Pravda class Submersible (1935)

Soviet Navy Series IV (1935-56), 3 boats: Pravda, Zvezda, Iskra

The “Pravda” (“Truth”) class, also the name of an early Soviet propaganda newspaper, was an attempt to design an oceanic, cruiser-style submarine for commerce raiding, following a trend started in 1917 with the German U-Kreuzer of the U151 and U139 class, inspiring the British X1, French Surcouf, American Argonaut among others, before the London Treaty put a cap of submarine tonnage. The Soviets were not concerned by treaties and thus started working on what is also called the “Series IV”. Only three were built due to their great cost and technical issues. The first, Pravda, was lost off Hango in 1941 and the to others survived the war and were still around in 1952-56. A fourth boat was planned but cancelled. Greatly improved, the concept became the K-class.

Development

Origins

The genesis for the “Pravda”, as seen aboven was the existence of German cruiser submarines back in WW1. They were first used in 1917-18, rampaging the US east coast. These were mostly the U-151 class derived from civilian trade submarines (Deutschland class) and the next Navy staff own design U-139 which only entered the war too late to really make its mark. Germany planned many more “U-Kreuzer” with improved performances to be delivered over the years but none was completed when the war ended in November. Suvivors were attributed to entente powers postwar, including Japan, which studied them, but Russia fell, replaced by the Soviet regime after a brutal and long civil war, now seen as the pariah of the east, so excluded from naval treaties. Thus, Soviet authorities were free to develop whatever submarine type they liked.

So in 1929 already, the concept of a commerce raiding submarine doubling as fleet submarine was formulated. The new type was intended to operate with the surface fleet and thus needed a great speed, around 20-22 knots. This was a challenge for any navy, especially the USN struggled to get the correct solution for almost two decades. The initial design envisaged also 130 mm (5.1 in) guns for surface action, like classic submarine cruisers, but not to carry a seaplane, albeit this was also envisioned for a time. However given its technological challenges, it was not easy to develop, neither to build.

An Asafov “squadron submarine” design

Around 1925-26 already, A.N. Asafov, who worked for the OGPU Technical Bureau of Leningrad, proposed a preliminary design for a fleet submarine, which displacement, would be similar to the Dekabrist-class and with as main feature a very large buoyancy reserve of approximately 80-90%. It made it possible to significantly reduce the draft, supposedly improving seaworthiness, necessary for fast surfaced operations in a squadron. This project was assigned the following missions:
-Taking part in squadron operations by approaching attacking enemy ships of vanguard forces, and during its withdrawal from the battle.
-To attack enemy landing forces underway or alongside light forces.

The preliminary design was called a “squadron submarine”, when reviewed and approved by V. M. Namorsi Orlov on October 11, 1930. On November 23, 1930, the design was approved by the Revolutionary Military Council in its first form. It was planned to carry six torpedo tubes with ten torpedoes total and two 130mm guns in turrets, plus 37mm anti-aircraft gun for a generous top speed of 24 knots surfaced, and range of 9,650 miles (23 miles submerged at 11 knots). The main diesel engines types and location was still to develop.

Construction starts (1931)

By mid-January 1931, working drawings were prepared despite limited knowledge on such large types. On May 21, “Pravda” (Type “P”, later IV series), was laid down, followed by two more on December 19, in great haste, given such unusual requirements, was a recipe for disaster. In fact, many numerous shortcuts, compromises and questionable design solutions had been chosen in what was essentiually a largely superficial development. Both chief designer Asafov and the shipard led to endless disputes and delays, notably concerning the practical diving depth and maneuverability while submerged.

To ensure a high surface speed, she was given a destroyer-like hull, and for seaworthiness, a high freeboard. This gave the Pravda class a large reserve of buoyancy, but resulted in a long diving time as well as an insufficient diving depth even for that time and especially for such large boat. It was also obviously large and thus easy to detect, vulnerabile even to artillery fire when surfaced. It had lengthened breakwaters on the bow torpedo tubes resulting in the tail hitting them when launched, a dangerous shortcoming. Other were gradually revealed during testing. Pravda appeared almost impossible to control when submerged elow 4 knots. And at a sea state 5 or greater when surfaced, she pitched and rolled so much she could not use her artillery at all, as well as exposing her propellers to enemy fire.

