IJA Radar

Discussions on all aspects of the Japanese Empire, from the capture of Taiwan until the end of the Second World War.
Mil-tech Bard
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Re: IJA Radar

#16

Post by Mil-tech Bard » 09 Sep 2014, 21:00

Akira Takizawa wrote:It was planned to deploy one shooting radar at each AA gun battalion. AA gun battalions had various AA guns from 75mm to 12cm.

Taki

Do you have any idea how many "Koku Joho Rentai" were involved in the Okinawa Campaign in 1945 and to which Air Armies/Fleets/Sectors they were associated with?

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fontessa
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Re: IJA Radar

#17

Post by fontessa » 09 Sep 2014, 22:25

Hello Mil-tech Bard,
Mil-tech Bard wrote:
Akira Takizawa wrote: It was planned to deploy one shooting radar at each AA gun battalion. AA gun battalions had various AA guns from 75mm to 12cm.
Taki
Do you have any idea how many "Koku Joho Rentai" were involved in the Okinawa Campaign in 1945 and to which Air Armies/Fleets/Sectors they were associated with?
"Koku Joho Rentai" was not deployed to Okinawa. Instead, the 32nd Army Air Intelligence Unit (originally 32nd Army Radar Unit) was organized on 1 April, 1945. The composition of it was as follows.
- HQ: 36men
- Signal Unit: 441men
- 4 Radar Units: 1,474men
Total: 1,951men
4 Radar Units were equipped with 9 fixed, 11 field use and 4 type 4 radars.

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Re: IJA Radar

#18

Post by Mil-tech Bard » 11 Sep 2014, 20:52

1 April, 1945?

Okinawa was aready under attack?!?

Who did these radar units belong to before that?

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fontessa
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Re: IJA Radar

#19

Post by fontessa » 12 Sep 2014, 12:31

Hello Mil-tech Bard,

From October 1944, the unit took a duty as the 32nd Army Radar Unit which were the forerunner. Of course it belonged to the 32nd Army. And reorganization into the 32nd Army Air Intelligence Unit was ordered by Army Regulation “A” No. 24 dated 8 February 1945.

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Re: IJA Radar

#20

Post by Mil-tech Bard » 12 Sep 2014, 23:34

fontessa,

Which islands in the Ryukus chain was the 32nd Army Radar Unit/32nd Army Air Intelligence Unit stationed upon?

In particular, did Kume Jima had a radar belonging to 32nd Army Air Intelligence Unit?

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fontessa
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Re: IJA Radar

#21

Post by fontessa » 13 Sep 2014, 03:01

Hello Mil-tech Bard,

I attached the radar coverage of the 32nd Army Radar Unit on 3 January, 1945.
It was scheduled to place a radar station at 沖大東島 (Okino Daito Jima).
There was no radar station at Kume Jima.
32FNr.jpg
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Re: IJA Radar

#22

Post by Mil-tech Bard » 13 Sep 2014, 04:08

Fontessa,

There may have been no 32nd Army station there.

There most certainly a Tachi-6 radar on Kume Jima.

US Marines over ran one when they took the island and the US Navy ferret planes and ship based interception gear tracked it until a few days before it was over run.

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fontessa
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Re: IJA Radar

#23

Post by fontessa » 13 Sep 2014, 05:30

Hello Mil-tech Bard,

Even if a radar station was placed at Kume Jima, I couldn't find the evidence in Japanese records.

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fontessa
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Re: IJA Radar

#24

Post by fontessa » 16 Sep 2014, 13:28

Hello Mil-tech Bard,
fontessa wrote: Even if a radar station was placed at Kume Jima, I couldn't find the evidence in Japanese records.
I found that there was a Navy, not Army, radar station at Kume Jima.
According to the web page below, Navy radar stations (special observation posts type “E”) were deployed to the following places.
- 沖縄南端 Okinawa Honto South end
- 久米島 Kume Jima
- 宮古島 Miyako Jima
- 石垣島 Ishigaki Jima
- 与那国島 Yonakuni Jima
- 南大東島 Minami Daito Jima
- 沖永良部島 Okinoerabu Jima
http://books.google.co.jp/books?id=iJRB ... B6&f=false
NavyRadarStations.jpg
NavyRadarStations.jpg (26.95 KiB) Viewed 525 times
There were several kinds of Navy observation posts.
特設見張所甲 Special Observation Post type “A”: Observation Post equipped with wire and radio signal facility as communications measures
特設見張所乙 Special Observation Post type “B” equipped with wire signal facility
特設見張所丙 Special Observation Post type “C” equipped with radio signal facility
特設見張所丁 Special Observation Post type “D” equipped with searchlights and sound locators
特設見張所戊 Special Observation Post type “E” equipped with anti-air radars
特設見張所辛 Special Observation Post type “F” equipped with anti-sea surface radars

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Re: IJA Radar

#25

Post by Mil-tech Bard » 18 Sep 2014, 19:19

The US Army documents on the surrender of Japanese forces on the Northerm Ryukus listed

- 沖永良部島 Okinoerabu Jima

as one of the islands that surrendered a radar.

I also have a US Navy fighter squadron strike report of it being straffed in late June 1945 in very low overcast skies.

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Re: IJA Radar

#26

Post by Mil-tech Bard » 18 Sep 2014, 19:21

Which Naval commands did these Navy radar stations (special observation posts type “E”) report too?

