Koolhoven Aeroplanes Foundation

Preserving the work of the Dutch airplane constructor Frederick Koolhoven (1886-1946)


On May 10 1940, the invasion of The Netherlands, German bombers took off to cripple the Dutch airfields. At the airport Waalhaven of Rotterdam, the N.V. Koolhoven Aeroplanes was their first target. The factory was laid in ashes. Airplanes, drawings, documents, photographs, all was lost.

Today Frederick Koolhoven (pronounced: "Coalhoven") and his designs have almost been forgotten, but in its days, with 1200 employees and a well filled order-book, his factory was certainly as important as our 'national pride' Fokker.

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Koolhoven's work was very innovative and visionary. In 1919, when passenger planes were all converted military planes, he built the B.A.T. F.K.26 'Commercial', the world's first aircraft specifically designed for commercial aviation, or the world's first airliner. His F.K.41 was one of the world's first high winged sportscoupes. The F.K.55, a contra propelled fighter, was unquestionably his most spectacular design.
Some of his designs became a great success, some were failures. Yet, many times these failures possessed features that were far ahead of their time. From Koolhoven's designs nearly 3000 airplanes were built.

It's the Foundation's goal to assure Koolhoven's deserved place in history. First priority in this is to gather as much remaining material as possible. Thanks to institutional archives and gifts from personal possessions, the Foundation has been able to form the most comprehensive archive and collection on Koolhoven. - Still it happens that material is thrown away, because people are just not aware of its historical value. Making the Foundation known hopefully prevents further loss of valuable material. - Interviews with former employees or other people who can give information from their own experience, are also appreciated sources.
Working at the files, sorting out all the information, takes a lot of time. It is needed first to make the building of replicas possible. Though the Foundation's files do contain drawings of some types, there are no complete sets. Building the desired replicas depends heavily on research.

Only one original Koolhoven has survived, a B.A.T. F.K.23 'Bantam' which is restored by volunteers of the Koolhoven Aeroplanes Foundation.

The Koolhoven Aeroplanes Foundation (Stichting Koolhoven Vliegtuigen) is founded in 1989 by aviation enthusiast Jan den Das, aviation historian Theo Wesselink and technical curator Harry van der Meer.

British Aerial Transport F.K.23 'Bantam'

When the British Aerial Transport Company closed down in 1920, the 'Bantam' was part of the property bought up by Ogilvy Aviation, a trader in second hand aircraft and parts. After Mr. Ogilvy’s death in 1953, the 'Bantam' remains, one cut up fuselage plus wings of two different 'Bantams', were donated to the Shuttleworth Collection and stored in a barn for many years. In 1975 the remains were moved to someone who planned to restore the 'Bantam', but the material got returned in 1989 without any work done and some vital parts lost.


Around 1990 it was decided that only aeroplanes collected by Richard Shuttleworth himself would be kept in the Shuttleworth Collection and the 'Bantam' remains were offered for closed bids. Thanks to the enthusiast support from the Stichting Vroege Vogels (Early Birds Foundation), the newly formed Koolhoven Aeroplanes Foundation was able to make his bid for this last surviving, original Koolhoven aircraft in the world. All other interested gentlemen welcomed the thought of this and withdrew their bids!

April 1991 the remains of the 'Bantam' arrived in hangar 8 at Schiphol Airport and a restoration team was formed:

Project identity, static: British Aerial Transport F.K.23 'Bantam' I
c/n 15, 1917
F-1654 / K-123 / G-EACN
Project identity, flying: British Aerial Transport F.K.23 'Bantam' I
c/n 18, 1917
F-1657 / K-155 / G-EAFN
To have a connection between the 'Bantam' and The Netherlands, it was decided to finish her as the civil K-123. With this registry the aircraft was a daily highlight of the E.L.T.A. in 1919, the first big aviation exhibition in The Netherlands. K-123 and Koolhoven's private 'Bantam' G-EAJW together, daily performed aerobatics that thrilled the audience.

