The SU-100M self-propelled gun is in the spotlight of the mock-up committee.
The Su-100M is one of a kind.
Passions surrounding the self-propelled artillery unit
Tank Barely taller than the average man? With a crew of four? It seems like a joke now, but in the immediate postwar years, the idea of ultra-low-profile vehicles captivated military strategists. Fortunately, almost all of these projects never reached production. One such project was Object 416, initially planned as a tank but later transformed into the SU-100M self-propelled gun. Readers are presented with a selection of once-top-secret documents revealing the nuances of the armored vehicle's development.
Document 1
Conclusion of the mock-up commission for review of the wooden mock-up of the SU-100 self-propelled gun from Plant No. 75 of the USSR Ministry of Transport Engineering.
In accordance with the order of the Commander of the Armed Forces and Mechanized Forces of the Armed Forces No. from 20/D 1950, in the period from March 23 to March 31, 1950, at the 75th MTRM plant (Kharkiv), a wooden model of the SU-100 self-propelled artillery gun was examined by a model commission consisting of the following members: Chairman of the commission - Major General of the Tank Troops MARKOV P. L., Deputy Chairman - Engineer-Colonel KOLOBKOV A. V., members of the commission:
- from GBTU - Engineer-Colonel Vasiliev P.N.; Engineer Colonel M. M. URUSOV; Engineer Lieutenant Colonel M. P. VOLGIN; Engineer Major G. A. KURDENKOV; Engineer-Captain S. D. BENEVOLENSKY
- from the General Staff of the Ground Forces – Colonel MALYSHKO N. G.; Engineer-Lieutenant Colonel DOBROV N. V.
- from the Chief Artillery Management – Engineer Lieutenant Colonel P.V. KONOVALOV
- from the Ministry of Armaments – Chief Designer of Plant No. 172 Tsirulnikov M. Yu.
- from Plant No. 75 – Deputy Chief Designer F. A. MOSTOVOY
Plant No. 75 (the Kharkiv V.A. Malyshev Transport Machine-Building Plant – editor's note) presented the Commission with a full-scale wooden model of the SU-100 self-propelled gun for review. Upon comparison of the model with the drawings and technical requirements of the Scientific and Technical Committee of the State Technical University, it was determined that the model met the technical requirements in its main dimensional characteristics and could be accepted for review.
Upon review of the submitted model, the Commission determined:
1. The crew arrangement shown on the model (3 people to the left of the gun and 1 loader to the right) cannot be considered satisfactory.
2. The height of the fighting compartment is insufficient.
3. The driver and commander instruments are not installed in accordance with the tactical and technical requirements.
4. The D10-T gun was installed without changes with a recoil resistance force of 26 tons, instead of the D10-T type gun with a reduced recoil resistance force, as stipulated by the tactical and technical requirements.
Plant No. 75, taking into account the above-mentioned shortcomings, produced a new working model of the turret and presented it to the Commission for re-examination on March 28, 1950.
The newly presented model of the turret and fighting compartment has the following characteristics:
1. Tower with a running diameter of 2400 mm with circular rotation.
2. The M-63 cannon, designed by Plant No. 172 of the Ministry of Armament, is shifted 75 mm to the left of the turret axis. The SG-43 machine gun is coaxial with the cannon.
3. The crew is located in the turret; the driver and loader are on the right, the gunner and commander are on the left of the gun.
4. The driver is equipped with a TPV-1 observation unit, consisting of 3 periscopic prismatic devices.
5. The gunner is equipped with mock-ups of the TS-2 articulated sight and the S-71 mechanical sight as sights.
6. The self-propelled gun commander has a commander's cupola with models of beveled triplex blocks and a TKI device.
7. The height of the fighting compartment allows the crew to work in a sitting position with the hatches closed.
8. The location of the ammunition has not been finalized and can be considered conditional.
9. The emergency hatch is located in the rear of the self-propelled gun. It can be used with the turret in any position.
10. There are 3 hatches for the crew to enter and exit: the driver’s hatch has a diameter of 570 mm, the loader’s hatch has a diameter of 550 mm, and the commander’s hatch has a diameter of 540 mm.
11. The power plant and transmission have not been modeled.
After reviewing the presented model, determining the convenience, crew operation and removing the visibility diagram, the frontal part of the turret was redesigned to accommodate a D10-T type gun with reduced recoil resistance and made within the dimensions of the serial D10-T gun.
Since the transverse dimensions, position of the breech, breech face of the tube and guard of the M-63 gun and the D10-T type gun are the same, the convenience of the crew in the fighting compartment is also the same.