Drastic Design Revisions (1932-33)

P3 sitka 1942
Serious technical disagreements on key design issues led to suspend the construction of the IV Seriesal together until they were resolved gradually, so completion of the overall design was delayed even at paper stage, until September 1932. The overall design was approved at last by the Revolutionary Military Council on October 7, 1932, and lots of changes to a number of tactical and technical aspects were approved. The diving depth was now set at 75 meters with a stability margin of 1.5. Top speed was maintained to 23 knots, but displacement increased to 931 cubic meters. On October 19, 1932, the USSR Defense Committee decreed to resume construction on Pravda as a prototype for the two others, mothballed until all problems had been solved.

Due to the insufficient strength of the pressure hull, the increased diving depth, and the need to increase the buoyanvy of the pressure hull, the design was radically revised. The main outer hull, already quite well-developed as Pravda was 25% complete at that time (the remaining two were 20%-10%, respectively) was forced to have a significant redesign. Intermediate frames were added to increase the safety margin. By September 12, 1935, Pravda was simply submerged, our of her dock at sea, still unmanned, to 72.5 meters, under the sub rescue catamaran “Kommuna”. She couldn’t achieve a greater diving depth that the one setup, but even this exceeded expectations, leaving everyone satisfied. The Chief of the Naval forces approved a maximum diving depth of 70 meters, working depth of 50 meters base don this. Construction then resumed on the two mothballed hulls.

Differing Designs

The Pravda-class differed from other classes in ways, having two complete hulls, one outer, one pressure for maximum buoyancy, and for the first time the pressure hull had external frames and it was divided into seven compartments (see later). Numerous drives performed with Pradva and the position of the electric motors in the holds, hard to reach made maintenance overly difficult, resulting in an unreliable operation overall.

Design: Series IV

They were double hull boats, with eight compartments, plagued an an underpowered machinery, long diving time, poor seakeeping as well as weakness in hull strength. So early in service they needed stiffening and weight cutting. Yakubov and Worth both argued they were acartainly the worst Soviet submarines of that era. They were soon relegated to secondary duties like training at completion and after the loss of the lead boat, the remaining two had their conning towers rebuilt for faster diving time.

Hull and general design

stem
main ballast tank ventilation valve
towing hook
jackstaff
mooring rope reel
upper “sword” of the sonar fairing
gangway
guard rail
cleat
bollards
forward radio mast
lifeboat
torpedo tubes
forward hydroplanes
firing cylinders
oxygen cylinders
main ballast tank seacocks
main ballast tanks
torpedo loading hatch
annular gap tank
torpedo replacement tank
fuel tank
provisions replacement tank
torpedo boom
berths
dining tables
footrests
spare torpedoes
galley
storage battery
latrine
emergency telephone buoy
duck
provisions tank
entrance hatch to the provisions tank
sofas
officers’ cabins
battery pit
ship’s oil reserve tank
searchlight
chain locker
“R-130” bilge centrifugal pump
commander’s cabin
personal belongings locker
100 mm bow gun
sonar room
magazine hatch
bow hydroplane steering column
aft hydroplane steering column
diving and surfacing station
magazine
anti-aircraft periscope shaft
low-pressure turbocharger
commander’s periscope shaft
artillery shell feed elevator
radio room
power network distribution board
conning tower
entrance hatch
100mm artillery ammunition first shot fender
anti-aircraft periscope
bridge railing windows
masthead light
magnetic compass
commander’s periscope
gunnery crew access shaft to the stern gun
sidelight
45mm gun
diesel air supply shaft
100mm stern gun
shell replacement tank
service fuel tank
engine room seacock drive
signal mast
backup diesel engine cooling pump
backup oil pump
diesel M1OV49/48
diesel exhaust
guard rail antenna
barring device electric motor
thrust bearing
tool cabinet
oil cooler
regeneration cartridge boxes
diesel exhaust muffler
desk
horizontal rudder guard
propulsion motor control station
guard rail
lockers
high-pressure air cylinders
stern radio mast
propeller shaft
propulsion electric motor
disengaging cam clutch
Mitchell thrust bearing
shaftline rigid coupling
Voltage-step-down unit (booster)
High-pressure air compressor
Bilge piston pump
Watermaker
Fresh water tank
Log tank
Washbasin
Vertical rudder drive
Fore trim tank
Aft trim tank
Wakelight
Stern hydroplane drive
Vertical rudder stock
Vertical rudder
Stern hydroplanes
Propeller
Flagpole
surge tank.

