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In the late 1950s, Otto Funk was the director of apprentice-training at the Heinkel plant in Speyer. As an exercise for apprentices, airframes were designed for assembly using a variety of construction techniques.
In 1990, Otto's son Peter Funk (along with Dirk Breitkreuz) founded B&F Technik to mass-produce the FK9 design. The B&F (Bücker und Funk) name also covers reproductions of earlier Bücker Flugzeugbau designs (retaining their old RLM type numbers) - eg: the BF 131B Jungmann and BF 133 Jungmeister. [1] However, here we will focus on the Funk "FK' series of designations.
A note on Funk/B&F 'FK' Designation Style
It is common to see these designations rendered as FKx, FK-x, Fkx, and FKx. Since the latter is what is most often painted onto airframes by the manufacturer, I have standardised upon the unhyphenated and unspaced FKx style. The 'FK' series runs sequentially with two exceptions. There is no apparent 'FK13' (although it is not at all uncommon to avoid the number 13). And the reason for an out-of-sequence FK51 designation for the reduced-scale replica P-51D Mustang sportsplane will, I trust, be obvious.
'FK' Designations & Corporate Identity
Since Otto Funk was an employee of the Heinkel works at Speyer, his earliest designs are often referred to as Heinkel aircraft. [2] As noted above, the B&F Technik Vertriebs GmbH corporate entity was created in 1990 by Peter Funk with business partner Dirk Breitkreuz. In 2010, the corporate trading name was changed to FK-Lightplanes - which had two components. FK-Lightplanes Sp. z o.o. Sp.K. of Krosno in SE Poland (aka 'FK-Lightplanes Poland') handed basic component construction. In turn, B&F Technik became FK-Lightplanes Germany - as the designer and final assembler of 'FK' aircraft as well as provider of sales and support services.
Poland-based FK-Lightplanes Sp. z o. o. Sp.K. eventually became the separately run Fusion Aeronautics sp. z o. o which intends to produce its own designs as well. Then, it seems, that FK-Lightplanes in general was swallowed up by Wuhan Wenfa Aerospace Technology Development Co., Ltd. - operating as the Wenfa Aerospace Group based in the Hubei province of the PRC. (I found if difficult to confirm firm information about this take-off and would be grateful for any details other members can provide.)
___________________________________________
[1] The high-winged B&F BF 139 Clubman Classic may be inspired by Carl Bücker's historical Bü 134 cabin aircraft but the B&F offering is actually based on the airframe of Otto and Peter Funk's FK9.
[2] A comparison might be made with the T.K. series of aircraft created at the de Havilland Aeronautical Technical School prior to WW2. Such designs were associated with de Havilland but, as apprentice projects, they never received designations in the 'DH' sequence.
___________________________________________
Otto Funk, Peter Funk, Bücker & Funk 'FK' Designations
FK1 - 1959 Greif 1 single-seat performance sailplane; x 2
- FK1a: Pod-and-boom fuselage; trapazoidal wings; 'V'-tail
- FK1a: Built at Heinkel, Speyer;* bonded-metal constr.**
-- * Funk was a student at Speyer; aka Heinkel Greif 1
-- ** Laminated aluminum used only on low-load structures
-- ** Wings had a mix of aluminum & polystyrene foam ribs
- FK1b: Dec 1960 deriv. w/ autonomous T/O turbojet-power
- FK1b: 1 x 101 lbf BMW 8026 diesel turbojet; span 15.00 m
-- BMW jet in pod; angled downward at 30° to aid take-off
FK2 - 1962 Greif 2 single-seat performance sailplane; x 1
- FK2 : Pod-and-boom + 100° 'V'-tail; glass fibre construction
- FK2 : Effectively a 'plastic' vers. of the FK1; built at Heinkel*
-- * Built as test piece for apprentices at Heinkel; reg. D-7014
FK3 - 1968 single-seat performance sailplane; 13 x FK3 built*
- FK3 : Similar layout to FK1 & FK2 except a conventional tail
- FK3 : Mainly metal structure (GRP nose + foam wing filling)
-- * 2 x Fk3 prototypes; 11 x prod'n by VFW-Fokker, Speyer
- FK3 : Won 1968 Italian Championship; span 17.40 m
-- 1970 RFB Sirius 1 integrated fan a/c based on FK3
-- Sirius 1 proofed the concept for RFB's Fantrainer
FK4 - 1971 autonomous T/O sailplane w/ folding engine; x 1
- FK4: Prototype (D-KEUL) built as Akaflieg Karlsruhe AK 1*
-- * Students of Akademische Fliegergruppe Karlsruhe e.V.
