Monday, 8 December 2014

Some observations about the Ki-78

As a follow-on to discussion of the Friendship Scale Models Ki-78 kit some further observations about that interesting aircraft. The experimental (Ken-3) high speed research plane (試作 [研三] 高速研究機- shisaku [ken san] kousoku kensan kyuu ki) was the outcome of an initially civil research initiative into high altitude and high speed distance flight subsequently taken over by the Army as the Ki-78. The abbreviation 'Ken' was for kensan (研鑽 - research or study). The background and basic details of its origin, development and testing are readily accessible through Francillon* and even Wiki so won't be laboured here beyond some interesting details which are seldom explored.

* Francillon, René J., Japanese Aircraft of the Pacific War (Putnams)

Ki-78 - note dark prop blades, absence of Hinomaru and lack of wheel covers

The project began in 1938 under the auspices of the Aeronautical Research Institute at the University of Tokyo but was taken over by the Army in May 1940, whereupon the projected design was designated Ki-78 and Kawasaki were requested to create two prototypes based on a completed wooden mock-up.

Note also absence  of counter balances on elevators

The aeroplane was diminutive, with length and span just over 26 feet. The wing had a laminar flow, low-drag profile (with a very fine leading edge) of low area designed by Echiro Tani with three different types of wing section applied - LB-510-3A16, LB-510-3B14.5 and LB-5103B12. This resulted in a high wing loading and tricky low speed flight during take-off and landing exacerbated by limited vision from the tiny streamlined cockpit canopy. The take off speed was 128.13 mph and landing speed was 106.25 mph. Combination Fowler and split flaps were augmented by drooping ailerons to improve low speed lift. As the main flap deployed the split flap opened to correspond and when the flaps were fully down a synchronised system dropped both ailerons to 10 degrees down. 

The selected power plant was an imported Daimler-Benz DB 601A of 1,175 hp enhanced with water-methanol injection to 1,550 hp. Wing fuel tanks held a total of 250 litres and 60 litres of methanol were carried. Various cooling systems were considered including surface evaporation but ultimately conventional radiators in closely faired housings either side of the rear fuselage were decided on. 

An initial test flight was made from Gifu at dusk on 26 December 1942 with Kawasaki test pilot Saizaburo Kataoka at the controls. All went well and he reported that the acceleration of the aircraft was phenomenal. Following further test flights an issue with elevator flutter was encountered at a speed of 393.75 mph at 3,608 feet as a result of which modifications were made which may have incorporated the counter balances seen in some photographs. Speed tests continued satisfactorily through September to December 1943 culminating in the highest speed recorded of 435 mph at 11,539 ft during the 31st test flight on 27 December 1943. Ultimately the Ki-78 suffered the ignominious fate (below) of many historic Japanese aircraft which if preserved would now be considered priceless.

AZ Models What if?

A 244th Sentai Ki-78 approaches USN Helldivers - is it going to ram them?

The 2010 AZ Models 1/72 injection moulded kit was issued in two versions, each containing parts for two models. It appears to be exactly similar to the Planet Models resin kit which is reviewed here. The rear fuselage looks a wee bit suspect compared to the photographs, a little stunted and hump backed, slightly too deep from the rear of the cockpit back. Checking the dimensions suggests that the kit is short in length by almost a scale foot, just over 4 mm, and this takes away slightly from the sleek look of the original. For those who are bothered by this it is feasible to separate the fuselage at the panel line just in front of the tail and insert a plastic card plug to increase the length, sanding down the depth of the fuselage at top and bottom to achieve a sleeker appearance. The radiators are also too deep but correcting them is more difficult; removing and replacing them with plastic card not being an easy proposition. The relatively thick leading edge of the wing also needs work to represent the razor sharp edge of  the original.

The prototype schemes as presented in AZ 7302 - the second looks very orange!