The recoil devices of the M-63 cannon are located below, and those of the serial D10-T cannon are located above, as a result of which, when installing each of these cannons, the front of the turret changes in accordance with the location of the recoil devices, which entails a change in visibility from the driver's seat.
Conclusions and offers
As a result of examining the model of the self-propelled gun's fighting compartment and practical determination of crew convenience, the Commission came to the following conclusions and proposals:
1. The crew's position in the fighting compartment—the commander and gunner to the left of the gun, and the driver and loader to the right—provides the most comfortable working conditions for all crew members. Therefore, further development of the self-propelled artillery project should be carried out with this crew arrangement. The Commission considers a crew arrangement of three on one side of the gun and one on the other unacceptable.
2. The gun's offset to the left of the turret ring axis, as implemented on the model, ensures the necessary operating comfort for the driver and loader while maintaining normal operating conditions for the gunner and commander. Plant No. 75 must submit a technical justification and calculation for the feasibility of offsetting the gun from the turret axis to the Scientific and Technical Committee of the State Technical University of the Russian Federation (STC GBTU) for review, along with the technical design.
3. To improve the working conditions of the driver-mechanic, it is necessary:
- Extend the footrest to the maximum possible size.
- Move the pedals forward a little and spread them to the sides.
- The distance from the lower prisms of the viewing devices to the hatch cover should be increased so as to ensure the ability to freely place the head in a tank helmet.
- Make the driver's seat more comfortable for sitting, and make the backrest reclining.
- Provide special footrests for the driver-mechanic, which are necessary when the self-propelled artillery vehicle is moving downhill.
- Move the control column to the left.
4. For the gunner’s convenience, it is necessary:
- Move the TS-2 sight to the left so that the distance from the box for the wedge exit (on the gun fence) to the center of the eyepiece is at least 100 mm.
- Install the controller in front of the gunner in a place convenient for use.
- Move the radio station back a little so that it does not interfere with the gunner’s work with the manual drive of the turret rotation mechanism.
- Lower the eyepiece of the TP-2 sight down so that the distance from the axis of the eyepiece to the roof allows free placement of the head in a tank helmet.
- Extend the platform and make rests for the gunner’s feet.
5. The installation of the commander's cupola and observation instruments within it has not been properly tested; wooden mockups were installed in its place. It is necessary to further mock up the commander's cupola with the installation of the instruments. The cupola design should be refined by reducing its height.
6. To ensure a high rate of fire and facilitate loading conditions, Plant No. 75 must develop a mechanism for feeding shots to the loader, and Plant No. 172 (Motovilikha Plants, Perm – editor’s note) must develop a mechanical system for feeding the shot into the barrel chamber.
7. The loader must be equipped with an MK-4 device for observation forward and to the sides.
8. The commander's and loader's hatch covers must open forward. The hatches are of adequate size and allow entry and exit for the crew in winter uniform.
9. The shots located in the hull of the self-propelled gun in front of the driver must be moved to another location: to the fighting compartment or to the rear.
10. Testing on a model has established that it is possible to install in the turret of the self-propelled gun either a 100-mm cannon with the dimensions of the serial D10-T cannon, or a newly designed 100-mm M-63 cannon from Plant No. 172, while the crew's operating comfort when installing both cannons is equal.
11. When installing the M-63 cannon and with the turret positioned with the cannon forward, visibility from the driver’s seat is satisfactory, since the front edge of the vehicle is visible, and the obscured space lies within the limits of tactical and technical requirements.
When installing the D10-T cannon with reduced recoil resistance and the turret positioned with the gun forward, visibility is unsatisfactory, since the left wing of the vehicle is not visible, although the unobserved space does not exceed the tactical and technical requirements.
When the turret is traversed to the right at 60°, as designed, visibility from the driver's station is impaired. The blind spot extends beyond the tactical and technical requirements, extending up to 10 meters ahead of the vehicle, and obscures the front edge of the vehicle.
When installing the M-63 cannon at the same rotation angle, the unobserved space in front of the vehicle is within the tactical and technical requirements, and visibility of the right side of the front edge of the vehicle is ensured.
When turning the turret to the left at an angle of 15° to 90°, visibility from the driver's seat with both systems installed is practically the same and meets the tactical and technical requirements, ensuring visibility of the front edge of the vehicle.
With the turret with the D10-T gun rotated to the right at 15°, visibility from the driver's seat is unsatisfactory, since the left wing of the vehicle cannot be seen, although the blind spot on the left alone exceeds the permitted tactical and technical requirements and reaches 5,5 meters.
Having examined the visibility schemes from the driver's seat for two variants of the D10-T type guns at different turret rotation angles and having tested them on a model, the Commission considers it necessary to note that the installation of the M-63 gun achieves the best visibility for the driver.