* From original drawings by the Rubin Central Design Bureau of Marine Engineering.

Powerplant

Diesels and Electric Engines

A distinctive feature of the design was the M10V49/48 diesel engines, producing 2,700 hp at 465 rpm. This was the first time diesel engines of this power were used on domestic submarines. The engines were supplied by MAN in Augsburg, Germany, and featured a relatively low power-to-weight ratio for the time (approximately 13 kgf/hp), significantly lower than the diesel engines used on early-series submarines.

The battery consisted of two groups, each containing 112 EK-type batteries, housed in two battery pits. The main electric motors had a power output of 2 x 550 hp. The total fuel capacity was 89 tons.

Ballasts

The main ballast was located in 10 mid-hull tanks and two end tanks. The main ballast tank seacocks (68 valves with a total area of approximately 11 m2) had remote electric drives with flexible elements in the form of spring clutches. Therefore, this seacock drive design was no longer used on domestic submarines. The main ballast tank ventilation valves had remote pneumatic drives, similar to the main ballast tank ventilation valves of Series II and Series III submarines. Unlike the submarines of the first three series, a quick-dive tank
was not provided. The water-drainage systems consisted of one Rateau pump and two piston bilge pumps, similar to those used on previous submarines. To bleed the main ballast tanks with low pressure, two Brown-Boveri turbocompressors were installed, each with a capacity of 60 m³/min (turbocompressors of this capacity were never used on any other domestic submarines). Otherwise, the equipment of the Series IV submarines differed little from that of the Series II submarines.

Armament

As said above the original armament planned two single 130mm gun turrets for and aft plus 37 mm, either twin or single mounts. This was all revised before completion with two 100mm standard deck guns and a single 45 mm AA, amaking them relatively underarmed, but the lack of torpedoes was the greatest issue of the design. So little time was spent in the design that despite the immense byouancy reserve and generous double hull, no practical solution was found to include more reserve torpedoes. Given the long time spent reloading batteries, a day or more, this was plenty enough to extract torpedoes from the outer hull and reload the tubes, albeit waters needed to stay still, which was not a guarantee in winter in the Baltic.

Torpedoes

Four tubes at the bow (with all the issues for launching them solved), two stern, and ten torpedoes in reserve, meaning potentially four in reserve only. This was not much for boats their size and precluded their use alongside the fleet (which was impossible due to their low speed to start with).

21-inches type 53-27

The story of the first 21-inches Soviet torpdoes started under Imperial Russia, as a model called the pattern 1917 designed to carry a warhead of 476 lbs. (216 kg) at 3,280 yards (3,000 m) and 45 knots or 10,940 yards (10,000 m) at 30 knots thanks to its Wet-heater. It never entered service due to the Revolution but formed the basis for the first Soviet torpedo, the “53-27” project. It is interesting to point out the simple type identifier, rather than “model and the year”, precising the caliber 53 cm and year (1927) was judged more compact, precise and efficient.

The first model adopted was the 533 mm 53-27 type. It was universal, designed to be used from large surface combatants down to MTBs and submarines. Design started likely in 1923 and was accepted in 1927, about the tilme the Dekabrist class were completed, so they were obtained probably in 1928-29 as production ramped up given their urgent need in the whole fleet.
They weighted 3,770 lbs. (1,710 kg) for a body that was 22.97 feet (7.0 m) long, carrying a 584.2 lbs. (265 kg) warthead, with simple percussion cap for the detonation mechanism, and thanks to their Wet-heater they reached 3,700 m at 45 knots. The dual setting mode was abandoned as too complicated. It was produced en masse until 1935 and really became widespread.

Deck Gun: 45/43 21K (1934)

Installed at completion on the Series III. This was a navy version of the Army 45 mm Pattern 1932 anti-tank gun. The navalized mount had a semi-automatic breech. Tested in 1934, accepted in 1935 after tests with the originally intended automatic breech mechanism failed. Standard AA mount until 1941-42, replaced by the 37 mm/67 but in production until 1947. Not efficient, semi-automatic, no time fuze. Total prod. 2,799 guns. It was largely used on submarines either as AA gun or main deck gun on small Schchuka types.