The first kit AZ 7302 features the actual prototype in two schemes, the painted scheme being shown as orange with the photographic reference panels in red and white. The second kit AZ 7303 presented the Ki-78 in various permutations of what-if warlike garb providing three spurious markings options for the 244th Sentai, the IJN Yokosuka Kokutai and possibly the 1st Sentai, but without identifying them as such. However, the high wing loading and closely cowled power plant made it extremely unlikely that any weapons could be fitted without extensive modification to the airframe, probably resulting in something heading towards Ki-61 territory anyway. The top speed of 435 mph achieved by the Ki-78 was without armament, armour or fuel protection, whereas the armed and armoured Ki-61-II Kai achieved 379 mph at 19,685 ft.  There appears to be no provision in the kit for representing any armament. If the Ki-78 was going to be deployed belligerently it was probably suitable only for use as a fast air-to-air rammer against the B-29!

The 3 markings options in the What if? kit AZ 7303

The Platz Kit

The Platz kit consists of a solid fuselage, single piece wing and separate tailplanes very finely moulded in grey resin. The radiators are moulded integrally to the fuselage with neatly recessed intakes. There is no interior and the canopy is solid clear resin. All other parts, spinner, prop, undercarriage components and tailwheel are cast in good quality white metal. A decal sheet provides the Hinomaru, red prop blade warning stripes and black and white photo reference markings. The comprehensive instructions are in Japanese but all the colours are called out in English. In comparison to the AZ Models kit the Platz kit better captures the svelte look of the original aircraft.

Platz (Unlimited Air Models) Ki-78 'Kensan' Box Art

This kit is now shown as discontinued at HLJ (despite what it says there the Platz instructions do include details for the dark grey option). But if you really want one it can still be ordered direct from Platz and in confidence as they have an excellent mail order service via Hobby Collective. Use the contact form at their site and they will send a confirmation in English and a PayPal invoice on receipt of an email order.

AZ Models vs Platz ~ note position of vertical panel line forward of tail

Colour Schemes

There were two main schemes, documented and evidenced by photographs. The overall metal finish as seen in the photographs above, varied by the addition of an anti-glare panel and Hinomaru in six positions, as shown below. The sequence of at least three different schemes is debatable but the different propeller blade finishes provide clues. The polished blades with red warning stripes usually represent an earlier IJAAF standard whilst the dark brown painted blades with yellow warning stripes came later.

Note prop blade finish and apparent black and white wing tip markings

Whether the metal finish was anodised or treated in any way is unknown. The overall painted finish has been depicted in Japanese sources as a glossy medium blue grey with a matted anti-glare panel (in the same colour) and six photographic reference panels in black and white, three on each side of the fuselage. In addition the upper wing tips had black and white chord wise stripes. The Platz kit depicts the Hinomaru in six positions but the aircraft has also been depicted without upper wing Hinomaru.

The blue-grey painted finish

The Platz 1/72nd scale resin kit showing the two main finishes

Why this painted finish has so often been depicted as orange is puzzling. IJAAF experimentals and prototypes do not appear to have followed IJN requirements or Army-Navy conventions and were generally unpainted. Despite the Naval General Staff Order No.162 ‘Army-Navy Agreement With Regard To Distinguishing Markings For Friendly Military Airplanes’ of 21 August 1942 which called for experimental aircraft to be painted yellow (黄色 - ou-shoku) where possible, Kawasaki Army experimental prototypes before and after Ken-3 remained unpainted - e.g. Ki-60, Ki-61, Ki-64. In any case the Army colour was more an orange-yellow than the deep orange suggested by the AZ Models kit and other depictions. The reason for painting Ken-3 in the unusual blue grey scheme is obscure; whether that was connected to the secrecy of the first test flight or whether it just represented an attempt to improve aerodynamics by filling, painting and smoothing the airframe is unknown. 

United Air Models (Platz) prototype model in flight

The Platz kit suggests that the grey finish was used for the 31st test flight on 27 December 1943 and that it has often been described as dark grey but that Takeo Doi (the Kawasaki designer responsible for the Ki-61 Hien) maintained that it was a light grey. With medium greys the degree of darkness or lightness perceived in the colour is often subjective. But however dark or light it was it wasn't remembered as orange!