July 1918, K-123 was flown to France in order to be tested, together with two other allied types, against a captured Fokker D.VII. The 'Bantam' proved to be superior to the D.VII in two out of three tests.

The 'Bantam' was extremely fast. In those days fighters had top speeds from 90 to 115 mph ... the 'Bantam' reached 142 mph!

The restoration of the 'Bantam' started with a careful selection of the aged and corroded material. Three wings appeared to be in such good shape that they only needed repair.

The fuselage however was cut up in many pieces, yet the front and tail sections had survived. With an archaeologist approach it was all succesfully reconstructed and rebuilt upside down, using the top longeron as datum line.

Most steel parts were badly corroded, as were the aluminum fillers used all over the place. Without exception steel nails had been used in the wood, which in 80 years had corroded to ten times there size; they had to stay in the wood as they were.

The static 'Bantam' is fitted with the original Wasp engine. The flying 'Bantam' will need a reliable replacement as the Wasp was known to be very unreliable because of its poor design and construction.

A jar with synthetic cassaine glue, almost the same as used in 1918, was obtained from Guy Black in England. From a received subsidy flying wires could be bought from Bruntons in Scotland, the same manufacturer as in 1918.

The restoration has been done the hard way. Wherever possible, broken parts and pieces of wood were repaired instead of replaced. Thanks to this meticulous approach, the reconstruction of the ‘Bantam’ consists of an exceptional high percentage of original material: 90 to 95%.

August 2003 the B.A.T. F.K.23 'Bantam' from 1917, is restored to its full glory; twelve and a halve years to turn a 'pile of firewood' into a beautiful swift looking aircraft. Five engineers have spent their time to the 'Bantam', along the way helped by some 20 other people providing skills, knowledge or parts. These people can look at their work with great satisfaction; it has become a museum piece of great historical value.

The proud members of the restoration team. From left to right: Harry van der Meer, Arie Groen, Piet van der Horst, Lou Kolsteeg and Herman Beker.

The help of the Stichting Vroege Vogels, in particular their secretary Jaap Mesdag, has been crucial for the project. Without them taking care of the finances, it would not have been possible to bring the remains of the last existing Koolhoven aircraft to The Netherlands.

Today the 'Bantam', the last real life example of Koolhoven's work, is on public display in the main exhibition hall of the Dutch National Aviation Theme Park Aviodrome, that also contributed to the project by providing accomodation and facilities for the restoration.

British Aerial Transport F.K.26 'Commercial'

World's first aircraft specifically designed for commercial aviation, 1919

When the end of World War I came near, aircraft builders saw their military orders cancelled and the interest for civil aviation as a new market grew. In the very first period after the war, commercial aviation started with the use of dumped military aircraft, scouts and bombers with the necessary modifications. These aircraft were far from comfortable. Passengers were placed in open cockpits, dressed up in thick suits and flying helmets as the only protection against the elements.

Frederick Koolhoven, at the time running the factory of the British Aerial Transport Company, had realized himself that with the aircraft of the time, traveling by air would be no competition for the comfort of trains and ships. He chose to create an aircraft especially for the transport of passengers. The first day after the armistice was signed (November 11, 1918) he started working at the drawings of the B.A.T. F.K.26.

It was for the first time in history, an aircraft was specifically designed for commercial aviation. Frederick Koolhoven had thought about what was needed and came up with a new concept: a comfortable cabin located near the centre point of gravity, fully enclosed by the fuselage and the cockpit placed behind. The F.K.26 could take four passengers; large numbers of passengers were not to be expected in those days.

The prototype, c/n. 29 / K-102 / G-EAAI, made its first flight from Hendon Airfield in April 1919. It was flown by the illustrious major Christopher Draper who was very content with the F.K.26’s flight characteristics.
The F.K.26 had one disadvantage. The cabin door had been kept very small out of fear that a larger entrance would weaken the construction of the fuselage.

