Thursday, 9 July 2020

Tried And Tested Pt.1

A History of the Yokosuka Naval Technical Air Arsenal         
Part 1 Kaigun Kokusho (1932-1939)

The following article first appeared in the issue number #7 of our magazine "Arawasi International", Sept-Dec 2007. It was a collective effort of the editors of the magazine at the time and was planned as a series. Unfortunately, for various reasons it was never completed. We hope to do so on this blog.

Perhaps because they handled the less glamourous aspects of aviation—from research, aircraft and engine manufacture and distribution to repairs and modifications—the IJN’s four Naval Air Arsenals have tended to receive scant attention from aviation historians. But some idea of the importance of these establishments to the war effort can be gauged by the 31,700-strong workforce present at all branches at the end of the Pacific War.
These civilian and military personnel represented the last members of an organization that had not only gone head to head against major aircraft manufacturers for IJN contracts, but also provided those manufacturers with extensive technical assistance. These close ties were mirrored in many military aircraft designs retaining the “Y” identifier—for the key Naval Technical Air Arsenal at Yokosuka, Kanagawa Prefecture—even though production was contracted out to aircraft manufacturers in the civil sector.
The Naval Air Headquarters had assumed responsibility for the management of all naval aviation projects at the time of its inception on April 1, 1927. Five years later, on April 1, 1932, the Kaigun Kôkûshô (Naval Air Arsenal) that formed at Yokosuka came under the Naval Air Headquarters’ umbrella.
Another reason for the dearth of coverage, apart from material only available in Japanese, has been the confusion caused by the changing, shortened forms of the Japanese names that were bestowed on the Yokosuka site. Often the activities of other sites have been erroneously attributed to or described under the catch-all Yokoshô (the shortened Japanese for Yokosuka Naval Air Arsenal) banner, although this was merely one location. Steeped in naval arsenal history since 1869, Yokosuka was to be part of a Naval Air Arsenal setup only early in the organization’s history.
The evaluation of new aircraft was the remit of the Yokosuka Kôkûtai, which was collocated with operational units at nearby Oppama air base. Yokosuka had had aspects of aviation tacked on to its naval arsenal activities since 1913 and its reputation as a research and design establishment dated back to 1917, when it manufactured the first operational naval aircraft designed in Japan.
Yokosuka, 1932-style, acted as the hub for aircraft manufacture and ordnance, aero-engines and flight testing, in collaboration with the Kasumigaura Branch of the Naval Technical Research Institute. Design teams from the Hiro Arsenal were transferred to work under one roof at the Kôkûshô, as it came to be called.
Under its first commander, Rear Admiral Edahara Yurikazu, the Kôkûshô was organized into seven departments:

1. Sômubu – Administrative Affairs Department
2. Kagakubu – Science Department (research into aircraft components and performance; aircraft testing)
3. Hikôkibu – Aircraft Department (aircraft design; component research; aircraft building and maintenance; armament design)
4. Hatsudôkibu – Engine Department (aircraft engine design; research and testing of fuel and lubricants; design, manufacture and maintenance of engines)
5. Heikibu – Weapons Department (research and testing of aircraft weapons)
6. Hikôjikenbu – Aircraft Testing Department (aircraft flight testing and research; test the performance and basic flying characteristics of new aircraft immediately after their delivery from the manufacturers; accident investigation). 
7. Imubu – Medical Affairs Department

This was to remain unchanged until April 1, 1939, when the organization’s title was changed to the Kaigun Kôkû-Gijutsushô (Naval Technical Air Arsenal, or Kûgishô), the name it was to retain until just a few months before the end of hostilities in 1945.

Industry Links (1): Mitsubishi
The relationship between the Kôkûshô and industry became closer as the 1930s progressed and Japan became enmeshed in a conflict with China, although it was not until July 7, 1937, that IJNAF units were to be involved in a major action.   
In 1932, the year in which the Kôkûshô was established, the Naval Aircraft Establishment was organized and what turned out to be the overly ambitious 7-Shi equipment acquisition programme was initiated. The IJN’s requirements for a series of aircraft ranging from carrier-based fighters and bombers to reconnaissance seaplanes were to remain unfulfilled, as the Kawanishi E7K1 reconnaissance seaplane was the only design placed in quantity production and the Hiro G2H1 attack bomber was produced in limited numbers.
The efforts that were put into avoiding a repeat of this situation gave renewed vigour to the Japanese aviation industry. So much so that just two years later the 9-Shi (1934) programme resulted in several famous Japanese aircraft entering production, including the Mitsubishi A5M series of carrier-based fighters, later allocated the Allied codename Claude, and the Mitsubishi G3M (Nell) attack bomber. The availability in numbers of these two types in particular permitted the Japanese military to pursue its military ambitions when the Sino-Japanese War flared up in earnest in July 1937.

