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Tachikawa Hikoki Kabushiki Kaisha
As noted in the Ishikawajima Aircraft Designations thread, the Imperial Japanese Army became a majority shareholder of the Ishikawajima Hikoki Seisakusho and, in 1936, rebranded their holding as the Tachikawa Hikoki Kabushiki Kaisha (or the Tachikawa Aircraft Company Ltd.).
See: https://www.secretprojects.co.uk/threads/ishikawajima-aircraft-designations.41539/
I have never found any consensus on whether pre-WW2 and wartime Japanese aircraft designations should be rendered with a 'dot' or a hyphen. So, I've randomly chosen to used a hyphen. Equally randomly, transliterated sub-type letters are capitalized. Idiosyncratically, for aero-engines, I've adopted the form Ha 'dot' number 'hyphen' sub-type number. For modified engine models, I've capitalized the suffixes.
BTW: Apologies in advance for the absense of most diatritical marks on transliterations (my computer won't support many such marks).
Tachikawa Hikoki Kabushiki Kaisha Aircraft Designations
The transition from Ishikawajima to Tachikawa designations is a bit awkward. The KS-1 is clearly related to the older Ishikawajima designs but also belongs under Tachikawa (so I will duplicate this designation in my Tachikawa listing. Conversely, the 1935 dates for the Ki-9 and Ki-17 trainers clearly makes them Ishikawajima designs. However, they are universally known as Tachikawa products. So, I will list them under a separate Tachikawa Kitai number listings
As a manufacturer largely dedicated to supplying the Imperial Japanese Army, it makes sense that the majority of Tachikawa's products are known by their official Kitai numbers. Those will be listed below in numerical order. However, first I will address anomalous designations.
Tachikawa Aircraft Designation Prefixes
Some non-Kitai Tachikawa designations simply continue the Ishikawajima pattern - eg: the 1939 KS-1 for the Ministry of Railways. In this case, KS-1 stands for the first Kogata sokuryo-ki or Small Survey aircraft. I'll define such Tachikawa role acronym designations below in alphabetical order:
KS = Kogata sokuryo or 'Small Survey' aircraft; eg: KS-1
LO = Not an acronym, this is an IJN designation (see below)
SS = Seisoken Shiken or 'Stratospheric Trial' aircraft; eg: SS-1
R = Renshuki or 'Coach' referring to a training aircraft; eg: R-38
TS = Tachikawa Supotsu or 'Tachikawa Sport' aircraft; eg: TS-1
Y = Yuso-ki or '(Civilian) Transport aircraft'; eg: Y-39 and Y-59
As note above, the 'LO' for Tachikawa's version of the Lockheed Model 14 was anomalous only in the sense that the IJA-owned Tachikawa was building transport aircraft for the Imperial Japanese Navy! So, LO was not an acronym (nor was it an abbreviation for 'Lockheed'). Instead, LO was an short-form style designation of the IJN - 'L' being the IJN code for Yuso-ki (Transport aircraft) while 'O' was the IJN manufacturer's code assigned to the Tachikawa Hikoki K. K..
Tachikawa 'Plan' Designations - Some Design Concepts
A number of Tachikawa military aircraft concepts were given simple 'Design' or 'Plan' numbers. Presumably this means that these concept were at a fairly early stage of development and did not warrant Kitai numbers. I include these 'Plan' types directly below since they don't 'fit' into the designation lists.
I have only found two groups of numbered Tachikawa 'Plan' designs - one is shown with Arabic numerals, the other with Roman numerals. Were both used? Since I have no idea which style was preferred, I've stuck to the style shown in the sources I'd found.
The first was by SPF member Christophe Meunier (Tophe) who revealed a series of related but mysterious Tachikawa concepts. From their appearance, it is not even clear what the role of these 'Plan' concepts was intended to be. All of Tophe's comparisons are with fighters. So, perhaps Tachikawa intended these concepts as multi-seat fighters. Or were they recce-bombers or pure reconnaissance types? I just don't know.
Tachikawa Plan 1A - (Project) Radial-engined multi-seat aircraft
- Design 1B: Tophe compared appearance to Piaggio P.119*
-- * I am not sure if this actually implies a centrally-placed engine
Tachikawa Plan 1B - (Project) Inline-engined multi-seat aircraft
- Design 1B: Tophe compared appearance to the Soviet MiG-3
Tachikawa Plan 2 -- (Project) Twin-fuselage, twin-engined a/c
- Design 2 : Dai Ni An; inline-engined but related to Design 3 (?)
- Design 2 : Large canopy to port; shallow canopy to starboard
Tachikawa Plan 3 -- (Project) Twin-fuselage, twin-engined a/c
- Design 3 : Dai San An; radial-engined;* related to Design 2 (?)
