Koolhoven F.K.45

The Koolhoven F.K.45 was an aerobatic biplane built to the requirements of one pilot who flew it at airshows in the mid-1930s. Only one was built.

F.K.45
F.K.45 Aerobatic
Role	Aerobatic aircraft
National origin	Netherlands
Manufacturer	N.V. Koolhoven Vliegtuigen
First flight	February 1932
Number built	1

Design and development

The F.K.45 was the result of a 1931 order from René Paulhan, a French test pilot with Nieuport-Delage, for a light aerobatic aircraft. It was first flown in February 1932, though not delivered to Paulhan for two more years. It was a single bay biplane, with equal span, unswept wings of constant chord and strong stagger, braced with N-form struts and flying wires. Ailerons were mounted on both upper and lower wings. The upper wing of the F.K.45 was held above the fuselage by a pair of short, outward leaning N-form cabane struts to the upper fuselage longerons. The single seat cockpit, set in an opening in the otherwise continuous, rounded fuselage decking, was under the wing trailing edge where a rectangular cut-out enhanced visibility. Its tailplane was mounted on top of the fuselage; the fin was quadrant shaped and the straight edged rudder extended down to the keel.^[1]

The F.k.45 was powered by a 115 hp (86 kW) Cirrus-Hermes IIB four cylinder inverted air-cooled inline, which drove a two blade propeller. Its undercarriage was of the fixed, conventional type, with the mainwheels on axles forming an inverted V and attached to the central fuselage underside. The main legs, with shock absorbers, were mounted on the upper longerons. There was a small tailwheel.^[1]

Operational history

The sole F.K.45 initially flew with the test registration Z1, then with the Dutch registration PH-AIF,^[1] but when it was handed over to Paulan on 24 April 1934^[2] it was placed on the French register as F-AMXT. Paulhan displayed it at airshows over the next two years and then sold it. In August 1938, the F.K.45 had logged only fifty hours of flight.^[1] It went on to two more owners^[2] but its final fate is unknown.^[1]

Specifications

Data from Wesselink^[1]

General characteristics

• Crew: One
• Length: 5.57 m (18 ft 3 in)
• Wingspan: 7.04 m (23 ft 1 in)
• Gross weight: 580 kg (1,279 lb)
• Powerplant: 1 × Cirrus-Hermes IIB 4-cylinder inverted air-cooled inline, 86 kW (115 hp)
• Propellers: 2-bladed

Performance

• Maximum speed: 210 km/h (130 mph, 110 kn) at sea level