Koolhoven
Encyclopedia
N.V. Koolhoven was an aircraft manufacturer based in Rotterdam
in the Netherlands
. From its conception in 1926 to is destruction in the Blitzkrieg
in May 1940, the company remained the Netherlands' second major aircraft manufacturer (after Fokker
). Although many of its aircraft were as unsuccessful economically as they were brilliant from a design standpoint, the company managed to score several 'hits', amongst them the FK-58 single-seat monoplane fighter, the FK-50 twin-engine passenger transport and the FK-41
, built in England under licence by Desoutter.
returned from England to his native Netherlands. The postwar years had not been good to him: The British Aerial Transport Company
for which he was chief designer went bankrupt and all other manufacturers were struggling for survival themselves too hard to think of hiring. The Netherlands, Koolhoven hoped would be better. Yet, even there he found that while the Netherlands new airline KLM was a willing taker for all planes it could get, the market was almost completely owned by Fokker
. Out of other options Koolhoven returned to his old job and worked as an automobile engineer for the Spyker
automobile factory.
In 1921, his luck began to change when a group of businessmen founded the N.V. Nationale Vliegtuig Industrie
(National Aircraft Industry, inc.), and hired him as their chief designer. Still the time was not yet ripe for a second Dutch aircraft manufacturer and, just like with BAT, N.V.I. continued to spew out technically advanced designs that attracted attention from all over the world... but virtually no orders. The company lasted only four years.
At the demise of N.V.I. Koolhoven had become sufficiently business-savvy to convince several of the N.V.I. shareholders that the company would still be viable, if only he would have complete control of the operations. Apparently enough of the shareholders agreed and even while N.V.I. was being dissolved, its assets were almost immediately taken over by a new company: N.V. Koolhoven vliegtuigen (Koolhoven aircraft, inc.).
for its first five years, 1925 to 1930, the company managed to stay afloat by making one-off purpose-built airplanes on command, slowly branching out into the private plane sector and over and over again trying to break into the military market. In 1930, the company finally struck gold with the FK-41
high-wing tourist monoplane. Although N.V. Koolhoven itself only built7 Fk-41's the airplane was built in license in England as the Desoutter Mk.I
and later improved as the Mk.II . Still, of the typical Koolhoven plane only one or two were built.
By 1933 however the military market picked up and Koolhoven increasingly built trainers and observation aircraft for the Dutch air force as well as for various other countries. By 1938, with a new war looming, its order books continued to fill as air forces from all over Europe were virtually fighting over each plane that rolled off the production line. Even France found itself buying Koolhoven FK-58 fighters as its own aircraft industry was unable to keep up with the demand from the Armée de l'Air
In 1938, the Koolhoven factory at Waalhaven covered 8000 square meters and boasted 1200 employees. While still no match for Fokker, Koolhoven had established itself firmly as the number 2 manufacturer in the Netherlands.
The end came on May 10 1940. In the first hours of the Blitzkrieg
, as a prelude to the invasion of the Netherlands, the Luftwaffe
set out to destroy as much as possible of the Dutch air force on the ground. On the morning of that day, a massive armada of German bombers appeared over Waalhaven
and almost completely destroyed the airfield with all it surrounding facilities. This also included the Koolhoven factory and within just a few hours, Koolhoven's company had been reduced to a pile of rubble. More important, with the factory also disappeared all drawings, models, documents of Koolhoven's projects. Even today, the only photographs remaining of Koolhoven's planes are newspaper clippings and private snapshots.
Frederick Koolhoven died of a stroke, July 1, 1946. His company, although without means of production, continued to exist as a holding. Over the next 10 years various attempts were made to start up new projects, but apart of the construction of two prototype sailplanes nothing happened and in 1956 N.V. Koolhoven Aeroplanes was finally closed and liquidated.
and BAT
, projects FK-29 to FK-34 for N.V.I.
and projects FK-35 to FK-59 for his own company. The first 'true' Koolhoven airplane therefore would have been the FK-35. However on formation of the N.V. Koolhoven, Frits Koolhoven took with him the design of the FK-30
"Toerist" light sportsplane original designed for NVI, but not built. Several "Toerists" built by the new FK Koolhoven therefore constitute the earliest airplanes of that company, if not by production date, then at least by numbering.