12. Based on the examination of the turret mock-ups of the SU-100 self-propelled gun with variants for installing the D10-T and M-63 cannons, the Commission considers it appropriate to recommend installing the M-63 cannon, designed by Plant No. 172, in the SU-100 self-propelled gun, as it provides better visibility for the driver and reduces the weight of the self-propelled gun by 200 kg.
13. When modeling the engine-transmission compartment, pay special attention to:
- possibility of easy installation and removal of diesel engine.
- access to injectors, valves, fuel pumps, water and oil pumps, air cleaners, fuel and oil filters and their removal and installation.
- the possibility of the best protection and easy cleaning of the engine and transmission compartment from dust and dirt.
- easy access to adjustment points.
Conclusion:
1. Having examined the full-scale model of the fighting compartment of the SU-100 self-propelled gun, the Commission considers it necessary for Plant No. 75 and Plant No. 172 to take into account and implement all comments and suggestions set out in this report when finalizing the technical design.
Dissenting Opinion No. 1
Considering that the 100-mm tank gun "D10-T" is in service and its production has been mastered, and the driver's visibility, if necessary, can be brought up to the visibility of the M-63 gun by slightly raising the driver's observation device, I consider it expedient not to develop a new gun (M-63), but to adopt the 100-mm tank gun "D10-T" for the self-propelled artillery, installing a muzzle brake on it.
Engineer Colonel Konovalov
Dissenting Opinion No. 2
Based on the tactical purpose of the designed self-propelled artillery vehicle, I consider it necessary, in addition to the armament adopted for it, to install a 14,5 mm anti-aircraft machine gun on the surface of the turret, making it easy for the loader and commander of the vehicle to fire from it.
The machine gun must have two positions: combat and travel. When in the travel position, it must pivot behind the rear of the turret, not exceeding its height.
The purpose of installing an anti-aircraft machine gun:
1. Make self-propelled artillery vehicles, to a certain extent, active in the fight against enemy aircraft and thereby solve the issue of their air cover with anti-aircraft weapons of this caliber.
2. The presence of such a machine gun on a self-propelled artillery vehicle will increase the firepower of the self-propelled artillery vehicle against ground targets and the immediate defense of the crew.
Colonel Malyshkin
Document 2
Comments on the manufacturability of facility No. 416 (for mechanical assembly shops)
The fundamental design solution for the main components of the vehicle (turret, gearbox, hull, chassis) gives reason to assume that after eliminating the above-mentioned comments and technological refinement of the components and parts during the working design process, the 416 vehicle will be more technologically advanced and less labor-intensive than the T-44 and T-54 tanks.
I. BOX (housing)
1. It's not rigid enough in the transverse direction, which will cause significant difficulties and lead to deformation during welding. It needs to be reinforced with ribs and the bottom should be corrugated while maintaining the same thickness.
2. Reinforce the running sheet with a beam or ribs to ensure normal operation of the running sheet.
3. Make the balancer brackets identical (abandon paired ones).
II. CAP (tower)
1. Redesign the lock at the joints of the cap sheets, since the designed structure is labor-intensive for mass production (processing dovetails and blind grooves).
III. FINAL TRANSMISSION.
1. The final drive cover requires simplifying the bearing hole (remove the flange and replace it with a spring ring), making the end surfaces in the same plane, and it is advisable to replace the threaded fastening of the drive wheel with a different design.
IV. GEARBOX
1. Blind holes (cantilever boring, making measurements difficult) are not desirable in the crankcase.
2. Revise the design of the gears to ensure grinding of the teeth (M-7) of all gears.
3. In the gear blocks, move the M 5,5 crown beyond the rim in the axial direction.
V. The wheel disk needs to be simplified, since the adopted design is labor-intensive to manufacture and will require a large amount of rolled metal.
VI. The design utilizes a large number of torsional joints, the production of which, even for a prototype, requires the manufacture of complex cutting tools.
VIII. ON METAL-CUTTING EQUIPMENT.
For prototypes, it is necessary to modernize the gear shaping machine for processing the tooth of the running gear.
To set up serial production, the plant must provide the following unique machines:
a) at least 3-4 large-sized rotary machines (diameter of the plan-washer not less than 3200 mm) for processing the ring and cap.
b) a machine for processing the under-turret sheet of the box
c) 2 gear shaping machines for products with a diameter of 2600 mm
d) a cylindrical grinding machine for grinding the outer diameter of the side cover
d) thread milling machine with a center height of 500 mm
e) planetary grinding carousel type for grinding the inner diameter of the side cover.
g) machines for grinding torsion bars.