In models of the Ki-78 some variation in the metal finish scheme could be achieved by differencing the fabric covered flying control surfaces which were finished in aluminium dope and by representing an anodised or coated finish on the metal panels to give a slightly golden or amber effect. The anti-glare panel on the metal finish was possibly painted in the standard Army # 32 Koku ran shoku (黒藍色 - black indigo colour) which was a blueish-purple black similar to the colour of aubergines (eggplant). For the blue-grey finish a paint like the French gris bleu foncé is suggested, a little darker than FS 35164 and just a little more blue than RAL 7031 Blaugrau. Humbrol 79 Matt Blue Grey and Revell 79 Greyish blue (which is supposed to match RAL 7031) are in the ball park but bear in mind that the finish was glossy and that will slightly darken the appearance of the paint. The prop blades on the grey scheme appear to be polished metal with red tip stripes and the rear faces painted dark brown or possibly black.

Interior colours are anyone's guess but the Army standard at the time was the dark blue-grey of # 3 Hai Ran Shoku (灰藍色 - ash [grey] indigo colour). Was that same colour also used on the exterior?

Whichever kit is selected the diminutive Kansen makes an interesting display companion to Kawasaki's Ki-60 and  Ki-61 or in any collection of experimental prototypes.

Image credits: Artwork unknown; Photographs: SanDiego Air and Space Museum and web; Post-war photo courtesy James F Lansdale; Box art © AZ Models; Platz model images © Platz ; with special thanks to Tetsuya Inoue 

Thursday, 4 December 2014

Horatio Hernández and Friendship Scale Models

Back in May when I blogged the images of John Haas' superbly scratch-built Ki-77 I briefly mentioned the Friendship Scale Models 1/72 mixed media kit of that type. Friendship Scale Models was the brainchild of the late Horatio Hernández, perhaps one of the unsung pioneers of Japanese aviation modelling. Horatio was an enthusiastic modeller of Japanese aviation history of the Second World War and of the inter-war period. His own favorite scale was 1/72nd so that was the scale he chose for Friendship Scale Models. In the period from circa 1991 to 1995 he also distributed Model Art, Model Graphix and other Japanese publications within Mexico. 

I had the privilege, all too briefly, of corresponding (old style) with Horatio at the turn of the century. It was about an aircraft of mutual interest - the Ki-44 - and I still have the working dossier copy that he had prepared and sent to me with meticulously catalogued examples of that machine and his carefully considered questions about their markings and colour schemes. In early 1992 Horatio conceived the idea of making resin kits of the rarer types of Japanese aircraft under the brand name Amigo Models and approached the Smooth-On distributors of silicon rubbers and urethane resins in Mexico as a potential source of resin. Smooth-On advised Horatio to make the larger parts of the bigger kits he planned to create by using the vacuum forming process.

In early 1993 Horatio changed the name of his company to Friendship Scale Models and issued his first kit of the Kokusai Ki-59 as FSM-001. Unfortunately I have been unable to locate any images of this kit, built or unbuilt. Horatio's second kit was the Ki-77 as FSM-002 (above). In contrast the third and sadly the last kit was the diminutive Kawasaki Ki-78 experimental research aeroplane as FSM-003, of which I do have an example. After this third kit Horatio had problems with the vacuum forming arrangements and his future planned releases were never made:-

FSM-004 Nakajima Ki-87
FSM-005 Tachikawa Ki-94
FSM-006 Mitsubishi Ki-57
FSM-007 Tachikawa Ki-54
FSM-008 Aichi H9A1 (planned for 1994)

That was a great pity because the Ki-78 is exquisite, both in the quality of moulding and presentation, putting some more mainstream manufacturers to shame.

The Ki-78 is moulded in buff-coloured resin with a solid fuselage and separate one-piece wing as the main components. All the remaining parts are delicately moulded in resin with the exception of the vacuum-formed canopy, still perfectly clear. Unusually for such a limited run resin kit two identical sheets of well-printed decals are provided, stencil markings included. There is a summary history of the type, references and colour scheme notes, together with plans showing the two scheme options. This was, and is, a quality product revealing a labour of love.

