Koolhoven F.K. Aircraft DesignationsKoolhoven F.K.1  1911
Heidevogel (
Heatherbird)
 F.K.1: Improved Farmantype biplane, aka '
Holland'
 Controversial designation, possibly not assigned
ArmstrongWhitworth F.K.1  1914
Sissit biplane* scout
 F.K.1: Small singleseat, singlebay scout, x 1
 F.K.1: 1 x 50 hp Gnome rotary tractor,** span (??) m
 Controversial designation, possibly desig. A.W.1
 * F.K.1 originally conceived of as monoplane scout
 ** F.K.1 originally designed to have 80hp engine
 F.K.1 mod. w/ fixed tailplane and enlarged ailerons

https://78.media.tumblr.com/b57627470911ca175bf9e7a82f4d9c11/tumblr_inline_nicqbltcPK1t90ue7.jpg  F.K.1 named
Sissit but aka '
Queen Anne'***
 *** Suggesting that the design was overweight?
British Deperdussin F.K.2  1912 2seat trainer
 F.K.2: 'Anglicised' Deperdussin TT monoplanes
 F.K.2: 1 x 60 hp or 100 hp engine,* span 10.50 m
 * Both Anzani radials and Gnome rotaries fitted
 Controversial designation, possibly not assigned
British Deperdussin F.K.2  1912 singleseat trainer
 F.K.2: 'Anglicised' Deperdussin Type A monoplane
 F.K.2: 1 x 35 hp Anzani Y3 engine, span 8.50 m*
 Ground trainer** aka 'School Type' or 'TaxiType'
 * Span for standard Deperdussin A was 8.76 m
 ** Albeit capable of short hops/delivery flights

https://www.awm.gov.au/collection/C159106  Controversial desig., from 1926 Koolhoven list
ArmstrongWhitworth F.K.2  1915 2seat recce biplane
 F.K.2: Tandemseat, 2bay biplane, x 2 (7 ordered)*
 F.K.2: (Orig.) 1 x 70 hp Renault, span 12.22 m
 F.K.2: (Mod.) 1 x 90 hp Renault aircooled V8
 * Contract No.94/A/103 (53285334) became F.K.3s
 Controversial desig. but no record of an 'A.W.2'
British Deperdussin F.K.3  1912 2seat scout/trainer
 F.K.3: 'Anglicised' Deperdussin Monocoque monoplane
 F.K.3: 1 x 70 hp Gnome rotary engine, span 10.50 m
 aka "70 hp Gnome" by Frits Koolhoven himself
ArmstrongWhitworth F.K.3  1915 2seat recce biplane
 F.K.3: Tandemseat, 2bay biplane, improved F.K.2*
 F.K.3: 1 x 90 hp RAF 1a V8 engine, span 12.22 m
 B.E.2c repl. but inferior, most used as trainers
 * Modernized structure, aka '
Little Ack', x 343
 aka "100 hp RAF twoseater scout" by Koolhoven
 3v:
http://flyingmachines.ru/Images7/Putnam/AW/561.jpgBritish Deperdussin F.K.4  [Project] 1911 scout/trainer
 F.K.4: 'Anglicised' Deperdussin Monocoque monoplane
 F.K.4: 1 x 100 hp Gnome rotary engine, span 10.50 m
 Controv. desig., aka "100 hp Gnome Déperdussin 1911"
ArmstrongWhitworth F.K.4  1915 2seat airship gondola
 F.K.4: 1 x 100 hp Green inline 4cyl, span n/a, x ~20
 F.K.3 fuselage reused as SS.4049 airship gondola*

http://members.ziggo.nl/henrikaper/koolhoven/armstrongwhitworth/images/armstrongwhitworthfk4.jpg  * SS.27 airship also used an F.K.3based gondola**
 ** It's unclear whether these were designated F.K.4
British Deperdussin F.K.5  1912 2seat scout/trainer
 F.K.5: 'Anglicised' Deperdussin Monocoque monoplane
 F.K.5: 1 x 100 hp Gnome rotary engine, span 10.50 m
 Controv. desig., aka "100 hp Gnome Déperdussin 1912"
ArmstrongWhitworth F.K.5  1915 3seat escort fighter
 F.K.5: Singleengined unequal triplane heavy fighter
 F.K.5: 1 x 250 hp RR
Eagle V12, span (??) m, x 1
 Twin gun nacelles mounted on widerspan middle wing