The of the Koolhoven foundation lists 26 Koolhoven designs, starting with the F.K.30
and then going from F.K.35 to F.K.59. It however also notes that the designs F.K.37, 38, 39 and 59 were never built, while only giving pictures of wooden models for the designs F.K.35 and F.K.36. Jane's Encyclopedia of Aviation only lists the Koolhoven designs F.K.40
, 41
, 42, 43
, 46
, 48
, 49
, 51, 52, 53
and 58
but mentions a F.K.50-b bomber project, which the Koolhoven foundation site doesn't.
The best-known amongst those designs are the F.K.41 high-wing monoplane, which was built in license as the Desoutter Mk.II
and the F.K.50 twin engine transport monoplane, two of which were used by the Swiss aircraft company alpar
. Amongst the military designs, the most successful were the Koolhoven F.K.51 biplane
reconnaissance aircraft, which saw service in extensive numbers in the Dutch air force from the mid-Thirties until the Second World War, the Koolhoven F.K.52 biplane which was used by the Finnish Air Force
and the Koolhoven F.K.58
single-seat monoplane fighter. The latter was the plane ordered by France
and flew in the Armée de l'Air during the Battle of France
A complete list of the Koolhoven aircraft and projects is given below:
, a Koolhoven design. Its site also has the most complete list of all Koolhoven designs.
Rotterdam
Rotterdam is the second-largest city in the Netherlands and one of the largest ports in the world. Starting as a dam on the Rotte river, Rotterdam has grown into a major international commercial centre...
in the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
. From its conception in 1926 to is destruction in the Blitzkrieg
Blitzkrieg
For other uses of the word, see: Blitzkrieg Blitzkrieg is an anglicized word describing all-motorised force concentration of tanks, infantry, artillery, combat engineers and air power, concentrating overwhelming force at high speed to break through enemy lines, and, once the lines are broken,...
in May 1940, the company remained the Netherlands' second major aircraft manufacturer (after Fokker
Fokker
Fokker was a Dutch aircraft manufacturer named after its founder, Anthony Fokker. The company operated under several different names, starting out in 1912 in Schwerin, Germany, moving to the Netherlands in 1919....
). Although many of its aircraft were as unsuccessful economically as they were brilliant from a design standpoint, the company managed to score several 'hits', amongst them the FK-58 single-seat monoplane fighter, the FK-50 twin-engine passenger transport and the FK-41
Desoutter Mk.II
-Bibliography:* Kalevi Keskinen, Kari Stenman: Koulukoneet - Suomen ilmavoimien historia 22, Itä-Uudenmaan paino, Loviisa, 2003, ISBN 951-98751-5-8* Tervonen, Ismo: Veljekset Karhumäki Suomen ilmailun pioneereina 1924-1956, Apali Oy, ISBN 952-5026-25-6....
, built in England under licence by Desoutter.
History
In 1920, aircraft designer Frederick 'Frits' KoolhovenFrederick Koolhoven
Frederick Koolhoven was an aircraft designer in Britain and his native Netherlands.Koolhoven was born in Bloemendaal, Netherlands. After training as an engineer in Liège and Antwerp, he worked from 1907 as a mechanical engineer for Minerva in Antwerp, and also drove in races and rallies for them....
returned from England to his native Netherlands. The postwar years had not been good to him: The British Aerial Transport Company
British Aerial Transport
British Aerial Transport Company Limited was a British aircraft manufacturer from its formation in 1917 to its closure in 1919. The company was based at Willesden, London.-History:...
for which he was chief designer went bankrupt and all other manufacturers were struggling for survival themselves too hard to think of hiring. The Netherlands, Koolhoven hoped would be better. Yet, even there he found that while the Netherlands new airline KLM was a willing taker for all planes it could get, the market was almost completely owned by Fokker
Fokker
Fokker was a Dutch aircraft manufacturer named after its founder, Anthony Fokker. The company operated under several different names, starting out in 1912 in Schwerin, Germany, moving to the Netherlands in 1919....
. Out of other options Koolhoven returned to his old job and worked as an automobile engineer for the Spyker
Spyker
Spyker was a Dutch car manufacturer, started in 1880 by coachbuilders Jacobus and Hendrik-Jan Spijker, but to be able to market the brand better in foreign countries, in 1903 the 'ij' was changed into 'y'...
automobile factory.
In 1921, his luck began to change when a group of businessmen founded the N.V. Nationale Vliegtuig Industrie
NVI
NVI or nvi may refer to:* Nvi, a text editor* Avial NV, an airline * no value indicator, a non-denominated postage stamp* Navoiy Airport, in Uzbekistan * Negative volume index, a financial analysis method...
