of pushing the Soviets back across the river, the Germans attempted to put a cork in the bottle, cutting the bend off with elements of the 48th Tank Corps, headed for Kremenchug. An attempt by the Soviet command to prevent the Germans from concentrating their forces with an airborne landing came too late and was poorly prepared. The planes got lost, paratroopers were spread out over a large area, and could do little against the approaching German tanks.

Infantry could not punch through a defensive line reinforced by tanks. We needed our own, but it was impossible to carry them across a river with improvised methods like logs or rafts. Light A-3 pontoons (made from inflatable boats) managed to carry 24 SU-76 SPGs over the river on the night of September 29th. An attempt to use two pontoons to carry a T-34 ended poorly. "When the third tank drove onto its ferry, it broke apart and sank along with the tank. The tank and pontoons were extracted from the water. No more attempts were made to transfer T-34 tanks on A-3 pontoons."

The army's pontoon brigade tried to build two crossings, but their 16 ton capacity meant they could only be used to deliver supplies to the foothold. The N2P ferry park, equipped to transfer tanks, only reached the shore on October 6th. A bridge began construction, but was delayed by artillery and bombs.

Change of Direction

In these conditions, an offensive was only ready by October 12th. The Germans had plenty of time to plug the opening. Two attempts to break out of the "bottle" were unsuccessful. The 27th and 40th Armies tried to attack, but could not penetrate the German defenses and let the tanks out to operate in the clear. Even the tanks of the 3rd Guards Tank Army could not significantly change the situation. The foothold was reliably blocked. Just the first offensive cost the 3rd Guards a hundred knocked out T-34s, 24 of them permanently.

Meanwhile, on September 24th, Stavka ordered the Voronezh Front HQ to move the main strike from the Bukrin foothold to the Lutezh foothold further north. Primarily, this meant relocating the Front's chief striking force, the 3rd Guards Tank Army. This was no easy task. It meant withdrawing about 400 tanks, 3500 cars, hundreds of tractors and guns. This wasn't much easier than moving them across the river.

Thankfully, cloudy weather with low clouds and a thick fog over the river that lasted nearly until noon concealed the crossing, while only hindering it slightly. All repairable tanks were abandoned on Stavka's orders. In exchange, the army received over 200 new tanks and SPGs. At dawn on November 2nd, the 3rd Guards Tank Army concentrated on the Lutezh foothold. Another day later, the German forces blocking the foothold came under fire from an artillery barrage. The result of 203 mm fire was impressive. In the first hours after the barrage, only individual mortars and guns could fire back. The infantry took the first two kilometers without significant resistance.

In the first day of the offensive, only infantry divisions pushed back the Germans. Rybalko's army stepped into battle on November 4th. The reports read: "The enemy was not expecting massed tank action in this sector. This is confirmed by the fact that the tank army encountered little meaningful anti-tank obstacles in their penetration." Knocked out tanks at Bukrin successfully captured the attention of the German high command and its forces. Few of them remained at Lutezh. Even the sapper groups of the 3rd Guards ended up eliminating or capturing small leftover enemy groups.

On the midnight of November 5th, tank brigades of the 7th Guards Tank Corps occupied the northern outskirts of Svyatoshino and cut off the Kiev-Zhitomir highway. The remaining German forces had only one direction to retreat in: the Kiev-Fastov highway and railroad. This trip was the last for many that tried to take it. Battles for Kiev raged on until November 6th. In the middle of the day, the last pocket of resistance was cleared out.

On the dawn of that day, the 91st Independent Tank Brigade moved out to Fastov, crushing everything in its path. By the evening, it was at the city's outskirts. Facing heavy resistance, brigade commander Yakubovskiy feigned an attack from the east, but attacked from the north with his main forces (a tank and an infantry battalion). By the morning of November 7th, Fastov was cleared of the enemy.

General Schell's Counterattack

The Germans tried to fight back. The task was given to the fresh 25th Tank Division, newly arrived from France. F. Mellentin left a very creative description of the events in his memoirs: "During the day of November 7th, the advance guard saw Russian T-34 tanks south of Fastov, and ran in panic. These inexperienced men ran in horrible disorder until General Schell, the division commander, personally intervened and collected his units. They managed, with great difficulty, to tear away from the pursuing Russians, losing almost all of their transport. On November 8th, von Schell arrived at the HQ at Belaya Tserkov and his division came under our command."