- Design 3 : Large canopy to port; suppressed canopy to stbd.**
-- * Engines drove long nose shafts; cooling via annular spinners
-- ** Canopy suppressed to maximize aerodynamic benefits
-- https://www.secretprojects.co.uk/th...ects-of-the-1920s-and-1930s.27630/#post-39921
-- See online Forked Ghost segment (pg.12): https://www.kristofmeunier.fr/Fg_2.pdf
The second group of 'Plan' types appear in Edwin M Dyer's Japanese Secret Projects: Experimental Aircraft of the IJA and IJN 1939-1945. In this book, are listed three related Tachikawa concepts for high-speed heavy bombers designs - the Plan I, Plan II and Plan III - which Dyer describes as "all variations on the same theme with minor differences". They were:
Tachikawa Plan I - High Speed Heavy Bomber; 6 x crew
- Plan I : 4 x 2,000 hp Nakajima Ha-145s; span 24.47 m
-- Wing area 85.00 m2 ; Length 17.67 m ; Loaded 19 T
-- Max. 684 km/h; Cruise 480 km/h; Range; 4,899 km
-- 1,500 kg bombs; 1 Ho-5 20mm; 2 7.7 mm Type 89s
Tachikawa Plan II - High Speed Heavy Bomber; (?) x crew
- Plan II: 4 x 2,000 hp Nakajima Ha-145s; span 28.49 m
-- Wing area 80.00 m2 ; Length (??) m ; Loaded 17.9 T
-- Max. 694 km/h; Cruise 490 km/h; Range; 5,049 km
-- 1,000 kg bombs; no details on defensive armament
Tachikawa Plan III - High Speed Heavy Bomber; (?) x crew
- Plan II: 4 x 2,200 hp Mitsubishi Ha-211 MB; span (??) m
There were, of course, a large range of Tachikawa aircraft projects and concepts developed to varying degrees. Sometimes descriptions are quite garbled - eg: an undesignated Tachikawa parasol light 2-seat intended for "initial training of R-38 pilots". Since the R-38 is, itself, a 2-seat parasol ab initio trainer, something is amiss. In all likelihood, the 'mystery' plane was the Tachikawa R-38. Others doubtless await 'discovery'.
If there are other unbuilt Tachikawa aircraft projects to which other SPF members can connect designations - internal Tachikawa, IJA, etc. - I'd love to hear about them.
As noted in the Ishikawajima Aircraft Designations thread, the Imperial Japanese Army became a majority shareholder of the Ishikawajima Hikoki Seisakusho and, in 1936, rebranded their holding as the Tachikawa Hikoki Kabushiki Kaisha (or the Tachikawa Aircraft Company Ltd.).
See: https://www.secretprojects.co.uk/threads/ishikawajima-aircraft-designations.41539/
I have never found any consensus on whether pre-WW2 and wartime Japanese aircraft designations should be rendered with a 'dot' or a hyphen. So, I've randomly chosen to used a hyphen. Equally randomly, transliterated sub-type letters are capitalized. Idiosyncratically, for aero-engines, I've adopted the form Ha 'dot' number 'hyphen' sub-type number. For modified engine models, I've capitalized the suffixes.
BTW: Apologies in advance for the absense of most diatritical marks on transliterations (my computer won't support many such marks).
Tachikawa Hikoki Kabushiki Kaisha Aircraft Designations
The transition from Ishikawajima to Tachikawa designations is a bit awkward. The KS-1 is clearly related to the older Ishikawajima designs but also belongs under Tachikawa (so I will duplicate this designation in my Tachikawa listing. Conversely, the 1935 dates for the Ki-9 and Ki-17 trainers clearly makes them Ishikawajima designs. However, they are universally known as Tachikawa products. So, I will list them under a separate Tachikawa Kitai number listings
As a manufacturer largely dedicated to supplying the Imperial Japanese Army, it makes sense that the majority of Tachikawa's products are known by their official Kitai numbers. Those will be listed below in numerical order. However, first I will address anomalous designations.
Tachikawa Aircraft Designation Prefixes
Some non-Kitai Tachikawa designations simply continue the Ishikawajima pattern - eg: the 1939 KS-1 for the Ministry of Railways. In this case, KS-1 stands for the first Kogata sokuryo-ki or Small Survey aircraft. I'll define such Tachikawa role acronym designations below in alphabetical order:
KS = Kogata sokuryo or 'Small Survey' aircraft; eg: KS-1
LO = Not an acronym, this is an IJN designation (see below)
SS = Seisoken Shiken or 'Stratospheric Trial' aircraft; eg: SS-1
R = Renshuki or 'Coach' referring to a training aircraft; eg: R-38
TS = Tachikawa Supotsu or 'Tachikawa Sport' aircraft; eg: TS-1
Y = Yuso-ki or '(Civilian) Transport aircraft'; eg: Y-39 and Y-59
As note above, the 'LO' for Tachikawa's version of the Lockheed Model 14 was anomalous only in the sense that the IJA-owned Tachikawa was building transport aircraft for the Imperial Japanese Navy! So, LO was not an acronym (nor was it an abbreviation for 'Lockheed'). Instead, LO was an short-form style designation of the IJN - 'L' being the IJN code for Yuso-ki (Transport aircraft) while 'O' was the IJN manufacturer's code assigned to the Tachikawa Hikoki K. K..
