Nothing Special   »   [go: up one dir, main page]

Showing posts with label T-29. Show all posts
Showing posts with label T-29. Show all posts

Monday, 25 January 2021

Armoured Confusion

Works on Soviet tank building are published with striking regularity. Some are the results of many years of archival research, but many are based on prior works. There is nothing shameful about this, as skillful compilation is an art of no lesser value than writing from scratch. However, an issue with credibility may arise when picking secondary sources, and even primary documents can contain mistakes often caused by a lack of information. As a result, dozens of myths were built around Soviet tank building over the course of decades that live on today. This article will discuss such myths connected to pre-war tank building in the Soviet Union.

Saturday, 28 September 2019

The Golden Standard

The fate of the Soviet T-29 medium tank was a complex one. The development of a 20-ton amphibious PT-1 tank began in April of 1933. First the tank was developed in two variants, later this number grew to four. The T-29-4 and T-29-5 had the highest priority. The T-29-2 was skipped. There are plenty of strange aspects such as this in the T-29's history.

Initially the T-29 was being developed in Moscow by the technical department of the Economics Directorate of the United State Political Directorate (EKU OGPU) under the direction of N.A. Astrov. N.V. Tseits also too part in the development. Like Astrov, he spent a portion of his career working from prison. Later, development moved to Leningrad, and Tseits moved after it, eventually becoming the chief designer on the T-29 project. Such a debut promised a complicated fate for the T-29.

Monday, 25 March 2019

Future of Soviet Tanks

"February 21st, 1938
To People's Commissar of Defense, Marshal of the Soviet Union, comrade Voroshilov
...
Using existing tanks in the Red Army
  1. Existing 862 T-18 tanks should be used as mobile anti-tank guns in fortified regions in the event that modernization results in satisfactory results. Modernization work is currently being performed. If the modernization is unsuccessful, the T-18s should be removed from service and melted down. There are no spare parts for the T-18, and they are not being produced.

Tuesday, 17 February 2015

T-29 Torsion Bars

The T-29 is a fairly well known successor to the T-28, largely being the same tank but on a Christie suspension. It is also fairly well known that T-28 has a prototype with torsion bars. However, here's a rare combination of the two, a T-29 with torsion bars (Object 115).


"Torsion bar suspension (designed by personal initiative)
  1. Design of the "torzion" bar suspension on the T-29 tank.
  2. A proof of concept of the "torzion" bar suspension (1937-1938)"
And yes, it is written "torzion" in the original, including quotation marks.

Friday, 13 June 2014

T-29CN

The T-29 wasn't just singular project, turns out there were two more vehicles on its chassis. From the V. Lehn collection:

"Explanatory memo and calculations for the T-29 technical project (convertible drive tank T-29CN)

The proposed technical project of the T-29CN vehicle is a medium tank weighing 35.5 tons, meant for combat in a well reinforced area, suppressing large enemy concentrations, destruction of concrete fortifications, and fighting tanks.

Comparative characteristics of the T-29, T-29C, and T-29CN.

Catergory T-29 T-29C T-29CN
Vehicle type
Medium, convertible drive
Combat mass, tons 27.5-28 30.5 32-32.5
Size
Length (of hull), mm 6670 6900 7000
Width, mm 3180 3180 3200
Height, mm 2820 2940 2980
Clearance on tracks, mm 500 500 545
Track width, mm 500 500 500
Armour (hull)
Front 30 30 30 vertical
Side