https://www.secretprojects.co.uk/forum/index.php/topic,7951.msg232709.html#msg232709British Deperdussin F.K.6  1912 2seat floatplane
 F.K.6: Tractor monoplane floatplane for Admiralty
 F.K.6: 1 x 100 hp Anzani 10cyl. radial, span 14.00 m
 '
Seagull', orig. simply 'Hydro Monoplane'
 NB: Attrib. to Lt. JC Porte, RN
with Koolhoven
 Controversial desig. from Koolhoven's 1926 list
ArmstrongWhitworth F.K.6  1915 3seat escort fighter
 F.K.6: Singleengined unequal triplane heavy fighter
 F.K.6: 1 x 250 hp RR
Eagle V12, span 18.89 m, x 1*
 Gun nacelles mounted further outboard on middle wing
 * No.7838, 7841 and 36843685 (for RNAS) cancelled
 3v:
http://flyingmachines.ru/Images7/Fighters/252.jpg  3v:
http://flyingmachines.ru/Images7/Putnam/AW/721.jpgArmstrongWhitworth F.K.7  1916 2seat recce biplane
 F.K.7: 1 x 160 hp Beardmore inline, span 13.26 m, x 1
 F.K.7: Intended replacement for the F.K.3 and B.E.2c
 F.K.7 production plans transferred to improved F.K.8*
 * A411 built, order for A729 to A777 was cancelled
ArmstrongWhitworth F.K.8  1916 2seat recce biplane
 F.K.8: Prod'n vers. of F.K.7 scout/light bomber*
 F.K.8: 1 x 160 hp Beardmore inline, span 13.26 m
 * Rebrande to match Royal Aircraft Factory R.E.8?
 aka '
Big Ack' (vs F.K.3 '
Little Ack), x 1,650
ArmstrongWhitworth F.K.9: [Project] 1916 2seater
 F.K.9: aka "180 hp Lorraine twoseater, 1916"*
 * According to retroactive 1926 Koolhoven list
 Unclear whether related to Clerget F.K.9 design
ArmstrongWhitworth F.K.9  1916 quadruplane fighter
 F.K.9: 2seat fighter, private venture to Spec.No.2c
 F.K.9: 1 x 110 hp Clerget rotary, span 8.46 m, x 1
 F.K.9: [Project] "180 hp Lorraine twoseater, 1916"
 Central Flying School trials dictated modifications*
 * New wings, cowling, an increased u/c track, etc.
 Further revised F.K.9 ordered into prod. as F.K.10
ArmstrongWhitworth F.K.10  1916 quadruplane fighter
 F.K.10: Improved development of F.K.9 airframe
 F.K.10: 1 x 130 hp Clerget rotary, span 8.61 m
 8 built,* prod. order issued but later cancelled
 * Including 2 by Phoenix Dynamo Manufacturing Co.
 * Inprod. Sopwith
1 1/2 Strutter found superior

https://www.secretprojects.co.uk/forum/index.php/topic,25577.msg277796.html#msg277796ArmstrongWhitworth F.K.11  [Project] 1916 multiplane
 F.K.11: Fifteenwing design, planned engine unknown*
 F.K.11 was to employ the fuselage from the F.K.10
 * Probably the 130 hp Clerget 9B as per F.K.10

https://www.secretprojects.co.uk/forum/index.php/topic,25577.msg277795.html#msg277795 
http://members.ziggo.nl/henrikaper/koolhoven/armstrongwhitworth/images/armstrongwhitworth15wings.jpgArmstrongWhitworth F.K.12  1917 (no firm details)
 F.K.12: Poss. FK.8 w/ mod cooling, u/c, exhausts
 Koolhoven confused F.K.12 w/ F.K.6 in 1926 list
ArmstrongWhitworth F.K.13  1917 biplane reccefighter
 F.K.13: Higherpowered F.K.8 derivative, x 1 (N513)*
 F.K.13: 1 x 200 hp Sunbeam
Maori, span (??) m
 aka Fleet Fighter Reconnaissance Biplane, not accepted
 * Note: this serial falls between final 3 x F.K.10s

http://members.ziggo.nl/henrikaper/koolhoven/armstrongwhitworth/images/armstrongwhitworthfk13.jpgArmstrongWhitworth F.K.14  [Project] unbuilt fighter
 F.K.14: No details, identified by Koolhoven as A.W.

https://www.flightglobal.com/FlightPDFArchive/1953/1953%20%200618.PDFArmstrongWhitworth F.K.15  [Project] airship gondola
 F.K.15: Gondola design for 1912
Beta II airship
ArmstrongWhitworth F.K.16  [Project] airship gondola
 F.K.16: Gondola design for 1912 North Sea airship*
 * F.K.16 gondola based on the fuselage of F.K.3
ArmstrongWhitworth F.K.17  [Project] airship gondola
 F.K.16: Gondola design for 1912 North Sea airship*
 * F.K.16 gondola based on the fuselage of F.K.3**
 ** Koolhoven himself may have had no involvement
ArmstrongWhitworth F.K.18  [Project] flying boat
 F.K.18: "2engine flying boat" according to FK*
 * But also called F.K.22 precursor by Koolhoven
 JM Bruce repeated fighter claim in
Flight letter

https://www.flightglobal.com/FlightPDFArchive/1953/1953%20%200618.PDFArmstrongWhitworth F.K.19  [Project] unbuild aircraft
 F.K.19: No details, identified by Frits Koolhoven*
 * Or ArmstrongWhitworth light aircooled engine**
 ** If so, unlikely to have Koolhoven involvement
BAT F.K.20  [Project] 1917 shipboard biplane fighter
 F.K.20: Singleseat, singleengined naval biplane
 Claimed derived from A.W. F.K.18 fighter concept
 Archeiven.nl lists "FK20, BAT
jager ... shipplane"
 F.K.20 seems to lead to both F.K.21 and F.K.22

http://www.britishaviationptp.com/b/bat.html 
https://www.flightglobal.com/FlightPDFArchive/1953/1953%20%200618.PDF 
http://members.ziggo.nl/henrikaper/koolhoven/britishaerialtransport/images/britishaerialtransportfk20.jpgBAT F.K.21  1917 2bay biplane fighter trainer
 F.K.21: Singleseat* trainer (no other details)
 * Archeiven.nl lists "FK21, BAT
éénpersoonsjager"
 * 'BAT singleseat fighter', fuselage as F.K.20