Tachikawa 'Plan' Designations - Some Design Concepts
A number of Tachikawa military aircraft concepts were given simple 'Design' or 'Plan' numbers. Presumably this means that these concept were at a fairly early stage of development and did not warrant Kitai numbers. I include these 'Plan' types directly below since they don't 'fit' into the designation lists.
I have only found two groups of numbered Tachikawa 'Plan' designs - one is shown with Arabic numerals, the other with Roman numerals. Were both used? Since I have no idea which style was preferred, I've stuck to the style shown in the sources I'd found.
The first was by SPF member Christophe Meunier (Tophe) who revealed a series of related but mysterious Tachikawa concepts. From their appearance, it is not even clear what the role of these 'Plan' concepts was intended to be. All of Tophe's comparisons are with fighters. So, perhaps Tachikawa intended these concepts as multi-seat fighters. Or were they recce-bombers or pure reconnaissance types? I just don't know.
Tachikawa Plan 1A - (Project) Radial-engined multi-seat aircraft
- Design 1B: Tophe compared appearance to Piaggio P.119*
-- * I am not sure if this actually implies a centrally-placed engine
Tachikawa Plan 1B - (Project) Inline-engined multi-seat aircraft
- Design 1B: Tophe compared appearance to the Soviet MiG-3
Tachikawa Plan 2 -- (Project) Twin-fuselage, twin-engined a/c
- Design 2 : Dai Ni An; inline-engined but related to Design 3 (?)
- Design 2 : Large canopy to port; shallow canopy to starboard
Tachikawa Plan 3 -- (Project) Twin-fuselage, twin-engined a/c
- Design 3 : Dai San An; radial-engined;* related to Design 2 (?)
- Design 3 : Large canopy to port; suppressed canopy to stbd.**
-- * Engines drove long nose shafts; cooling via annular spinners
-- ** Canopy suppressed to maximize aerodynamic benefits
-- https://www.secretprojects.co.uk/th...ects-of-the-1920s-and-1930s.27630/#post-39921
-- See online Forked Ghost segment (pg.12): https://www.kristofmeunier.fr/Fg_2.pdf
The second group of 'Plan' types appear in Edwin M Dyer's Japanese Secret Projects: Experimental Aircraft of the IJA and IJN 1939-1945. In this book, are listed three related Tachikawa concepts for high-speed heavy bombers designs - the Plan I, Plan II and Plan III - which Dyer describes as "all variations on the same theme with minor differences". They were:
Tachikawa Plan I - High Speed Heavy Bomber; 6 x crew
- Plan I : 4 x 2,000 hp Nakajima Ha-145s; span 24.47 m
-- Wing area 85.00 m2 ; Length 17.67 m ; Loaded 19 T
-- Max. 684 km/h; Cruise 480 km/h; Range; 4,899 km
-- 1,500 kg bombs; 1 Ho-5 20mm; 2 7.7 mm Type 89s
Tachikawa Plan II - High Speed Heavy Bomber; (?) x crew
- Plan II: 4 x 2,000 hp Nakajima Ha-145s; span 28.49 m
-- Wing area 80.00 m2 ; Length (??) m ; Loaded 17.9 T
-- Max. 694 km/h; Cruise 490 km/h; Range; 5,049 km
-- 1,000 kg bombs; no details on defensive armament
Tachikawa Plan III - High Speed Heavy Bomber; (?) x crew
- Plan II: 4 x 2,200 hp Mitsubishi Ha-211 MB; span (??) m
There were, of course, a large range of Tachikawa aircraft projects and concepts developed to varying degrees. Sometimes descriptions are quite garbled - eg: an undesignated Tachikawa parasol light 2-seat intended for "initial training of R-38 pilots". Since the R-38 is, itself, a 2-seat parasol ab initio trainer, something is amiss. In all likelihood, the 'mystery' plane was the Tachikawa R-38. Others doubtless await 'discovery'.
If there are other unbuilt Tachikawa aircraft projects to which other SPF members can connect designations - internal Tachikawa, IJA, etc. - I'd love to hear about them.