On November 9th, the tank regiment of the 25th Division arrived from Kirovograd. The division had orders to do whatever it takes to stall the Russians advancing to the south and south-west. This time, the Germans made it all the way to the eastern ourskirts of Fastov before the attack failed. The Germans losses were so great that the 25th Division was incapable of performing any offensive action for several weeks.

The fate of the 25th Tank Division is well illustrated in a drawing in the report of the captured inventory department of the 3rd Guards Tank Army. The mountain of scrap that marks December 1943's 556 tons recovered contains a tank with a distinctive cross on its armour. Not a surprising fate for tanks of a broken and retreating army. Next year, these masses of scrap would become even more frequent for the Germans.

Andrei Ulanov is an historian and an author of books and articles on the Great Patriotic War. His most prominent works are "Order in Tank Forces" and "First T-34s" (co-authored with Dmitriy Shein). Currently, he is working on books on AT measures of Soviet infantry and combat use of T-34 tanks in 1942.

Sources

• CAMD RF fond 315 (3rd Guards Tank Army)
• D. Shein, Tanki Vedyet Rybalko
• V. Goncharov, Bitva za Dnepr
• V.F. Mellentin, Tankoviye Srazheniya 1939-1945: Boyevoye primeneniya tankov vo Vtoroy Mirovoy Voyne

Original article available here. 

SU-18

"Installation of a 76 mm mod. 1927 regimental gun in a T-18 tank

According to orders from the Artillery Directorate given to engineer D.I. Ilyukhin, the feasibility of the aforementioned vehicle must be investigated, with the following requirements:

1. Ability to shoot on the move.
2. 20-25 shells carried on board.
3. Possibility of using a muzzle brake.
4. Independent use in battle.
5. If possible, use the 25 caliber gun with a muzzle brake.
6. Leave room in the hull for a telephone and radio.
7. If possible, leave the center of mass in the same place.
8. Minimize the changes required to the gun and tank.

Based on the technical requirements, the following solutions can be used:

1. 76 mm mod. 1927 gun with a muzzle brake, reducing the recoil length to 0.8 meters. The maximum elevation would be 12 degrees, which achieves the requirement for a range of at least 3800 meters.
2. 76 mm mod. 1927 gun without a muzzle brake, with a maximum recoil length of 1 meter. The maximum elevation is 8 degrees, which limits the range to 2800 meters.

The 0.8 meter recoil length is the greatest we can allow with the current design. A 1 meter recoil length would mean that the engine compartment cover would have to be redesigned.

The bore axis height is finalized as 1800 mm, which gives a stability reserve of K=1.173.

Moving on the design of the SPG, the following must be individually examined.

1. A 76 mm mod. 1927 gun, adapted to the T-18.
2. The T-18 tank's equipment.

1. The gun can use the same oscillating part, with the following changes:

1. The muzzle must be threaded to accept a muzzle brake.
2. Attach the muzzle brake according to blueprint #2687 of the AU design bureau.
3. Re-cut the counter-piston to account for the reduced recoil length.
4. The mass of the tank is calculated as follows:
1. Mass of the tank (empty): 4700 kg
2. Mass of the gun: 400 kg
3. Total: 5100 kg, without accounting for the reduction of mass achieved by removing the turret.
5. Limit the elevation mechanism range to prevent knocking against the platform. Alternatively, cut slots in the platform to increase range, keeping in mind that the driver's view may be obstructed.
6. Remove the trigger mechanism from the gun mount and fire using a cord (like in mod. 1902).
7. Cut the gun rails by 50 mm in order to prevent it from knocking against the back of the crew compartment when recoiling.
8. The mount must be specially cast from steel, rotating on an axle attached to the platform, held at the top by a round nut. In order to resist rear and forward movement, three pins are screwed into the platform at each end. The pins will move their cylindrical parts through the openings in the mount and hold the latter with bolts or splints.
   The mount uses the elevation mechanism from the mod. 1927 gun. The turning mechanism is new. Maximum elevation is 12 degrees with a muzzle brake, 8 degrees without.
   The oscillating section is fixed to the platform during marches with a travel lock. The travel lock has full and half rollers, which enables it to lock the elevation and traverse in one movement.
   The sight is used from the mod. 1927 76 mm regimental gun.

