The Pentagon's Chinese Military Power Report 2020 predictably comments on high numbers of Chinese submarines. But as most of the subs are conventional and quality of China's conventional and nuclear subs cannot be assessed or publicized the only safe USN reaction is to build more Virginia-class SSNs more quickly.
See the Report https://media.defense.gov/2020/Sep/01/2002488689/-1/-1/1/2020-DOD-CHINA-MILITARY-POWER-REPORT-FINAL.PDF especially:
- the intro pages i and ii
- the Chinese Navy (PLAN) Chapter, beginning page 44 and
- especially the submarine page 45.
- the Map page 49 detailing Chinese naval command regions and numbers of subs types in each
region is very interesting.
See the Report https://media.defense.gov/2020/Sep/01/2002488689/-1/-1/1/2020-DOD-CHINA-MILITARY-POWER-REPORT-FINAL.PDF especially:
- the intro pages i and ii
- the Chinese Navy (PLAN) Chapter, beginning page 44 and
- especially the submarine page 45.
- the Map page 49 detailing Chinese naval command regions and numbers of subs types in each
region is very interesting.
10 comments:
I saw the photos of the type 218SG being launched and in the water. Part of it looks surprisingly quite angular, next to the type 212. The conning tower is also very large, I thought the trend for next generation submarines is toward tiny sail tower.
KQN
Hi KQN [September 5, 2020 at 9:29 AM]
It is possible Invincible's/Type 218SG's sail/fin/conning tower is large to permit Type 218SGs to sit on the seafloor (while powered by its ultra-quiet AIP)
while being able to extend their antennas and photonic masks to a greater seafloor-to-surface height in more positions in the Singapore and Malacca straits.
Pete
A good photo of the RSS Invincible/Type 218SG is here
https://www.janes.com/defence-news/news-detail/singapores-first-invincible-class-submarine-commences-trials-as-pioneer-crew-begins-training
Hi Pete,
It can be dangerous to sit on the seafloor, I saw an article, can't find it now, when a Norwegian sub did that and they got sucked to the seafloor and almost didn't get free.
/Kjell
Kjell is right. DE subs can and do sit on the sea floor at times. But considering the fact that at low speeds (< 5 knots) they are already likely running on AIP and are silent, I think the benefits are minimal.
Also any movement in the sea bed could hit your rudder or fins and even scrape your hull. Not to mention if get stuck by suction and then emergency blow your ballast, you are going to broadcast your position to everyone and Charlie's aunt.
Of course, N subs usually never do that as their sea water scoops are located in the lower part.(at least the Indian Akula SSN has its sea water scoop in the bottom side)
PS: Randy Topechka of Canada has posited this on the net
"There is however an old Soviet submarine trick that I remember reading about once but can’t find information on. I can’t vouch for the validity of this either, But they would apparently find themselves a nice thick ice pack that was relatively smooth, place themselves there, and slowly raise their depth and make themselves slightly positively buoyant. The effect would be to press the sub against the bottom of the ice pack and hide in the ice noise. The would then deploy the towed array which would hang down like a dipping sonar, and they would sit there like a hole in the water and listen.
As I said though, I’ve only found one reference to this anywhere, and have no idea if it’s true or not so take it with a grain of salt."
I emailed Pete about the Type 218 trial images recently, which you can find on the photographer's FB in finer detail:
https://www.facebook.com/permalink.php?story_fbid=3427949463934306&id=572774889451792
The Type 218, in my eye, seems to resemble the Type 214 more than a Type 212 or Dolphin 2 class.
Yes, sitting on the seabed is a Cold War technique:
https://youtu.be/uX9vwK4y3Ug
Hi /Kjell and GhalibKabir
Yes currents, shifting seafloor formations and hard spiky rock could make seafloor sitting perilous. The floor would need to be well designated.
Also having to accelerate from 0 to 4 knots (or more) might be noisy if a sitting sub needs to react to an ASW platform or sensor coming by.
Special mission subs having thrusters may be part recognition that seafloor sitting has problems.
Thanks GhalibKabir for the Randy Topechka tip.
There's a good discussion here https://www.quora.com/Do-US-Navy-submarines-ever-sit-on-the-bottom-of-the-ocean
with comments from Randy Topechka, Ron Thompson, and "Michael Cochrane, former Reactor Engineer Consultant (Part Time) (2016-2018)"
Enough material for me to do a future article on this.