The amount of data included is impressive

Assembly diagram showing component parts of the kit

Provision is made for the model to be finished in-flight with wheels up with the covers moulded in the closed position. The fuselage radiators are separate parts (whereas they are moulded integrally to the fuselage in both the AZ Models and Platz kits) and a pilot seat is included. The resin is finely moulded with delicately recessed panel lines and the overall shape captures the compact, svelte appearance of the original aircraft. There is a nice build of what I think might be the FSM kit by Jim Schubert at the Wings of Peace website here.

The decal sheet complete with stencils ~ the photo reference marks should be black and white

The main resin components of the Ki-78 kit - the detail parts are equally finely moulded

Plans included - a quality product

After FSM's pioneering 1/72nd scale Ki-78 came the superb Platz resin model in 2003, then the Planet Models resin kit and ultimately the AZ Models limited run plastic kit in 2010, two models in each box, from which a proliferation of orange models unfortunately appeared, of which more anon. In 1/48th scale there were the Japanese Raccoon and Czech MTS resin kits.

At his home in Mexico City Horatio liked to wear traditional Japanese dress for comfort and inspiration, one might say that he was immersed in his enthusiasm for the subject. He attended model contests, bringing ten or so models with him. Later he moved to Guadalajara on the other side of Mexico and into modelling obscurity. I am indebted to Guillermo for his personal insight about Horatio but if any readers have additional knowledge, anecdotes or examples of the kits (especially the Ki-59)  it will be a pleasure to be able to add them here as a lasting tribute to Horatio's passion for the subject. It is a particular regret that I cannot include an image of Horatio himself. Horatio Hernández and Friendship Scale Models, Aviation of Japan salutes you. Gone but not forgotten.

Image credits: Ki-77 box art via net; others author's collection 

Tuesday, 2 December 2014

Otaki 1/48th Hayate Trio by John Haas

Prompted by the blog series on Hayate colour schemes John Haas has very kindly photographed his trio of Otaki Ki-84 Hayate builds for Aviation of Japan. In pre-internet days these models were inspired by the Aircam Aviation title on Hayate and Donald W Thorpe's seminal 'Japanese Army Air Force Camouflage and Markings'. This natural metal Ki-84 of the 29th Sentai was finished in Rub'n'Buff Sterling Silver over a base coat Polly-S Dark Grey.

The 29th Sentai originated in July 1939 as a mixed two Chutai unit operating both Type 97 recce (Ki-15 'Babs') and Type 98 Chokkyo (Ki-36 'Ida'). In March 1941 the 1st Chutai was transferred to the 28th Sentai and a new 1st Chutai formed with the Type 97 light bomber (Ki-30 'Ann'). In July of that year the unit became the 29th Dokuritsu Hikotai as a HQ unit with its 1st Chutai becoming the 87th Dokuritsu Chutai and its 2nd Chutai becoming the 66th Dokuritsu Chutai, both units being deployed in China on ground support operations. In July 1942 it was transferred to the 2nd Air Army in Manchuria taking up residence at Hailin. In February 1944 it was re-organised as a fighter unit, at first with the Type 97 fighter (Ki-27 'Nate') to provide conversion training and then the Type 2 single seat fighter (Ki-44 'Shoki'). It moved to Taiwan (Formosa) in July 1944  as part of the 13th Air Brigade (together with 30th and 31st Sentai) with the bulk of the 2nd Air Division in preparation for the defence of the Philippines. After a tour of operations over China from August to October in that year it was sent to the Philippines in November. It began to re-equip with the Ki-84 in December 1944 but was badly used in the Philippines and withdrew to Taiwan in January 1945.   

The Otaki kits from the mid-1970s were considered advanced at the time with their finely recessed surfaces and interior details. They had a minimum of parts, eschewing the moveable gimmicks and motorisation favoured by other Japanese manufacturers. Other features were their clean moulding, ease of assembly and relatively inexpensive cost. An Otaki Hayate in my own collection was bought in Hong Kong in the late 1970s for HK$9.90 (about £0.80p or US$1.27). Current releases, re-issued under the Arii brand retail for approx £4 or US$6 in Japan and are intermittently available at a 20% discount from HLJ - a real bargain and an excellent antidote to AMS or for painting/spraying practice. The main failings of the Otaki kits are shallow wheel wheels and rather chunky 'armchair' pilot's seats that seemed to be based on a single design fabricated from boilerplate on Clydeside. But to be fair at the time they first appeared many manufacturers were still producing kits with open see-through wheel wells.