http://www.britishaviationptp.com/b/bat.html 
https://www.flightglobal.com/FlightPDFArchive/1953/1953%20%200618.PDF 
http://members.ziggo.nl/henrikaper/koolhoven/britishaerialtransport/images/britishaerialtransportfk21.jpgBAT F.K.22  1918 singleseat biplane fighter, x 3
 F.K.22: Unstaggered 2bays, monocoque fuselage
 F.K.22: (As planned) 1 x 120 hp ABC
Mosquito  F.K.22: 1st/3rd prototype, 170 hp ABC
Wasp I radial
 F.K.22: 2nd prototype, Gnome
Monosoupape rotary*
 * 2nd airframe later fitted w/ 110 hp Le Rhone 9J
 aka BAT
Bantam II (see F.K.23
Bantam I)**
 ** JM Bruce lists F.K.22
Bat or
GnômeBat 
https://www.flightglobal.com/pdfarchive/view/1952/1952%20%203424.html 
http://www.airwar.ru/image/idop/fww1/fk23/fk235.jpgBAT F.K.23  1918 singleseat biplane fighter, x 3
 F.K.23: 1 x 170 hp ABC
Wasp I radial, span 7.62 m
 F.K.23 was a refined development of the F.K.22

http://www.airwar.ru/image/idop/fww1/fk23/fk236.jpg  aka BAT
Bantam I (BAT
Bantam II was F.K.22, above)
 F.K.23A: Dutch NVI version,* 1 x 200 hp ABC Wasp II
 * Based on a surplus F.K.23 airframe bought from BAT
 F.K.23(??): F.K.23 refitted w/ AS
Lynx IV in Neth.**
 ** Another of the 12 F.K.23 airframe bought from BAT

http://www.airwar.ru/image/idop/fww1/fk23/fk234.jpg  3v:
https://www.flightglobal.com/pdfarchive/view/1919/1919%20%200663.html 
https://www.secretprojects.co.uk/forum/index.php/topic,13780.msg135102.html#msg135102BAT F.K.24  1919 tandem 2seat biplane trainer, x 1*
 F.K.24: 2bay biplane, widetrack u/c, simple construction
 F.K.24: 1 x 170 hp ABC
Wasp I radial, span 8.10 m
 * 6 planned, only one built, orders cancelled Nov 1918
 aka BAT
Baboon, interchangable wing panels, elevators
BAT F.K.25  1918 singleseat biplane fighter, x 3
 F.K.25: 1 x 320 hp ABC
Dragonfly radial, span 7.72 m
 Prototype crashed killed test pilot Lt. Peter Legh*
 * Legh followed Koolhoven from ArmstrongWhitworth
 Devel. terminated due to unreliability of
Dragonfly  aka BAT
Basilisk  3v:
www.airwar.ru/image/idop/fww1/fk25/fk251.gifBAT F.K.26  1919 singleengine biplane 4pax airliner
 F.K.26: 1 x 350 hp RR
Eagle VIII V12, span 14.03 m
 F.K.26: 4 pax in fwd cabin, 1 x pilot in rear cockpit
 aka
Commercial Mk.I, 4 x built before BAT closed

http://members.ziggo.nl/henrikaper/koolhoven/worldsfirstairliner/  3v:
https://www.flightglobal.com/pdfarchive/view/1919/1919%20%200495.htmlBAT F.K.27  1918 2seat* biplane sporting a/c, x 1
 F.K.27: 1 x 200 hp ABC
Wasp II radial, span 7.90 m
 * Staggered sidebyside seating, aerobatic/racer

https://upload.wikimedia.org/wikipedia/commons/thumb/6/6a/BAT_F.K.27_010120_p19.jpg/450pxBAT_F.K.27_010120_p19.jpgBAT F.K.28  1920 highwing singleseat ultralight
 F.K.28: 1 x 40 hp ABC
Gnat HO2, span 4.57 m
 aka BAT
Crow, twinbooms w/ underslung pod

https://i.ebayimg.com/images/g/TYgAAOSw9NdXsoNO/sl300.jpgNVI F.K.29  1923 light passenger* biplane, x 1
 F.K.29: 1 x 100 hp Bristol
Lucifer, span 10.00 m
 * 1 + 2, F.K.29 was a refined BAT F.K.26 design

http://allaero.com/images/stories/koolfk29.jpgKoolhoven* F.K.30  1927 highwing 2seat light a/c
 F.K.30: Tandemseat podandboom pusher (pedestal)
 F.K.30: 1 x 50 hp Siemens radial, span 10.50 m
 aka
Toerist, sometimes also as
Weekend  * Design for NVI, built by Luchttuigenfabriek Koolhoven

http://www.airwar.ru/image/i/law1/fk30i.jpg  3v:
http://aviadejavu.ru/Images6/FT/FT1927/02/681.jpg  F.K.30F: [Project] Light flying boat derivative**
 ** The meaning of the 'F' suffix is unclear
NVI F.K.31  1923 2seat parasol reccefighter, x 17
 F.K.31: 1 x 420 hp Bristol
Jupiter IV, span 13.70 m
 F.K.31: LVA,* 1 x 400 hp Bristol
Jupiter radial
 * Perform. too low, 4 passed to LA/KNIL in NEI
 LA/KNIL a/c had modified horizontal tailplanes
 De Monge M.101 C2 : French licensebuilt, x 1**
 ** 20 x M.101 A2 ordered for Poland, cancelled
 1 x 420 hp GnomeRhône 9Ac (licensed
Jupiter)
 F.K.31: 8 x Finland, 450 hp Bristol
Jupiter IV

http://members.ziggo.nl/henrikaper/koolhoven/story/images/fk31.jpg  3v:
https://www.modelbrouwers.nl/albums/coppermine/albums/userpics/14089/FK_31_3.jpgNVI F.K.32  1925 tandem 2seat biplane trainer
 F.K.32: 1 x 130 hp Clerget 9B,* span 7.10 m, x 1
 * Offered with Bristol
Lucifer in place of rotary
 aka Koolhoven F.K.32, no F.K.32 orders placed

