"A torsion shaft sample has been sent to Detroit for further analysis": KV-1 at the Aberdeen Proving Ground
I. Basis for testing
A. The basis for testing this sample was obtained from a directive from the Ordnance Directorate.
Subject: "Agreed program of testing the Russian average tank T-34 and the Russian heavy tank KV."
II. Introduction
A. This sample arrived at the Research Center along with a medium tank. artillery Aberdeen in apparently new condition on November 26, 1942. The odometer read 54 km when the vehicle was commissioned at the Research Center. Both tanks—medium and heavy—arrived fully equipped with a very extensive set of tools, fixtures, and equipment, as well as spare parts and consumables for maintenance. This immediately demonstrated the seriousness of the Soviet Union's attention to supply issues.
B. This specimen was identified as the Russian KV-1 heavy tank. This was because all Russian documents referred to the vehicle as such. However, further examination revealed that in the Russian alphabet, the letter "B" is pronounced like the English "V." Furthermore, it was discovered that the tank was named after Marshal Kliment Voroshilov. Thus, it was definitively established that the correct designation for the vehicle was the Russian KV-1 heavy tank.
C. This example was apparently in new condition and saw very limited service before arriving at Aberdeen; it is considered representative of this model of tank. This model undoubtedly underwent a number of modifications, resulting in later production examples being improved variants.
D. It is reported that the design of this tank, like that of the medium tank, was developed within a short period of time after the invasion of Poland and before Germany's attack on the USSR. Consequently, this model is one of the Soviet Union's newest tanks. As expected from a new design, further development of the program revealed a number of specific deficiencies, which were included in the test reports.
E. The purpose of the tests and the requested information are summarized in the Summary Test Program for Russian Tanks. This directive, along with its supplement, is provided in Appendix A and is not reproduced here. However, the points of the specified test program (TSTP), along with the results, are summarized in Section VI. Various requested reports on components and assemblies are listed but not included in this report, as the size of such a summary document would be prohibitively large.
The original directive and its supplement (see Appendix A) were almost completely completed before the vehicle was shipped to Fort Knox. After its return, the vehicle was not put into service because it required extensive repairs. This procedure was postponed until a reliable source of spare parts could be identified to ensure proper repairs to the tank. Below is a summary of the test items requested but not completed; it is hoped that spare parts will be provided and these tests can be completed:
1. Point No. 4 – Engine bench tests
This point was not completed due to tight deadlines. The tank requires a major overhaul before further investigation can begin. A translation of the specifications of this 12-cylinder V-shaped diesel engine [note: referring to the V-2] from the Russian manual is included in Appendix D.
2. Point No. 14 – Determining the ability to cross a ford
Not determined. Estimated value: 4 feet [note: approx. 1,22 meters].
3. Point No. 16 – Driving on slopes
During an attempted test, the main clutch slipped. The friction linings were replaced and adjustments were made, but this step is pending a major engine overhaul.
4. Point No. 19 – Determining the traction force on the hook
While attempting to record this value, the water in the radiators boiled. The engine was retuned, but this stage of the test was not possible at that time.
F. Along with this tank model, a fairly complete set of photocopies of its component parts and assemblies was received. However, many of these were missing dimensions, and some were not specific to the specific tank being tested. For the aforementioned reason, these sketches could not be reproduced in the quantity and quality required for inclusion in this report, and it is proposed that they be deposited with the Foreign Material Branch so that they are available to interested parties who wish to inspect the vehicle at the Aberdeen Proving Ground.
III. Conclusions
A. The design of the Russian KV heavy tank is fundamentally sound and easily amenable to mass production using low-skilled (semi-skilled) labor. The key identified features are:
1. Lack of final mechanical processing of the armor; the edges appear to have been cut with a gas cutter.
2. Absence of unnecessary operations for mechanical processing of parts throughout the tank.
3. A clearly expressed principle of interchangeability of components and assemblies between the T-34 and KV tanks.
B. Some of the outstanding features of this tank include:
1. Low and flattering silhouette.
2. Simplicity of design.
3. Good cross-country ability (low specific ground pressure).
C. During limited operation (running tests) conducted on this tank, it was found that although the tank has good operating speed and low rolling resistance, it lacks smoothness of ride and mechanical reliability.
D. Rolling resistance varied from 45 to 110 lb (20,4–49,9 kg) per ton (maximum), which is good for a machine fitted with open metal hinge (dry pin) steel tracks and can be attributed to the use of large diameter road wheels and a roller sprocket.
E. The torsion bar suspension is very efficient and, together with the track design, ensures very smooth movement and trouble-free operation of the track drive.
F. The thickness and slope of the hull and turret armor indicate excellent ballistic properties (projectile resistance), however, this, along with the absence of fenders (sponsons), limits the useful volume of the fighting compartment.