Specs

Gun Weight: 107 kg, length 2.3975 m, bore 2.0725 m, rifling 1.650 m
Rounds FRAG-Tracer OT-033 2 kg, HE O-240 2.89 kg, FRAG-Tracer OR-73A 2.32 kg
Muzzle velocity: FRAG-Tracer 880 mps and OR-73A 760 mps HE O-240 335 mps and F-73 760 mps.
Rate Of Fire: 25-30 rounds per minute
Single pivot Mount 21K 507 kg, -10 / +85° at 10-20°/sec. Recoil 27-30 cm.
Range (FRAG-tracer): 45°: 9,200 m, 85° 6,000 m. With HE at 45° 5,000 m.
Rounds provision c500, barrel life 4000 rds.

Sensors

Thes eboats were either completed with a Merkuriy or Mars-An or Mars-DM or Mars-ShM hydrophone when completed.

Mars-16 Hydrophone

A locally produced version of the Atlas Werke model, which proved ineffective for speeds above 3 knots due to noise interference. It was less a problem for a submarine underwater, which could ran at 4 knots on more discreet electric engines. It replaced the Mars-A, DM and ShM models on all boats in 1940-41. Installed in 1940-42 for the two boats that survived.

Series IV profile, as built

Series IV profile with the new CT as rebuilt 1942.

⚙ specifications
Displacement	1,200 tons surfaced, 1,870 tons submerged
Dimensions	90 (295.3 ft) x 8 m (26 ft), 3.10 m (10 ft) draft
Propulsion	2 shaft diesels MAN, 2x electric motors. 5,400/1,000 hp.
Speed	18.5 knots surface/7.7 knots diving
Range	5,700 nmi (10,600 km) at 10 kn (19 km/h)
Armament	2x 100mm deck guns, 1x 45mm AA, 6x 533 mm TTs (4 bow, 2 stern, 10)
Sensors	Hydrophones
Max depth	90m (295 ft) to 100m (340 ft)
Crew	54

Career of the Pravda class

Series IV Construction and Operation

These boats had a long building time, being laid down in 1931 and completed in 1936:
П-1 [P-1] Правда was ordered as N°218 at 189 Yd (Ordzhonikidze Yd) Leningrad, laid down on 5.1931, launched on 3.1.1934 and completed on 6.1936.
П-2 [P-2] Звезда (renamed 6.1949 B-31) had been ordered as N°219 at Ordzhonikidze and laid down 12.1931, launched 15.4.1935 and completed on 7.1936.
П-3 [P-3] Искра (6.1949 B-1) was ordered as N°220 at Ordzhonikidz, laid down 12.1931, launched 4.12.1934 and completed on 7.1936.

Studied in 1929 under the first five-year plan, these sister units, similar to those designed by the Japanese, suffered from poor design, although their construction lasted five years. Their hull was too light, badly compartmentalized, they were excessively noisy, slow, not very seaworthy nor easy to handle. In addition, they were poorly armed, with only six tubes and ten torpedoes in store, despite generous dimensions. Their batteries did not charge fully even after twenty hours, leaving them vulnerable when surfaced. This made it impossible to order more than the first three authorized units, Pravda, Zvezda and Iskra. The potential 4th was cancelled. They were used for training or as transport, demoted to the second line. Only Pravda was sunk during the war, hitting a mine in September 1942, the other two badly damaged off Leningrad by the Luftwaffe and German artillery, never properl repaired until late in the war, and still used for tests and training in the 1950s.

Modifications

Design modifications and poor weight control during construction already resulted in the submarine being clearly overloaded, so the auxiliary diesel generator and 130mm turret gun were cancelled for simpler 100mm deck guns and the twin 37 mm mounts replaced by a single 45 mm mount. To ensure the torpedoes could exit the bow tubes safely, the bow was shortened by 2.3 meters so from 90 to 87.7 meters overall, so that the breakwaters of the upper torpedo tubes ended less than 3.2 meters long and the superstructure was later modernized in 1939 for all three, with the large bulwark dropped for a lower one. In 1942, the survivors were modernized with a Mars-16 hydrophone.

