I decided to gather and sort these Kawanishi designations. So far, there seems to have been at least five distinct internal Kawanishi aircraft designation systems between 1920 and 1945.

**Kawanishi Kokuki KK - Internal Aircraft Designations**
Back in 2009,

**Maveric** speculated that there were two, distinct sequences of Kawanishi 'K' aircraft designations. I agree that this is the logical conclusion. The earlier numbered 'K' series - from 1920 to c.1928 - seems to have been eclipsed by lettered 'Type' designations. The earliest confirmed 'Type' designation is the Type E - the licensed-built Yokosuka K2Y1 of 1930. (More on Kawanishi 'Type' designation below.)

Where things get confusing is with the well-known H6K 'Mavis' This 1936 flying boat was first designated in both systems - as the Type S and as the K-23. That 1936 date confuses matters. It is late for the 'Type' system but that's not a problem. That K-23 makes things trickier.

**Maveric** had included the K-23 in both the first and second 'K' designation sequences. In the first sequence, this leaves a big gap between the 1927 K-12 '

*Sakura*' of 1927-28 and the K-23/H6K of almost a decade later. But that's life! Because the second Kawanishi 'K' series designations did not begin until 1939 (hence the removal of the K-20/N1K from my first ;K' series list). [1]

Once we excise the K-23 from the second 'K' series, we are left with a sequence made up of numbers which are multiples of 10 - ie: K-10, K-20, K-60, K-90, and K-100. [2] That leaves plenty of gaps but then, there are a vast numbers of Kawanishi projects and built types left unaccounted for in these sequences.

During WW2, Kawanishi also started using another internal designation system for projects - the 'KX' designation series. We known this sequence ran at least from KX-1 to KX-9 (but with plenty of 'gaps' in between). There was also an anomalous KR-1 research flying boat project - but I have no clue about that one!

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[1] See:

**snark**'s IJN Service Airplane Development Program Designations

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https://www.secretprojects.co.uk/th...plane-development-program-designations.28284/
[2] This excluded 'K-120' but 'K-200' fits the pattern (albeit with a huge gap being formed!).

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**Kawanishi Internal 'K' Aircraft Designations - 1st Series**
K-1 -- 1920 single-engined biplane mail-carrier aircraft; x 1

- K-1: 2-bay; equal-span; open rear pilot's cockpit; J-TAAB

- K-1: 1 x 200 hp Hall-Scott L-6 inline 6-cyl.; span (??) m

-- * 1922, re-engined with 180 hp** Austro-Daimler 6-cyl.

-- ** Power rating is odd for an Austro-Daimler; '185 hp'?

K-2 -- 1921 single-seat, low-winged monoplane racer; x 1

- K-2: Wire- then strut-braced wings; fabric-covered wood

- K-2: 1 x 244 hp Hall-Scott L-6 inline 6-cyl.; span 9.67 m

K-3 -- 1921 fast commercial biplane derived from K-1; x 1

- K-3 : Single-bay, equal-span* wings; open rear cockpit

- K-3 : Rear pilot cockpit; side-by-side pax; span 10.03 m

- K-3 : Prototype; 1 x 305 hp Maybach Mb.IVa inline 6-cyl.

- K-3B: Airframe mods; 230 hp Benz Bz.IV; J-TEEG/J-COEG

-- * Albeit with the ailerons on the lower wings protruding

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https://www.secretprojects.co.uk/threads/early-kawanishi-Typees.27563/#post-277229
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https://www.secretprojects.co.uk/threads/early-kawanishi-Typees.27563/#post-277330
K-4 -- (??)

- K-4B: Modified K-3 (

**hesham**)

K-5 -- 1922 mail-carrier/cargo/passenger transport biplane; x 1

- K-5 : Cabin side-by-side 4 x pax; forward open pilot's cockpit

- K-5 : 1 x 305 hp Maybach Mb.IVa inline 6-cyl.; span 18.70 m

- K-5 : Unequal-span wings* with partial Warren truss bracing

-- * Considerable dihedral on lower wings, none on the uppers

-- Completed Oct 1922; trials showed K-5 to be underpowered

K-6 - 1923 3-seat, passenger-carrying biplane floatplane; x 1

- K-6 : 2-bay biplane; finless underslung rudder, twin floats

- K-6 : 1 x 305 hp Maybach Mb.IVa inline 6-cyl.; span 13.60 m

- K-6 : Reduced-scale design with Mb.IVa to replace the K-5*

-- * No more powerful engine avail. to designer Eiji Sekiguchi

-- K-6 c/n 1 Prototype; J-TEOS; to Kawanishi's Nippon Koku KK

-- Orig. with open 2-seat pax cockpit; later enclosed canopy

-- K-6 c/n 601; Jan 1924 mod. for Around Japan Flight, J-BAEE

-- Named '