20 sloped 30 sloped
Roof 8 15 (front), 10 (rear) 20 (front), 15 (rear)
Floor 10 15 (front), 10 (rear) 20 (front), 15 (rear)
Armour (main turret)
Side 20 vertical 20 sloped 30 sloped
Roof 10 15 15
Armour (machinegun turrets)
Side 20 vertical 20 sloped 30 sloped
Roof 10 15 15
Armament
Gun KT-27 L-10 L-10
Caliber
76.2 mm
Amount
One
Machineguns, type and caliber 5 7.62 mm DT 5 7.62 mm DT
2 12.7 mm DK
5 7.62 mm DT
2 12.7 mm DK
Ammunition
76.2 mm shells 67 102 94
7.62 mm bullets 6678 (106 belts) 6300 (100 belts) 6300 (100 belts)
12.7 mm bullets 0 1500 (30 belts) 1000 (20 belts)
Crew 5 6 6
Gun angle, horizontal 360 360 360
Gun angle, vertical -5 to +25 -5 to +65 -5 to +65
Machinegun turret angle, horizontal 180 180 180
Machinegun turret angle, vertical -7 to +25 -7 to +25 -7 to +30
Machinegun on the main turret 360 degrees, +/- 15 elevation 360 degrees, +/- 15 elevation 360 degrees, +/- 15 elevation
Speed on tracks
First gear, 1450 RPM 8.1 8.1 5.37
Second gear, 1450 RPM 16.8 16.8 10.4
Third gear, 1450 RPM 33.5 33.5 19.4
Fourth gear, 1450 RPM 56 56 33.4
Fifth gear, 1450 RPM - - 52.0
Reverse 8.1 8.1 5.44
Maximum speed, 1700 RPM 65.6 65.6 61.0
Fuel capacity, in liters 720 800 870
Range
On tracks, off-road, km 190 160 160
On wheels, on average road 220 200 200
Passability
Trench in first gear, width in meters 3.3 3.4 3.5
Escarpment in first gear, height in meters 0.9 0.9 0.95
Water depth 1.3 1.3 5 (underwater)
Grade, degrees 35 35 40
Maximum tilt (motion), degrees 15 15 30
Maximum tilt (tipping over), degrees 45 45 45
Ground pressure (no sinking) 0.744 0.775 0.77
Ground pressure (100 mm deep) 0.68 0.712 0.7
Special equipment
Smoke launcher Yes Yes Yes
Flamethrower No Yes Yes

Special equipment of tank T-29CN
  1. Starostin's smoke launcher, with reserve: one
  2. Fanned out flamethrowers in the rear with a range of 25 meters and fuel for 15 shots: two
  3. Chemical protection device: good for two hours in poisoned atmosphere
  4. Watertighness for underwater presence: good for one hour
  • Crew: 1 commander, 1 driver, 2 gunners, 2 machinegunners.
  • Fuel capacity in two tanks: 870 liters
  • Oil reserves: 65 liters
  • Engine: M-17, 675 hp with 1450 RPM. Water cooled, axis type cooling fan, engine can be started with an inertial electric starter or by hand.
  • Transmission:
    • Main friction clutch: dry three-disk friction clutch with Ferodo lining. 
    • Pedal force required: 31.5 kg.
    • Gearbox: parallel, five gears forward, one reverse.
    • Steering mechanism: dry multi-disk metallic friction clutch, up to 20 kg of force for actuation.
    • Brakes: ribbon type, metallic with Ferodo lining, actuated by foot pedal or levers. Used for braking the vehicle and controlling descent on slopes up to 45 degrees. Force required for levers: 15 kg, foot pedal: 33.6 kg.
    • Final drives: two.
    • Wheel drive gearboxes: six.
    • Intermediate shafts for wheeled travel: four.
    • Driveshaft: spicer type: six.
      The transmission allows for constant synchronization of wheeled and tracked drive, allowing motion and control with one broken track.
  • Suspension: BT type, with ten doubled coil springs and 8 oil shock absorbers for 8 rear wheels.
    • 10 independent road wheels, 840 mm in diameter, with elastic doubled tires, 2 by 175 mm. 6 wheels are drive wheels. Two wheels are support wheels. Two wheels can be steered with in wheeled mode.
    • Upper suspension: 8 rigidly attached return rollers, 350 mm, rubber lining.
    • Idlers: metallic, with tightening device inside the hull: two.
    • Track: metallic, stamped, 150 mm by 500 mm track link, heigh with track teeth: 175 mm. Amount of tracks: 198-200 per vehicle.
  • Communications:
    • Radio NTK-1
    • Colour semaphore
    • Signal flags
    • Internal TPU communication device
  • Electric equipment:
    • G-030 generator, 3 kW
    • Type 6-SG-E144s battery: 4
    • Turret motor: 1.65 kW
    • IS-5 starter: 0.25 kW
    • Headlight
    • Headlight for night shooting
    • Electric lights in the tank, backlight for instruments, stop signal, horn, regulator relay, etc.
    • Starter magneto: 1
    • Magneto motors: 2
  • Range: 160 km on tracks off-road, 200 km on wheels on a highway.
  • Size:
    • Length: 7300 mm
    • Width: 3200 mm
    • Height: 2980 mm
    • Clearance:
      • On tracks: 545 mm
      • On wheels: 490 mm