2. T-18's equipment

Make the following changes in order to install the gun:

1. Remove the cupola and central turret.
2. Remove the driver's hatch and its frame, replace it with a solid 15 mm thick plate.
3. Attach a chrome-nickel steel box under the front plate with rivets to make a foundation for the gun.
4. Replace the front angle bar with a more robust one.
5. A special platform must be made to hold the gun. For this, 40x40x6 angle bars are attached to the front plate to hold the left and right trails. Cut openings in them to reduce weight and, if possible, maintain the driver's field of vision. Above the trails is a 15 mm thick plate with an axle for the mount.
   The top plate is attached to the front angle bar.

3. Gun shield

In order to protect the crew, a gun shield is used, composed of a front-top plate, two side plates, and a rear plate with a two piece hatch. 

Parts of the shield are attached together with angle bars and rivets. The front angle bar provides rigidity and connects the gun shield and platform. It is attacked to the front and side plates, and is bolted to the platform. The rear hatch is to only be closed when under fire, and needs to be open to allow for longer recoil.

The SPG will have a 3.5 mm thick gun shield, which will weigh 136.96 kg. In order to improve protection, a second variant with a 16 mm front shield was developed, increasing the weight to 438.15 kg. 

4. Crew locations

The SPG will be crewed by three people:

• Driver
• Gunner
• Loader, also setting the detonators

The driver's location is unchanged. The gunner will have a special seat. The third crewman does not have a seat and is placed on the floor of the tank. In order to protect the crew when shooting in cramped conditions, the project includes a flip up shield which is placed around the path of the recoil when shooting, preventing the crew from being hit by the recoiling breech.

5. Ammunition location

The place for ammunition has not been defined in the new project. It can be placed in the same place as before, or on the bottom of the tank in boxes. 

6. Mass and center of gravity

If the parts of the tank that have been removed weigh 500 kilograms, the mass of the vehicle is as follows:

• Tank mass: 4700 kg
• Removed components: 500 kg
• Tank mass without turret or cupola: 4200 kg
• Gun mass: 400 kg
• Mount mass: 197.5 kg
• Gun shield, 3.5 square meters: 183.3 kg
• Total mass: 4980.8 kg

The tank is approximately 280.8 kg heavier, and the center of mass moves 15.5 cm forward. The reserve of stability is K=1.6

7. Notes on using the 76 mm mod. 1927 regimental gun

The 76 mm mod. 1928 gun with a muzzle brake has a recoil length of 1000 mm and can only have a maximum of 8 degrees of elevation in this tank. This will give it a range of 3800 meters, which is the same as with the mod. 1927 gun at 12 degrees of elevation. Using the mod. 1928 gun reduced the tank's characteristics and made it much heavier. Consider it unsuitable for this purpose.

Senior engineer, department 11, Ivanov"

V. Lehn Collection

50 mm APCR Effectiveness

While exploring the confusion among Soviet battlefield investigators with German HEAT and APCR shells, kris_reid discovered the following curious fragment.

"...62 mm of armour was penetrated. A notable characteristic of this penetration was that both shells exploded in the fighting compartment without harming anyone, aside from the company commander, who was stunned.

During the same day, another Valentine was sent out without proper preparation, and was also hit.

Conclusions:

1. There are still combined forces commanders that do not understand tank tactics.
2. The enemy has a long-barrelled 50 mm anti-tank gun that fires thermite shells that can burn through 62 mm of armour. The shell itself burns up and the remainder is ineffective at harming the crew."

50 mm gun firing HEAT shells? Of course not. The damage described (little internal damage, no trace of shell) is characteristic of APCR. After penetrating the armour, the hard tungsten carbide core shatters into small pieces, which are difficult to recognize as a penetrating element. 

Anti-Molotov Grilles

"On October 14th, 1939, as a part of testing program approved by the chief engineer of factory #174, trials of experimental engine grilles were performed to test the permeation of flame and incendiary fluid into the engine compartment.

Trials were conducted on a T-26 tank with the engine working at 2000 RPM. Gasoline in bottles was used as an incendiary fluid, which were thrown at the engine grille, and ignited by open flame near the grille openings.