No orders were placed for the F.K.26. Nevertheless it was decided to produce three more F.K.26, c/n. 30 to 32, registrations K-167 / G-EAHN, G-EANI and G-EAPK. These aircraft were registered at the name of B.A.T. and mainly used for charter flights in England and to Europe.

With major Christopher Draper as the pilot and Frederick Koolhoven as one of the passengers, the second F.K.26, K-167 / G-EAHN, was flown to Amsterdam to be demonstrated at the ELTA, the first Dutch aviation exhibition of August 1, 1919.

The ELTA meant the start of the airline COBOR, a cooperation between Frederick Koolhoven and the Dutch lieutenant L. Coblijn. COBOR started a weekly service Londen - Amsterdam (airfield Hounslow - airfield Soesterberg) at September 18, 1919. Unfortunately, the F.K.26 aircraft were claimed at unpredictable occasions by the English Air Ministry for military transport. This and the winter break after late October, forced COBOR out of business.

Despite its good performance, the F.K.26 did not become a commercial success. Airline companies preferred making a choice out of the many cheap offers of dumped military aircraft and convert them for passenger transport, rather than investing in new aircraft.
Of the four F.K.26 produced, only one had been sold. The G-EAPK bought in 1920 by Instone Airline, flew a regular service between Croydon and Paris until July 1922.

In 1937 the prototype of the F.K.26 was found back at Ogilvy Aviation, a trader in second hand aircraft and parts. Frederick Koolhoven brought the aircraft to his factory in The Netherlands, had it restored and donated it to the Dutch Aviation Museum at airport Schiphol in 1938.

After the invasion in 1940, all aircraft and parts had to be handed over to the Germans who either re-used or destroyed the material. About ten aircraft from Schiphol, including the F.K.26 prototype, were loaded on flat deck boats for transport to the Fokker factory in the north of Amsterdam. The boats were hidden in the polder where their cargo was safe for the RAF ground attacks, but not for a group of locals who decided not to let 'them' have it. By night, the F.K.26 prototype has been pushed overboard, along with the other aircraft.
Until today, this historical aircraft lies in its grave, deep in the soil of a Dutch polder.


Wingspan : 14,03 m. / 46 ft. 0.36 in.
Length : 12,61 m. / 41 ft. 4.46 in.
All-up weight : 2050 kg. / 4525 lb.
Engine : 350 hp Rolls Royce 'Eagle'
Maximum speed : 196 km./h. at 3050 m. / 122 m.p.h. at 10,000 ft.
Passengers : 4
Production : 1 prototype and 3 production aircraft

About the statement and other first airliners

by Henri Kaper, webmaster

When you use the words "world's first" there will be people who do not agree. Just like the flight of the Wright Brothers, as "the world's first motorized flight", is still being questioned because before this famous occasion there were the short flights made by Richard Pearse and Gustav Weißkopf. Some others believe it is Clément Ader who should be honored. Today the Wright Brothers are generally accepted as the world's first because their flight was regarded as true, controlled flight. (Another reason was that there was no convincing proof for the earlier claims.)
In the same way the question of which aircraft was the world's first airliner is not a matter of plain historical dates ... it also depends on the definition of "airliner".

Frederick Koolhoven was not the first to foresee passenger transport by air. From the beginning of aviation people had fantastic visions of future possibilities and a few made first efforts to bring them into practice. Like Albessard who built a tandem monoplane with a passenger cabin in 1912. He gave up on the aircraft after unsuccessful tests which were performed with only the pilot aboard.

At the end of 1911, the famous Louis Blériot had also built a cabin aircraft for four passengers and a pilot outside. This Blériot XXIV 'Limousin' was a special order for a certain Henri Deutsch de la Meurthe.

There have been a few more aircraft like these, built for several reasons. Aircraft were still a bit of a circus act and taking more people up in the air was already quite a feat; some were solely build for these record attempts. These first passenger aircraft may have been a sign of things to come; they were no airliners yet ... there's a difference. It was simply to early for commercial aviation. Aviation first needed the technical development made in World War I.