G. The rear location of the drive wheel apparently makes the tank less vulnerable and helps maintain track tension on the road wheels when overcoming obstacles.
H. The ammunition is conveniently located low in the vehicle's hull; however, it is impossible to draw any conclusions about its level of protection, as ballistic tests (shooting at the armor) have not been conducted.
I. Firepower is roughly comparable to the M4 Sherman tank. Although the Russian tank is armed with a 76mm gun, the muzzle velocity of the projectile is only approximately 100 feet per second [approx. 30 m/s] higher than that of the M3 75mm tank gun. The secondary machine guns are reliable and feature an extremely simple design, allowing for easy production and installation.
J. The sights are excellent, and the observation devices, although crude [primitive in execution], meet the requirements. The overall visibility from the tank is good.
K. The air starting system [pneumatic starter] is an effective auxiliary means.
IV. Recommendations
A. It is recommended that an engine overhaul be performed if it is deemed advisable to further investigate those characteristics which have not yet been investigated.
B. Until further instructions are received regarding the implementation of point "A" above, it is considered that this report should be the final one within the framework of the project, and the Russian KV heavy tank itself should be left at the disposal of the Foreign Materiel Branch.
C. The air starting system should be further investigated as a reliable auxiliary method of starting the engine.
V. Information from other sources
A. In order to illustrate combat use and form an objective opinion on the claimed effectiveness of this vehicle, an attempt was made to collect all available data from previous sources.
B. No other Russian heavy tanks had previously been tested at our Research Center; however, a Russian medium tank [T-34] was delivered in the same batch and tested during the same period. Both tanks are typical representatives of the latest types of armored vehicles used by the Russians.
C. According to available reports, there are two modifications of this tank [note: referring to the KV-1 and KV-2]. The main difference lies in the primary armament.
D. From a lecture given at the German tank school in Wünsdorf in March 1942 (the translation is contained in Military Attaché Report No. 2955, December 1942, from Cairo, Egypt), we learned about the place of the heavy tank in the Russian tactical picture. The practice of using medium and heavy tanks together apparently developed into an established principle. Upon breaking through the front line, the heaviest tank (usually the KV) would stop to observe and draw fire from anti-tank artillery. As soon as the position of such guns was identified, the heavily armored tank would immediately attack and crush the anti-tank gun on the move. This action allowed lighter tanks (usually the T-34) to engage the German tanks directly.
E. An excerpt from the intelligence bulletin "Tactical and Technical Trends No. 5" of August 13, 1942 gives the following description of the Russian KV heavy tank:
New heavy tank
Twelve months of war brought significant changes to the design of Red Army tanks. The new heavy tank was named "Kliment Voroshilov" (commonly referred to as the "KV"). It is 22 feet (~6,7 m) long, 10,9 feet (~3,3 m) wide, 8,9 feet (~2,7 m) high, and weighs 51,2 tons (note: these are American "short tons"; in the metric system, this is ~46,4 tons). Ground clearance is 1 foot 4 inches (~40 cm), and the tank can ford water obstacles 5–5,5 feet (~1,5–1,7 m) deep. Its length allows it to cross ditches 12–14 feet (~3,6–4,2 m) wide.
The KV's suspension rests on six rollers on each side, each with a central groove, giving them the appearance of a double roller setup. Each roller is independently suspended on a rocker; the track flange passes through this groove, preventing lateral movement. There are three carrier rollers and one idler.
Improvements have been made to the track link design and the way they are connected. The outer edges of the tracks are free of protrusions that could trap snow or mud. The track surface has a waffle pattern, providing reliable traction in snow and mud and reducing lateral slippage. Therefore, additional lugs for snow and mud are not required.
A new method for connecting the tracks has been developed. Each track section or plate has nine lugs, which are connected by a floating pin. The pin itself is secured in place by small discs or lock washers, which are in turn held in place by a spring ring installed in a recess between the track lugs. This prevents a pin from falling out of the lugs in the event of a break, which could lead to a track rupture and immobilize the tank.
The turret, cast in a single piece, weighs approximately 10 tons. The turret's frontal armor is 3,54 inches [90 mm] thick, making it exceptionally strong and capable of withstanding sustained enemy fire. It can rotate 360 degrees, either electrically or manually. Heavy steel blocks (mounted on edge) are welded to the base of the turret to deflect projectiles that would otherwise jam the turret.
Below is information about the armament and armor of this tank:
(a) Turret armament: 76mm long-barreled gun (on some KV models, a 152mm gun is installed in a specially designed turret [note: KV-2]).
(b) One 7,62 mm machine gun, coaxial with the main gun.