Chief of SKB-2, Kotin
Project manager, Tseits

Meeting minutes from January 13th, 1938
Printed on February 19th, 1938"

Tuesday, 11 March 2014

Kubinka

The Kubinka tank museum is home to not only a large number of rare (and sometimes unique) exhibits, but a large amount of them are fully equipped and in working order. This has been the goal of the museum since its inception. Here are the conclusions of a commission regarding some unique exhibits from April 1st, 1941.

"T-100 #810.
Condition:
  1. The vehicle is completely unprepared for storage. All transmission, motor, turret, and electric components are covered in rust.
  2. The vehicle is stored on pallets. Tracks and rims of road wheels are covered in rust.
Commission conclusions: perform technical inspection #3 and keep in the museum.

T-100Y #1352
Condition:
  1. Fighting compartment, gun, engine, and transmission parts are covered in rust.
  2.  The vehicle is not stored on pallets, and is not prepared for long term storage.
Commission conclusions: perform technical inspection #3 and transfer to the Artillery Directorate.

T-29
Condition:
  1. The rubber tires on five road wheels have come off.
  2. Most track links are damaged.
  3. The left front frame is missing the roller nut.
  4. The vehicle arrived from the factory recently, is completely painted, and in a satisfactory condition.
Commission conclusions: keep in the museum.

T-46
Condition:
  1. The turret is not fully equipped. There are no ball mounts in the turret, protective cups for the PT-1, right turret hatch, gun port caps, gun mantlet, frame, or periscope glass.
  2. The crew seats and electric turret motor are missing.
  3. The vehicle arrived from the factory recently, is completely painted, and in a satisfactory condition.
Commission conclusions: re-equip the vehicle and keep in the museum.

T-111
Condition: 
  1. The vehicle is fully equipped, arrived from the factory recently, is completely painted, and in a satisfactory condition.
Commission conclusions: keep in the museum.

SU-14 #23547
Condition:
  1. Currently being repaired at the workshop, needs repairs for both side friction clutches, main friction clutch, and technical inspection #3. It is being prepared for trials.
Commission conclusions: return to Artillery Directorate upon completion of trials.

Ricardo #15200
Condition:
  1. The right half-turret is in pieces, has been removed from its place and kept in the bay.
  2. The gun is missing, and the gun carrier on the left is missing.
  3. The artillery crew seats are missing.
  4. The leather from seats and cushions in the driver's compartment is missing.
  5. Both magnetos and all sparkplugs are missing, wires are torn throughout the vehicle.
  6. The track has frozen into the ice, the vehicle is rusted inside and outside, and not painted.
Commission conclusions: re-equip the vehicle, correct defects, and keep in the museum.

Vickers 12-ton
Condition:
  1. 4 sockets and ball mounts are missing from the fighting compartment.
  2. The gun and mantlet are missing.
  3. The lever cap for the engine grille is missing.
  4. The vehicle was not placed on a pallet, the tracks have frozen into the ice. Oil is pooling under the engine.
  5. The vehicle is clean and in a satisfactory condition.
Commission conclusion: re-equip the vehicle and keep in the museum."

The "Ricardo" vehicle mentioned is a British MkV, one of the initial exhibits at the museum. The sparkplugs from that tank were stolen in early 2000s and sold to a Western collector. Such a shame they weren't originals.

Here's the story of another exhibit. See if you can guess what it was.

