The Koolhoven F.K.54 was a Dutch single-engine, three-seat touring aircraft with a

retractable undercarriage Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...

. It flew shortly before the start of

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

and its development was abandoned after its first flight as attention turned to military aircraft.

Design and development

The F.K.54 was most notable as Koolhoven's first aircraft with a

. It was a high-wing monoplane; its wings tapered in plan and had rounded tips. They were braced with a pair of near-parallel

strut A strut is a structural component commonly found in engineering, aeronautics, architecture and anatomy. Struts generally work by resisting longitudinal compression, but they may also serve in tension. Human anatomy Part of the functionality o ...

s on each side between wing

spars The United States Coast Guard (USCG) Women's Reserve, also known as the SPARS (SPARS was the acronym for "Semper Paratus—Always Ready"), was the women's branch of the United States Coast Guard Reserve. It was established by the United States ...

and the lower

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...

longerons In engineering, a longeron and stringer is the load-bearing component of a framework. The term is commonly used in connection with aircraft fuselages and automobile chassis. Longerons are used in conjunction with stringers to form structural ...

, assisted by short

jury strut In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in c ...

s. The F.K.54's fuselage was flat-sided, with a 140 hp (104 kW)

de Havilland Gipsy Major The de Havilland Gipsy Major or Gipsy IIIA is a four-cylinder, air-cooled, inverted inline engine used in a variety of light aircraft produced in the 1930s, including the famous Tiger Moth biplane. Many Gipsy Major engines still power vintag ...

four cylinder inverted inline air-cooled engine in the nose driving a two blade

propeller A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...

A three-seat, glazed cabin was located under the wing, entered by a port side door. The rear fuselage continued aft at cabin roof height, tapering towards the tail. The

tailplane A tailplane, also known as a horizontal stabiliser, is a small lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters and gyroplane ...

was mounted on top of the fuselage; the fin was straight-edged with a rounded top with a

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally aircraft, air or watercraft, water). On an aircraft the rudder is used primarily to ...

that extended down to the keel. The novel undercarriage was

hydraulically Hydraulics (from Greek language, Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is th ...

operated, the wheels lifting rearwards into the fuselage under the passenger seats. Long, horizontally hinged curved doors then enclosed wheels and legs.

Operational history

The F.K 54 was built for Mr. Van 't Groenewoud, one of the auditors of NV Koolhoven Aircraft. Though the registration reservation ''PH-APR'' was made in January 1937 the F.K.54 did not fly until around the autumn of 1938, delayed by Koolhoven's increasing concentration on warplanes. These efforts also prevented the resolution of problems with the undercarriage retraction mechanism. The F.K.54 was neglected and ultimately destroyed because of the war; it was lost to bombing on 10 May 1940 during the

German invasion of the Netherlands The German invasion of the Netherlands ( nl, Duitse aanval op Nederland), otherwise known as the Battle of the Netherlands ( nl, Slag om Nederland), was a military campaign part of Case Yellow (german: Fall Gelb), the Nazi German invasion of t ...

Specifications

References

{{Koolhoven aircraft F.K.54 1930s Dutch sport aircraft Single-engined tractor aircraft High-wing aircraft Aircraft first flown in 1938