P-1 Pravda

On May 21, 1931, Pravda was laid down in Leningrad (November 1930, the name “Pravdist” was proposed) but in September 15, 1934 she reveived the pennant “P-1” before being launched on January 3, 1934 and the Summer, submerged to determine submersion time and other parameters, in a testing basin. Water leaked the pressure hull, causing the submarine to settle to the bottom. It was dicovered later a ventilation shaft and valve had been not closed. The fan motor and the nearby blowers in the hold were flooded. She was returned to the shipyard for repairs. By September 12, 1935 she made a deeper unmanned dive under 72.5 meters as seen above under control, hold by the salvage ship Kommuna near the Stensher lighthouse. She dived with an additional 40 tons of cast iron ballast stowed in the pressure hull. Before this she had measurement gauges fitted to measure hull deformation, and a microphones for listening hull noise in each compartment, with Speakers located on Kommuna. The battery was shut off, the crew exited the submarine when all was ready and she sank at a rate of 0.5 meters per minute, reaching the limits of Kommuna’s buoys and remained there for one hour and 56 minutes. After the ascent back to the surface lasted for 3 hours.

On June 9, 1936, she had her acceptance certificate signed and entered service after 6.3 million rubles had been spent in R&D and construction, making her the costiest Russian submarine ever built so far. On July 23, 1936 she was assigned to the Baltic Fleet, 9th D-class submarine, 1st BrPL for training and on August 18, she joine the 11th D-class submarine, 1st BrPL in Kronstadt. Then from December 1937 to November 6, 1939 she was modernized, modified, repaired, in Leningrad. In 1938 she was reclassed into the 4th BrPL, a training unit. By November 1940she sortied with her sisters P-2 and P-3 in the Baltic Sea, stopping at Tallinn, Riga, and Libau and on February 11, 1941 they joined a separate division of the Baltic Fleet, the Training Submarine Battalion based in Oranienbaum. On June 22, 1941 she continued training at Oranienbaum as it was reorganized, but on on September 8, she was returned to Kronstadt and, after unloading torpedoes, took on cargo to be carried to Hanko. On September 9, she departed with 19.6 tons of cargo (food, ammunition, and medicine) but in the evening she was escorted to the area of Gogland by BTSh-211 and SKA.

She never arrived at her rendezvous point, on September 11. Possible causes was a mine in the “Yuminda” or “Korbetta” mine barrages on September 10-11, or personnel error, or equipment failure. She was supposed to be kept surfaced at 18 knots. 55 perished when she sank, perhaps as late as the 16 or 17th. She as officially decommissioned on October 6 and stricken. The wreck was rediscovered in the Summer 2008 duing surveys along the route of the Nord Stream gas pipeline. Back in 2002, naval historian Konstantin Strelbitsky manage to reconsititure the Combat Log of the Hanko Naval Base and pointed out a report from the of the 72nd SNIS post reporting an explosion near Russare Island. Now it is assumed he saw P-1 blown by a mine. This was confirmed by the 2012, May 4-7 operatons launched by the survey vessel “Sibiryakov” visiting the wreck. The team was a Joint Russian-Finnish International Underwater Search Expedition which explored many more wrecks to turn them to military burial sites. That day, military honors, a gun salute were held and a memorial plaque deposed.

P-2 Zvezda

On December 19, 1931 Zvezda (Star) was laid down in Leningrad (November 1930, name “Chekist” considered), but renamed P2 on September 15, 1934 and by April 15, 1935 she was launched after many modifications after being mothballed, just 25% complete for years. On July 9, 1936 she had her acceptance certificate signed and was Commissioned on July 23, assigned to the Baltic Fleet, 9th D-class, 1st BrPL. On August 18, 1936 she was versed to the 11th D-class submarine; 1st BrPL in Kronstadt and in the Spring 1937 she escorted the battleship Marat to the Southern Baltic in an official visit to Britain. From December 1, 1937 to November 6, 1939 she was overhauled and modenrized in Leningrad, in between she was recalled into the 4th BrPL a new training unit. By November 1940 with her sister she cruised to Tallinn and Libau. By February 11, 1941 she joined a separate training division based in Oranienbaum like her sisters, and on September 8, transferred back to Kronstadt. By June 25-26, and October 25, she entered Narva Bay to shell coastal targets. On the morning of October 26, near B. Tyuters Island, she was unable to trim due to the additional load of shells and, and submerged with a bow trim of 25-28°, creating an electrolyte spill, multiple failures, chlorine being released.