"To the deputy chief of the Armoured and Motorized Forces HQ, Guards Major-General of the Tank Forces, comrade Markov

On the issue of: obtaining a transport for the transportation of the SU-380 to the NIBT proving grounds.

One 380 mm self-propelled howitzer on the Tiger-H hull was discovered at Kirchmeiser's factory (Germany). The deputy chief of the Armoured and Motorized Group of the Soviet Occupation Force in Germany, Guards Engineer-Colonel comrade Karpenko responded to the inquiry from the GBTU chief, stating that the SU-380 will be sent to the NIBT proving grounds after receiving transport.

Since it is imperative that the SPG be delivered to the proving grounds urgently, I ask for you to order the allotment of one railroad platform for the transport of the SU-380 to the NIBT proving grounds (Kubinka railroad station, West railroad).

USA BTU KA Chief, Major-General of the Tank Engineering Forces, Demyanenko"
CAMD RF 38-11369-709

The SPG in question, is, of course, the Sturmtiger. 

Friday, 21 February 2014

Suspensions


"T-28 Characteristics:
  1. Mass: 28000 kg
  2. Suspension type: half-side long bogeys
  3. Base: L=5870 mm, L1=325 degrees, L2=262 degrees
  4. Stabilization angles: a0=4 degrees, a1=64 degrees 30', a2=57 degrees 30'
  5. Number of road wheels: 24
  6. Wheel travel: 113.5 mm
  7. Spring potential energy per ton: 9.6
  8. Modulus: 0.238 I/cm^2
  9. Effective hp per ton: 18
Note: this is not the reinforces suspension.

Evaluation of the tank:

On the robustness of the suspension.
The miserly potential energy reserve of the springs makes it easy to receive harsh blows, and destroys the suspension. Bumps 250-300 mm tall are already critical for the tank in third gear at 25 kph. 
The damage touches all elements of the suspension: balancers, levers, caps, everything up to the rivets. Since harsh blows on striking terrain are local, the carrier and road wheels, too. The overall load is comparatively small, but that should not be a cause for considering the existing robustness reserve sufficient. When the tank gets off a bump, all road wheels hit simultaneously, which deforms a series of parts. This phenomenon softens the overload. 

On shaking:
The short travel of the road wheels, large number of wheels, small potential energy reserve of the springs, and a long base result in short amplitudes of linear and angular shaking, with a large period. In terms of comfort of firing on the move, the vehicle presents a good platform.

On crew workspace:
The seats of the commander and driver are not designed for fast movement on off-road terrain.

Conclusion: 
The main idea behind the T-28's suspension is that a road wheel will share its force with other wheels in the bogey. This idea is present in the design, but only works in practice on relatively small bumps, as the wheel travel is miserly and harsh shaking happens on bumps that are 200 mm tall. When the vehicle falls at an angle, the bogey doesn't work, and the blow is very harsh to the first wheel. The kinetic energy of the entire tank, minus the first carrier's spring, is absorbed through elastic deformation of the suspension elements. 

Installation and removal are very difficult. When the outer candle breaks, the tank's skirt armour hits the ground, and makes movement impossible. In order to climb over a steep obstacle, the fenders must be removed. An advantage of the suspension is the calm movement, resulting in high precision fire on the move. A disadvantage is that half of the road wheels do not participate in the softening of the blow due to deformation of the springs. The aforementioned stresses decrease deformation and increase the harshness of the blow. 

It is reasonable to maintain the smoothness of the travel while switching to a simpler, more robust suspension.

T-29 Characteristics:
  1. Mass: 28500 kg
  2. Suspension type: individual candle
  3. Base: 3765 mm
  4. Stabilization angles:  65 degrees 40', 60 degrees
  5. Number of road wheels: 4
  6. Road wheel travel: 170 mm
  7. Spring potential energy per ton: 33
  8. Modulus: 0.224 I/cm^2
  9. Effective hp per ton: 24.9
  10. Inertia radius relative to the perpendicular axis: 2.22
Evaluation of the tank:

On the robustness of the suspension:
Due to the high energy reserve of the springs, as well as the tires, which are not counted here, the T-29's suspension is sufficiently robust, as the blow is felt far after all other tested vehicles. 
The T-29 can travel on bumps up to 0.6 meters tall at 3rd gear with almost no danger to the suspension (at 30-35 kph).
The spring stem is a weak point, as their cut is insufficient. The effective horsepower is sufficient for fast off-road movement.

