April 6, 2018

Russian Navy and Export Kilo submarine issues & their diesels

KQN made interesting comments on April 6, 2018 concerning Russia's Kilo submarines and their diesels. Pete has added comments in square [...] brackets Comment is:

"I think the main difference between the [more advaced Kilo diesel] 7-2D42M and [older] 4-2DL42 is the increased performance [of the 7-2D42M] using 2 stages turbochargers and intercoolers. 
[The 7-2D42M's increased performance (see the April 3, 2018 Table) includes 1500 kW mchanical output at 750 rpm. This compares with the 4-2DL42's 1000 kW at 700 rpm.]

[The 7-2D42M and 4-2DL42] trace their origins back to the 30/38 in the 1930s. [1] 

In my view the 30/38 is similar to the old British Gardner engines [2], they are both very economical low speed engines. None of the 30/38 variants, including the 7-2D42M, can run at speeds higher than 750rpm. 

I am speculating given these engines [have] long crankshafts, long stroke high torque, [the] Kilo SSK is optimized for low speed patrols [around 4 knots?], meaning running their engines at 400-500rpm.

Specifically for the six Kilo 636s exported to Vietnam or all 636s? One of two possible pump jet outlets can be seen as the hole immediately to the right of the propeller shroud and below the tail plane (or is that an exhaust outlet?) (photo courtesy DANVIET.vn via FDRA

One difference I notice between the Russian [Navy only] 636.3 and the [for export] 636.1 (looking at photos of the Vietnamese Kilo [above)]) is the existence of pump jet outlets on both sides, at the rear just below the horizontal tailplane on the 636.3. They are for very low speed [2 to 3 knots?]  shallow depth operation I think. 

[I'm] not sure where the auxiliary propellers on the [plain 636, 636M or] 636.1 are located. In my view the main weakness of the Kilo 636.3 or 636.1 is the sonar suite. Few Russian submarine designs have the prominent spherical bow [eg. on the Collins with torpedo tubes underneath] sonar due to the [obstructive] location of the Kilos torpedo tubes. With sonar, passive performance is directly related to the surface area. There are also no flank sonar arrays that I am aware of.

Russia needs to sell SSKs to get cash, especially in light of the vaporware that is the Kalina SSK. [not to mention endless delays in exporting a mature Amur class SSK]. So 
I think there are 4 potential areas for performance improvements on the Kilo SSK:

1.  improved sonar performance. May be add the flank arrays. Improved electronics (I have read [the

     Russians] use dated CPUs)
2.  replace Lead-acid batteries (LABs) with Lithium-ion batteries (LIBs) [on newbuild Kilos, 
     Lada-Amurs and Kalinas]. This will require new [diesel-generator] gensets.
3.  optimize the sail/fin, better meshing with the hull
4.  better skewed propeller design. If you compare the German type 212 propeller to the 636

     propeller, you can clearly see the German propeller is much better."


[1]  This may refer to the six cylinder Kolomna [D42?] 30/38 with 30/38 meaning 300mm bore and 380mm stroke. (see IUSS Alumni Association website).]

[2]  During World War II (1939–1945) British multipurpose diesel builder, L. Gardner and Sons Ltd's war work consisted mainly of building diesel engines of their own design. Their 4LK bus engines were also used as the main powerplant in the Royal Navy’s X class and XE class midget submarines.

KQN and Pete


Anonymous said...

Hi Pete

Official details of D49 and D42 are introduced in [2] and [3]. JSC "Kolomensky Zavod" produces diesel engines on the basis of two standard sizes [1]: Д49=D49 (ЧН26/26=ChN26/26; bore 260mm, stroke 260mm) andД42=D42 (ЧН30/38=ChN30/38, bore 300mm, 380mm).
D49s are V8, V10, V16 and V20 diesel engines (8ChN26/26, 10ChN26/26, 16ChN6/26, 20ChN26/26) [2], and are used for general, Navy and submarines.
D42s are L6 and L8 diesel engines (6Ch30/38, 8Ch30/38) and 6Ch30/38 is used for general [3], Navy and project 636s.

[1] http://www.proatom.ru/modules.php?name=News&file=print&sid=7504
A turbocharger 2TK or 6TK (TK-38) is adopted, but two stage air cooling/two stage turbocharger system is adopted for 6Ch30/38 (2-7D42) for project 636.3 [4].
[4] https://www.korabel.ru/equipment/item_view/345171.html


Peter Coates said...

Thanks Anonymous [at 7/4/18 4:05 AM]

I'll turn the details into an article tomorrow (Monday).



Anonymous said...

Hi Pete

Kilo submarine equips with i) one main propulsion motor (eg., 5.5MW, max speed 500rpm), one small propulsion motor at low speed or economic range and two small reserve motors, and ii) three propulsion propellers , i.e., one main propulsion moter and two identical small reserve propellers. The reserve propeller is set inside of tube in light hull (Kilo has double hull structure consisted of the outer light hull and the inner pressure hull) .

The shaft for main propeller (eg., max speed 250rpm) is connected with the stern side of the small propulsion motor by elastic coupling, the bow side of the small propulsion motor is connected with the shaft by elastic coupling, and this shaft is connected with the stern side of the main propulsion motor by the rubber-pneumatic clutch (KHP).

At low speed range (eg., 3knot/h), the main propulsion motor is not connected with the shaft and the main propeller is driven only by the small propulsion motor to achieve economic and silent operation.

At high speed range, the main propulsion motor is connected with the shaft by KHP. The shaft speed (propeller speed) is reduced by reduction gear of the main propulsion motor, because speed of the main propulsion motor (eg., max speed 500rpm) is significantly higher than propeller speed (eg., max speed 250 rpm).

As existence of reduction gear means vibration at high speed, improved Kilo 636.3 seems to have bigger acoustic fingerprint than modern submarines driven by PSMS or DC motor without reduction gear. Frankly, platform of Kilo is too old and new platform for modern technologies such as PSMS, LIBs and high power diesels are needed in Russian conventional submarine.


Josh said...


Almost every SSK has a much smaller bow sonar array than the spherical arrangement used in US nuke boats - in fact as far as I can think of all boats generally lack the baffled, large spherical sonar and amid ship torpedo tubes of US nuke boats except for RN nukes and the new Russian Yasens. That said, the 636 family and its predecessors were not optimized for ASW work. They are primarily a low cost anti-surface assets, and their sonars are perfectly adequate for that. Realistically, except for perhaps China none of the users of Kilo envision a sub on sub engagement as being especially likely.