Flight, March 1938

FOR ADVANCED MILITARY TRAINING
“Low-Mid-Wing” Monoplane by Koolhoven : Cheetah Engine Standard

   RESEMBLING in layout the little Koolhoven Junior, a new advanced trainer has lately been completed at the Koolhoven plant. Designated the F.K.56, the type is a two-seater ol mixed construction. The inner portions of the gull-type wings are swept upward, bringing the outer panels to a height corresponding to the mid-wing position. Mr. Koolhoven claims that this arrangement combines the structural simplicity of the low-wing layout with the better handling qualities anti improved stability of the mid-wing type.
   The fuselage, which has two seats in tandem, with a trans­parent roof, is a welded-steel-tube structure, but the wing is of wood with box spars, three-ply ribs and stressed three-ply skin. Slotted ailerons are incorporated. The undercarriage has two independent halves utilising Koolhoven oleo struts, Dunlop medium-pressure tyres and hydraulic brakes. The tracking Ecta tail-wheel is restrained by shock-absorber cords.
   An Armstrong Siddeley Cheetah engine is fitted as standard, out alternative power plants are the Wright Whirlwind or Pratt and Whitney Wasp Junior. There is a sixty-gallon fuel tank the forward fuselage bay and an oil tank behind and above engine.
   Armament comprises two fixed machine guns in the wing, these being placed behind the rear spar according to a patented Koolhoven method. A special Koolhoven mounting is provided for the rear free gun. The spaciousness of the rear cock­pit allows for the installation of a bomb sight, camera, or wireless apparatus, and bombs may be carried below the wings.
   Data relating to the F.K.56 are: Span, 38ft.; length, 26ft.; wing area, 215 sq ft.; weight empty. 220 lb.; normal flying weight, 3,305 lb.; top speed, 187 m.p.h.; landing speed, 56 m.p.h.; climb to 13.000ft.. 17.6.min.; service ceiling, 19.000ft.; range. 500 miles.