One attraction of Ginga as a model, despite its rather limiting warpaint and whether the old Revell or more recent Hasegawa kit is selected, is the potential for conversion to various experimental or night fighter variants. Only one IJN combat unit operated Ginga as a night fighter, that being the 2nd Hikotai of 302 Ku at Atsugi, which operated a Gekko buntai and a Ginga buntai. Coverage of the type in the original Revell kit and by Hasegawa has confused Ginga with the re-designed night fighter variant Kyokkô ( 極光 - Aurora) manufactured by Kawanishi rather than Nakajima but the detailed relationship between Kyokkô and the Type 16 Ginga is an ongoing problem so far unresolved.
In May 1943 the IJN directed Kawanishi to produce Kyokkô based on Ginga but with the engine changed to the Kasei Type 25. This request was reportedly made in response to the high demand for the Homare engine and problems due to increased production. In addition to the engine change which required a re-designed cowling, bombing equipment was removed, a retractable tail wheel was installed and fuel tank capacity was reduced for the rationale that the night fighter would not require a long range capability.
Kawanishi production of Kyokkô at their Konan (or Fukae) plants replaced HSK2 'Emily' flying boat manufacture, with some parts being manufactured at the Takarazuka plant. Progress was slow, with the first and only aircraft completed in June 1944 against a requirement for three and only 28 produced by the end of the year against an order for 162. From January to May 1945 only 68 were produced against requirements for 428, so when production ceased that month only 96 Kyokkô had been manufactured, the majority of which were converted back to bomber configuration as the Type 16. The USSBS (United States Strategic Bombing Survey) report on Kawanishi production referred to the type as the 'Frances fighter' but it is unknown exactly how many were accepted into IJN service as Kyokkô and how many were re-purposed as the Type 16 Ginga.
The Type 5 30mm fixed machine gun originated from an Auguat 1942 17-shi requirement for a special, large calibre machine gun with the design of the 17-shi otsu weapon. It was formally accepted as the Type 5 30mm fixed machine gun Model 1 in April 1945, an original Japanese design considered 'efficient' by the USSBS. It fired a 30 x 122 cartridge from a disintegrating belt at the rate of 500 rounds per minute, achieving a muzzle velocity of 760 metres per second. There is little doubt that this weapon was intended for Kyokkô as official drawings exist from the IJN's 1st Technical Arsenal (formerly Aeronautical Technical Arsenal) showing the method of installation between fuselage stations 17-19 and at a fairly low angle of 20°.
The 20mm oblique weapons used were the Navy Type 99 Mk 2 20mm fixed machine gun of which there were five models utilising various belt or drum feeds. The model used in converted Ginga and in Kyokkô are uncertain. The D4Y2 'Judy' was fitted with an oblique Model 4 with Kawamura belt feed, whilst Gekkô was fitted with the Model 3 with 100-round drum magazines.
CPO Hideo Hayashi tested Kyokkô at the flight test centre of the Technical Arsenal and then with 302 Ku. In his opinion Kyokkô was inferior to Ginga in terms of manoeuvrability and subsequently under Lt Hamano the 2nd Hikotai used the Type 11 Ginga converted to night fighter configuration and referred to in the unit as the Type 21. The so-called Type 21 night fighter retained the bomb bay for intruder missions and for the dropping of air-to-air ordinance.
Hasegawa have released a number of Kyokkô and Type 21 night fighter kits beginning in 1996 with CP2 (51202) with options for the overall yellow prototype, depicted on the box art (shown above), and YoD-196 of 2nd Hikotai, 302 Ku with twin oblique 20mm armament. This kit was re-issued as a Limited Edition in 2016 with the same two options but with new box art (shown below).
Finally in 2022 kit no. 02413, another Limited Edition, was released as 'Kugisho P1Y1-S Ginga (Frances) Type 11 Night Fighter 302nd Flying Group' with box art as shown above. Options include YoD-153 as depicted on the box art and YoD-191 with a fuselage DF loop, both converted Type 21 night fighters with twin, oblique 20mm armament.