One 7,62 mm machine gun in the rear of the turret.
Armament in the hull:
One 7,62 mm machine gun in the frontal part `[offensive machine gun]`.
Two spare 7,62mm machine guns can be used to replace the turret or frontal machine guns; one of these can be mounted on the turret roof for anti-aircraft fire or even used on a tripod for dismounted combat.
(c) Reservation:
(d) Forehead: 90 mm (3,543 in)
Sides: 75 mm (2,952 in)
Roof: 40 mm (1,574 in)
Engine Hatch: 30 mm (1,181 in)
Turret sides: 75 mm (2,952 in)
Stern: 40 mm (1,574 in)
Bottom: 30 to 40 mm (1,181 to 1,574 in)
The gun's ammunition complement consists of 90 armor-piercing and incendiary [note: the Americans likely mistook the high-explosive fragmentation shells for incendiary] rounds. The former are stowed behind the loader, while the latter are distributed throughout the turret, under the floorboards (the fighting compartment floor), and in the driver's compartment. The turret carries 3000 machine gun rounds in drum magazines.
The KV tank is powered by a 600-horsepower, 12-cylinder V-shaped diesel engine (V-2K), which transmits torque through the transmission and final drives to the drive wheels (sprockets) at the rear of the tank. The engine is noted to be very noisy. The tank is equipped with both electric and pneumatic (compressed air) starters.
The transmission has five forward gears (four normal and one low/emergency) and one reverse gear. The tank's internal fuel tanks hold 158,5 gallons (~600 liters) of fuel; additional fuel can be carried in external (hinged) tanks, which can be jettisoned after emptying or before entering combat. The standard off-road range without using the external tanks is 110–125 miles (~175–200 km). On improved roads, the tank can reach a top speed of approximately 21 mph (~34 km/h).
The KV crew consists of five people: the commander, driver, loader, gunner, and radio operator. Sometimes a sixth crew member is a mechanic. The commander, loader, and gunner are stationed in the turret. The driver and radio operator sit side by side in the front of the vehicle, in the control compartment.
The radio is located in the front, to the left of the driver. A whip antenna is mounted in the front of the tank. Internal communication within the tank is via a telephone [tank intercom – TPU]. Communication between tanks is visual – either by hand signals or flags [note: in case of radio failure or absence].
The Russians' experience in tank battles taught them lessons that influenced the design of their vehicles. The turret is positioned far forward to allow tank infantry (desyanti) to use it as a shelter (shield) while riding on the tank's armor. Every precaution has been taken to prevent unwanted "passengers" (enemy infantry) from landing on the armor. There are no external fastenings, tools, sharp protrusions, etc.; this serves the dual purpose of depriving enemy "fellow travelers" of handrails to grab onto and also reducing the likelihood of a Molotov cocktail or other projectile getting stuck on the armor.
The tank's fenders are very narrow, so enemy tank destroyers attempting to jump aboard risk being crushed by the tracks. The newest American tanks with sponsons have no fenders as such, solving these problems through the hull design itself. As an additional measure of crew protection, the hatch on the turret roof is designed in such a way that it cannot be opened from the outside. Furthermore, opening the hatch from the inside requires a special tool [note: the Americans likely haven't fully figured out the mechanism of the Soviet latch].
F. British Technical Intelligence Report No. 78 of January 7, 1943 states that there are three types of KV tanks:
1. The first type is the KV-1. It is armed with a 76,2 mm cannon and, according to reports, was criticized by the Germans for mechanical unreliability. The main clutch is weak, and gear shifting is only possible when stopped. Visibility from the driver's seat is poor. However, the armor provides good protection, making the tank difficult to disable.
2. The second type is the KV-1 (Reinforced) [note: KV-1 with armor plates]. This is the same tank described above, but with additional armor plates (armor plates) welded onto vulnerable areas. The tank undergoing testing here is considered to fall into this category. The same criticisms regarding mechanical reliability apply to it.
3. The third type is the KV-2. This tank is identical to the first, except for modifications to the turret to allow the installation of a 12,2 cm [122 mm] or 15,2 cm [152 mm] howitzer. The same criticisms apply to it, in addition to the fact that the turret cannot be traversed if the tank is at an angle.
VI. Discussion:
A. Every effort was made to complete all aspects of the prescribed test program; however, after most of the information had been obtained, but before all the characteristics had been investigated, the tank was sent to Fort Knox for examination by the Armored Force Board. Upon its return, the vehicle was deemed in too poor a condition to undergo further testing without first undergoing a major overhaul.