Pete
Thanks Shawn C
For this comment "I emailed Pete about the Type 218 trial images recently, which you can find on the photographer's FB in finer detail:
https://www.facebook.com/permalink.php?story_fbid=3427949463934306&id=572774889451792
The Type 218, in my eye, seems to resemble the Type 214 more than a Type 212 or Dolphin 2 class."
I reckon, comments posted under articles that we can all see and share are best.
Re https://www.facebook.com/permalink.php?story_fbid=3427949463934306&id=572774889451792 Yes the 218 may also look like a 214. There have been credible comments for several years that "4" is an "unlucky number" in Cantonese culture (which includes Singapore). So 4 was avoided and made 8. see https://en.wikipedia.org/wiki/Chinese_numerology#Four
Thanks also for https://youtu.be/uX9vwK4y3Ug on "Explanation of the 4 most common Soviet Submarine tactics NATO observed during the Cold War. Ice Picking, Bottom Sitting, Laying on liquid sand (soil), and Station Keeping. Featuring Leroy's cousin, Ivan!"
Regards
Pete
Hi Pete,
Maybe the A26 will have a thruster, at least FMV has sponsored a master thesis about it (unfortunate it is in Swedish, but maybe the pictures could be inspiring).
/Kjell
Hi /Kjell at September 9, 2020 at 9:15 PM
Thanks for the Swedish FMV sponsored Master's Thesis on thruster(s) for A26s at http://www.diva-portal.org/smash/get/diva2:1119103/FULLTEXT01.pdf
Fortunately on page 2 its Abstract is in ENGLISH:
"Thruster for NGU/A26 - Dimensioning and concept generation" By Emil Riddervold Sandberg & Markus Lindblom.
"This thesis work has been conducted on the behalf of the Swedish Defense Material
Administration [FMV], which by directive from the Swedish Armed Forces has procured two
new submarines of type A26 for delivery in 2024.
For certain operations A26 will need to be able to be dynamically positioned in water currents of various speeds. Forthis, it is estimated that there is a need for some type of thruster in the ship’s forebody. Such a solution has never previously been implemented on a Swedish submarine, and it is therefore necessary to conduct preliminary studies to calculate the resulting forces, powers and dimensions, as well as generate conceptual
suggestions for the design of such a system.
The main objective of the project is to generate one or more conceptual proposals
for the Swedish Defense Material Administration. The eligibility of the proposals
should be based on the acquired specified requirements.
An initial wide-ranging study has been performed to identify the types, sizes and
installation solutions of already existing thrusters and their principle function. During
the initial study, the materials, machine elements and components suitable for the
given application were also examined.
In order to determine for which flow angles and speeds the system is able to position
the submarine, simplified power and torque calculations have been made. These
should be seen as a valid basis for general approximations regarding the positioning
ability of the concepts although further development of the concepts requires more
detailed calculations to be made.
During the concept generation, it was determined which type of thruster is best
suited for the application. Subsequently, a number of simple, function-modeled
suggestions were generated to evaluate possible ways of integrations. Two of these
proposals were later selected for final detail modeling. The final choices of both
thruster type and concepts have been based on listed set of advantages and
disadvantages, which were then, evaluated using decision matrices.
The results of the calculations that have been carried out shows that it is possible to
dynamically position the submarine using a thruster system. This is under the
presumption of the rudders being able to contribute with transverse force generation.
A thruster is also found to be able to position the submarine with transverse forces
only, implying that the only argument for using a, in the horizontal plane, rotatable
thruster is the “limp-home” function.
Two particularly detailed conceptual proposals have been modeled; one that strictly
complies with the specified volume requirement and one which, with certain
adaptation to the internal geometry of the ships forebody, goes beyond the volume
restriction. Both concepts are considered to be principally and technically feasible,
with reservations of some specific solutions. The definitive concepts are meant to
serve as a basis for possible further development of the systems.
The designed models and the calculations underlying these are all of a generic nature.
They are fully adequate as a basis for this project but should not be seen as
representative of the A26 in its entirety."
Its easy to cut the Swedish text from the pdf then paste it into the Google Translate
Good Illustrations on:
- page "7" to "13" determined as footer in actual "hardcopy" text (not as drop-down pdf functional metering)
- pages 16 - 17 likewise
- 23 - 24
- many other good illustrations and graphs
Regards
Pete
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