There has been one successful scheduled service before World War I though. The Tampa-St.Petersburg line starting at January 1, 1914, was the world's first airline. The aircraft used for this service was a flying boat, the Benoist Type XIV, which suited the enterprise because it had an extra seat next to the pilot's. Some people came to think of this aircraft as the "world's first airliner", but in this case the airline is the milestone, not the aircraft. Besides, the Type XIV was not the first of its kind, so how about its predecessors then? The Benoist Type XIV fits best in the category 'general aviation'. It was the first aircraft that has been used for an airline; not an airliner.

The "airliner" is a specific type of aircraft, designed for the use of airlines, which concept takes comfort and economy in account. Therefore other types of aircraft that have been used for airlines, be it general aviation aircraft or converted military aircraft, are no true airliners. Like, if some Ford T-model would have been used for the first paid fares by road, it still wouldn't be a bus.
It's the intention with which the aircraft was designed and built that matters ... was the design originally meant for the commercial transport of passengers?

The Sikorsky 'Le Grand' from 1913, the world's first four-engined aircraft, is occasionally mentioned as the world's first passenger aircraft. The purpose of its comfortable cabin however was to take high ranked officers on demonstration flights. The 'Le Grand' was built for one single reason: to prove the military that such huge aircraft could be flown; an idea that met a lot of skepticism in those days. It was not an airliner or even a passenger aircraft ... the 'Le Grand' was the forerunner of the WWI multi engined strategic bomber.

In the last days of World War I the Farman company built the prototype for what should have been the 'Goliath' bomber, was it not that the war ended. The design was converted to a civil version which is successfully flown by several airlines. Still, the Farman F.60 'Goliath' was a bomber by origin.

Similarly the Vickers Vimy 'Commercial' was a spin-off from the well known Vickers Vimy bomber.

At this point, in April 1919, the B.A.T. F.K.26, was completed and first flown. It was the first aircraft that was specifically designed for commercial aviation from the start. To my opinion this is a sound and objective definition for "world's first airliner".

Before World War II the B.A.T. F.K.26 was widely regarded as the first airliner, but then, when the history of the Koolhoven company became ignored and forgotten, the B.A.T. F.K.26 became forgotten as well. (Historical matters need spokesmen or they will be forgotten.) So it happened that two more aircraft are claimed to be the "world's first airliner".

In the same year Prof. Hugo Junkers, pioneer in metal aircraft, constructed his Junkers F 13. The F 13 had a cabin for four passengers, a fifth passenger could be seated next to the pilot. The Junkers F 13 was completed and first flown in June 1919 ... two months later than the B.A.T. F.K.26.
The Junkers F 13 was the first all metal airliner, but not the "world's first airliner". Yet, it must be said that the F 13 was really ahead of his time and successful for years. Some F 13's have flown until the end of the twenties.

In the United States the remarkable Alfred Lawson had his vision of mass transportation by air and assigned Vincent Burnelli to build the aircraft that would be the beginning of it all. The 'Lawson Airliner' was a big aircraft with eighteen seats, which had its first flight at August 19, 1919 ... four months later than the B.A.T. F.K.26.
Shortly after, Alfred Lawson was a great talent for publicity, he took his aircraft on a city-to-city tour and presented it as "World’s First Airliner" and "World's Largest Airplane". He was not aware, but probably wouldn't have cared either, that both claims were not true.
Unlike the B.A.T. F.K.26 and the Junkers F 13, the 'Lawson Airliner' has never been in service with an airline.

The Fokker F.II, the first of the very successful Fokker airliners, made its first flight as late as October 1919. The F.II had a cabin for four passengers and has flown in service with the KLM and the Lufthansa.
(Its predecessor, the V.44 or F.I, was built very much like a military aircraft, with open cockpits. Because the B.A.T. F.K.26 and the Junkers F 13 had shown a better solution, the Fokker V.44 project was cancelled before completion.)

The world is a busy place. Frederick Koolhoven was not the only one having the idea, yet he was the first to realize it ... the first true airliner in history.