B. The cover letter to the test directive instructed our directorate to dismantle and ship the radio equipment from both Russian tanks [the KV and T-34] to the Signal Corps Laboratory at Camp Coles. This was accomplished, after which a separate document was issued, entitled "Camp Coles Engineering Report No. 6," on the subject: "Russian Radios and Intercoms Installed on the Russian T-34 Medium Tank and the Russian KV Heavy Tank." This report on the radio equipment proved too voluminous to be included in this document. Therefore, several copies of it were sent to the Ordnance Office in a separate package.
C. The accompanying letter also included a request to refrain from any live-fire (armor firing) or destructive testing of any kind and to maintain the vehicle in good condition. These instructions were followed, and it is believed that this tank received the same, if not better, care than any other vehicle undergoing testing. The fact that the vehicle now requires a major overhaul can be attributed to a combination of factors, namely, a lack of operational experience with this vehicle and some initially poorly designed components.
D. Upon arrival, the tank was restored to working order, and the prescribed testing program began; however, an inevitable delay occurred due to the vehicle being shipped to Fort Knox, Kentucky, for examination by the Armored Forces Committee. All data and logs were shipped with the vehicle, and an estimated three months of testing time were lost before this material could be compiled into a report.
E. A summary of the information requested in the summary program and its supplement is provided below in the same order in which it was requested and in accordance with the TSTP [Tank Standard Test Program] items, together with answers or references to the sections of this report containing the information requested.
The Russian KV heavy tank's test program
According to the directive, the first stage of this program was to study the vehicle's design and its overall performance. The standard TSTP 1935-709 program, with the following modifications, was used as the basis for achieving this stated goal:
ITEM #1 – Test Objects (Following Items Only)
A. Determining the comparative strategic mobility of a vehicle. The characteristics that influence a tank's effectiveness in this regard, along with the observations made, are listed below to provide a basis for comparison.
1. Speed - satisfactory, 21 mph [~34 km/h].
2. Ability to operate in various environmental conditions – the cooling system's poor performance limits its ability to operate in a wide temperature range. Water boiled during cooling system testing.
3. Ease of control - difficult to steer (turn) at high speeds on hard surfaces; difficult to downshift due to massive gears in the gearbox [note: a known problem with the main clutch and gearbox on KV tanks].
4. The required amount of fuel and lubricants is within normal limits (moderate).
5. Fuel capacity - 158 gallons [~600 liters].
6. Performance characteristics – good starting, reliable powertrain. Poor air filters and cooling system performance lead to the need for more frequent maintenance than necessary.
7. Ground pressure is 10,4 pounds per square inch (~0,73 kg/cm²). For a vehicle of this size, this is considered a very good figure, allowing this tank to traverse more difficult terrain than American tanks could handle.
8. Obstacle Climbing Ability – Climbed vertical walls up to 24 inches (~60 cm) high. Performed poorly on sand; performed very well on a washboard course and a shell crater.
9. Fording ability - not determined; estimated at 48 inches (~1,22 m), limited by the height of the engine air intake louvers.
10. Power per ton of weight (specific power) - 11,5 hp per ton.
11. Weight - 52 tons [note: "short" American tons; in the metric system ~47,1 tons].
12. Weight distribution is good.
13. Overall dimensions are good.
B. Determination of comparative tactical mobility of the vehicle:
1. Power per ton of weight - 11,5 hp per ton.
2. Speed - 34 km/h.
3. Acceleration – up to 34 km/h in 27 seconds.
4. Handling - poor on paved roads, better on rough terrain because the steering system (side clutches with brakes) works best on soft ground [note: on soft ground the tracks may partially slip, smoothing out the jerks when turning].
5. Driving on slopes was not determined due to slippage of the main clutch.
6. Driving on sand, mud and snow - good in mud and snow, bad on sand.
7. Specific ground pressure - 10,4 pounds per square inch (~0,73 kg/cm²).
8. Obstacle Clearance - 24" (~60cm) vertical wall.
9. Fording ability - not determined, estimated at 48 inches (~1,22 m).
10. Visibility (visibility limits) – good.
C. Identification of defects affecting durability and mechanical reliability:
1. After a short period of vehicle operation, the air cleaners on this tank's engine were tested. Based on the findings, this air cleaner cannot be considered satisfactory according to our specifications. This should accelerate wear on this engine and negatively impact its mechanical reliability.
2. The engine cooling performance is unsatisfactory by our standards and, if not compensated for by the engine design itself, may become a clear source of mechanical failure affecting the reliability and service life of the machine.
3. The steel tracks and track pins showed a short service life, with noticeable pin wear becoming evident after just 242 miles (~390 km) at the Aberdeen Proving Ground. Track life is reported to be approximately 600 miles (~965 km), after which the pins and excessively worn tracks require replacement. This is considered excessive track wear and is a factor affecting the vehicle's reliability and service life.