In the absence of a decal sheet John hand painted the bomb-carrying hawk tail emblem on the tokkô tai Ki-84 '16' from the 520th Rinji Bôju Sentai referring to an illustration in one of the Aircam titles.

John's third Otaki Hayate build (below) depicts '325' of 1st Chutai, 73rd Sentai in similar scheme, painted with Polly-S and Humbrol colours.

The 73rd Sentai was one of the late war units formed in Japan on Hayate in May 1944 together with its sister units in the 21st Air Brigade, the 71st and 72nd Sentai. The unit was more or less annihilated in the Philippines where it had provided 3rd phase reinforcement as part of Sho Go # 1 staging via Shanghai and Heito, Formosa. The tail marking was reportedly not distinguished by the Chutai colour, being red on unpainted machines and white on camouflaged machines. The Chutai colour distinction was restricted to the spinner, sometimes the radio antenna mast and the lower rudder on which the aircraft number was painted.

Some of the unit's pilots and aircraft were lost in suicide operations in the Philippines but it was unlikely that any of the 21st Air Brigade Hayate units were ever at full strength there and probably little more than over-sized Chutai in numbers. The bulk of the Brigade was evacuated in January 1945 and the 73rd was unofficially disbanded in March 1945, its surviving pilots and aircraft being incorporated into the 71st Sentai which had been transferred to the 12th Air Division. 

Hōfu Airfield, Yamaguchi Prefecture, Japan

The 71st ended the war at Hōfu (Bofu), Japan in the Western District as part of the 6th Air Army where it relinquished its Hayate as part of the Sei Go (Control) reorganisation and was partially re-equipped with the Ki-61 Hien, having only seven on strength in July 1945. After the war Hōfu was repaired and reconstructed by No.5 Airfield Construction Unit RAAF  for use by 81 Wing RAAF as part of the occupation forces. It was subsequently used by the USAF 347th Fighter Wing equipped with F-61 'Black Widow' and F-82 'Twin Mustang' night fighters.

Splendid Rikyu Watanabe art for first (?) issue Otaki Hayate

There were at least two versions of Otaki Hayate box art painted by Rikyu Watanabe, both showing the same 47th Sentai machine in combat with a P-51. I cannot recall seeing any earlier Otaki Hayate box art (with the 'white' logo and Rising Sun flag on the box):-

The first (?) artwork showed the P-51 being shot down but the subsequent artwork, perhaps re-considered for the anti-violence era, depicted a more ambiguous outcome with the Hayate pilot watching the Mustang banking behind him. Both types of box art appeared overseas via Scale Craft, the first early issues having an adhesive label on the box and both subsequently appearing in boxes re-printed with the Scale Craft logo.

Second Hayate Box Art as released via Scale Craft in USA

The original kit offered decal options for '40', 2nd Chutai, 47th Sentai (as shown on the box art) and '91', 3rd Chutai, 73rd Sentai together with a 1st Sentai example that required the rudder to be painted (it was not understood at the time that this unit also painted the elevators in the Chutai colour). Upper surface of the 47th Sentai example was called out as dark green colour (暗緑色) using Gunze Sangyo laquer # 16 with the under surface to be left in the colour of the plastic - grey-green - and clear varnished. The upper surface colour depicted on the box art seemed to become a brighter green with each re-issue but the original is most true to life. Hayate was never the colour of a well known frog.

Current Arii Re-issue via HLJ

For those wishing to retro-build Otaki's Hayate there are good alternative decal sheets available, two from Lifelike as 048-13 and 048-31 and a Sky Models sheet 48-041, the latter having no less than 21 subjects. There are also several Montex masking sets available for those who might wish to paint Hayate markings, although they are designed for the more modern Hasegawa kits, and plenty of aftermarket detail enhancement sets in resin and photo-etch. Pairs of resin replacement seats are available from Ultracast (with or without seat belts) and from SBS with photo-etch seat belts.