Tail markings
Most Mitsubishi aircraft delivered to the Kûgishô received a tail marking comprising the following:
1. Katakana “” (KO) denoting Kôkûshô
2. First two digits of the aircraft’s short designation
3. A number that either showed the number of prototype (1st, 2nd, 3rd, etc.) or the last, usually two, digits of the aircraft’s serial number

Exceptions to the above rule are seen below in the B5M1 “KO-361” and the F1M2 “KO-S21.” The significance of these markings and the reason why these particular aircraft received these tail marking is unknown.

Mitsubishi Type 0 Observation Seaplane (F1M2, Pete)
One of the first F1M2 prototypes, 1938. Note the twin-blade propeller and the absence of spinner.
(Photos: Encyclopedia Vol. 1)

Mitsubishi Type 97 Carrier Attack Bomber (B5M1, Mabel)
One of the two B5M1 prototypes, which were put through comparative trials with a Nakajima design for nine months from February 1937.
(Photo: Arawasi)

Mitsubishi J2M1 Raiden (Jack), s/n 706
Sixth prototype of the 14-Shi interceptor fighter that was with the Aircraft Testing Dept. at Oppama air base, Kanagawa Prefecture, July 1942.
There are no known photos of the first five prototypes. Note the shape of the cowling and the canopy, which gave the impression of a racer and was not actually liked by pilots accustomed to the A6M Zero-sen. The aircraft was overall light Mitsubishi gray (hairyokushoku). Top test pilot Kofukuda and 381st Kôkûtai veterans remember this aircraft as being overall orange, so perhaps it was over-painted at some stage.
(Photos: Encyclopedia Vol. 1)
For more on the particular "Raiden", check HERE.

Mitsubishi J2M3 Raiden-kai (Jack), s/n 3034
Test production (34th prototype) at Oppama air base, late 1943.
J2M3s had a thick bulletproof windshield and the main fuel tank of the fuselage was protected by rubber sheeting combined with layers of rubber sheet and sponge. The radio antenna was raked forward to make the line longer and improve the quality of the reception.
(Photos: Encyclopedia Vol. 1)

(Photos: FAOW#61)
For more on the particular "Raiden", check HERE.

Mitsubishi K7M1
The second of only two prototypes built in 1938, both of which were assigned to the Yokosuka Kôkûtai for liaison and transport duties.
(Photo: Encyclopedia Vol. 1)

Mitsubishi Type 1 Land-Based Attack Bomber (G4M3, Betty)
The overall-orange third prototype G4M3 after delivery to Kûgishô, February 1944. “G4” is the shortened aircraft designation and “33” is the last two digits of the serial number (all G4M3 prototypes received their tail number in the 30s).
The main differences between the G4M2 and G4M3 were: self-sealing wing fuel tanks; different tail gun position; higher-angled horizontal tail surfaces; the wing-root fillet and airframe differences. However, this early G4M3 prototype has exactly the same fuselage as a G4M2 and only has the G4M3’s wing-root fillet.
(Photos: Encyclopedia Vol. 1)

Mitsubishi G6M1 Land-Based Trainer (Betty)
The aircraft was originally conceived by the IJN to carry augmented armament to protect Betty formations. Nevertheless, performance dropped significantly and in the end it was used as an unarmed crew trainer from late 1940. 
The overall paint scheme (NMF) is standard pre-war style, which was discontinued from February 1941. The tail was painted red to make the aircraft more visible in the event of an emergency landing on water.
(Photo: Encyclopedia Vol. 1)

Mitsubishi A7M "Reppu" (Sam)
The third A7M2 with Mitsubishi Ha-43 engine. It was originally the second A7M1 with Nakajima NK9K Homare engine.
(Photo: NARA via Arawasi)

Friday, 3 July 2020

IJAAF & IJNAF wrecked aircraft #35 - Guam Pt.2 & Tinian

The wrecks today are a bit more complicated and more difficult to identify.
Let's start with a video first.

In the beginning there is a "Betty" bomber the full marking of which is not clear. It is probably another 1001Ku aircraft similar to the one we saw in the previous post. So, the full marking could be "01-345".

Then there is the wreck of an Aichi D3A2 "Val".

The tail marking is not clear. It's "??2-2?".

Now, let's see another video, from here.

In the beginning and the end of the video there are views of the same "Val" and the tail marking is now more clear "322-2?". 