- AK 1: 1 x 28 hp Hirth F10A HO4 pusher; span 15.00 m
FK5 - (Project) 1979 FK3 adapted to 15 metre racing class
- FK5 : Short-span devel. of FK3; constr. begun at Speyer*
-- Constr. abandoned at 80% complete; reasons unknown
FK6 - 1985 single-seat high-winged ultralight a/c; x 3 (?)
- FK6 : Pod-and-boom fuselage; pusher prop; 100° 'V'-tail
- FK6 : Glass fibre construction; reg. as a 'motor glider'
FK7 - (Project) 1985 FK6 deriv. meant for apprentice build
- FK7 : (??) no other details
FK8 - (Project) 1985 FK6 deriv. meant for apprentice build
- FK8 : (??) no other details
FK9 - 1989 high-winged, fixed u/c cabin light a/c; x 500+
- FK9 : Cabin ultralight based upon wing concept of FK6
- FK9 : 1 x 80-100 hp Rotax 912/912S HO4; span 9.81 m
- FK9 : Fabric-covered steel-tube fuselage; carbon wings
- FK9 : Design by Otto & son Peter Funk; ~40 x FK9 built
- FK9 Mark II: 1995 revised prod'n model w/ higher cruise
- FK9B : US Mk II vers.; imported by Fk-Lightplanes USA
- FK9B : US shorter-winged variant had a span of 9.11 m
- FK9 Mk III: 1996 redesigned composite constr. version
-- NB: Both Mk II & Mk III were produced simultaneously
- FK9 Mk III: Carbon fibre wings; optional folding mech.
- FK Mk III Utility: 2000 'professional duty' development
- FK Mk III Utility: Revised wing design; higher payload
- FK9 Mark IV : 2003 revised model; larger cabin & tail
- FK9 Mark IV : Repl. Mk III; can be used as glider tug
- FK9 ELA : 2009; to 'European Light Aircraft' standards
- FK9 ELA : Revised Mark IV to meet EASA ELA category
-- Alpha Bravo FK9 Mk III: 2001 FK9 for Brazilian market
-- Alpha Bravo FK9 Mk III: Initial 10 x Brazilian imports
-- Alpha Bravo FK9 Mk III: Later a/c assembled in Brazil
-- Alpha Bravo FK9 Mk IV: 2006 Brazil-assembled Mk IV
-- Alpha Bravo FK9 Mk IV: Also offered w/ diesel engine
FK10 - 1994 tandem 2-seat derivative of 1985 FK6; x 1
- FK10 : Layout identical to FK6 pod-and-boom pusher
- FK10 : 1 x 53 hp Göbler-Hirth 2704 2-cyl.; span (??) m
- FK10 : Glass fibre construction; registration D-MTDD
-- Built by trainees in MBB Speyer apprentice workshop
FK11 - 1997 2-seat lightplane; twin props on outriggers; x 1
- FK11 : Tandem-seat, low-wing; spatted 'taildragger' u/c
- FK11 : 1 x 55 hp Mercedes Benz 3-cyl.;* span 8.80 m
- FK11 : Mixed construction; steel-tube around mid engine
-- * Liquid-cooled 599 cc Suprex from Mk I Smart Car
-- * Angled struts w/ toothed belt-drives to 2 x propellers
FK12 - 1997 Comet tandem 2-seat; biplane ultralight
- FK12 Comet: Equal-span sports a/c; mixed constr.*
- FK12 Comet: 1 x 80-to-130 hp HO4;** span 6.74 m
-- * Fuselage tubular structure (steel fwd; aluminum aft)
-- * Coverings of carbon fibre and glass-fibre laminates
-- ** Rotax opt'l 80 hp 912 UL; 100 hp 912 iS or 912 UL-S
-- ** 115 hp Lycoming YO-233; 130 hp UL Power UL350iS
- FK12 Special Limited Edition: 2011 improved Comet
-- Improvement mods to wings; tail surfaces; u/c; etc.
FK13 - (??) hypothetical designation (perhap avoided?)