The commander ordered a quick surfacing, after which she was attacked by enemy aircraft. Two bombs near-missed by 5 meters her port side causing one man was wounded, four shrapnel holes near the conning tower. While back between the Seskar and the Shepelevsky islands she was shelled by a coastal battery. At 18:18 on October 26, she was back to Kronstadt. On the 29th, she was sent to Leningrad for repairs. By December 21, under tow by the icebreaker “V. Molotov” she returned to Kronstadt, her guns removed, 700 tons of diesel fuel loaded into her ballast tanks. She received a new camouflage paint when departing for operations again, shelled by enemy coastal artillery in the Peterhof-Strelna area for 44 minutes, herself was cornered for 10-minutes, received 14 hits to the superstructure. On December 30, as part of a convoy, she returned to Leningrad under her own power after being fired upon in the passage for repairs. She remained moored in Leningrad for the winter. On April 4, 1942 while moored at the Petrograd pier, Bolshaya Nevka river, she was hit by shrapnel during a German air raid, while moored next to her sister P-3.

In May she was mothballed and on July 28, withdrawn from frontline actions, then on January 7, 1943, transferred to the Baltic Fleet Submarine Division for Overhaul. On August 10 1944 she was decommissioned, reclassified as test submarine, transferred to the Naval Research Institute. On November 15 1945, she was integrated into the R&D unit of the Baltic Fleet and from 25 Feb. 1946 the North-Baltic Fleet. By December 30, here unit was reformed and she ended in the “8th fleet” in 1947. In April 1948 her unit was reformd again but by 1950 she was no longer listed. On January 12, 1949 she was recalled as a “large submarine” and on June 9, renamed B-31. By August 9 1955 she was disarmed, stripped, converted into a hulk and by June 20, 1956, she was stricken. Placed on the list on dismantling and sale, acted on August 17, 1956, sent for scrapping at the Turukhanny Islands complex of Leningrad.

P-3 Sitka

On December 19, 1931, Sitka (shark) was laid down in Leningrad. In November 1930, the name “Iskrovets” was proposed. She was renamed on September 15, 1934, P-3, launched December 4, commissioned on July 9, 1936, integrated in the fleet on July 23, 1936, assigned to the Baltic Fleet’s 9th D-class submarine, officially Commissioned by order of the People’s Commissariat of Defense and on August 18, joining the 11th D-class submarine based in Kronstadt. From December 1, 1937 to November 6, 1939 she wa soverhailed Leningrad and reclassed in the training unit of the fleet. By November 1940 she made a squadron cruise to Tallinn, Riga, and Libau but on February 11, 1941 she is sent to the separate training division in Oranienbaum. On July 16, she collides with B-2 in the Gulf of Finland, main ballast tank punctured, repaired in drydock. On September 8, she is transferred back to Kronstadt in a dock with three Destroyers and on the 23th her dock is hit by a bomb (air raid). She is puncture near frames 44-45, a fire destroyed the second battery group as well as the water mains, and outer hull.

On October 29, she is transferred back to Leningrad and placed in the city’s artillery defense system using her gun for AA defence. On April 4, 1942 she takes shrapnel damage from two 250-kg bombs exploding nearby, destroying the “Lieutenant Schmidt” Bridge in Leningrad. The near-hit happened 8-10 m from her stem blating the plating of main ballast tanks No. 1 and 2, both pierced. On May 1 she is mothballed, on August 14 withdrawn from the fleet and by Januar 7, 1943, transferred to the Division of Construction and Repairs of the Baltic Fleet. By June 21 1944 like her sister she is decommissioned, reformed as static training submarine at F.E. Dzerzhinsky Higher Naval Engineering School. On August 25, 1945 wit the war over, she is transferred to a test unit for the Baltic Fleet in Kronstadt and on November 15, enters a new unit, reformed in 1946 as the North-Baltic Fleet. Long story short she remained mostly mothballed and on June 2, 1952 she is decommissioned, stricke, sent for dismantling, but handed over to the Naval Research Institute No. 11 for experimental use and destructive tests. The remainder were scrapped in 1955.