Ishikawajima Aircraft Designations

[Apophenia]

Ishikawajima Hikoki Seisakusho

The Ishikawajima Aircraft Manufacturing Company was formed in 1924 as a division of the Ishikawajima Shipbuilding & Engineering Co., Ltd. (There was also an automotive division which later became Isuzu.) Ishikawajima Hikoki Seisakusho survived as a private firm until 1935 or 1936 (the dating is confused). However, by 1936, the Imperial Japanese Army has acquired a controlling interest and changed the name to Tachikawa Hikoki Kabushiki Kaisha (or the Tachikawa Aircraft Company Ltd.).

Ishikawajima Hikoki Seisakusho Aircraft Designations

Between 1927 and 1930, Ishikawajima assigned role prefixes and type numbers to their aircraft designs. The 'R' prefix stood for Renshuki (Coach), indicating a training aircraft. The 'T' prefix stood for Teisatsu (Reconnaissance). Later designs had more complex designation prefixes - like KKY for Kogata Kei Kanja Yusoki (Small Light Patient Transport) for an aerial ambulance.

Some late Ishikawajima designs will be listed under Tachikawa as that is how they are known. Examples are the 1935 Ki-9 and Ki-17 military trainers. For such designs, see the separately posted Tachikawa Kitai number listings.

It is not clear whether unbuilt aircraft projects were assigned designations. One seemingly undesignated design was the Ishikawajima 'urban air defense fighter', a biplane whose development was terminated in November 1927. [1]

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Ishikawajima Aircraft Designations

R-1 - 1927 2-seat tandem biplane ab initio trainer, x 1
- R-1 : Private venture for IJA; Shiro Oshihara design*
- R-1 : 1 x 80 hp ADC Cirrus I 4-cyl. inline; span 9.60 m
- R-1 : No IJA interest; redesig. CM-1 ('Cirrus Motor')
-- * Overseen by Richard Vogt; influenced by DH Moth

R-2 - 1927 2-seat tandem biplane ab initio trainer, x 2
- R-2 : Revised R-1 redesign with steel-tube fuselage*
- R-2 : 1 x 90 hp ADC Cirrus II 4-cyl. inline; span 9.60 m
-- * Tail & wings similar to R-1 but parallel vs N struts
- R-2: Both evaluated by IJA; returned to Ishikawajima

R-3 - 1930 2-seat tandem biplane ab initio trainer, x 2*
- R-3 : Mariyuki Nakagawa design; mixed wood/metal constr.
- R-3 : 1 x 110 hp Cirrus Hermes I 4-cyl.; span 10.11 m
-- * Some sources claim that up to 5 x R-3s were built (??)
-- * With extra tankage, J-BEPB flew Tokyo to Rome in 1931

R-4 - (??) hypothetical designation

R-5 - 1927 2-seat tandem biplane ab initio trainer, x 2
- R-5 : New trainer by chief designer Mariyuki Nakagawa
- R-5 : 1 x 135 hp Cirrus Hermes Mk.IV; span 9.55 m
- R-5 : (I) Evaluated by IJA and returned to Ishikawajima
- R-5 : (II) Built later for Japan Students Aviation League
- R-5 : (II) 1933, Japan Students Aviation League, J-BISB
-- 1st R-5 also to Japan Students Aviation League, J-BAAG

T-1 - (Project) tandem 2-seat reconnaissance aircraft
- T-1 : No other details

T-2 - 1927 tandem 2-seat recce biplane prototypes, x 2
- T-2 : Unequal-span, single-bay biplane; wood constr.
- T-2 : (I) 1 x 500 hp Hispano-Suiza 12G; span 14.01 m
- T-2 : (I) 1 x 600 hp Kawasaki BMW VI; span 14.01 m
-- Contest won by metal Kawasaki KDA-2/Army Type 88

T-3 - 1928 tandem 2-seat recce biplane prototype, x 1
- T-3 : T-2 design revised for all-metal construction*
- T-3 : 1 x 600 hp Kawasaki BMW VI V12; span 14.01 m
-- * Which is reflected in J-BBCA being assigned c/n 3
-- * Steel-tube fuselage; fabric over duralumin wings

KKY-1 - 1933 single-engined ambulance biplane, x 25*
- KKY-1: DH.83 Fox Moth-inspired Endo Ryokichi design
- KKY-1: 1 x 135 hp Cirrus Hermes Mk.IV; span 10.00 m
- KKY-1: Pilot + med. attendant + 2 x stretcher patients
- KKY-2: 1 x 150 hp Gasuden Jinpu Model 3; span 10.00 m
-- Kogata Kei Kanja Yuso-ki (Small Light Patient Transport)
-- * Built 1933-1939-40, most w/ Gasuden radial engine
- KS-1: 1939 Ministry of Railways aerial survey a/c, x 2 [2]
- KS-1: 1 x 150-160 hp Hitachi Jinpu 3 7-cyl. radial**
-- ** Brand name change; Gasuden was a subsidiary of Hitachi

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[1] This 1927 'urban air defence fighter' was to have been a biplane powered by a 500 hp engine - probably the same Hispano-Suiza 12G from the Ishikawajima T-2 reconnaissance biplane. The IJA examined the drawings of Ishikawajima's submission but rejected the concept.

[2] Although a Tachikawa product, the KS-1 is included here as a development of the Ishikawajima KKY-1.

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 thread on Tachikawa Kitai number listings:

-- See: https://www.secretprojects.co.uk/threads/tachikawa-aircraft-designations.41540/#post-598546

 

[hesham]

Amazing work as usual dear Apophenia,

ad for T-1,it was a tandem two-seat reconnaissance biplane project,

 

[Apophenia]

... for T-1,it was a tandem two-seat reconnaissance biplane project,

Thanks hesham! That was my suspicion but I couldn't find any confirmation.

Based on the timing and your information, the T-1 was obviously dropped in favour of the T-2. Perhaps they were the same airframe with different engine types? Perhaps the T-2 airframe design was simply superior? Who can say?