FK14 Polaris - 1999 low-wing, light sport a/c; x ~90
- FK14 : Side-by-side 2-seater; fixed & spatted u/c*
-- * In most cases, a tricycle; optional 'taildragger'
- FK14 : Initial prod.; glass fibre structure (incl. wings)
-- aka FK-Lightplanes FK14; aka (generic) Funk Fk14
- FK14B : 2003; revised structure; carbon fibre wings
- FK14B : 1 x Rotax 912 UL series HO4; span 9.04 m
- FK14B2 Polaris: Spoilers & slotted flaps (for STOL)
- FK14B2 LeMans: Open cockpit; 'roadster' windscreens
- FK14B2 LeMans: Also redesigned rudder and wingtips
- Cirrus SRS: (Project) 2007-2009 planned US prod'n variant
-- Cirrus Design Co. to meet LSA rules; only test bed flew
FK15 - (Project) Dedicated ab initio trainer deriv. of FK14
- FK15 : Easier handling, less expensive FK14 derivative
- FK15 : 1 x Rotax 912 UL series HO4 (?); span 9.04 m (?)
- FK15 : Cheaper to produce airframe with better handling
-- https://www.secretprojects.co.uk/threads/b-f-technik-aircraft-and-projects.36325/#post-433014
FK16 - (Project) 2010 hybrid propulsion a/c (w/ ISB-Mainz)
- FK16 : Combination electric (for T/O) and turbojet drive
-- 2 x belt-driven outrigger propellers (folded in jet flight)
-- 1 x (unspecified) turbojet flight engine between T-tails
- FK16 : Layout not unlike that of experimental 1997 FK11
-- https://www.secretprojects.co.uk/threads/b-f-technik-aircraft-and-projects.36325/#post-433014
FK51 - Mustang; 2014 ScaleWings' 70% scale P-51D replica
- FK51 : Austrian-designed; built by FK-Lightplanes Poland
- FK51 : 1 x 100-to-115 hp Rotax HO4 engine;* span 7.90 m
- FK51 : Tandem 2-seater; primarily carbon fibre structure
-- * 100 hp Rotax 912S or 912iS or turbocharged 115 hp 914
-- SW51: Later prod'n; taken over by Austrian ScaleWings
-- https://www.scalewings.com/sw-51-mustang/
In 1990, Otto's son Peter Funk (along with Dirk Breitkreuz) founded B&F Technik to mass-produce the FK9 design. The B&F (Bücker und Funk) name also covers reproductions of earlier Bücker Flugzeugbau designs (retaining their old RLM type numbers) - eg: the BF 131B Jungmann and BF 133 Jungmeister. [1] However, here we will focus on the Funk "FK' series of designations.
A note on Funk/B&F 'FK' Designation Style
It is common to see these designations rendered as FKx, FK-x, Fkx, and FKx. Since the latter is what is most often painted onto airframes by the manufacturer, I have standardised upon the unhyphenated and unspaced FKx style. The 'FK' series runs sequentially with two exceptions. There is no apparent 'FK13' (although it is not at all uncommon to avoid the number 13). And the reason for an out-of-sequence FK51 designation for the reduced-scale replica P-51D Mustang sportsplane will, I trust, be obvious.
'FK' Designations & Corporate Identity
Since Otto Funk was an employee of the Heinkel works at Speyer, his earliest designs are often referred to as Heinkel aircraft. [2] As noted above, the B&F Technik Vertriebs GmbH corporate entity was created in 1990 by Peter Funk with business partner Dirk Breitkreuz. In 2010, the corporate trading name was changed to FK-Lightplanes - which had two components. FK-Lightplanes Sp. z o.o. Sp.K. of Krosno in SE Poland (aka 'FK-Lightplanes Poland') handed basic component construction. In turn, B&F Technik became FK-Lightplanes Germany - as the designer and final assembler of 'FK' aircraft as well as provider of sales and support services.
Poland-based FK-Lightplanes Sp. z o. o. Sp.K. eventually became the separately run Fusion Aeronautics sp. z o. o which intends to produce its own designs as well. Then, it seems, that FK-Lightplanes in general was swallowed up by Wuhan Wenfa Aerospace Technology Development Co., Ltd. - operating as the Wenfa Aerospace Group based in the Hubei province of the PRC. (I found if difficult to confirm firm information about this take-off and would be grateful for any details other members can provide.)