http://resolver.kb.nl/resolve?urn=urn:gvn:SFA03:SFA022811881&size=largeNVI F.K.33  1925 3engined highwing 10pax airliner
 F.K.33: 3 x 230 hp AS
Puma,* span 17.80 m, x 1
 * 2 x tractor engines, 1 x pusher above wing
 F.K.33: 1 x prototype operated by KLM 192526
 3v:
http://airwar.ru/image/idop/cw1/fk33/fk331.gifNVI F.K.34  1925 parasol 3seat reccefighter seaplane
 F.K.34: Private venture twinfloat naval recce a/c
 F.K.34: 1 x 520 hp HispanoSuiza 12G, span 13.00 m
 Series of accidents involving floats, no MLD order

https://images.memorix.nl/nda/thumb/620x620/9a071cf18f5127c55338d2e71de68fd3.jpg  3v:
http://www.airwar.ru/image/idop/other1/fk34/fk341.gifKoolhoven F.K.35  1926 2seat variable config. a/c
 F.K.35: Assembled as monoplane/biplane/floatplane*
 * Sole unflown F.K.35 built as lowwing monoplane
 F.K.35: 1 x 600 hp Bristol
Pegasus VI, span 10.50 m
 aka (erroneously) as the NVI F.K.35, never flown
 Archeiven.nl lists
tweepersoons jager/verkenner 
https://www.flightglobal.com/pdfarchive/view/1926/1926%20%200881.html 
http://members.ziggo.nl/henrikaper/koolhoven/koolhovenvliegtuigen/images/koolhovenfk35.jpgKoolhoven F.K.36  [Project] 1926 enlarged F.K.35
 F.K.36: Assembled as monoplane/biplane/floatplane*
 * As per F.K.35 but with slightly larger airframe
 * Twinfloat seaplane F.K.36 display model built
 Other sources say F.K.36 as float vers. F.K.35**
 ** According to Wesselink/Postma, 1981, pg.59
Koolhoven F.K.37  [Project] 1927 trimotor airliner
 F.K.37: Highwing monoplane similar to NVI F.K.33
 F.K.37: 3engined* pax aircraft intended for KLM
 * Arranged as per F.K.33 but all tractor radials
Koolhoven F.K.38  [Project] 1927 fighter study
 F.K.38: Singleengined, related to F.K.39 (below)
 F.K.38: No other details
Koolhoven F.K.39  1927 2seat fighter studies
 F.K.39: [Project] Various design studies*
 Display model shows parasol with radial**
 * Prob.
Pegasus but may be
Jaguar  ** See Wesselink/Postma, 1981, pg.52

http://members.ziggo.nl/henrikaper/koolhoven/koolhovenvliegtuigen/images/koolhovenfk39.jpgKoolhoven F.K.40  1928 highwing light transport
 F.K.40: 1 x 230 hp GR
Titan,* span 14.50 m
 PHAES, sole F.K.40, served Republican Spain
 * Offered with alt. 300 hp P&W
Wasp Junior 
https://www.flightglobal.com/FlightPDFArchive/1930/UNTITLED0%20%200211.PDF  3v:
http://aviadejavu.ru/Images6/FT/FT1930/02/2112.jpg  F.K.402m: [Project] 2 x wingmounted engines*
 Inline inverted 4cyl., prob. DH [/i]Gipsy Major[/i]s
 aka
Ontwerp 1094
Koolhoven F.K.41  1928 3/4seat cabin monoplane, x 6
 F.K.41: Highwing strutbraced, fixed main u/c
 F.K.41: 1 x radial or aircooled 4cyl, span 10.50 m
 F.K.41 prototype: 1 x 75 hp Siemens Sh.13A radial
 c/n 4101, reg, HNAER/PHAER, aka
Sportcoupé 
http://www.maritiemdigitaal.nl/index.cfm?event=popup.viewimage&img=imh%2FAfbeeldingen%5C030003.jpg 
http://aviadejavu.ru/Images6/FT/FT1929/07/357.jpg  F.K.41a : (Hypothetical desig., no evidence)
 F.K.41b: 1 x 120 hp DH Gipsy III, eg c/n 4105 PHAGQ

http://www.maritiemdigitaal.nl/index.cfm?event=popup.viewimage&img=imh%2FAfbeeldingen%5C030002.jpg  F.K.41c : (??) 1 x online mention,* 105 hp
 * 1932 League of Nations Air Commission document, pg.220

http://digital.library.northwestern.edu/league/le00069f.pdf  F.K.41d : (Hypotetical desig., no evidence)
 F.K.41e : Orig. desig. for the F.K.42, c/n 4201
 F.K.41/I : Koolhoven desig. for Dessoutter Mk.I
 aka F.K.41 Mk.I, 1 x 105 hp
Cirrus Hermes  F.K.41/II: Koolhoven desig. for Dessoutter Mk.II
 Same as F.K.41 Mk.II, 1 x 130 hp DH Gipsy
Koolhoven F.K.42  1929 2seat training monoplane
 F.K.41e: c/n 4104, orig. desig/serial of F.K.42
 F.K.41e/'42 was new fuselage with F.K.41 wings
 F.K.42 : Tandem seat parasol trainer, x 1 PHAGO
 F.K.42: 1 x 110 hp
CirrusHermes,* span 10.50 m
 * Some sources list 230 hp GnomeRhône
Titan**
 ** Presumably in a confusion with the F.K.40
Koolhoven F.K.43  1931 highwing cabin monoplane
 BFK.43: Baxterbuilt 1st prototype, PHAF
 F.K.43: 1 + 3 pax light cabin air taxi,* x 12
 F.K.43: 1 x 130 hp DH
Gipsy Major, span 11.00 m
 * 9 x KLM use, usually listed as x 6 [1]
 'Fokhoven': Postwar prod'n by Fokker, x 8
 'Fokhoven': 1 x 165 hp AS
Genet Major IA** 7cyl
 Ordered by Frits Diepen Vliegtuigen NV
 ** As per Fokker S.IX trainer, aka AS
Civet I
 3v:
https://modelbrouwers.nl/media/cache/f3/cf/f3cf4eb1ca83f835e30ca361e03442a0.jpgKoolhoven F.K.44  1931 sports monoplane, x 2*
 F.K.44: 115 hp
CirrusHermes IIB, span 11.00 m
 F.K.44: Highwinged lightplane, PHAJM
 Special order a/c,* aka '
Koolmees' (
Tomtit)
 * c/n 4401 never completed, order cancelled
 * c/n 4402 for Jacob Mees (hence '
Koolmees') [2]