Trials showed that despite a large amount of gasoline (13 bottles), no burning fluid seeped into the engine compartment. Flames sucked in by the cooling system scorched the insulation on high voltage wiring. As the wiring was burned out, the engine reduced its revolutions, and stopped completely after some wires crossed. As well as the insulation, the rubber lining by the turret platform was burned by the flame. The flame did not affect the gasoline tank.

Based on aforementioned trials, it can be stated that the experimental grille can protect the engine compartment from penetration by burning fluids. Observations after the engine stopped showed that the gasoline fully evaporated from the carburettor."

V. Lehn Collection

Tractor Trouble

For the Soviet Union, the start of the Great Patriotic War happened at a very poor time. Yes, everyone knows about restructuring after purges and rebuilding fortifications at new borders, but few people know about another problem: a shortage of artillery tractors. Existing tractors no longer fully satisfied the RKKA, and projects to replace them haven't really taken off. The loss of major industrial centers during this time didn't help.

"To the chief of the GABTU Auto-Tractor Directorate

In a response to the inquiry by the 3rd department of the GABTU ATU, I report the list of artillery systems that require tractors for towing. Currently, factories do not produce any tractors to tow them, and it is impossible to replace them with foreign made tractors, as they are too weak.

1. 107 mm M-60 gun: 4300 kg
2. 76 mm AA gun model 1931: 4970 kg
3. 152 mm model 1910/34 gun: 7820 kg
4. 122 mm model 1931 gun: 7800 kg
5. 152 mm model 1937 gun: 7930 kg
6. 203 mm model 1931 howitzer "B-4":  18150 kg (transported in pieces)
7. 152 mm model 1937 gun "Br-2": 18345 kg (transported in pieces)
8. 280 mm mortar "Br-5": 18420 kg (transported in pieces)
9. 210 mm gun "Br-17": 20800 kg (transported in pieces)
10. 305 mm howitzer "Br-18": 20800 kg (transported in pieces)

In order to tow these guns, the Red Army artillery branch (newly formed regiments, high power regiments, front artillery regiments) needs 3300 tractors.

Additionally, no tractors are being built to tow guns that weigh less than 3000 kg. Currently, foreign wheeled tractors are being used for this task that, naturally, cannot be a good replacement for an artillery tractor. 

6000 tractors are needed to towing guns that weigh less than 3 tons."

CAMD RF 38-11492-54

Here is how the guns were transported. The heavy Komintern tractor could take a B-4 all by itself.

But the lighter and weaker Kommunar needed help, either by attaching two tractors to one gun or towing it in two pieces. 

Engine-Hours

Guderian's saying about an engine being as much of a weapon as a tank's gun could not have been more true about WWII, where operations failed or succeeded not because of millimeters of armour and gun caliber, but mobility, strategic and operational, allowing the destruction of massive groups of enemies. I have already explored the reliability of some vehicles, but what about the ones that are lesser known, but no less important than big names like T-34 and Sherman?

The above is a table of vehicles that arrives for repairs at Repair Base #7 in December of 1940. The columns are as follows:

1. Number (column largely cut off by scanner)
2. Unit
3. Region and dislocation
4. Vehicle type (A-26 is T-26, A-7 is BT-7, A-5 is BT-5, and A-2 is BT-2)
5. Date of arrival
6. Hull number
7. Engine number
8. Engine-hours total
9. Engine hours since last repairs

With some vehicles, we're seeing some pretty good numbers! Data on the T-26 is sparse, but the one that has had its time calculated is at a whole 195 hours and 20 minutes! Although, its neighbour has only worked 86 hours before landing in the repair bay, so that's not exactly a good showing. For all the flak BT tanks caught for using worn our aircraft engines, they seem to be doing pretty well. An aged BT-2 clocks in at as much as 284 hours and 10 minutes, and 179 hours from the other isn't too shabby. Overall, there aren't any poor showers from the BT series, with the worst performer only working for 100.5 hours since it was last repaired. Overall, the tanks are pretty robust as well, raking in hundreds of engine hours over their entire lifespan. Clearly, by 1940, the BT was a refined and mature design. Sadly, by this time it was completely obsolete.

Speaking of obsolete tanks, other pages in the folder include the tanks being sent off from the repair base back to the army after being fixed. These tanks include a fair number of dual-turreted T-26es, tanks that have been out of production for nearly a decade at this point!