On shaking:
The large spring travel of the wheel results in significant (compared to the T-26 and T-28) angular shaking, the amplitude of which is determined, in the event of a non-harsh blow, by the angle of the tank relative to its center of mass, until the full compression of the spring, in which case the harsh blow is determined by the stabilization angle and inertia. The large reserve of potential energy of the springs and tires results in large (like on BT tanks) amplitude of shaking for linear vibrations (on lower gears, the amplitude is lower than the height of the bumps on higher gears, it is higher), since the compression of the springs and rubber can throw up the vehicles to significant heights. The shaking of the T-29 is such that there is a reason to preserve this suspension design, but attempt to reduce it, with maybe a shock absorber.

On crew workspace:
The seats of the commander and driver are not designed for fast movement on off-road terrain.

Conclusions:
The T-29 suspension type was chosen correctly.
The robustness of the suspension and convenience of maintenance are superior to the T-28.
The shaking of the vehicle is adequate. There is reason to reduce it by adding shock absorbers.

T-35 Characteristics:
  1. Mass: 50000 kg
  2. Suspension type: paired, with two degrees of freedom
  3. Potential energy of the spring per ton: -
  4. Modulus: 0.034 I/cm^2
The vehicle was not trialled. The conclusions are given as a result of calculations and logical reasoning.

Conclusions:
The T-35 suspension allows for larger springs, allowing for a more favourable spring potential energy reserve than other paired suspensions, like the T-18 and T-46.

Summary:
As expected from theoretical calculations, and confirmed by experiments, starting at 20 kph, tanks start losing contact with the ground when traversing bumps longer than their suspension travel: jumping. As a result of this, there is a strike when the tank hits the ground. The tank's movement will be characterized in two ways when moving on off-road terrain at high speeds:
  1. Non-stop jumping: losing contact with the ground and landing. Let's call this type of movement glissade. 
  2. Non-stop hard strikes from hitting bumps and falling, which leads to harsh overload of suspension elements. 
Therefore, vehicles meant to travel quickly off-road should have a high reserve of potential energy in their springs compared to static load. 

On evaluation of suspension designs:
Out of the two tested suspension designs, T-29 and BT, the T-29 is more correct."

Thursday, 20 February 2014

T-29 Blueprint Delays


Spetsmashtrest chief comrade Army Commander Neim
Director of the S.M. Kirov Experimental Vehicle Factory comrade Barykov
Director of the Kirov Factory comrade Ter-Asaturov

After military trials of the experimental T-29 prototype in the end of 1935, the Experimental Kirov Factory began developing blueprints for production of the first batch of T-29s at the Kirov factory. In March of 1936, these blueprints were submitted for approval.
On April 11th, ABTU representative brigade-engineer comrade Sviridov, along with Kirov factory representative and KB chief comrade Ivanov, and deputy director of the Kirov factory comrade Ginsburg composed their conclusions on the blueprints, which included required changes, the need for which was identified in factory and military trials, but were not included in the blueprints by the factory (the trials were held in the third quarter of 1935). Additionally, new changes were identified. These conclusions were approved by factory director Ter-Asaturov and experimental factory director Barykov. Work on changes to the blueprints was split between the Kirov factory and the experimental factory, as agreed by the two directors. 

In May of 1936, RKKA Armament Chief, Army Commander 2nd grade comrade Khalepskiy urgently requested these blueprints to get them signed at ABTU.

Three months elapsed since April 11, 1936. Currently, neither the Kirov factory nor the experimental factory have provided ABTU with updated blueprints. I know that the Kirov factory is working on correcting T-29 blueprints, but the experimental factory does not do its duty, and works slowly, delaying the production of T-29 tanks at the Kirov factory. I ask that your factories:
  1. Provide ABTU with corrected T-29 blueprints for signing.
  2. Develop final requirements for production and acceptance of T-29 vehicles. 
Please give your factories the proper instructions.