Image credits: Model and book photographs © 2014 John Haas; Box art © Otaki/Arii; Map via Google Earth

Sunday, 30 November 2014

1/48th scale Mitsubishi Ki-83 Scratchbuild by John Haas

Here is another beautiful 1/48th scratchbuilt model by John Haas featuring the elegant Mitsubishi Ki-83. This one is a 'delayed action' feature presented here long after John sent me the photographs due to an extended senior moment. It has been lurking behind the scenes as a draft article awaiting some Japanese documentation with your host 'dumb and happy' in believing that he had already posted it. 

The fuselage and wings are made of solid woodblock, whilst the empenage and smaller parts are made of plastic rod and sheet material. The upper surface was painted in Humbrol Authentics HJ3 A3 Green (see here for an explanation of the origin of this paint colour not to be confused with Thorpe's A3) whilst for the under surface John used Polly-S Acryl Light Grey A/N 2 based on the light appearance seen in photographs. John estimates that his models take an average of about 2 months to  complete, spending 2 hours each evening and longer at the weekends.

Mitsubishi's Ki-83 was developed in response to a 1943 Army specification for a two seater fighter capable of operating at high altitude and long range. Although sometimes described as a 'heavy fighter' or 'long-range escort fighter' in English the Japanese designation was 'experimental long-range fighter' (試作遠距離戦闘機). The design had a troubled development and its first flight did not take place until November 1944.  It was the fastest of all wartime Army fighters achieving 686 kph (426 mph) at 8,000 m (26,000 ft) with remarkable agility for a twin-engined design. Post-war American testing with high octane fuel pushed the speed to 762 kph (473 mph) at 7,000 m (23,000 ft). Some ambiguity persists as to how its envisaged role was gradually modified during development and especially the role of the second crew member 'buried' in the rear fuselage, originally tasked as a navigator. Armament consisted of two 20mm Ho-5 and two 30mm Ho-105 cannon  installed in the nose. 

In total four prototype aircraft  were constructed but production plans were never realised and the original concept had been overtaken by events. Further development as a long range attack aircraft with a bombing capability was planned as the Ki-103 and a camera-equipped reconnaissance version intended to replace the Ki-46 as the Ki-95 but neither concept progressed beyond the design stage.

I'm not aware of any injection moulded kits of this type in 1/48th scale but a 1/72nd kit was issued by MPM in 2000 and then re-issued under the Special Hobby label with spurious 'what if' box art and markings. Calin Ungureanu's build of the MPM kit can be found here.

Image credits: All photos © 2014 John Haas; box art © MPM/Special Hobby

Friday, 28 November 2014

Belligerent Dinah ~ The 17th Dokuritsu Hiko Chutai

The 17th Independent Air (or Flying/Flight) Squadron (in Japanese Dokuritsu Hiko Dai 17 Chutai - 独立飛行第17中隊 - literally Independent Air No.17 Squadron) had its origin in the 101st Independent Air Squadron established in Japan in July 1941. The unit was originally equipped with the Type 97 Headquarters Reconnaissance Aeroplane (97 Shiki Shireibu Teisatsu-ki - 九七式司令部偵察機) known as the 97 Shi-tei (九七司偵) and usually referred to in the West as the Ki-15 'Babs'. The unit marking was a stylised bird silhouette in black or red superimposed on a broad white  horizontal band across the fin and rudder. The Flight (Shotai - 小隊 - usually three aircraft) and aircraft number within the Flight were indicated by a coloured star on the rudder for the Flight leader and one or two diagonal stripes painted on the fin for the second and third aircraft in the flight.