4. Throughout the tests, significant problems with the steering clutches and the main clutch were encountered. It's important to note that the spare parts kit supplied by the Russians included new assemblies for both these and other components, indicating their awareness of this weak point.
D. Comparison of the machine with similar machines tested previously:
1. No Russian-designed or -produced tank has ever been tested at the Aberdeen Proving Ground. The Russian T-34 medium tank is undergoing testing at the same time.
2. This machine appears to be essentially of the Christie type, of which there are reports at the Aberdeen Proving Ground.
3. During performance tests such as acceleration and rolling resistance [traction resistance] testing, the results obtained on this vehicle were compared with those of the American T1E1 heavy tank [note: prototype of the M6 heavy tank].
Mechanical inspection
A. A thorough mechanical inspection of the vehicle was conducted immediately upon its arrival at the Artillery Research Center. The vehicles (tanks) were opened in the presence of two Russian officers; both tanks were found to be in good condition.
B. The crude gas cutting of the armor and the rough fitting of parts in areas where higher quality workmanship was not required immediately caught my attention. The assembly of the components also demonstrated the application of principles of motion studies [note: ergonomics and labor rationalization], indicating steps toward mass production methods.
Another interesting fact is that components of both Russian tanks (medium and heavy), such as instruments, sensors, starters, relays, water and fuel pumps, are completely interchangeable. The engines of these two tanks are similar, differing only in the injection system, so most parts are directly interchangeable. This assertion is supported by service logs, which repeatedly mention parts being borrowed from one tank to maintain the performance of the other. The global design concept (standardization program) suggested by these facts likely significantly simplified the Russians' maintenance tasks by reducing the number of spare parts needed to repair the vehicles. This assertion is true if these two tank models studied constitute the core of the Soviet vehicle fleet.
C. Samples of motor oil, transmission oil, and diesel fuel were analyzed by the Automobile Division's Laboratory Division. Samples were also sent to Texas Company.
D. The torsion bar suspension generated considerable interest—it performed extremely well throughout all tests and showed very little wear considering the amount of work performed. A sample of the torsion bar shaft from this tank was sent to Detroit for further analysis.
E. The tank's engine also attracted immediate interest, as it was discovered that the piston stroke of the left-hand cylinder bank was shorter than that of the right-hand cylinder bank. This stroke was 180 mm and 186,7 mm for the left and right banks, respectively. The difference in piston stroke was explained by the use of a hinged connecting rod design. The connecting rods for the right-hand pistons are the main connecting rods, while the connecting rods for the left-hand cylinder bank are hinged to them [trailing connecting rods]. The diameter of the circle described by the main connecting rods of the right-hand cylinder bank is 6,7 mm larger than the diameter of the circle described by the pins of the trailing connecting rods of the left-hand cylinder bank.
Engine bench testing
A. Because the directive called for the maximum number of operational tests to be conducted and data to be collected as quickly as possible before the vehicle was shipped to the Army Ground Forces, engine rig testing was not performed in the proper sequence recommended by the TSTP program. When the vehicle returned from Fort Knox, Kentucky, it was determined that a major overhaul would be required before satisfactory rig testing could be conducted. The Automotive Division suspended this item until it was certain that a source of spare parts for engine overhaul would be available.
Determining the center of gravity
A. This was done by the hanging method, the results are as follows: 41-3/8 inches [~105,1 cm] above the ground, 9 feet 4 inches [~2,84 m] in front and 9-7/8 inches [~25,1 cm] above the center of the drive wheel.
B. This center of gravity is an imaginary point located approximately 1 inch [~2,54 cm] behind the center point of the tank's length and 1 inch [~2,54 cm] below the center point of the tank's height.
Determination of load distribution and specific pressure on the soil
A. The specific earth pressure was determined to be 10,4 psi [~0,73 kg/cm²] at a subsidence depth of 0 inches for a weight of 104,000 lbs [~47,174 kg].
B. Load distribution was determined by using a pair of load cells (weighing devices) under each side of the vehicle.
Determination of ranges and firing zones
A. To answer this question, we have virtually complete data obtained during tests of the gun, ammunition, and sighting devices. The gun on the T-34 medium tank is the same as that on this heavy tank, and all data was obtained on it [note: this refers to the 76-mm tank gun, the ZIS-5 on the KV, and the F-34 on the T-34].
Definition of requirements for lubricants
A. All oil and lubricant samples accompanying the vehicles were analyzed. These samples are believed to cover the full range of Russian requirements and provide a representative picture of Russian lubricants. However, the vehicles were operated with standard US Army lubricants and did not require any special types of lubricants that were not already available.
Determining launch characteristics
A. No official starting performance tests were conducted, but this car started easily, as evidenced by log entries. This was primarily achieved by the provided air-starter system. The crankshaft speed achieved by this method was quite satisfactory for starting the engine.
