Air Enthusiast 1972-03 / Plane facts

The Koolhoven F.K.55 photographed prior to its single flight test.

Jane's All the World Aircraft 1938 / 03 - All the world's aeroplanes

The Koolhoven F.K.55 Single-seat Fighter Monoplane (1,000 h.p. Lorraine "Sterna" engine driving two airscrews in opposite directions).

Air Enthusiast 1972-03 / Plane facts

The Koolhoven F.K.55 during ground trials at Welschap airfield.

Air Enthusiast 2001-01 / ??? - Salon Stars

A Dutch design that was much-studied at the Salon was the radical Koolhoven FK-55 fighter prototype. A single-seater, it was powered by a 12-cylinder Lorraine Petrel of 860hp (641kW) mounted in the centre-section and driving the two-unit, counterrotating, propellers via an extension shaft. Production FK-55s were to have been powered by a Lorraine Sterna of 1,200hp (895kW) and been fitted with a 20mm cannon in the propeller boss and four machine-guns in the wings. The FK-55 flew for the first and only time on June 30, 1938, for just a couple of minutes. It was fitted with fixed undercarriage for this flight, although a fully retractable unit was to be fitted to production examples.

Flight 1936-11 / Flight

The sensational Koolhoven fighter with its twin airscrews and Lorraine Petrel engine mounted behind the pilot.

Flight 1938-12 / Flight

The latest version of the Lorraine Sterna with extension shaft and oppositely rotating airscrews. This combination has been fitted in the Koolhoven F.K.55 fighter.

Flight 1936-11 / Flight

TWIN-SCREW. The Koolhoven single-seater fighter to be shown at the Paris Salon has two airscrews revolving in opposite directions.

Air Enthusiast 1972-03 / Plane facts

The arrangement of the power plant and extension shaft of the F.K.55.

Авиация и Космонавтика 1994-01 / М.Маслов - Соосные воздушные винты /Авиационная наука и техника/

Flight 1936-11 / Flight

The method of driving the two airscrews of the Koolhoven (Lorraine Petrel).

Flight 1936-11 / Flight

A cooling "gill" on the New Koolhoven fighter.

Air Enthusiast 1972-03 / Plane facts

The F.K.55 in its proposed definitive form with retractable undercarriage.