Following the Doolittle raid on Japan in April 1942 the air defence capability of the homeland was urgently reviewed. The 17th Air Brigade (Hiko Dan - 飛行団) was established  on 30 April 1942 to provide air defence of the Kanto sector, which included the Imperial Palace, the Tokyo-Yokohama area, Tachikawa and other vital points. The new Air Brigade comprised the 244th and 5th Air Regiments (Hiko Sentai - 飛行戦隊) both initially equipped with Type 97 fighters (Ki-27 ‘Nate’), the 4th Independent Air Squadron equipped with Type 2 two-seat fighters (Ki-45 ‘Nick’) and a Brigade Headquarters Reconnaissance Squadron which was to be the 101st.

In August 1942, following assignment to the HQ of the 17th Air Brigade, the 101st was formally re-designated as the No.17 Air Brigade Headquarters Reconnaissance Squadron  (Dai 17 Hikodan Shireibu Teisatsu Chutai - 第17 飛行団 司令部 偵察 中隊) and began operating a mix of 97 Shi-tei  aircraft together with the elegant twin-engined Type 100 Headquarters Reconnaissance Aeroplane (100 Shiki Shireibu Teisatsu-ki - 百式司部偵察機)  known as the 100 Shi-tei (百式司偵) and usually referred to in the West as the Ki-46 ‘Dinah’. The role of the unit, based at Chofu and under the command of Capt Takahiko Yasuda, was long range air defence reconnaissance for the Kanto sector, conducting continuous sector patrols of the approaches air space, reporting incursions in co-operation with coastal radar units and then tracking enemy formations to provide a running commentary on their type, number, altitude and heading to facilitate  interception by fighter units. Each sector patrol was usually flown by a flight of three aircraft, one of which would be assigned to track any observed incursion by an enemy bomber formation whilst the others continued to patrol. Although an organic part of 1st Air Army the 17th Air Brigade was under the operational control of Eastern Army Command for air defence purposes. In January 1943 Capt Kitagawa who had previously served with the 81st Sentai took over command of the reconnaissance unit. 

With re-assignment as a brigade HQ squadron the marking of the unit changed to a stylised ’17’ in red laid over a horizontal bar in cobalt blue symbolising the coastline and the headquarters status of the unit (cobalt or sky blue was the arm of service colour for Army Air and was usually used to denote command status).  Stars and diagonal stripes continued to be used to indicate aircraft within Flights but this system was later simplified to display one to three coloured horizontal stripes painted on the rudder.

On 10th March 1944 the 17th Air Brigade was re-organised and expanded to become the 10th Air Division (Hiko Shidan - 飛行師団) under the temporary command of Maj Gen Shoichi Sato, with a strength of six fighter regiments and one independent air squadron. At the end of March the 17th Air Brigade’s former HQ reconnaissance unit was re-designated as the 17th Independent Air Squadron (Dokuritsu Hiko Dai 17 Chutai - 独立飛行第17中隊), the title by which it is best known in Western documentation and depictions. In May 1944 the 10th Air Division Division was transferred from 1st Air Army to the direct command of the C-in-C of the General Defence Command (GDC) but with operational control remaining with Eastern Army Command.

At that time the 17th was rated as a unit of average ability and listed as having no less than fifty 100 Shi-tei aircraft of which about half were capable of Ta-Dan air-to-air bombing, as well as a few fighters of an unspecified type. The strength of the squadron was remarkable, on a par with that of a fighter sentai, and it was formed into two sections, a reconnaissance section and a fighter section equipped with the Ta-Dan capable Ki-46 aircraft. The selection of the Ki-46 to pioneer the Ta-Dan bombing  technique against the expected B-29 formations was based mainly on its status as the fastest climber and best high altitude performer in the Army’s air arsenal, a performance proven in competing trials and tests with fighter types. The Ta-Dan tactic involved dropping canisters of small cluster-type bombs in the path of the B-29 formations.