Definition of protection from detection
A. The vehicle's noise and visibility levels were deemed normal. The steel tracks on steel road wheels are noisy on paved roads, but the tank's movement over rough terrain is considered within acceptable noise levels.
B. The low silhouette of the vehicle greatly contributes to its camouflage in normal field conditions.
Determining the ability to overcome obstacles
A. Throughout the tests, the vehicle climbed a 24-inch [~60 cm] vertical wall and demonstrated obstacle-crossing performance equal to or superior to standard American tanks.
Determination of fording ability
A. While not determined by actual testing, calculations indicate that the tank can ford water to a depth of approximately 4 feet [~1,22 m], limited by the height of the cooling air outlet ports. However, driving through water at any speed will be difficult due to water splashing onto the sloped frontal armor plate, obscuring the driver's view.
Determining turning and handling characteristics
A. The turning diameter on dirt was found to be approximately 26 feet [~7,9 m]. Drivers reported that the vehicle's handling characteristics were very poor throughout testing. However, after gaining experience with the system (side clutches and brakes), it was found that the tank could maneuver almost as easily as American tanks. The tracks and suspension had a very smooth and clean ride, but track slippage during turns was detrimental to the road surface.
B. Although the crew's work stations are well-positioned, the driver's station is uncomfortable due to its proximity to the sloped frontal armor. This impacts the tank's handling characteristics, as it has been found that the driver requires extensive and thorough training to achieve maximum control efficiency.
Driving on slopes
A. This test has yet to be completed. Difficulties with the main clutch while the car was still in good condition prevented this point from being explored.
B. However, this point will be investigated after the engine has been overhauled and rebuilt.
Determination of suspension elasticity, ride smoothness and stability (steadiness) of the gun platform
A. The tank has been tested on a washboard track and it has been determined that the tank can withstand maximum speed without excessive pitching or vibration.
B. The study of the torsion shafts of the suspension of this tank is included in the logs (reports) for the period from December 25, 1942 to January 7, 1943.
C. Film footage of this stage of the tests was produced and is included in Aberdeen Proving Ground (APG) Film No. 566, entitled "Russian Heavy Tank KV and Russian Medium Tank T-34".
D. No track breaks (failures) occurred during testing; however, after approximately 200 miles [~320 km], significant wear on the track pins became noticeable.
Determination of tractive effort on the hook, acceleration characteristics, fuel consumption and rolling resistance (traction)
A. The towline pull was not determined due to boiling water in the cooling system. The engine was retuned, but this overheating issue was never resolved, so the towline pull could not be measured due to time constraints.
B. Practical data on fuel consumption were not obtained, but in the manual for the Russian tank these data are indicated as 160 - 180 grams per hour per horsepower of produced power [specific fuel consumption].
C. Rolling resistance (traction resistance) varied from 45 pounds per ton at 35 mph [note: obvious typo in original report, the KV could not travel at 56 km/h; probably meant 3,5 mph] to 110 pounds per ton at 19 mph [~30 km/h].
Operation in sand, mud and snow
A. The tank operated in shallow snow, mud, and ice, without any difficulties anywhere on the Perryman cross-country course, even when the course was in its worst condition. Interestingly, there is a 2-inch [~5 cm] difference in ground clearance between the Russian heavy and medium tanks, with the heavy tank having the higher ground clearance. Although they have the same ground pressure, these extra 2 inches [~5 cm] of ground clearance saved the heavy tank from getting stuck where the medium tank got stuck.
B. Even in the most sticky mud, it was noted how clean the suspension remained. In fact, by the time the vehicle returned to the hangar after the mud tests, the suspension itself had completely cleared itself of all the mud and was clean.
Study of crew comfort and safety
A. No specific tests were conducted to determine this parameter.
B. However, throughout all the vehicle testing, considerable attention was paid to determining the vehicle's impact on the crew. The cramped fighting compartment, poor or difficult control, and difficult gear shifting created a constant fatigue factor, making operating the tank very tiring. The driver's station is equipped with soft padding in areas where there is a risk of hitting the armor.
A detailed study of the KV-1 air purifier
1. Laboratory tests of this air purifier were conducted at the request of the Foreign Materials Department in order to identify the advantages and disadvantages of its design and performance characteristics, as well as for comparison with American-made units of similar purpose.
2. The air cleaner tested was one of two such units used on the Russian KV heavy tank, which is currently undergoing study and testing at this proving ground. It was apparently designed for use with the vehicle's 600 hp, 38,9 liter, 12-cylinder diesel engine. The engine's maximum speed is limited by the governor to approximately 1800 rpm, at which point the air demand is approximately 31,1 cubic meters per minute, based on an estimated cylinder filling factor of 85%. The maximum air flow per air cleaner is 15,6 cubic meters per minute, and this is the value used for the laboratory tests, the results of which are presented in this report.