(National Aircraft Industry, inc.), and hired him as their chief designer. Still the time was not yet ripe for a second Dutch aircraft manufacturer and, just like with BAT, N.V.I. continued to spew out technically advanced designs that attracted attention from all over the world... but virtually no orders. The company lasted only four years.
At the demise of N.V.I. Koolhoven had become sufficiently business-savvy to convince several of the N.V.I. shareholders that the company would still be viable, if only he would have complete control of the operations. Apparently enough of the shareholders agreed and even while N.V.I. was being dissolved, its assets were almost immediately taken over by a new company: N.V. Koolhoven vliegtuigen (Koolhoven aircraft, inc.).
for its first five years, 1925 to 1930, the company managed to stay afloat by making one-off purpose-built airplanes on command, slowly branching out into the private plane sector and over and over again trying to break into the military market. In 1930, the company finally struck gold with the FK-41
Desoutter Mk.II
-Bibliography:* Kalevi Keskinen, Kari Stenman: Koulukoneet - Suomen ilmavoimien historia 22, Itä-Uudenmaan paino, Loviisa, 2003, ISBN 951-98751-5-8* Tervonen, Ismo: Veljekset Karhumäki Suomen ilmailun pioneereina 1924-1956, Apali Oy, ISBN 952-5026-25-6....
high-wing tourist monoplane. Although N.V. Koolhoven itself only built7 Fk-41's the airplane was built in license in England as the Desoutter Mk.I
Desoutter Mk.II
-Bibliography:* Kalevi Keskinen, Kari Stenman: Koulukoneet - Suomen ilmavoimien historia 22, Itä-Uudenmaan paino, Loviisa, 2003, ISBN 951-98751-5-8* Tervonen, Ismo: Veljekset Karhumäki Suomen ilmailun pioneereina 1924-1956, Apali Oy, ISBN 952-5026-25-6....
and later improved as the Mk.II . Still, of the typical Koolhoven plane only one or two were built.
By 1933 however the military market picked up and Koolhoven increasingly built trainers and observation aircraft for the Dutch air force as well as for various other countries. By 1938, with a new war looming, its order books continued to fill as air forces from all over Europe were virtually fighting over each plane that rolled off the production line. Even France found itself buying Koolhoven FK-58 fighters as its own aircraft industry was unable to keep up with the demand from the Armée de l'Air
In 1938, the Koolhoven factory at Waalhaven covered 8000 square meters and boasted 1200 employees. While still no match for Fokker, Koolhoven had established itself firmly as the number 2 manufacturer in the Netherlands.
The end came on May 10 1940. In the first hours of the Blitzkrieg
Blitzkrieg
For other uses of the word, see: Blitzkrieg Blitzkrieg is an anglicized word describing all-motorised force concentration of tanks, infantry, artillery, combat engineers and air power, concentrating overwhelming force at high speed to break through enemy lines, and, once the lines are broken,...
, as a prelude to the invasion of the Netherlands, the Luftwaffe
Luftwaffe
Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....
set out to destroy as much as possible of the Dutch air force on the ground. On the morning of that day, a massive armada of German bombers appeared over Waalhaven
Waalhaven
thumb|right|250px|Waalhaven Airport in 1932, with the [[LZ 127 Graf Zeppelin|Graf Zeppelin]] in the background.The Waalhaven is one of various harbours in the Port of Rotterdam in the Netherlands and used to be home to an airport, Vliegveld Waalhaven . It was the first civilian airport in the...
and almost completely destroyed the airfield with all it surrounding facilities. This also included the Koolhoven factory and within just a few hours, Koolhoven's company had been reduced to a pile of rubble. More important, with the factory also disappeared all drawings, models, documents of Koolhoven's projects. Even today, the only photographs remaining of Koolhoven's planes are newspaper clippings and private snapshots.
Frederick Koolhoven died of a stroke, July 1, 1946. His company, although without means of production, continued to exist as a holding. Over the next 10 years various attempts were made to start up new projects, but apart of the construction of two prototype sailplanes nothing happened and in 1956 N.V. Koolhoven Aeroplanes was finally closed and liquidated.