http://1000aircraftphotos.com/Contributions/Shumaker/11772L.jpgKoolhoven F.K.45  1932 singleseat sports biplane*
 F.K.45: Singlebay biplane, c/n 4501, FAMXT**
 F.K.45: 1 x 115 hp
CirrusHermes IIB, span 7.00 m
 * Commis. by French testpilot, René Paulhan
 ** Temporary registration Z1(PH), then PHAIF
Koolhoven F.K.46  1933 2seat tandem biplane trainer
 F.K.46: 1 x 130 hp DH
Gipsy Major, span 8.00 m, x 12
 F.K.46
Cabriolet: Fitted with removable canopy
 F.K.46L: Lightweight version, 1 x prototype only*
 F.K.46L: 1 x 95 hp Walter
Minor 4cyl, span 8.00 m
 * PHALA c/n 4609, destroyed Schiphol 10 May 1940
 F.K.46S: 'School' vers., aka '
De Koe' (
The Cow)

http://www.airwar.ru/image/idop/other1/fk46/fk464.jpgKoolhoven F.K.47  1933 2seat tandem sports biplane
 F.K.47: 1 x 130 hp DH
Gipsy Major, span 8.00 m
 Improved F.K.46, 1 x prototype only (PHEJR)*
 * Crashed at Bonn, July 1933, later repaired
Koolhoven F.K.48  1934 highwing 6passenger feederliner
 F.K.48: Mixed constr. (wood wing, steeltube fuselage)
 F.K.48: 2 x 130 hp DH
Gipsy Majors, span 15.20 m, x 1
 KLM RotterdamEindhoven route, air taxi, crew trainer
 PHAJX '
Ajax' KLM RotterdamEindhoven route 'til 1936
 Thereafter, flew short routes, & as air taxi/trainer
 3v:
http://aviadejavu.ru/Images6/FT/FT1935/01/1462.jpgKoolhoven F.K.49  1935 highwing twinengine photo a/c*
 F.K.49: 2 x 130 hp DH
Gipsy Majors, span 16.00 m, x 1
 '
Foto verkenner' (photorecce) intended for LVA**
 ** '950' only, other 2 x LVA a/c, never completed
 Onboard darkroom, opt'l 2stretcher medevac or 4 pax
 3v:
http://aviadejavu.ru/Images6/FT/FT1935/11/6112.jpg  F.K.49A: 3 variants with wider/longer nose, 5 pax
 Turkish Air Force, 2 x 305 hp Ranger V770B4
 Finland (
Merivartiolaitos),* 2 x 285 hp Hirth 508C
 * Finnish Coast Guard, ordered two float/wheel gear
 Finnish F.K.49A flown as LVA 1001 before delivery
 F.K.49R: Romania vers., 2 x 240 hp Argus As 10 C3
 2 incomplete F.K.49R destr'd Waalhaven, 10 May 1940
Koolhoven F.K.50  1935 highwing 8passenger feederliner
 F.K.50: 2 x 400 hp P&W
Wasp Junior T1Bs, span 18.00 m
 F.K.50: Mixed constr. (wood wing, steeltube fuselage)
 F.K.50 : 1st & 2nd a/c, 2 + 8, single fin & rudder
 c/n 5001/HBAMI, c/n 5002/HBAMO, 355 hp
Wasp Junior  3v:
http://aviadejavu.ru/Images6/FT/FT1935/10/4001.jpg  F.K.50A: 3rd a/c, twin fins/rudders, smaller cowlings
 F.K.50B: [Project] Turret military variant, not built
 F.K.50B: Lgr. radials, retr. u/c, nose/dorsal turrets
 F.K.50B intended for Spain, too late for civil war