When deciding to replace the T-54 tank with the Object 416 in serial production at Plant No. 75, the "401" artillery tractor (heavy artillery tractor, AT-T – editor's note) must be discontinued. The current organization and layout of artillery tractor production is based on the manufacture of identical and similar components for the T-54 and AT-T in the same workshops.
Parallel production of the 416 and 401 models will increase the range of manufactured parts and assemblies in the same quantities for which the workshops are designed: 100, 200, and 700 for the T-54 and AT-54 are impossible. Therefore, it would be advisable to simultaneously consider the development of an artillery tractor based on the 416 self-propelled gun.
Chief Technologist of Plant No. 75 Pomeranets
Document 3
CONCLUSION
Scientific and Technical Committee of the Main Armored Directorate of the USSR Ministry of Defense on the technical design of the SU-100 self-propelled artillery vehicle, developed by Plant No. 75 of the Ministry of Transport Engineering.
I. History issue
Resolution of the Council of Ministers of the USSR No. 4752-1832ss
As of 15.10.49, Plant No. 75 is required to develop a technical design for the SU-100 self-propelled gun in the 1950 quarter and produce a working model of the turret, and to produce one prototype for factory testing in the 4th quarter of 1950.
This topic was included in the armored vehicle development plan for 1949-1950 at the suggestion of Marshal of the Soviet Union Comrade Konev, with the goal of developing a prototype self-propelled artillery vehicle to replace the SU-76 in rifle regiments.
The preliminary design of the SU-100 self-propelled artillery vehicle was first submitted by Plant No. 75 for consideration by the HTR GBTU on March 14, 1950, but due to a number of deviations from the approved tactical and technical requirements, it was returned to the plant for correction and revision.
In March of this year, at Plant No. 75, a commission appointed by the order of the Commander of the Armed Forces and Mechanized Forces of the Soviet Army No. 0053 of 20.3.50 examined a wooden model of the SU-100 self-propelled gun, made in full size.
After reviewing the mock-up of the self-propelled gun's fighting compartment, the commission recommended installing the M-63 gun in the self-propelled gun instead of the D10-T gun with a muzzle brake, as this would provide better visibility for the driver and reduce the weight of the self-propelled gun by 200 kg. It also approved the following crew placement in the fighting compartment: the commander and gunner on the left, and the driver and loader on the right of the gun.
To ensure loading conditions and a high rate of fire, the commission proposed that Plant No. 75 develop a mechanization for feeding shots to the loader, and that Plant No. 172 develop a mechanical feed system for the shot into the barrel chamber.
After revision and correction, Plant No. 75 re-submitted the project to the GBTU PTK on May 6, 1950, which was reviewed on May 15, 1950 at the GBTU STC self-propelled artillery mounts section and on May 18, 1950 at the GBTU STC plenum.
As a result of the review of the project, the following decision was made:
1. The presented technical design generally satisfies the tactical and technical requirements issued for the design of the SU-100. The general layout is approved.
2. Invite Plant No. 75 to revise the technical design in accordance with the conclusion of the GBTU Scientific and Technical Committee. Specific aspects of the technical design should be urgently coordinated with Plant No. 172, the Turbomotor Plant, and the Tire Industry Research Institute. Once finalized and approved, the technical design should be submitted to the GBTU Scientific and Technical Committee for approval.
2. Invite Plant No. 75 to revise the technical design in accordance with the conclusion of the GBTU Scientific and Technical Committee. Specific aspects of the technical design should be urgently coordinated with Plant No. 172, the Turbomotor Plant, and the Tire Industry Research Institute. Once finalized and approved, the technical design should be submitted to the GBTU Scientific and Technical Committee for approval.
On September 13, 1950, the technical design of the SU-100 self-propelled artillery vehicle, revised according to the conclusion of the Scientific and Technical Committee of the State Technical University, approved by the Commander of the Armed Forces and Mechanized Forces of the Soviet Army on May 27, 1950, was presented to the Scientific and Technical Committee of the State Budgetary Institution.
On September 22, 1950, the project was considered at the plenum of the Scientific and Technical Committee of the State Technical University.
Between October 18 and 25, 1950, representatives of the Scientific and Technical Committee of the State Technical University examined a wooden model of a self-propelled artillery vehicle at the plant, made in full size and brought into line with the submitted project.
II. Project Summary
The SU-100 self-propelled artillery vehicle (SPG) is designed using a fundamentally new layout, pioneered in tank design. The crew, including the driver, is located in the turret. The engine features a horizontal cylinder arrangement. The turret is armed with a 100mm M-68 cannon designed by Plant No. 172 MV, with a muzzle velocity of 900 m/s and a recoil resistance of no more than 16 tons. The cannon is mounted in the turret, offset 65 mm to the left from the turret axis.