Aircraft
Apart from the Heidevogel of 1911, Koolhoven designed 59 aircraft, which he consecutively numbered FK-1 to FK-59. About half of this were design studies that were never built. Koolhoven designed projects FK-1 to FK-28 in England for Armstrong WhitworthArmstrong Whitworth
Sir W G Armstrong Whitworth & Co Ltd was a major British manufacturing company of the early years of the 20th century. Headquartered in Elswick, Newcastle upon Tyne, Armstrong Whitworth engaged in the construction of armaments, ships, locomotives, automobiles, and aircraft.-History:In 1847,...
and BAT
Bat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
, projects FK-29 to FK-34 for N.V.I.
NVI
NVI or nvi may refer to:* Nvi, a text editor* Avial NV, an airline * no value indicator, a non-denominated postage stamp* Navoiy Airport, in Uzbekistan * Negative volume index, a financial analysis method...
and projects FK-35 to FK-59 for his own company. The first 'true' Koolhoven airplane therefore would have been the FK-35. However on formation of the N.V. Koolhoven, Frits Koolhoven took with him the design of the FK-30
Koolhoven F.K.30
|-References:* *...
"Toerist" light sportsplane original designed for NVI, but not built. Several "Toerists" built by the new FK Koolhoven therefore constitute the earliest airplanes of that company, if not by production date, then at least by numbering.
The of the Koolhoven foundation lists 26 Koolhoven designs, starting with the F.K.30
Koolhoven F.K.30
|-References:* *...
and then going from F.K.35 to F.K.59. It however also notes that the designs F.K.37, 38, 39 and 59 were never built, while only giving pictures of wooden models for the designs F.K.35 and F.K.36. Jane's Encyclopedia of Aviation only lists the Koolhoven designs F.K.40
Koolhoven F.K.40
|-References:* *...
, 41
Desoutter Mk.II
-Bibliography:* Kalevi Keskinen, Kari Stenman: Koulukoneet - Suomen ilmavoimien historia 22, Itä-Uudenmaan paino, Loviisa, 2003, ISBN 951-98751-5-8* Tervonen, Ismo: Veljekset Karhumäki Suomen ilmailun pioneereina 1924-1956, Apali Oy, ISBN 952-5026-25-6....
, 42, 43
Koolhoven F.K.43
-See also:...
, 46
Koolhoven F.K.46
-See also:-References:*...
, 48
Koolhoven F.K.48
|-References:* *...
, 49
Koolhoven F.K.49
|-References:* *...
, 51, 52, 53
Koolhoven F.K.53
|-References:* *...
and 58
Koolhoven F.K.58
|-See also:-References:NotesBibliography* Green, William. Warplanes of the Second World War, Volume Three: Fighters. London: Macdonald & Co. Ltd., 1961. ISBN 0-356-01447-9....
but mentions a F.K.50-b bomber project, which the Koolhoven foundation site doesn't.
The best-known amongst those designs are the F.K.41 high-wing monoplane, which was built in license as the Desoutter Mk.II
Desoutter Mk.II
-Bibliography:* Kalevi Keskinen, Kari Stenman: Koulukoneet - Suomen ilmavoimien historia 22, Itä-Uudenmaan paino, Loviisa, 2003, ISBN 951-98751-5-8* Tervonen, Ismo: Veljekset Karhumäki Suomen ilmailun pioneereina 1924-1956, Apali Oy, ISBN 952-5026-25-6....
and the F.K.50 twin engine transport monoplane, two of which were used by the Swiss aircraft company alpar
Alpar
Alpar may refer to:* People:** Ignác Alpár , Hungarian architect** Gitta Alpár Hungarian-born actress* Alpár, village a.k.a. Tiszaalpár...
. Amongst the military designs, the most successful were the Koolhoven F.K.51 biplane
Biplane
A biplane is a fixed-wing aircraft with two superimposed main wings. The Wright brothers' Wright Flyer used a biplane design, as did most aircraft in the early years of aviation. While a biplane wing structure has a structural advantage, it produces more drag than a similar monoplane wing...
reconnaissance aircraft, which saw service in extensive numbers in the Dutch air force from the mid-Thirties until the Second World War, the Koolhoven F.K.52 biplane which was used by the Finnish Air Force
Finnish Air Force
The Finnish Air Force is one of the branches of the Finnish Defence Forces. Its peacetime tasks are airspace surveillance, identification flights, and production of readiness formations for wartime conditions...
and the Koolhoven F.K.58
Koolhoven F.K.58
|-See also:-References:NotesBibliography* Green, William. Warplanes of the Second World War, Volume Three: Fighters. London: Macdonald & Co. Ltd., 1961. ISBN 0-356-01447-9....
single-seat monoplane fighter. The latter was the plane ordered by France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
and flew in the Armée de l'Air during the Battle of France
Battle of France
In the Second World War, the Battle of France was the German invasion of France and the Low Countries, beginning on 10 May 1940, which ended the Phoney War. The battle consisted of two main operations. In the first, Fall Gelb , German armoured units pushed through the Ardennes, to cut off and...