Radar and Hakkô
Other than the photo of YoD-161 there appear to be no other photos of night fighting P1Y with radar equipment. The equipment on YoD-161 does not have the antennae configuration of the FD-2 radar installed on the Nakajima J1N1-S 'Gekko' (Irving) and appears to be of the H-6 type more usually associated with ASV, as asserted in Model Art 595 on Japanese night fighters, than AI search radar. Without confirmation of the armament it is difficult to determine whether the equipment was an experimental night fighter AI radar installation. However, author Bill Gunston in 'Night Fighters - A development and combat history' (Patrick Stephens Ltd., 1976) asserts that 'Radar was fitted (in the P1Y1-S Ed.) related to the J1N1-S (e.g. the FD-2 Ed.) but derived from the widely used ASV installation with a completely different dipole aerial array, there being a single large Yagi array in the nose and an axial trio of dipoles along each side of the rear fuselage.' The book is without source notes so Mr Gunston's proposition might have been based solely on that photograph of YoD-161. Extraordinarily in a book which contains photos and schematics of most night fighting aircraft and although Japanese night fighters are described, there are no photos or schematics for any of them!
Model Art # 595 also has an interesting article by Mr. 神野 speculating on the identity of the night fighting aircraft 'Hakkô' (Corona of the Sun) reported as possibly the provisional name for Kyokkô, but Hakkô and Kyokkô have been reported to have differed in the following points;
Hakkô - a modification of Ginga (with Homare engine) with installation of oblique firing 20mm machine guns
Kyokkô - Ginga upgraded with Kasei type 25 engines and with installation of oblique firing 20mm machine guns
The first Japanese document to reveal the Hakkô name was the October 1943 'Plan for the production of aircraft in 1944'. This document set out the intention to produce 180 Hakkô armed with six 20mm cannon, positions unspecified. The second Japanese document to reveal the Hakkô name is a report from the Navy Aircraft Division Headquarters (海軍航空本部部報) of January 1944. In this report Hakkô was required to be equipped with one 30mm and four 20mm guns. But after this report the Hakkô name does not reappear in any IJN documents. Then in March 1944 the Kyokkô name suddenly appears with the same proposed armament. In July 1944 Kyokkô armament is re-proposed as four 20mm guns (presumably similar to Gekkô with two dorsal oblique and two ventral oblique?) The author of the article asked Mr. Takehiko Shibata of the National Institute of Defense Studies Library what the reason might be for the disappearance of Hakkô and appearance of Kyokkô, and Mr Shibata suggested the following;
'When the national budget was approved by the Diet in 1944, the Imperial Navy had concerns about the availability of the Homare engine (produced by Nakajima), and decided to produce a night fighter version of Ginga with Kasei engine (produced by Mitsubishi). This night fighter was initially named as Hakkô (白光), but 白 is quite similar in shape to 月 when hand written. (The Nakajima J1N1 Gekkō was named 月光 - 'Moonlight' Ed.) Also 白光 (Hakkô) has the same pronunciation as 発光 (ray of light), so quite confusing. Probably the Hakkô name was used for application of the budget, but soon afterwards the IJN stopped using confusing Hakkô and changed it to less confusing Kyokkô.'
Schematics accompanying the article show a P1Y2-S equipped with the 玉-3 (Gyoku-3) radar equipment and armed with one 30mm and two 20mm oblique dorsal machine guns. 玉-3 had an annular-type antenna of two rings and a central circular plate contained within the nose of the aircraft. The article contains photos of the equipment and a test-bed instalment speculated for Kyokkô. An accompanying model is shown as Yo-201 (red) with a solid nose and single 30mm oblique machine gun. The scope views of this radar are also illustrated. According to post-war Allied intelligence documents 10 sets were constructed and a few installed. A solid nosed Kyokkô night fighter equipped with 玉-3 radar would make an unusual and interesting model but the question of the armament configuration remains uncertain.
The Hasegawa kits suggest upper surfaces of dark green - Gunze Mr Color 15 IJN Green (Nakajima) with silver (natural metal) under surfaces and cowlings variously dark green or Mr Color 125 Cowling Color (blue-black). Robert C Mikesh assessed the upper surface colour of the NASM Ginga in night fighter configuration (s/n 8923 manufactured June 1945) as comparable to Thorpe's N2 (Munsell 10 G 3/2) and measured it as close to Munsell 5 G 3/1, closer in appearance to D2, and confirming that the under surface was natural metal. He noted in particular the intensity of the red of the hinomaru on this aircraft. The question of D2 vs D1 probably warrants a blog article on its own but is explained further in the AoJ IJN Greens PDF, now updated with some additional data on this issue.
With special thanks to Keishiro Nagao of Lifelike Decals for his kind assistance in the preparation of this blog post.
Image credit: All box art © Hasegawa Corp 1996-2022; Cowling comparison © 1972 Model Art magazine; Paint chips © 2023 Aviation of Japan