3. The air cleaner is shown in the attached photographs of Aberdeen Proving Ground (APG) Nos. 75607 and 75608. The attached drawing of the APC Auto LB-192 also shows a schematic diagram of the unit. Air enters the air cleaner through a 133 mm diameter inlet pipe, which is offset by approximately 67 mm from the horizontal centerline of the unit, and its center is 175 mm above the recommended oil level. The location of the air intake is such that the air is imparted a vortex motion as it enters the expansion chamber; there, it strikes a convex deflector (deflector), which is loosely mounted in the center so that it has considerable freedom of movement. The force of the air flow tilts this deflector at such angles that it is partially immersed in the oil reservoir and captures small portions of the oil.
At high airflow rates, the deflector begins to rotate, breaking the oil on its surface into small droplets and being carried by the airflow into the filter element and onto the walls of the expansion chamber. After swirling in the expansion chamber directly above the deflector and oil bath, the air passes upward through a 162 mm diameter central opening in the spiral oil baffle, then into the filter element located at the top of the air cleaner, and exits through an 89 mm diameter outlet in the center of the unit's top cover. Oil trapped in the filter element flows down onto the spiral oil baffle and then back into the expansion chamber.
The filter element is approximately 279 mm in diameter, 127 mm in height, and made of soft corrugated wire (wire tangle/gimp). It should be noted that the Aberdeen Proving Ground photograph 75608 and the APC Auto LB-192 drawing show a small protrusion (pocket) located directly below the air intake and above the oil level in the air cleaner. There are five holes in the wall of the air cleaner housing between the expansion chamber and the cavity of this protrusion. The purpose of this appendage is unknown; it can only be assumed that it is intended as a trap for some of the dust contained in the air.
4. The tests conducted and the methods employed complied with current U.S. Army air cleaner specifications, with the exception that the recovery (self-cleaning capability) test was conducted at the engine's maximum air demand, rather than at 1,5 times its maximum air demand, due to the unit's low airflow capacity. All comments regarding the satisfactory performance of the air cleaner are based on the current U.S. Army requirements against which the unit was compared.
Conclusions
1. The clean air cleaner's flow rate was 16,1 cubic meters per minute, which is only 104% of the engine's maximum air consumption and provides an extremely small safety margin compared to American-made units.
2. The aerodynamic drag, recorded at 297 mm H2O at maximum engine airflow (15,6 cu. m/min) and a clean filter, is less than the maximum allowable value of 381 mm H2O according to the current US Army specification and is therefore considered satisfactory.
3. A flow test with the air cleaner tilted at 30° from the vertical showed that oil began to be carried away from the filter after 27 minutes of operation at 100% of the engine's maximum air demand (15,6 cubic meters/min), which is an extremely unsatisfactory result.
4. The recorded cleaning efficiency at maximum engine air flow was 97,53% compared to 97,5% for the American-made reference air cleaner tested simultaneously; the result was deemed satisfactory.
5. The air cleaner performance at 20% of the engine's maximum air flow rate (3,1 cubic meters per minute) was 88,5%, compared to the minimum of 90,0% required by the current U.S. Army specification; this result is considered unsatisfactory. Furthermore, there is reason to believe that this figure could have been even lower if the air cleaner had not been run in at maximum air flow rate immediately prior to testing.
6. The results of the tests on cleaning efficiency and dust holding capacity at 75% of the maximum air flow rate show that the efficiency decreased from 97,02% (after feeding 310 grams of dust) to 83,7% (after feeding 2480 grams of dust), while the aerodynamic resistance increased from 165 mm H2O to 371 mm H2O. These values are unsatisfactory.
7. The results of the recovery test (self-cleaning ability) were completely unsatisfactory, as the low throughput of the unit did not allow the test to be conducted at the required air flow rate (23,4 cubic meters per minute), and the filter flushing intensity at the flow rate of 15,6 cubic meters per minute at which the test was conducted was insufficient to significantly reduce aerodynamic drag. The reduction in drag over 15 minutes of operation after adding fresh oil to the purifier ranged from 622 mm H2O to 587 mm H2O, which is an extremely unsatisfactory result.
8. The air purifier's design requires breaking the seals in the clean air line for maintenance. However, once this is done, the filter element remains easily accessible for cleaning.
9. The filter element is loosely assembled and can move vertically by up to 12,7 mm. This is a design flaw, as the element is subject to excessive wear, especially when partially clogged, when air pulsations caused by the intake strokes of each engine cylinder cause the element to move up and down.