ABTU chief, RKKA Division Commander Bokis

Comrade Koshkin! Please give an answer.

Ginsburg, July 28th, 1936

Answer: all work will be done by August 14th, 1936, of which ABTU has been informed.

Koshkin, August 10th, 1936"

Saturday, 19 October 2013

T-28 vs. T-29

The T-28 was a bit of an odd tank. The project started in 1931, but the tank did not participate in any real wars until 1939. In the meantime, Soviet engineers had plenty of fun with it. One of the experiments was to replace the spring suspension with a convertible drive Christie suspension, making the T-29. The T-29 was a lot faster than the T-28. However, not everyone preferred the new tank.

RGASPI 558-2-128, a letter from the Kirov factory director to Stalin.

"On the production of fast T-28 and T-29 tanks in 1936

I reported on October 6th, 1935, that T-28 tanks produced in 1935 include improvements to their construction that increase the speed by 50%, by 16-20 kph on average.

The new speeds gives new value to the T-28 as a medium tactical unit and opens great potential for further improvements.

Meanwhile, ABTU RKKA is proposing shutting down the production of these vehicles in 1936, shifting over to convertible drive T-29s. They forget that it will take 4-6 months of hard work to produce as many of these vehicles as we now produce T-28s, in the meantime, no new T-28s or T-29s can be built. 

This transition not only weakens the mobilizational readiness, but once again puts the Kirov factory in a position of having to learn to produce a new vehicle, and take 1-2 years to perfect the process. 

As worldwide automobile and tractor manufacturing experience shows, technical progress moves in the direction of perfecting existing products of the factories.

The speedy T-28A vehicle, with a maximum speed of 65 kph and average speed of 48 kph surpasses the average speed of the T-29, which is 42 kph on tracks and 39 kph on wheels.

You can see that the T-29 is still inferior to the T-28A in its tactical characteristics, requires further design refinements, and the former cannot be viewed as a vehicle that is capable of replacing the latter. Until today, tank specialists did not think it possible that heavy vehicles could survive lengthy high speed runs due to wearing out tracks and breaking track links.

The T-28A was equipped with experimental tracks, and cast track links show good results. We can also guarantee a high speed distance of 1000 kilometers with the T-28A using stamped tracks. 

Due to the above, I firmly maintain my opinion that the T-29 should not be put into production given its current construction, and I ask for your personal directive to retain the T-28 tank in production at the Kirov factory, with the improvements that have already been performed, and will be performed later."

Let's read some more about these improvements to the T-28.

"The T-28 has been produced at the Kirov factory since 1933. Over the past 3 years, design and production changes increased the combat capabilities of the vehicle. The T-28 had a maximum speed of 45 kph, and an average speed of 30 kph on a good road. 

At the end of 1935, due to initiative shown by SKB#2 engineers comrades A.P. Efimov and O.M. Ivanov, changes to the suspension have been made, as a result of which, the T-28 will be capable of a much higher top speed.

As a result of energetic work by engineers, mechanics, and assemblers, the experimental vehicle was ready for the 18th anniversary of the October Revolution. The vehicle passed factory trials, showing a top speed of 65 kph, and an average speed of 46 kph. This speed is an unsurpassed record among heavy tracked vehicles in the world. 

The tracks and road wheels, previously weaknesses of the tank, showed high reliability after changes to their design. The changes made to the vehicle drastically increase its combat performance and maneuverability, and will be applied to all T-28s produced at the Kirov factory in 1936.

Next year, one T-28A vehicle will be produced above quota, with increased speed, an improved turret, and an AA machine gun mount. 

In order to further improve the vehicle by making it easier to drive and quieter during motion, we will design and produce a vehicle based on the T-28 medium tank with a steam-powered engine and convertible drive."


This is a photograph of what is likely the last T-29, on the territory of factory #100 in Chelyabinsk, in 1942. According to the factory's documentation, it was recycled in 1943 along with several other experimental vehicles, including the KV-7.