I don't have the Google Translate-Fu to get it from your link.

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Re: IJA Radar

#27

Post by Mil-tech Bard » 18 Sep 2014, 19:29

This is more background on the Kume Jima radar. The following is typed from the after action report (AAR) of the naval invasion force commander for Kume Shima in early July 1945 --
Commander Task Group 31.24 ( ComDes Ron 63)
Subject: Action Report - Capture of KUME SHIMA, Okinawa Gunto, 25-27 June 1945

----
6. Conclusion

Destroyers who hare done Radar Picket duty around Okinawa the past three months
have long been suspicious of KUME SHIMA. Bogies seemed to appear if by magic, from the
shadows of this island; and on the few occasions they were able to use a round trip ticket,
disappear as strangely into KUME.

The landing strip, immediately behind Green Beach, contained a number
of wrecked planes. indicating it my have been used for emergency landings. The
strip itself, however, was reported to be in such poor shape that it could hardly
have been used as an operational or even staging field. It seems probable that a
radar and radio on KUME SHIMA served as a beacon to bogies approaching
the Okinawa Area from the south and west.


The destroyers, then, perhaps more so than any other units, will be
glad to see this island out of enemy hands. It should make a first
rate, unsinkable Radar Picket, and soon relieve the destroyers of their vigil
along the FORMOSA-OKINAWA Air Highway."

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Re: IJA Radar

#28

Post by Mil-tech Bard » 18 Sep 2014, 19:34

The Pacific War chapter (chapter 15) of SUMMARY TECHNICAL REPORT OF DIVISION 15, NDRC, VOLUME 1, RADIO COUNTERMEASURES stated the following regards Japanese radars in the Okinawa area.

Page 332 --
The final incident in the story of ship-borne countermeasures against enemy ground radar
came with the planning and execution of the invasion of Okinawa. An elaborate reconnaissance
of all features of the enemy defense in the Okinawa-Gunto had been carried out before
definite plans were consummated for Operation Iceberg. This reconnaissance had included radar
intercepts by aircraft, surface vessels, and submarines, as well as small-space and large-scale
photographic reconnaissance's permitting detailed pin points of several radar sites. Assessment
of this information revealed that the enemy's radar defense was probably limited to
EW equipment. A total of 10 to 12 such sets was eventually found, including the 7 listed
below:

2 Mark I Model 3
2 Mark I Model 1
2 Mark B
1 Mark CHI

In planning the operation, past experience, including Iwo Jima, strengthened the conclusion
that ship-borne jamming of EW ground radars would serve no useful purpose. Accordingly,
the operational order specified the conventional 24-hr intercept guards, with the addition
of definite jamming plans for protection against enemy airborne radar. (See subsection
entitled "Surface Vessels" of Section 15.5.4.)
and later:

Pages 333 - 334
As an adjunct to this function, the conventional intercept guards were maintained in order to discover, if possible,
the operating procedures which governed the use of enemy EW radar. Apart from the examples
of the preceding paragraph, this intercept operation further assisted by eliminating
a particularly annoying Mark CHI radar. It was discovered that this radar in the vicinity of
Chinen Saki was being used deliberately to jam the voice communication circuit of the TBS
equipment operating at 72.2 mc. Direction-finding fixes obtained from the TDY rotating antenna
were sufficient to permit low-level reconnaissance photographs to pin-point the enemy
set, and naval gunfire put it out of action.

To put the quoted passages above in context, bear in mind the following facts:

-The "CHI" radar listed below is the wartime US Navy code name for the post-war intelligence name "Tachi-6,"

-The Japanese Mark I radars transmitted on the same frequencies as SC and SK meterwave early warning radars on American
carriers and other surface ships,

-The "Tachi-6" broadcast on the same frequency as the US Navy's TBS ship-to-ship radios.

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fontessa
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Re: IJA Radar

#29

Post by fontessa » 20 Sep 2014, 10:00

Hello Mil-tech Bard,
Mil-tech Bard wrote: Which Naval commands did these Navy radar stations (special observation posts type “E”) report to?
According to Senshi Sosho Vol. 17, the command structure of Navy radar warning system was as follows.
“Lookout Station” is more suitable than “Observation Post” as the English translation for 見張所.

Okinawa Area Base Force Commander
- Ohshima Guard Unit Commander (Amami Ohshima Area)
---- Special Lookout Stations: 口永良部島 Kuchinoerabu Jima, 宝島 Takara Jima, Okinoerabu Jima
- The 43rd Minesweeper Division Commander (Okinawa Area)
---- Special Lookout Stations: Kume Jima, Miyako Jima, Ishigaki Jima, Yonakuni Jima
Okinawa Area Base Force HQ and the 32nd Army HQ exchanged radar information.

There were some mistakes in the book I have quoted. The map below shows correct Navy radar stations deployment.
NavyRadarStations2.jpg
NavyRadarStations2.jpg (25.59 KiB) Viewed 429 times
fontessa

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Wellgunde
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Re: IJA Radar

#30

Post by Wellgunde » 21 Sep 2014, 02:46

Thank you Fontessa for some interesting and valuable information.

Have you read Mr. Hosaka's other books?

Do you have a reference for lookout stations (types A through F) on Kyushu?
γνώθι σαυτόν

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