Shipbucket :: Japan, 2500-ton Escort Ship

Shipbucket http://67.205.157.234/forums/

Japan, 2500-ton Escort Ship http://67.205.157.234/forums/viewtopic.php?f=13&t=10014	Page 1 of 2

Author:	Rainmaker [ October 18th, 2020, 4:16 pm ]
Post subject:	Japan, 2500-ton Escort Ship
Japan, 2500-ton Escort Ship (2500トン型護衛艦) During the Fourth Defense Force Development Plan (years 1972 – 1976), the Japan Maritime Self-Defense Force (JMSDF) planned to introduce a successor to the Yamagumo – class destroyers. This new class was to be based on the preceding Yamagumo – class, however it would feature increased displacement and the introduction of several technologies which were new to the JMSDF, such as gas turbines and a point-defense missile system. Originally, three vessels were planned to be built from 1974 to 1976, however, due to the oil shocks arising from the 1973 Yom Kippur war and the OPEC embargo that followed, it became impossible for the Japan Defense Agency to fund the project. Ultimately, a sixth Yamagumo – class vessel would be built instead using the same intended hull number (DD-121 Yūgumo) as the first of the 2500-ton class. It was not all in vain however, as many of the innovations that arose during the development of this type were subsequently introduced on the Hatsuyuki – class destroyers and Ishikari – class destroyer escort during the next Defense Force Development Plan. Both types were equipped with Olympus TM3B gas turbine engine that was planned to be adopted on the 2500-ton type. Thus, the 2500-ton type can be seen as a developmental “bridge” between the Yamagumo and Hatsuyuki – class destroyers even though they were never introduced into service. Notes on the drawing: I have included several speculative details based on other JMSDF vessels of the period – namely the Sea Sparrow BPDMS. Because the indigenous FCS-2 fire control system was delayed entering in service, the Shirane – class DDHs were first equipped with the Signaal WM-25 when they were constructed in the late 70s. I would expect the US-surplus Mk 25 GMLS and the WM-25 to be replaced with Mk 29 and FCS-2-12 in a subsequent refit. Additionally, I am uncertain about the potential interference between the WM-25 and ESM systems located on the aft mast. The references seem to indicate the position of the notional Sea Sparrow fire control system atop the mast; however, this is also where ESM antennas were normally located on Yamagumo and Minegumo – class destroyers. This would likely not be an optimal setup, however in the spirit of not making my own changes to the references, I have left their position as-is. Thanks for reading, I appreciate any and all feedback – I’ve also included my references below. Wikipedia entry for 2500-ton Escort Ship (Japanese only)

Author:	superboy [ October 19th, 2020, 12:54 pm ]
Post subject:	Re: Japan, 2500-ton Escort Ship
nice! but artist drawings have no sea sparrow and found VDS sonar. why did the second version?

Author:	acelanceloet [ October 19th, 2020, 12:57 pm ]
Post subject:	Re: Japan, 2500-ton Escort Ship
Are you certain the WM egg would have been used as the FCS for the sea sparrow? I have never seen the WM egg being coupled with an Mk 25 launcher, as the Mk 25 was the launcher for BPDMS and the WM was used for Nato Sea Sparrow, which always used the Mk 29 launcher.

Author:	erik_t [ October 19th, 2020, 1:14 pm ]
Post subject:	Re: Japan, 2500-ton Escort Ship
Great drawing, and I appreciate the technical details. I don't see any major reason a WM20-series egg couldn't control Sea Sparrow in the BPDMS flavor, even if this was never done in real life.

Author:	Colosseum [ October 19th, 2020, 2:44 pm ]
Post subject:	Re: Japan, 2500-ton Escort Ship
Love it - fantastically executed and the JMSDF escorts have always been a favorite genre of mine anyway. Great work and ignore the naysayers with nothing better to do

Author:	odysseus1980 [ October 19th, 2020, 4:06 pm ]
Post subject:	Re: Japan, 2500-ton Escort Ship
Actually the drawing does not show WM, but the Japanese FCS Type 72 (let me check in home correct model).