https://www.secretprojects.co.uk/forum/index.php/topic,2742.msg21938.html#msg21938  3v:
http://aviadejavu.ru/Images6/FT/FT1936/08/23291.jpgKoolhoven F.K.51  1935 2seat advanced training biplane
 F.K.51: 1 x 350450 hp radial engine, span 9.00 m
 F.K.51: LVA trainer, 1 x 350 hp AS
Cheetah IX radial
 25 x LVA 2seat advanced trainer version (E1 to E25)*
 29 x LVA
verkennerversie (recce vers., 400 to 428)
 15 x MLD, E1 to E15, 19361937 (+ 2 x repl. a/c 1938
 45 x LA/KNIL (of 60 ordered) K1 to K45/K101 to K145
 * Some sources give 44 x total MvD delivers as of 10 May
 Pg 251
https://pure.uva.nl/ws/files/1764152/128309_12.pdf  F.K.51: Spanish vers., 1 x 400 hp AS
Jaguar 14cyl
 F.K.51bis: 1 x 450 hp Wright
Whirlwind R975E3
 Total F.K.51/F.K.51bis exports to Rep. Spain x 28
Koolhoven F.K.52  1937 2seat reccefighter* biplane
 F.K.52: Canopy, fixed main u/c, Fokker C.V repl't*
 * Offered as tweepersoonseenmotorig gevechtsvliegtuig
 * Or a generic '2seat, singleengined combat aircraft'
 F.K.52: 1 x 830 hp Bristol
Mercury VIII, span 9.80m
 F.K.52 prototype: 1 x 645 hp Bristol
Mercury VIS
 PHAMZ) crashed during 1937 LVA Soesterber demo.**
 ** Lower wing snapped off, design strengthened
 F.K.52: PHASW, 'ASX, 'ASY, 'ASZ, ' PHATA unsold
 1939: Spanish Republic offered to buy all 5 a/c
 End 1939: LVA places orders for 36 x F.K.52s***
 ***To replace C.X (which would then repl. C.Vs)
 Post May 1940: German occupiers scrap 2 x F.K.52s
 1940: Count von Rosen donates 2 x F.K.52 to Finns
 PHASW and PH ASX to
Ilmavaimot as KO129 & '130
 In Finnish service, FK.52 dubbed '
Kolhoveneiksi'
 3v:
https://modelbrouwers.nl/media/albums/642/8402/fk52_wesko1_6.jpgKoolhoven F.K.53  1936 2seat lt. cabin monoplane
 F.K.53: Low gull wings, sidebysideseating
 F.K.53: 1 x 62 hp* Walter
Mikron, span 10.50 m
 * Contemporary sources list power at 50 hp
 aka
Junior, designed by
ir. J. van Hattum
 F.K.53: 1936 c/n 5301, reg PHALH/PHALN/PHFKJ
 F.K.53: 1938 c/n 5302 registration PHATG

http://www.maritiemdigitaal.nl/index.cfm?event=popup.viewimage&img=imh%2FAfbeeldingen%5C030067.jpgKoolhoven F.K.54  1938 3seat cabin monoplane, x 1
 F.K.54: Highwing, rearwardretracting main u/c
 F.K.54: 1 x 130 hp DH
Gipsy Major II, span 11.00 m
 PHAPR commissioned by C.E. van 't Groenewoud

http://members.ziggo.nl/henrikaper/koolhoven/koolhovenvliegtuigen/images/koolhovenfk54.jpgKoolhoven F.K.55  1938 singleseat fighter a/c, x 1
 F.K.55: 1 x 720 hp Lorraine
Pétrel, span 9.60 m
 F.K.55: Shoulderwing, midengined, mixed constr.*
 F.K.55: Extension shaft from engine to contraprops
 * Steeltube fwd fuselage, wood aft, wooden wings
 F.K.55: 1936 mockup, Paris
Salon de l'Aéronautique  F.K.55: 1938 prototype w/ temporary fixed main u/c
 F.K.55: [Project] Prod. vers, Lorraine
Sterna V12
 F.K.55: [Project] Lowwinged derivative of F.K.55**
 ** Such a variant is reported, can anyone confirm?

https://www.secretprojects.co.uk/forum/index.php/topic,7244.msg63477.html#msg63477 
https://oldmachinepress.com/2016/07/20/koolhovenfk55fighter/Koolhoven F.K.56  1938 advanced combat trainer,* x 11
 F.K.56: 1 x 350400 hp radial engine, span 11.50 m
 * Or
overgangsvliegtuigen (transitional trainer)
 F.K.56: 1st prototype, 1 x 400 hp Wright R975E3
 F.K.56: 1st prototype, c/n 5601, civil reg. PHASB
 Gull wing, mod. F.K.51 fuselage, J. Weyer design
 F.K.56: 1939 2nd prototype, 1 x 350 hp AS Cheetah
 F.K.56: 2nd prototype, c/n 5602, civil reg. PHATE
 Straight wing, retr. u/c, E. Schatzki redesign
 PHATE destroyed by German bombing 10 May 1940
 F.K.56: 1939 preprod'n vers., for LVA, c/n 5603
 5603 w/o in crash, leading to stiffening of wings
 F.K.56: Prod'n, 420 hp Wright
Whirlwind R975E3
 F.K.56: Export vers. for Yugoslavia and Belgium
 c/n 5613 for Yugo. + 2 near completion, May 1940
 Belgian order for x 20 received 12 February 1940

http://www.belgianwings.be/images/Milpics/Interbellum/interbellum_a_m/Koolhovenfk5803.jpg  F.K.56 LVB: [Project] Improved F.K.56 for L.V.B**
 F.K.56 LVB: 1940, used F.K.58 tail, canopy, etc.
 Curtisstype main u/c, 2 x wing 7,9s, 1 x flex.
 ** LVB =
LuchtVaartBedrijf (Aviation Co)

https://modelbrouwers.nl/phpBB3/viewtopic.php?f=214&t=40639#p797535  Prob. last 4 F.K.56 orders transf. to F.K.56 LVB

https://db.wingstovictory.nl/documentatie/17FK56%20opmerkingen%20Harry%20van%20der%20Meer.pdfKoolhoven F.K.57  1938 twinengined feederliner, x 1
 F.K.57: Twintail, lowwing, spatted main u/c, 1+3
 F.K.57: 2 x 205 hp DH
Gipsy Six II, span 13.20 m
 c/n 4301 PHKOK commis. by JEF de Kok (hence reg.)
 Sole F.K.57 was destroyed at Ypenburg, 10 May 1940
 F.K.57: [Project] Military vers. with retract. u/c*
 * Offered to the LVA as multiengine pilot trainer

http://1000aircraftphotos.com/Contributions/KleinBernhard/6033L1.jpgKoolhoven F.K.58  1938 singleengined fighter*
 F.K.58: Singleseater, lowwing, retr. u/c
 F.K.58 aka Koolhoven
Ontwerp 1166
 F.K.58: 1 x 1,080 hp radial, span 10.97 m
 F.K.58 : 1 x HispanoSuiza 14Aa10, x 7
 F.K.58 : 1st prototype c/n 5801 PHATO
 W/O after 12 Jan 1939 accident, Ghent, BE
 F.K.58A: 1 x GnomeRhône 14N16,** x 14
 * Ordered by French
Ministère des Colonies  ** 10 x subcontracted to SABCA in Belgium
 F.K.58B: [Project] LVA, Bristol
Taurus III
 F.K.58B: 36 ordered 22 July 1939, none delivered [3]