___________________________________________
[1] The high-winged B&F BF 139 Clubman Classic may be inspired by Carl Bücker's historical Bü 134 cabin aircraft but the B&F offering is actually based on the airframe of Otto and Peter Funk's FK9.
[2] A comparison might be made with the T.K. series of aircraft created at the de Havilland Aeronautical Technical School prior to WW2. Such designs were associated with de Havilland but, as apprentice projects, they never received designations in the 'DH' sequence.
___________________________________________
Otto Funk, Peter Funk, Bücker & Funk 'FK' Designations
FK1 - 1959 Greif 1 single-seat performance sailplane; x 2
- FK1a: Pod-and-boom fuselage; trapazoidal wings; 'V'-tail
- FK1a: Built at Heinkel, Speyer;* bonded-metal constr.**
-- * Funk was a student at Speyer; aka Heinkel Greif 1
-- ** Laminated aluminum used only on low-load structures
-- ** Wings had a mix of aluminum & polystyrene foam ribs
- FK1b: Dec 1960 deriv. w/ autonomous T/O turbojet-power
- FK1b: 1 x 101 lbf BMW 8026 diesel turbojet; span 15.00 m
-- BMW jet in pod; angled downward at 30° to aid take-off
FK2 - 1962 Greif 2 single-seat performance sailplane; x 1
- FK2 : Pod-and-boom + 100° 'V'-tail; glass fibre construction
- FK2 : Effectively a 'plastic' vers. of the FK1; built at Heinkel*
-- * Built as test piece for apprentices at Heinkel; reg. D-7014
FK3 - 1968 single-seat performance sailplane; 13 x FK3 built*
- FK3 : Similar layout to FK1 & FK2 except a conventional tail
- FK3 : Mainly metal structure (GRP nose + foam wing filling)
-- * 2 x Fk3 prototypes; 11 x prod'n by VFW-Fokker, Speyer
- FK3 : Won 1968 Italian Championship; span 17.40 m
-- 1970 RFB Sirius 1 integrated fan a/c based on FK3
-- Sirius 1 proofed the concept for RFB's Fantrainer
FK4 - 1971 autonomous T/O sailplane w/ folding engine; x 1
- FK4: Prototype (D-KEUL) built as Akaflieg Karlsruhe AK 1*
-- * Students of Akademische Fliegergruppe Karlsruhe e.V.
- AK 1: 1 x 28 hp Hirth F10A HO4 pusher; span 15.00 m
FK5 - (Project) 1979 FK3 adapted to 15 metre racing class
- FK5 : Short-span devel. of FK3; constr. begun at Speyer*
-- Constr. abandoned at 80% complete; reasons unknown
FK6 - 1985 single-seat high-winged ultralight a/c; x 3 (?)
- FK6 : Pod-and-boom fuselage; pusher prop; 100° 'V'-tail
- FK6 : Glass fibre construction; reg. as a 'motor glider'
FK7 - (Project) 1985 FK6 deriv. meant for apprentice build
- FK7 : (??) no other details
FK8 - (Project) 1985 FK6 deriv. meant for apprentice build
- FK8 : (??) no other details
FK9 - 1989 high-winged, fixed u/c cabin light a/c; x 500+
- FK9 : Cabin ultralight based upon wing concept of FK6
- FK9 : 1 x 80-100 hp Rotax 912/912S HO4; span 9.81 m
- FK9 : Fabric-covered steel-tube fuselage; carbon wings
- FK9 : Design by Otto & son Peter Funk; ~40 x FK9 built
- FK9 Mark II: 1995 revised prod'n model w/ higher cruise
- FK9B : US Mk II vers.; imported by Fk-Lightplanes USA
- FK9B : US shorter-winged variant had a span of 9.11 m
- FK9 Mk III: 1996 redesigned composite constr. version
-- NB: Both Mk II & Mk III were produced simultaneously
- FK9 Mk III: Carbon fibre wings; optional folding mech.