A complete list of the Koolhoven aircraft and projects is given below:
- Koolhoven F.K.30Koolhoven F.K.30|-References:* *...
"Toerist" (Tourist) Light high-wing sports monoplane, 1927 - Koolhoven F.K.35 Seaplane scout and fighter, available as low-wing monoplane or biplane, 1926
- Koolhoven F.K.36 Larger biplane version of the F.K.35, 1926
- Koolhoven F.K.37 Design for a 3-engined airliner for the KLM (not built)
- Koolhoven F.K.39 Various design studies for a monoplane two-seat fighter (not built)
- Koolhoven F.K.40Koolhoven F.K.40|-References:* *...
Airliner for 4 or 5 passengers, 1928 - Koolhoven F.K.41Desoutter Mk.II-Bibliography:* Kalevi Keskinen, Kari Stenman: Koulukoneet - Suomen ilmavoimien historia 22, Itä-Uudenmaan paino, Loviisa, 2003, ISBN 951-98751-5-8* Tervonen, Ismo: Veljekset Karhumäki Suomen ilmailun pioneereina 1924-1956, Apali Oy, ISBN 952-5026-25-6....
, High-wing monoplane cabin "sport coupe", built in licence by Desoutter in England - Koolhoven F.K.42 High-wing open cockpit Private plane, 1929
- Koolhoven F.K.43Koolhoven F.K.43-See also:...
Three passenger cabin sportsplane/air taxi resemblant of the F.K.41, 1930 - Koolhoven F.K.44 "Koolmees" (tomtit) Private plane resemblant of the F.K.41/F.K.43
- Koolhoven F.K.45 Biplane aerobatic plane, 1931
- Koolhoven F.K.46Koolhoven F.K.46-See also:-References:*...
Biplane trainer, 1930 - Koolhoven F.K.47 Biplane private plane/trainer, 1933
- Koolhoven F.K.48Koolhoven F.K.48|-References:* *...
Six passenger twin-engined airliner used by the KLM, 1934 - Koolhoven F.K.49Koolhoven F.K.49|-References:* *...
Twin-engine photo- and cartography aircraft, purpose built for the Dutch air force 1935 - Koolhoven F.K.49A Multi purpose aircraft, 1937
- Koolhoven F.K.50 Eight passenger twin-engined airliner, a more powerful F.K.48, used by Alpair 1935
- Koolhoven F.K.51 Military biplane trainer with open seating, 1935
- Koolhoven F.K.52 Two-seat biplane scout and fighter with enclosed cabin, 1936
- Koolhoven F.K.53Koolhoven F.K.53|-References:* *...
"Junior" low/mid wing light touring plane, 1936 - Koolhoven F.K.55 High-wing monoplane cabin "Executive plane" with retractable gear, 1937
- Koolhoven F.K.55 Twin-engined experimental high performance fighter, 1936
- Koolhoven F.K.56 Low-wing monoplane two-seat advanced trainer and scout, 1937
- Koolhoven F.K.57 Twin-engined low-wing executive plane, 1938
- Koolhoven F.K.58Koolhoven F.K.58|-See also:-References:NotesBibliography* Green, William. Warplanes of the Second World War, Volume Three: Fighters. London: Macdonald & Co. Ltd., 1961. ISBN 0-356-01447-9....
Modern monoplane high performance fighter, 1938 - Koolhoven F.K.59 Multi-purpose development of the F.K.52, no information available whether built, last Koolhoven design, 1940
Legacy
Founded in 1989 by aviation enthusiast Jan den Das, aviation historian Theo Wesselink and technical curator Harry van der Meer, the Koolhoven Aeroplanes Foundation tries to keep the legacy of Frits Koolhoven's aircraft alive by restoring or rebuilding some of his most famous aircraft. Its highlight is the restoration of the only remaining FK-21 BAT BantamBAT Bantam
-External links:** Contemporary technical description of F.K.23 Bantam with photographs and drawings.-See also:...
, a Koolhoven design. Its site also has the most complete list of all Koolhoven designs.