Maveric: This might help a little on info:
Cox-Klemin 'C.K.' Aircraft Designation Series
C.K.1 - 1921 2-seat high-wing multi-purpose flying boat, x 1
- C.K.1: Twin-tailled amphibian, open cockpit/closed cabin
- C.K.1: 2 x 275 hp Isotta-Fraschini
Asso, span 17.93 m
-- C.K.1 prototype completed but prove incapable of taking off
-- 3v:
http://www.airwar.ru/image/idop/flyboat/ck1/ck1-1.gif
C.K.2 - 1924 re-engined Heinkel HD 17* USAAC observation a/c
- C.K.2 : Single-bay biplane tandem 2-seat observation a/c, x 2
-- * Heinkel design built by Svenska Aero AB as wk. nr. 216/217
- C.K.2A: 1 x 470 hp Napier
Lion W-12,** span 12.40 m***
-- ** Some sources say 1 x 450 hp Napier
Lion W-12 (IA ?)
-- *** Some sources say span was only 9.91 m, others 12.90 m
-- Eval. by USAAC at McCook Field, OH, as Cox-Klemin CK CO-2
-- C.K.2A/CK CO-2 airframe assigned USAAS Project number P-377
-- NB: Many sources confuse C.K.2A with Engineering Div.'s CO-1
- C.K.2B: 1 x 400 hp
Liberty L-12 engine, span 12.40 m
-- Eval. by USAAC at McCook Field, OH, as Cox-Klemin CK CO-2 [1]
-- C.K.2B/CK CO-2 airframe assigned USAAS Project number P-379
-- NB: Often confused with Engineering Div.'s/Gallaudet's CO-2
-- Dec 1926 civil reg. NC 1189, became sky-writer in Oct 1927
C.K.3 - 1923 Night Observation aircraft for USAAC Type VIII
- C.K.3: no details
-- In USAAS service, would have NO (Night Observation) desig.
C.K.4 - C.K.13 - (??)
C.K.14 - 1922 rebuilt/modified surplus Curtiss MF flying boat
- C.K.14: Uprated MF mod. to postwar
Seagull standards
- C.K.14: 1 x 180 Wright-Hispano E V-8 pusher,* span 13.75 m
-- * Replacing MF's original 100 hp Curtiss OXX-3 V-8 pusher
C.K.15 - C.K.17 - (??)
C.K.18 - 1925 3-seat multi-purpose biplane flying boat, x 1
- C.K.18: Single-bay, single-engined amphibian, reg NC2059
- C.K.18: 1 x 160 hp Curtiss C-6 tractor prop,* span 12.17 m
-- Cox-Klemin copy of licensed Nungesser NUA-1 amphibian
-- aka 'Stelling Amphibian' after its financer John Stelling
-- 3v:
http://www.airwar.ru/image/idop/flyboat/ck18/ck18-1.gif
-- * More likely 170 hp Curtiss R-600
Challenger radial
C.K.19 - 192? amphibian (no details), probably a flying boat
C.K.20 - C.K.27 - (??)
C.K.28 ?
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[1] There is no sign of the C.K.2B airframe being assigned a separate CK CO-2 sub-type designation.
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Anomalous Cox-Klemin Aircraft Designation
Cox-Klemin PS - 1925
Nighthawk postal aircraft, x 1
- PS: Single-seat* single-bay biplane, aka Heinkel HD 27**
- PS: 1 x 400 hp
Liberty L-12 V-12, span 13.60 m***
-- * Flown as tandem 2-seater; single-seater as mailplane
-- ** Sim. to HD 22, HD 27 was commissioned by Cox-Klemin
-- *** Some sources list span of only 12.40 m or 12.80 m
-- US Air Mail Service 1925-1928, destroyed by a tornado
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Cox-Klemin - US Army Air Service/US Navy Designations
T.W.2 - 1922 tandem 2-seat single-bay biplane trainer, x 3*
- T.W.2: Submitted to USAAS, ordered as a series of test a/c
- T.W.2: 1 x 300 hp Wright-Hispano Model H V-8,** span 8.84 m
-- * 2 x flying aircraft plus 1 x static testing airframe
-- ** Sources also list 'Hisso 150' & 180 hp Wright-Hispano E
-- ** It is possible that all three engine types were tested
-- USAAC serial numbers assigned were 68540, 68541, & 68542
-- Wright Field flight test Project numbers were P-264/P-286
-- Note: No evidence for T.W.2 - C.K.2 connection assertions
-- 3v:
http://www.airwar.ru/image/idop/other1/tw2/tw2-1.gif
XA-1 - 1923 single-engine biplane ambulance* medevac a/c, x 2
- XA-1: 2 x crew, 2 x litters vert. stacked in enclosed cabin
- XA-1: 1 x 420 hp Liberty L-12A V-12, span (equal) 13.41 m
-- McCook Field trials (P-383/P-421), became 23-1247/23-1248
-- 1 x deployed to Kelly Field, TX, 1 x at France Field, Canal Zone
-- * First aircraft type in USAAC 'A' for Ambulance category
--
https://www.nationalmuseum.af.mil/Upcoming/Photos/igphoto/2000571645/
CK CO-2 - 1924 Cox-Klemin C.K.2 (Heinkel HD 17)* biplanes, x 2
-- * Airframes built by Svenska Aero AB as wk.nr.216 & wk.nr.217
- C.K.2A: 1 x 470 hp Napier
Lion W-12, span 12.40 m **
-- *** Some sources say span was only 9.91 m, others 12.90 m
-- Eval. at McCook Field, OH, with USAAS Project number P-377
- C.K.2B: 1 x 400 hp
Liberty L-12 engine, span 12.40 m
-- Eval. at McCook Field, OH, with USAAS Project number P-379
-- No military equip't fitted, neither Cox-Klemin purchased
XS-1 - 1922 submarine-borne twin-float scout a/c, x 6*
- XS-1: Easily-disassembled single-seat, single-bay biplane
- XS-1: 1 x 60 hp Lawrance L-4 3-cyl radial, span 5.49 m
-- * Another 6 airframes were built by Martin as their MS-1
-- Aerofiles considers TW-2 mod. which is highly unlikely
XS-2 - 1923 submarine-borne twin-float scout a/c, x 1 conv.
- XS-2: One Cox-Klemin XS-1 (A6519) re-engined with Kinner
- XS-2: 1 x 125 hp Kinner B5 5 3-cyl radial, span 5.49 m
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Unbuilt Cox-Klemin Aircraft Project
Note that the Type designations are USAAS role classifications not Cox-Klemin numbers. Had such designs been accepted, they would have been assigned USAAS NBS-x (Type XII) and NBL-x (Type XIII) designations.
Cox-Klemin Air Service Type XII Bomber Proposal - 1924 Night Bombardment, Short-range
Cox-Klemin Air Service Type XIII Bomber Proposal - 1924 Night Bombardment, Long-range
It was neither the CO-2 nor the XO-4 (which doesn't even fit the contemporary US Army Air Service designation style). Instead, the C.K.2 was given the improbable and likely uniquely-styled designation CK CO-2!