Diagram illustrating the Ta-dan bombing technique against a B-29 in a frontal attack

Once the B-29 raids got under way the fighter strand to the 17th’s story expanded and developed. Whilst the Ta-Dan tactic proved ultimately disappointing, the speed, climb and altitude capability of the Ki-46 continued to be exploited by adapting officially sanctioned cannon armed variants to conduct the preliminary interceptions in an attempt to break up the intruding bomber boxes. However, unlike other units within the 10th Air Division, the 17th was not required to establish air-to-air ramming flights. The first armed versions of the Ki-46 flown by the 17th had the fuselage fuel tank removed and either one or two 20mm machine cannon installed in its place to fire obliquely from a position below and behind the target bomber. In the fall of 1944 the engineering section of the 17th managed to install a 37mm cannon in the oblique firing position and subsequently six Ki-46-II and a single Ki-46-III were converted to this heavier armament. 

Successful experimentation with armed variants of the Ki-46 culminated in development of the purpose-built Ki-46-III interceptor, which was far from being just an expedient stop-gap fighter as so often asserted. This aircraft had a long formal title - Hyakushiki San-gata Shireibu Teisatsu-ki Kaizô Bôkû Sentô-ki (百式 三型 司令部偵 察機 改造 防空 戦闘機 - Type 100 Model 3 Headquarters Reconnaissance Plane Remodelled Air Defence Fighter) sometimes abbreviated to Hyakushiki San-gata Bôkû Sentô-ki (Type 100 Model 3 Air Defence Fighter). The original version armed with just two Ho-5 20mm cannon in the nose intended to augment the Ta-dan capability was projected as the Ki-46-III Otsu whilst the addition of the oblique Ho-204 37mm cannon was projected as Ki-46-III Otsu + Hei.  The 17th claimed victories against the B-29 in the new interceptor with cannon and Ta-Dan attacks but the promise of the fighter Ki-46 was largely overtaken by events as the B-29 offensive switched to low altitude night bombing and long range and naval task force deployed American fighters began daylight incursions over Japan. 

In March 1945 the 17th were assigned to the newly established 30th Fighter Group (not to be confused with the 30th Sentai), a late war composite group (first formed to augment fighter capability in the Philippines campaign) consisting of 47th (Ki-84) and 244th Air Regiments (Ki-100), Shimoshizu Air Unit and 17th Independent Air Squadron, plus three heavy bombers from the Utsunomiya Air Instruction Division and two navigation air squads to provide navigational assistance. This second incarnation of the 30th was to provide escort capability to the 18th, 19th, 25th, 45th and 47th Shimbu tai special attack units and to take over the duties of 6th Air Army in defending the Kanto Sector when the 6th Air Army was re-deployed to oversee the Ryuku Islands defence operations. In July 1945 the 17th Independent Air Squadron was re-designated the 17th Independent Air Group (Dai 17 Dokuritsu Hikotai -  第17独立飛行隊).

Yatagarasu - the three-legged crow that inspired the insignia for Dai 17 Dokuritsu Hikotai  

The 30th Fighter Group was considered part of the mobile air defence forces required to respond to an invasion attempt against the homeland but after the implementation of the Sei Go (Control) operation in July 1945 its composition changed and by August 1945 it consisted of 59th and 244th fighter, 62nd bomber and 17th Independent Air Group,  reverting under the command of the 6th Air Army and deployed in the Western Sector of Japan. With assignment to the new unit the 17th changed its tail marking to a black three-legged crow - Yatagarasu - set against an orange disc representing the sun. The marking was designed for the unit by the artist Fumino but was applied to only a few aircraft, the majority retaining the former unit insignia or none at all. In Japanese mythology the three-legged crow was associated with divine guidance of the Emperor Jimmu on his journey from Kumano to Yamato but a full exploration of the whys and wherefores of this mythical bird would require another article in its own right.

Yatagarasu guides Emperor Jimmu on his journey from Kumano toYamato

For further details and data regarding Ta-dan equipped Ki-46 interceptors and units please refer also to this series at by Jim Lansdale.

This is an enhanced version of an article by the author first published in The Flak Sheet, the newsletter of IPMS North Central Texas - with thanks to Mark Smith for suggesting and inspiring it; Model photographs courtesy of Mark Smith; Ta-dan schematic from Japanese Air Weapons and Tactics, USSBS, Miiltary Analysis Division, 1947; Image of carved Yatagarasu via Green Shinto