FAOW #33, has another photo of the wreck on p.75 and the caption explains that it belonged to the 322Ku. Unfortunately the aircraft did not belong to the 322Ku which was a night fighter unit equipped with Nakajima J1N "Gekko", a small number of reconnaissance J1N1-C, only about four "Val" for training (as it was also two-seater) and mostly J1N1-S night fighters. The unit was based at Katori, Chiba Prefecture, during the Marianas campaign.
Another more probable suggestion is that it belonged to the aircraft carrier "Hiyo" which used the tail marking "322" or "22" until March 1944. But the ship took part in the Battle of the Marianas carrying elements of the 652Ku with "652-" as their tail marking.

According to Wikipedia:
"Two months later [November 1943], Hiyō's air group was reconstituted in Singapore with 24 Zeros, 18 D3As and 9 B5Ns; the ship departed Japan for Singapore on 24 November. She arrived on 3 December, loaded her air group and was almost immediately assigned duties as an aircraft ferry. On 9 December, Hiyō left Singapore en route for Truk with several deliveries on the way. The ship arrived there on 22 December and disembarked her aircraft before proceeding to Saipan to deliver more aircraft. The air group was transferred to Kavieng and later Rabaul to provide air cover for Japanese operations there where the fighters claimed 80 victories in exchange for 12 losses."

According to Combined Fleet:
"25 January 1944:
HIYO's air group is transferred to Vunakanau Airfield, Rabaul.
19-21 February 1944:
After losing more than half of his fighting power, the remnants of CarDiv 2's air group, consisting of 15 A6M2s, 14 D3A2s and 8 B5N2s, are transferred to Truk. HIYO's air group is subsequently disbanded.
2 March 1944:
HIYO's aircrew depart Truk for Japan without their aircraft."

Truk is 1000km distance from Guam on a straight line, so, in my opinion, either the aircraft was left on Guam during the ferry duties of the ship at the end of December 1943 or was flown from Truk to Guam around March 1944.  

Another aircraft that can be seen in the video is a Nakajima J1N "Gekko" with the number "28" on the nose and tail.

On the nearby island of Tinian another "Gekko" wreck, a J1N1-S, was found and there is a nice color photo of that aircraft with the number "75" on the nose. 
But also this one.

A number of "Gekko" wrecks were found on Tinian, like this one.
But the tail number is not clear enough. (all three b/w photos from here)

Another "Gekko" with partial tail marking "??-29" was also found on Tinian. This one, according to Japanese sources was a J1N-F with a turret, but it was removed and replaced with oblique firing 20mm cannons.
And finally a J1N1-C with tail marking "21-65" (see MA#510, p.244) belonging to the 321Ku.
It is very possible that all the "Gekko" aircraft belonged to the same unit; the 321Ku. 
The unit was organized on October 1, 1943, at Mobara, Chiba Prefecture, the first IJNAF night fighter unit, nicknamed "Tobi Butai" (鵄 部隊) (Tobi=black kite). After the end of February 1944, the unit was assigned to Katori (Ibaraki Prefecture), Tinian, Guam, Yap, Truk, Peleliu and other places. Their duties were anti-submarine patrol, reconnaissance, ship escort, night attacks and more. The unit headquarters were destroyed on Tinian and on July 10 it was disbanded.

Thursday, 2 July 2020

IJAAF & IJNAF wrecked aircraft #34 - Guam Pt.1

The first thing the U.S. Marines encountered during the landing on Guam on July 21, 1944, was an Aichi D3A2 "Val". According to Japanese sources, it took off from the aircraft carrier "Junyo" and had taken part with 26 other aircraft in the second attack wave during the Battle for the Marianas a.k.a. Battle of the Philippine Sea. They failed to spot their target and on their way to Guam they were attacked by enemy fighters shooting down nine of them.
According to Wikipedia:
"A second air strike of 27 D3As, 9 D4Ys, 2 B6Ns and 26 escorting Zeros was launched around 11:00, accompanied by at least 18 A6Ms and B6Ns from Shōkaku and Zuikaku. They had also been given an erroneous spot report and could not find any American ships. The 652nd aircraft headed for airfield at Rota and Guam to refuel while those from the other two carriers returned to them. A pair of Zeros and 6 D4Ys bound for Rota spotted the carriers Wasp and Bunker Hill en route, but failed to inflict any damage on the American ships while losing 5 D4Ys to anti-aircraft fire. Radar had spotted those aircraft headed for Guam and they were intercepted by 41 Grumman F6F Hellcats. Only a single A6M5, 1 D4Y and 7 D3As of the 49 Japanese aircraft survived the encounter and landed."

