"Tactical-Technical Requirements for Supreme Command Reserve Self Propelled Artillery
- The main purpose of Supreme Command Reserve Self Propelled Artillery is the destruction of pillboxes and dugouts with direct and indirect fire, destruction of fortifications in settlements and railway stations, destruction of headquarters and concentrations of enemy personnel and vehicles.
- Supreme Command Reserve Self Propelled Artillery should satisfy the following requirements:
- Minimal dimensions, mass, and bore axis height.
- Ability to fire from short stops without deploying trails.
- Maximum speed of 8-12 kph.
- Ground pressure of 0.5-0.8 kg/cm².
- Maximum grade of 30 degrees.
- Fuel capacity for 100 km of travel.
- Maximize the use of existing tank and tractor components (engine, transmission, suspension, gun mount, instruments). Most of the manufacturing process should consist of assembly and metalworking.
- Clearance: 350-400 mm.
- The oscillating part and upper mount of the 203 mm mod. 1931 howitzer (the use of the Br-2 gun is also possible) with the following characteristics:
- Caliber: 203 mm
- Muzzle velocity: 607 m/s
- Maximum pressure: 2350 kg/cm²
- Shell mass: 100 kg
- Explosive load: 15.09 kg
- Maximum elevation: 60 degrees
- Horizontal range: +/- 3 degrees (of the artillery system +/- 4 degrees)
- Recoil resistance: 60 tons
- Recoil length: 850-875; 1300-1400 mm
- Mass of the gun and mount: 17746 kg
- Mass of the barrel and breech: 5200 kg
- Bore axis: 1880 mm
- The armour of the SPG must provide:
- Protection of the engine (front) and transmission from penetration by the 76 mm gun (thickness must be 70-75 mm).
- Front armour must be 70-75 mm thick.
- Armour around recoil devices must be 30 mm thick in the front and 10 mm thick on the sides.
- Armour protecting the crew from the sides must be 25-30 mm thick.
- The breech and roof are unarmoured.
- The angle of the armour must be designed with the latest achievements in tank and shipbuilding.
- No less than 30 rounds of ammunition must be stowed onboard.
- The crew must be completely protected while loading. It is acceptable to replace the crane with a special tray.
- The firing devices and sights must allow for rangefinding, keeping in mind that there will be no forward observers or fire correcters.
- The rate of fire, convenience of service, and cooperation of the crew will be tested on the model.
Chairman of the NKV Technical Council, Satel"