The shots to the gun are located:
- 19 rounds in vertical stowage along the ring in the rear part of the turret on a suspended floor;
- 12 shots in the right aft part of the hull;
- 4 shots on the floor of the fighting compartment under the gun.
The crew of the self-propelled gun is located:
to the left of the gun is the gunner and the vehicle commander;
To the right of the gun is the driver and loader.
The clear diameter of the shoulder strap is 2370 mm.
The height of the fighting compartment allows the crew to work only in a sitting position.
The driver's workplace is distinguished by the fact that when the turret rotates, the driver's position relative to the inner walls of the turret changes, but at the same time remains parallel to the longitudinal axis of the self-propelled gun hull and thus the driver's field of view is always directed along the movement of the vehicle.
Pneumatic-electric control drives made it possible to control the self-propelled artillery vehicle using a push-button control panel at any position of the turret relative to the hull, but the driver-mechanic's visibility conditions limited this possibility to the following range: to the right up to 60°, to the left up to 90° from the direction of movement.
The turret of the self-propelled gun is cast, the hull is welded.
Armor protection is characterized by the following data:
Tower:
Forehead 110 mm at an angle to the vertical of 32°
Sides up to 78 mm.
Feed – 40 mm.
Roof – 20mm.
Housing:
Forehead - 60 mm at 60°
Side – 20 mm.
Feed - 20 mm.
Under-turret plate - 20 mm.
Roof of engine-transmission compartment - 20 mm.
Bottom - 6 mm.
The engine is a 12-cylinder, horizontally-arranged engine.
The cooling system is liquid.
The cooling system fan draws air through the air intake located in front of the turret on the right side of the vehicle, pulls the air through the radiator and directs it to the engine-transmission compartment units for cooling, then the air is sucked out by the ejector device and, together with the exhaust gases, is ejected through the exhaust openings on the left side of the vehicle.
Fuel and engine oil are stored in two fuel tanks, each with a capacity of 220 liters, and one oil tank, with a capacity of 65 liters.
The main clutch is a dry multi-disc type.
The gearbox is mechanical with constant mesh gears, has 5 forward gears and two reverse gears.
The turning mechanisms are two-stage planetary.
Final drives are single-stage.
Suspension – torsion bar, individual with six road wheels per side.
The support rollers are cast with removable rubber tires.
The caterpillar is metal, fine-link, with pintle engagement.
The driving wheels are double and located at the front.
In the presented project, in comparison with the project reviewed in May 1950, the following main changes were introduced, improving the design of the self-propelled artillery vehicle:
1. The width of the self-propelled artillery vehicle has been reduced from 3250 mm to 3150 mm.
2. The configuration of the frontal part of the turret and the roof has been changed and the angles of inclination of the frontal part of the turret have been increased.
3. The thickness of the engine-transmission compartment roof, turret roof and hull rear has been increased to 20 mm.
4. The engine and transmission compartment has been reconfigured: the engine has been moved to the left side of the hull, and the gearbox and cooling system fan to the right side of the hull.
5. The commander's cupola diameter has been increased from 740 mm to 820 mm.
6. A new design of gearbox with synchronizers has been developed.
7. The design of the final drives has been redesigned.
8. Instead of a manual oil priming pump, an electric pump is installed.
9. A duplicate mechanical drive for controlling the self-propelled artillery vehicle has been developed, and a more complete pneumatic-electric control from the turret has been developed instead of a pneumatic-mechanical one.
Document No. 4
Statement of claim of the Scientific Tank Committee (Moscow, Frunzenskaya Embankment, 44) against Plant No. 75 (Kharkiv, PO Box No. 61). Amount of claim: 31,062 rubles.
According to contract No. H2-99/4 dated December 3, 1951, and the supplementary agreement of March 25, 1952, Plant No. 75 was required to complete the work specified in the attached fine calculation by April 15, 1952. The contract stipulated that the cost of the work was 3.106.200 rubles.
The defendant violated his obligations and did not complete the work within the contractual timeframe.
In accordance with Article 9 of the agreement, the defendant was asked by letter dated May 14.5.52, 31 to voluntarily pay the fine owed to him in the amount of 062 rubles (1% of the cost of the work not completed).
The proposal was met with an unfounded objection.
In view of the above, I request that a decision be made to recover from Plant No. 75, in accordance with the attached calculation, the amount of 31.062 rubles, imposing on it the costs of paying the state fee in the amount of 621 rubles.
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