Desoutter Mk.I ... licence build of the Koolhoven F.K.41.


The F.K.41 was the base for the success of the Koolhoven factory. Allthough the Koolhoven factory would build only six of them, the licence production of Desoutter became a big success in England.

The F.K.41 was a high winged private and business plane with a closed cabin for one pilot and two passengers. It was one of the first aircraft in this, later common, configuration.
The prototype, engined with a 50 hp Siemens, made its first flight early 1928 and was registered July 19, as H-NAER (later changed to PH-AER).

Koolhoven F.K.41

The F.K.41 drew a lot of attention. Because of the many requests for information coming from England, the H-NAER was sent for demonstration flights and received a good press.
Marcel Desoutter, a once celebrated pilot, acquired the licence for the production of the F.K.41 in England and established the Desoutter Aircraft Company for this purpose.

Two F.K.41's, registered G-AAGC and G-AALI, were built by Koolhoven as production example, fitted with Cirrus Hermes I engines as would be used for the Desoutter's. The G-AAGC was collected by Marcel Desoutter personally and flown to the Desoutter factory in Croydon. With a lowered tailplane and remodelled engine cowlings and windscreen, it was exhibited as the Desoutter 'Dolphin' at the Olympia Aero Show of July 1929 in London.

The Koolhoven F.K.41 G-AAGC before it was modified to the Desoutter 'Dolphin'

The name 'Dolphin' was not used again. The machines built at Croydon were simply known as Desoutters until an improved version, the Desoutter Mk. II was built with a Gipsy III engine, redesigned ailerons and tail surfaces and fitted with wheel brakes. The Mk.II prototype, G-AAZI, first flew in June 1930, after which the earlier model became designated as Mk.I.

Twenty-eight Mk.I's and thirteen Mk.II's have been produced.

Three Mk.I's in front of the Desoutter Aircraft Company hangar

The restoration of the G-AAPZ

National Flying Services Ltd. placed a large order and eventually received 19 Desoutter's, which in black and bright orange were a familiar sight at their nation-wide chain of flying clubs, where they were used for instruction, pleasure flights and taxi work. In 1935 one of these planes, the G-AAPZ, was sold to Richard Shuttleworth and flown to Old Warden.
In 1985 Ken Hyde and his collegues Tony Dawson, Dennis Everden and Cliff Harrow, volunteers with the Shuttleworth Collection, started G-AAPZ's restoration with the intention to bring it back to flying condition as the planes in the Shuttleworth Collection are meant to be.

Restoration of Desoutter Mk.I, G-AAPZ

During the restoration Ken Hyde and his collegues encountered many problems. First of all the Desoutter proved to be in very bad shape. The wooden construction was eroded by moist and vermin. All connections of the water-based cassaine glue used in the thirties, had come loose. While testing, the wooden plates fell right out of the bottom. The Desoutter was standing like a house of playing cards.

Restoration of Desoutter Mk.I, G-AAPZ

In the end, about 90 % of the original wood had to be replaced. Structural parts were replaced for sure. Most of the original ironwork however, proved in radiographs to be safe to use.

Restoration of Desoutter Mk.I, G-AAPZ

Another major problem was the far from original state of the Desoutter. In 1937, Richard Shuttleworth had modified the G-AAPZ to his own ideas. It received a new landing gear, a more powerfull Menasco engine, a larger fuel tank and extra instruments. The windows were changed and the characteristic rudder was replaced with a modern shaped rudder.
The team had to spend quite some time to find out how the Desoutter was originally built and the search for missing parts was worldwide. Struts were found in the United States, a few instruments in India and Australia. Information about the size of the tyres was found in a message concerning the use of these planes by the British Red Cross.

Restoration of Desoutter Mk.I, G-AAPZ

Desoutter Mk.I, G-AAPZ

January 26, 1998, piloted by Shuttleworth chief pilot Andy Sephton, the Desoutter had its second maiden flight. Its first flight since 56 years.

Restoring the G-AAPZ was not an easy job, but in the end a very beautifull and unique airplane was added to the Shuttleworth Collection. A last flying tribute to Frederick Koolhoven.

Desoutter Mk.I, G-AAPZ, in flight

Wingspan 10,98 m. / 36 ft.
Length 8,23 m. / 27 ft.
Height 2,14 m. / 7 ft.
Wing area 17,65 sq. m. / 190 sq. ft.
Tare weight 498 kg. / 1,100 lb.
All-up weight 861 kg. / 1,900 lb.
Engine Cirrus Hermes I (105 h.p.)
Cirrus Hermes II (115 h.p.)
Maximum speed 185 km./h. / 115 m.p.h.
Cruising speed 156 km./h. / 97 m.p.h.
Initial climb 213 m./min. / 700 ft./min.
Ceiling 5486 m. / 18,000 ft.
Range 645 km. / 400 miles