Review of previously obtained data
Although air cleaners of this exact type have not been tested at this site before, it is clear that this unit is very similar to, if not an exact copy of, the older Vortox oil bath air cleaners.
Discussion of results
1. Tests of the air cleaner on the Russian KV heavy tank show that its flow rate and oil flushing efficiency are significantly below US Army requirements for units designed for engines of this class as those on this vehicle. As a result of poor oil flushing, which is particularly noticeable at low flow rates, the low air flow rate, cleaning coefficients (efficiencies), dust holding capacity, and the unit's self-cleaning capacity are unsatisfactory compared to current US Army requirements.
2. In fact, there is reason to believe that the 88,5% cleaning efficiency recorded at 20% of the engine's maximum air consumption was somewhat higher than it would have been had the cleaner not been operated at maximum air flow for 15 minutes immediately prior to this test. It is assumed that during this operating mode, some oil was carried upward by the air flow into the filter element, and that the 165 grams of dust introduced into the air cleaner during the cleaning efficiency test was insufficient to completely saturate (contaminate) this volume of oil. In our opinion, had a larger amount of dust been introduced into the cleaner, the efficiency would have decreased as the oil retained in the filter element at high air flow became saturated. This conclusion is supported by the fact that the unit's cleaning efficiency dropped from 97,02% to 83,7% when feeding 2480 grams of dust during the dust holding test, which was conducted at 75% of the maximum air flow.
3. Another indication of poor oil circulation is the fact that oil splashing and movement across the deflector (baffle) ceased after introducing 1550 grams of dust during the dust holding capacity test. This was due to the formation of a crust of compressed dust on the deflector's upper surface. Furthermore, aerodynamic drag increased steadily and rapidly throughout the test, instead of rising very slowly at the beginning and increasing sharply only after reaching the oil's dirt-holding capacity limit, as is typical with American-made units. This indicates that, although some oil splashing onto the expansion chamber walls was observed during the first part of the test, this splashing had little or no effect on the filter element.
This test had to be terminated after introducing 2480 grams of dust, and only two of the three planned performance checks were completed. For the results to be considered satisfactory, the air purifier's dust holding capacity had to be 6190 grams, the minimum filtration efficiency had to be at least 95%, and the maximum resistance had to be no more than twice the initial value.
4. Upon completion of this test, dry dust was found throughout the entire interior of the air cleaner, with the exception of the oil pan located beneath the deflector. A layer of compacted dirt approximately 12,7 mm thick had formed at the bottom of the cleaner, beneath the oil layer; a dry dust deposit approximately 6,4 mm thick was present on the walls of the expansion chamber, and the filter element contained a significant amount of dust. All of this dust was dry, with the exception of the outer contour of the filter element—a 12,7 mm wide area around its perimeter. A small amount of dry dust was also present on the underside of the deflector. This condition provides further evidence of the poor cleaning performance of this air cleaner.
5. When airflow was increased to the engine's maximum demand during the first 30 minutes of the recovery test (self-cleaning capability), which was conducted immediately following the dust capacity test, the only observable oil movement was its tendency to "creep" up the deflector and soften the dirt crust. No attempt was made to run the air cleaner at 1,5 times the engine's maximum airflow, as required by current US Army specifications, due to the unit's inherently low airflow capacity.
The air cleaner was then filled with fresh oil and operated for 15 minutes at maximum engine demand. During this time, the upper portion of the oil deflector was so cleaned that some oil began to splash onto the expansion chamber walls, and approximately 80% of the dirt on the deflector's underside softened. However, the deflector itself did not rotate, and by the end of the test, only a small amount of dirt had been washed off the expansion chamber walls. The fact that aerodynamic drag did not decrease significantly during this test indicates that oil circulation was insufficient to flush the lower portion of the filter element. For the air cleaner's self-cleaning performance to be considered satisfactory, drag during this test had to drop from 622 mm H2O to 348 mm H2O.
6. All tests described in this report were conducted using SAE 30 viscosity grade oils, complying with US specification 2-104A, as required by the current US Army air cleaner specification. Unfortunately, information on the viscosity grade of the oil originally used in these air cleaners (in the USSR) is currently unavailable. However, if an oil thicker than SAE 30 had been used, it is likely that the flushing intensity and dust holding capacity would have been somewhat lower than those observed in this test.
7. In summary, it can be concluded that the efficiency (cleaning coefficient) at maximum engine air demand, as well as the aerodynamic drag of a clean unit, are satisfactory compared to the current US Army specification. However, the air throughput, dust holding capacity, efficiency at low air flow rates, and self-cleaning capability are unsatisfactory. Consequently, this air cleaner should be considered significantly inferior to American equivalents that would be used on an engine of the type installed on the Russian KV heavy tank.
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