*Harukaze*' (Spring Wind) for Around Japan Flight

-- Later restored to passenger service; eclipsed by devel. of K-7

K-7 -- 1924 pax transport/air mail floatplane sequiplane; x 8*

- K-7 : Orig. for Nippon Koku KK pax-carrier but used for cargo

- K-7 : 1 x 260 hp Maybach Mb.IV inline 6-cyl.; span 12.00 m

-- * Some sources claim 1 x K-7; 9 x K-7A; + 1 x K-7B = x 11

- K-7A: 2+4 pax cabin floatplane for Nippon Koku KK; x 7

- K-7A: 2+4 cabin floatplane; c/n 1, 2, 702, 3, 5 (I), 5 (II), 6

-- 1925 K-7A c/n 5 (I) may have been K-6 airframe rebuild

-- 1927 K-7A c/n 5 (II) shared (I)'s J-CODE/J-BGAE regist'n

-- 1928 K-7A c/n 702 probably rebuilt 1925 c/n 2 airframe

- K-7B: As K-7A but able to accommodate floats or wheels

-- K-7B c/n 1 (J-COTU); Nippon Koku KK Nov 1925-Aug 1927

--

https://www.secretprojects.co.uk/threads/early-kawanishi-Typees.27563/#post-276636
K-8 -- 1926 long-range passenger transport/recce floatplane, x 7

- K-8 : Twin-float, parasol monoplane cabin a/c built in two forms

- K-8 : 1 x 305 hp Maybach Mb.IVa inline 6-cyl.; wing span varied

- K-8 : Original concept as airmail/pax-carrier for Nippon Koku KK

- K-8A: 1st prod'n model w/ deeper fuselage; span 17.60 m, x 5*

-- * Actually x 6; c/n 803 (J-BAJE) repl. destroyed c/n 3 (J-COMN)

- K-8B: 2nd prod'n model; slimmer fuselage; span 16.00 m; x 2**

-- ** c/n 6 (J-TUST/J-BDAE) 1928; c/n 7 (J-TUTU/J-BDAF) 1926***

-- *** Oddly c/n 7 reg. J-BEAE July 1928; later J-TUTU/J-BDAF (?)

K-9 -- (Project) 1925 high-winged cabin transport monoplane

- K-9: 2+6 pax; Sekiguchi drew from K-9 design for his K-12

- K-9 : 1 x 305 hp Maybach Mb.IVa inline 6-cyl.; span 18.00 m

-- Alternative engine considered was 400 hp Lorraine-Dietrich

K-10 Transport - 1926 passenger transport/air mail biplane; x 2*

- K-10 : Single-engined biplane by Eiji Sekiguchi; span 13.00 m

- K-10 : (As built) 1 x 400 hp Lorraine-Dietrich V8; 1+2 x pax

- K-10 : (As mod.) 1 x 260 hp Maybach M.IV 6-cyl.; 1+4 x pax

-- K-10 intended for use by Kawanishi's Nippon Koku KK airline

- K-10 : 2nd Prototype (as mod. 1st Prototype); c/n 2 J-CODF*

-- * Destroyed Feb 1927; repl. by new (rebuilt?) c/n 2 J-BCAE

K-11 - 1927 'Experimental Carrier Fighter' Prototypes, x 2

- K-11: Single-engined single-seat biplane naval fighter

- K-11: 1 x 500 hp BMW VI V12 engine; span 10.80 m

- K-11: Designed by Eiji Sekiguchi; no dihedral on wings

-- 2nd Prototype had mod. fuselage; IJN preferred A1N

-- 1 of 2 Prototypes reg. J-BAME for NKKK use; June 1927

K-12 - 1927 '

*Sakura*' long-range record attempt a/c; x 2

- K-12: Potential Trans-Pacific high-wing cabin monoplane

- K-12: 1 x 500 hp BMW VI V12 engine; span 19.05 m

-- Inspired by the Ryan '

*Spirit of St Louis*' but bigger

-- Long-distance flight/K-12 project cancelled in Nov 1928

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https://www.secretprojects.co.uk/threads/early-kawanishi-Typees.27563/#post-298999
K-13 to K-22

K-23 - 1936 Type S, later H6K 'Mavis' 4-engined parasol flying boat

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