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
--
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
--
https://www.secretprojects.co.uk/threads/early-kawanishi-Typees.27563/#post-277229
--
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
--
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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