Taurus export ban,
Mercury proposed [4]

Ontwerp (??): F.K.58 with German DB 600 IV12

Ontwerp (??): More powerful radial [5]
Koolhoven F.K.59  Designation reused at least 3 times
(NB: Projects below may not be listed chronologically)
 F.K.59 (1) [Project] Open 2seat sports plane*
 * "
Sportsplane" mentioned by Wesselink, 2012
 F.K.59 (2): [Project] Twinengine floatplane
 Midwinged, twinfloat MLD torpedobomber
 1937 design, fullscale mockup completed

https://www.secretprojects.co.uk/forum/index.php/topic,2742.msg140146.html#msg140146 
https://www.secretprojects.co.uk/forum/index.php/topic,2742.msg21897.html#msg21897  F.K.59 (3): [Project] Modernized vers. F.K.52
 F.K.59 (3): LVA 2seat reccefighter biplane
 F.K.59 (3): 1 x 840 hp
Mercury XV, span 9.80m
 36 x F.K.59 ordered for LVA on 21 November 1939**
 **
Mercury XVs deliv'd but constr. not begun
Koolhoven F.K.60  [Project] (??) no details
 F.K.60: (??) Reported as a Koolhoven project
 F.K.60: "mentioned shortly befory May 1940"

http://www.nederlandseluchtvaart.nl/forums/showthread.php?40337KoolhovenFK702  WhatIf: KoolhovenDesoutter FK60 (
dizzyfugu)
 WhatIf: Herculespowered F.K.58, (
Hood,WesWorld)
___________________________________________
[1] Full KLM F.K.43 fleet names were:
Bromvlieg,
Citroenvlinder,
Dar,
Juffertje,
Krekel,
Libel,
Luis,
Nonvlinder, and
Olietor. During WW2, four KLM F.K.43s were impressed for the LVA as 960, 963, 965 and 966.
[2] A wellknown sports flyer of the day, Rotterdam banker Jacob Mees directed a number of new investors to NV Koolhoven Vliegtuigen.
[3] Many sources claim a Dutch order for 40 x F.K.58Bs. If true, the 'extra' 4 x fighters were not covered by the MvD's 22 July 1939 order.
[4] Proposed alternative
Mercury VIII engines would have come from ML stocks. Option presented to Minister of Defence AHQ Dijxhoorn who rejected the
Mercurypowered F.K.58B in favour of more powerful US fighters. Dijxhoorn ordered 24 x CurtissWright CW21Bs in April 1940.
[5] The DB 600 and "more powerful radial" engines for F.K.58 developments is mentioned in
Blue Skies, Orange Wings by Noppen, pg 200. So too is the suggestion of alternative
Mercury VIII engines for F.K.58Bs but this is confirmed in
https://pure.uva.nl/ws/files/1764152/128309_12.pdf________________________
Known Frits Koolhoven Ontwerpen Numbers (and gaps)BAT (Design No.?)  [Project] Flying boat
 BAT flying boat design concept (no details)*
 * But see ArmstrongWhitworth F.K.18 discussion
Koolhoven
Ontwerp 1029  [Project] ~192? pusher fighter
 Midwing, twinboomed pusher fighter designed for export*

Ontwerp 1029: 1 x (??) hp radial,** span (??) m
 *
Ontwerp 1029 was offered to Sweden and Norway
 ** Singlerow engine, presumably a Bristol
JupiterKoolhoven
Ontwerp 1030 
Ontwerp 1088 (??)
Koolhoven
Ontwerp 1087  [Project] 193? 2seat biplane

Ontwerp 1087: Biplane trainer leads to F.K.46

https://www.secretprojects.co.uk/forum/index.php/topic,2742.30.htmlKoolhoven
Ontwerp 1088 
Ontwerp 1093 (??)
Koolhoven
Ontwerp 1094  [Project] 193? light cabin transport

Ontwerp 1094: aka F.K.402m, twinengined* F.K.40 deriv.
 * Wingmounted engines, appear to be DH
GispyMajors
Koolhoven
Ontwerp 1095 
Ontwerp 1098 (??)
Koolhoven
Ontwerp 1099  [Project] 193? twinengined bomber

Ontwerp 1099: 2 x inline engines, lowwing, twintails*
 Nose turret, dorsal gun position, ventral 'dustbin' position
 * Small, nearcircular and larger, ellipical fins proposed
Koolhoven
Ontwerp (??)  [Project] 1935 flying boat for MLD

Ontwerp (??): Pylonmounted wing, 3engined, '
stummeln'*
 * Dornier
Walstyle
stummeln sponsons specified by MLD
 Artist concept marked '189', nose & dorsal turret armament
Koolhoven
Ontwerp 1101  [Project] 193? singleseat biplane

Ontwerp 1101: Biplane fighter with retractable main u/c
 1 x (??) hp Lorraine 12H
Pétrel, radiator as per
Ontwerp 1117
Koolhoven
Ontwerp 1102 
Ontwerp 1104 (??)
Koolhoven
Ontwerp 1105  [Project] 1936 3seat reccefighter