Author:

Rainmaker [ October 19th, 2020, 4:24 pm ]

Post subject:

Re: Japan, 2500-ton Escort Ship

Hi all - thank you for all the kind replies!

superboy wrote: *

October 19th, 2020, 12:54 pm

nice! but artist drawings have no sea sparrow and found VDS sonar. why did the second version?

Superboy - if you refer to the schematic drawing, you can see that the notional point-defense missile system and associated fire control radar are shown in dashed lines. This is because the final configuration was yet to be determined but the intention was certainly to fit the system. Judging by the artist’s rendition, I believe that the SQS-35J would have been fully enclosed as was the case on later Japanese destroyers, thus I made the decision to render it in the same way. If someone has a better reference / part for that I would gladly use it.

acelanceloet wrote: *

October 19th, 2020, 12:57 pm

Are you certain the WM egg would have been used as the FCS for the sea sparrow? I have never seen the WM egg being coupled with an Mk 25 launcher, as the Mk 25 was the launcher for BPDMS and the WM was used for Nato Sea Sparrow, which always used the Mk 29 launcher.

erik_t wrote: *

October 19th, 2020, 1:14 pm

Great drawing, and I appreciate the technical details. I don't see any major reason a WM20-series egg couldn't control Sea Sparrow in the BPDMS flavor, even if this was never done in real life.

Erik and ace - the Japanese Shirane - class DDHs did in fact pair WM-25 with Mk 25 BPDMS when they were originally commissioned! There are many high quality photos available online where you can see this. This is why I chose to do the same here. The reason for this was that the indigenously designed FCS-2-12 was delayed entering service due to faults in the insulation of the domestically produced vacuum tubes. The system was originally intended to enter service in 1976, but was delayed til 1979. Thus the JMSDF had to take a last-minute decision to import two WM-25s for its two Shirane - class vessels then in the final stages of construction. I felt that since the 2500-ton class would be under construction just prior to this, it would suffer from the same issue of domestic FCS not being available, thus perhaps the same decision would have been made.

Author:	acelanceloet [ October 19th, 2020, 4:40 pm ]
Post subject:	Re: Japan, 2500-ton Escort Ship
That's quite interesting! Those might very well have been the last ships being fitted with the Mk 25, but at the same time one of the first WM egg installations IIRC.

Author:	odysseus1980 [ October 19th, 2020, 5:07 pm ]
Post subject:	Re: Japan, 2500-ton Escort Ship
Indeed, Japanese GFCS-2 Type 79 delayed, this on illustrations suppose to be Type 79. It is very similar with WM "egg" inside. The Type 72 is a analog FCS comparable with US Mk 57 & Mk 63.

Author:

Rainmaker [ October 19th, 2020, 5:19 pm ]

Post subject:

Re: Japan, 2500-ton Escort Ship

odysseus1980 wrote: *

October 19th, 2020, 5:07 pm

Indeed, Japanese GFCS-2 Type 79 delayed, this on illustrations suppose to be Type 79. It is very similar with WM "egg" inside. The Type 72 is a analog FCS comparable with US Mk 57 & Mk 63.

Thanks for your reply - this is correct to the best of my understanding. I’ve chosen to substitute Type 79 (FCS-2-12) for WM-25 for the reasons I mentioned in an above post.

Type 72 is also referred to as FCS-1, and comes in two varieties: FCS-1A equips ships with 5”/54 Mk 42 gun, FCS-1B equips ships with 3”/50 Mk 33. There are two FCS-1B equipped on the 2500-ton class and are depicted on the drawing. Interestingly, this is one of the few JMSDF ships that I’ve seen that were intended to equip first generation FCS-1 and second generation FCS-2 on the same vessel, pointing to the evolutionary nature of the class.

Page 1 of 2	All times are UTC
Powered by phpBB® Forum Software © phpBB Limited https://www.phpbb.com/