I believe the location is the Agat beach on Guam and either the same in very bad condition or another "Val" can be seen in the same location in the video below.

Another wrecked bomber was a Yokosuka D4Y "Suisei" (Judy) Model 12, tail marking "07-117" belonging to the 107 attack hikotai of the 503Ku. The unit had relocated from Truk to Saipan to take part in the aerial battle and some of the unit's bombers made forced landings on Guam. 

Yet another wreck, was a Model 52 Zero belonging to the 343Ku. The unit was organized on January 1, 1944, in Kagoshima and was nicknamed "Hayabusa Butai". Originally the 343Ku was to be an air defence unit equipped with Kawanishi N1K-J "Shiden" fighters, but delivery of the new type was slow and they were mostly equipped with Zeros. Around the end of March 1944, most of the unit first relocated to Tinian, then to Peleliu around the end of May and, finally, to Palau in the begining of June. Some elements left behind on Tinian island intercepted the attacking U.S. forces and then relocated to Guam. The main force of the 343Ku that was based in Palau relocated to Yap to take part in the battle of the Marianas but also used Guam as an advanced base. The unit was disbanded on July 10, 1944, after suffering very heavy losses.
Time for our second video.

The tail marking "01-312" indicates that this "Betty" belonged to the 1001Ku which received this designation on July 1, 1943, as a specialized transport unit and, apart from transports, was equipped with a variety of types including "Betty" bombers.

Sunday, 28 June 2020

IJAAF & IJNAF wrecked aircraft #33 - Saipan Pt.6

And now Group 4.
In the beginning there were only three Zeros in front of the hangar.

Zero14 was an A6M5 Model 52 with tail marking "61-120".

The tails of the other two Zeros (15 & 16) are not clear in the photos. But let's see the third video, of exceptional quality, from here.

From the beginning, we can see that the Zeros of Group 4 are now five.

A nice close up of the engine.

The Group 4 from a different angle.
The third Zero from the left is "61-120" and is under a camouflage net. Note the cowling cover of the second Zero from the left and the spinner. They are the same with the Zero in the photo below.
The tail marking is barely visible, but Zero15 is "8-28".
More photos of the Zeros of Group 4.

Unfortunately, we have found no more information about the rest of the Zeros in Group 4. At least for now.

There is one Zero found in a hangar that is not clear if it was brought out and was placed in a group. Tail marking is "61-125".

And ofcourse, there were Zeros that were too damaged to be of any use.

And some had various parts taken as souvenirs.

As mentioned in a previous post, the aircraft were placed on trailers...

...and were brought to Saipan harbor to be shipped to the U.S.A.
Above is Zero "8-36" of Group 3.
Zeros "61-131" and "8-03" of Group 3.

We discussed in older posts how various Japanese aircraft were transported to the U.S., in our 8-part series "Toraware no Nihonki", here. Some of these Saipan Zeros (13 Mitsubishi A6M Zeros, 1 Nakajima B5N "Kate" and 37 engines, according to Wikipedia) were ferried on board USS Copahee. The total of the Zeros we found in all groups is 18, which means five were left behind. The 1 "Kate" is without doubt "KEB-306" we saw in the previous post. Here's a list of all the Zeros we have identified in this series. 
From the "8" unit: "8-13" & "8-17" (Group 1), "8-07 & "8-34" (Group 2), "8-36" & "8-03" (Group 3), "8-28" (Group 4).
From the "61" unit: "61-197" & "61-180" (Group 2), "61-131" (Group 3), "61-120"(Group 4).
Total 11 out of 18 Zeros.

Let's see how these Zeros were placed on Copahee.
There are two without a tail marking. One more intact Zero on the top left, and another without an engine in the middle. I believe the one without an engine is Zero 10 of Group 2.
Here are the Zeros with their numbers.

There are four Zeros we could not place in the Groups.
"8-24", below is another photo. Note the lack of tail cone.

Another Zero is "61-121". There is also the Zero without a tail number and the one in the back of the photo with a "6" tail marking we can't read.

We know that "8-34" (Zero6) was also on Copahee as can be seen in the photo below and was placed in front of "8-24" and on the port side of "61-121".

Here's another photo of another group of Zeros carried by Copahee.
And their numbers.
We can't read with certainty the tail marking of the Zero on the top right.

So, from the total 13 Zeros on Copahee, we have identified 8 also spotted in the Groups, two that appear only on Copahee and one without a tail marking. Plus two we can't read their tail markings. 8+2+1+2=13. But actually if you look closer at the photos, you will notice there are 14 Zeros. Seven in the first Copahee photo plus "8-34" and six in the second photo. Where's "Kate"?...