- FK Mk III Utility: 2000 'professional duty' development
- FK Mk III Utility: Revised wing design; higher payload
- FK9 Mark IV : 2003 revised model; larger cabin & tail
- FK9 Mark IV : Repl. Mk III; can be used as glider tug
- FK9 ELA : 2009; to 'European Light Aircraft' standards
- FK9 ELA : Revised Mark IV to meet EASA ELA category
-- Alpha Bravo FK9 Mk III: 2001 FK9 for Brazilian market
-- Alpha Bravo FK9 Mk III: Initial 10 x Brazilian imports
-- Alpha Bravo FK9 Mk III: Later a/c assembled in Brazil
-- Alpha Bravo FK9 Mk IV: 2006 Brazil-assembled Mk IV
-- Alpha Bravo FK9 Mk IV: Also offered w/ diesel engine
FK10 - 1994 tandem 2-seat derivative of 1985 FK6; x 1
- FK10 : Layout identical to FK6 pod-and-boom pusher
- FK10 : 1 x 53 hp Göbler-Hirth 2704 2-cyl.; span (??) m
- FK10 : Glass fibre construction; registration D-MTDD
-- Built by trainees in MBB Speyer apprentice workshop
FK11 - 1997 2-seat lightplane; twin props on outriggers; x 1
- FK11 : Tandem-seat, low-wing; spatted 'taildragger' u/c
- FK11 : 1 x 55 hp Mercedes Benz 3-cyl.;* span 8.80 m
- FK11 : Mixed construction; steel-tube around mid engine
-- * Liquid-cooled 599 cc Suprex from Mk I Smart Car
-- * Angled struts w/ toothed belt-drives to 2 x propellers
FK12 - 1997 Comet tandem 2-seat; biplane ultralight
- FK12 Comet: Equal-span sports a/c; mixed constr.*
- FK12 Comet: 1 x 80-to-130 hp HO4;** span 6.74 m
-- * Fuselage tubular structure (steel fwd; aluminum aft)
-- * Coverings of carbon fibre and glass-fibre laminates
-- ** Rotax opt'l 80 hp 912 UL; 100 hp 912 iS or 912 UL-S
-- ** 115 hp Lycoming YO-233; 130 hp UL Power UL350iS
- FK12 Special Limited Edition: 2011 improved Comet
-- Improvement mods to wings; tail surfaces; u/c; etc.
FK13 - (??) hypothetical designation (perhap avoided?)
FK14 Polaris - 1999 low-wing, light sport a/c; x ~90
- FK14 : Side-by-side 2-seater; fixed & spatted u/c*
-- * In most cases, a tricycle; optional 'taildragger'
- FK14 : Initial prod.; glass fibre structure (incl. wings)
-- aka FK-Lightplanes FK14; aka (generic) Funk Fk14
- FK14B : 2003; revised structure; carbon fibre wings
- FK14B : 1 x Rotax 912 UL series HO4; span 9.04 m
- FK14B2 Polaris: Spoilers & slotted flaps (for STOL)
- FK14B2 LeMans: Open cockpit; 'roadster' windscreens
- FK14B2 LeMans: Also redesigned rudder and wingtips
- Cirrus SRS: (Project) 2007-2009 planned US prod'n variant
-- Cirrus Design Co. to meet LSA rules; only test bed flew
FK15 - (Project) Dedicated ab initio trainer deriv. of FK14
- FK15 : Easier handling, less expensive FK14 derivative
- FK15 : 1 x Rotax 912 UL series HO4 (?); span 9.04 m (?)
- FK15 : Cheaper to produce airframe with better handling
-- https://www.secretprojects.co.uk/threads/b-f-technik-aircraft-and-projects.36325/#post-433014
FK16 - (Project) 2010 hybrid propulsion a/c (w/ ISB-Mainz)
- FK16 : Combination electric (for T/O) and turbojet drive
-- 2 x belt-driven outrigger propellers (folded in jet flight)
-- 1 x (unspecified) turbojet flight engine between T-tails
- FK16 : Layout not unlike that of experimental 1997 FK11
-- https://www.secretprojects.co.uk/threads/b-f-technik-aircraft-and-projects.36325/#post-433014
FK51 - Mustang; 2014 ScaleWings' 70% scale P-51D replica
- FK51 : Austrian-designed; built by FK-Lightplanes Poland
- FK51 : 1 x 100-to-115 hp Rotax HO4 engine;* span 7.90 m
- FK51 : Tandem 2-seater; primarily carbon fibre structure
-- * 100 hp Rotax 912S or 912iS or turbocharged 115 hp 914
-- SW51: Later prod'n; taken over by Austrian ScaleWings
-- https://www.scalewings.com/sw-51-mustang/