Ontwerp 1105: 1 x radial or inline engine,* span (??) m
 720 hp Wright
Cyclone F52 or (??) hp V12 (
Kestrel?)
 Lowwing scout/light bomber (
verkenner/licht bommenwerper)

Ontwerp 1105 poss. rival to 1936 Fokker '
Gesloten verkenner'

http://www.maritiemdigitaal.nl/index.cfm?event=popup.viewimage&img=imh%2FAfbeeldingen%5C067818.jpg 
https://www.secretprojects.co.uk/forum/index.php/topic,2742.msg172430.html#msg172430Koolhoven
Ontwerp 1106 
Ontwerp 1112 (??)
Koolhoven
Ontwerp 1113  [Project] 193? lt. cabin a/c

Ontwerp 1113: Leads to 1936 F.K.53 2seat monoplane
Koolhoven
Ontwerp 1114 
Ontwerp 1116 (??)
Koolhoven
Ontwerp 1117  [Project] ~1936 2seat fighter/recce a/c

Ontwerp 1117: 1 x (??) hp RR
Kestrel V12,* span (??) m
 Strutbraced parasol wing, encl. cockpit, cantilever u/c
 * Air intake for coolant radiator situated above engine
 * Engine type may be Lorraine 12H
PétrelKoolhoven
Ontwerp 1118 
Ontwerp 1123 (??)
Koolhoven
Ontwerp 1124  [Project] 193? airliner

Ontwerp 1124: Twinengined sesquiplane
Koolhoven
Ontwerp 1125  [Project] 193? light feederliner

Ontwerp 1125: 2 x (??) hp aircooled inlines, span (??) m
 Semicantilever highwing, fixed main u/c, single tailplane
 Perhaps an early take on the F.K.49 retaining F.K.48 features
Koolhoven
Ontwerp 1125 
Ontwerp 1141 (??)
Koolhoven
Ontwerp 1142  [Project] 193? twinengine bomber

Ontwerp 1142A: Midwing fixed main u/c,* medium bomber

Ontwerp 1142A: 2 x (??) hp radial engines, span (??) m

Ontwerp 1142B: Twinfloat medium bomber/torpedo bomber

Ontwerp 1142B was offered to Norway (as M.F.11 repl.?)
 * Arrangement suggests connection with F.K.50 series

https://www.secretprojects.co.uk/forum/index.php/topic,2742.msg172412.html#msg172412Koolhoven
Ontwerp 1143 
Ontwerp 1150 (??)
Koolhoven
Ontwerp 1151  [Project] ~1937 civilian flying boat

Ontwerp 1151: 2 x 290 hp Menasco C6S4s,* span 16.00m

Ontwerp 1151: Small amphibian flying boat, 2 crew + 4 pax
 * C6S4
Super Buccaneer, 290 hp (for T/O), sust. 260 hp
 Mixed const. (wooden wings,** alum. fuselage), '
Stummeln'
 ** Folding wings seem to have been an option
Koolhoven
Ontwerp 1152 
Ontwerp 1153 (??)
Koolhoven
Ontwerp 1154  [Project] 1937 fighterbomber

Ontwerp 1154: Monoplane (
gevechtsvliegtuig?)
Koolhoven
Ontwerp 1155 
Ontwerp 1163 (??)
Koolhoven
Ontwerp (??)  [Project] 1938
Oceaanvliegboot 
Ontwerp (??): 100 ton, 180 pax, allmetal flying Boat

Ontwerp (??): twin props, grouped engines,* span 70.00 m
 Research begun 1936, design 1938, rejected by KLM's A. Plesman
 * From 2 x pairs tandem inlines up to 10 x 'raw oil' engines
Koolhoven
Ontwerp (??)  [Project] 1938 civilian flying boat

Ontwerp (??)  2 x (??) hp radial engines, span (??) m
 Engines on pylonmounted wings, '
stummeln' sponsons
Koolhoven
Ontwerp (??)  [Project] 1938 2seat reccefighter

Ontwerp (??): Midwing monoplane, cruciform tail, bomb bay

ir. Van der Eyk design, "modernised F.K.52"*
 * Monoplane concept actually more of an F.K.52 repl't
 * "modernised F.K.52" may be conf'n with F.K.59 biplane
Koolhoven
Ontwerp 1164  [Project] 19381939
jachtkruiser 
Ontwerp 1164: 2 x (??) hp engines, span (??) m

Ontwerp 1164: 4seat
jachtkruiser based upon F.K.50B
Koolhoven
Ontwerp 1165  [Project] (??)
Koolhoven
Ontwerp 1166  [Project] singleengined fighter

Ontwerp 1166: 1 x 1,000 hp radial engine, span ?? m

Ontwerp 1166: Singleseat French colonial fighter a/c

Ontwerp 1166 built as F.K.58, 1st flew 17 July 1938
Koolhoven
Ontwerp 1167  [Project] 19381939
jachtkruiser 
Ontwerp 1164: 2 x (??) hp engines, span (??) m

Ontwerp 1164: 4seat
jachtkruiser based upon F.K.50B
Koolhoven
Ontwerp 1168 
Ontwerp 1170 (??)
Koolhoven
Ontwerp 1171  1938 3seat twinfloat recce seaplane*

Ontwerp 1171: 1 x (??) hp radial engine,** span (??) m
 Lowwing monoplane, broad semicantilevered float struts
 * To same 1938 MLD contest as the equallyunbuilt Fokker T.10W
 * Based on exhaust outlet, engine is prob. Wright
CycloneKoolhoven
Ontwerp 1172  1939 twinengine transport monoplane

https://www.secretprojects.co.uk/forum/index.php/topic,2742.msg301245.html#msg301245Koolhoven
Ontwerp 11(??) ...