Flight, March 1934

A DUTCH FIGHTER

There must be many of our readers, who, although they are fully aware of the merits of the Fokker civil aircraft, are "in the dark" regarding the military types being produced by the firm. The following description of the Fokker D.XVII single-seater fighter, which, fitted with the Rolls-Royce "Kestrel" IIS engine, has been adopted by the Dutch Army Air Force, should be of interest to many, especially those who have had dealings with such aircraft as the Fokker D.VII or the equally famous Triplane

   THE Fokker D.XVII bears a strong family resemblance to the D.XVI. It may be remembered that this latter machine, fitted with the Armstrong-Siddeley "Panther" engine, was adopted by the Dutch Army Air Force. The D.XVII has larger wings than its forerunner and is fitted with a liquid-cooled engine in place of the air-cooled radial. Almost any modern "Vee" type engine may be fitted, Curtiss "Conqueror" and Rolls-Royce "Kestrel" engined versions having already been flown. Some D.XVII's which are at present being built will have the Hispano-Suiza 12 Xbrs or Lorraine "Petrel" engine. In the accompanying performance tables the power of the two French engines should be compared with that of the "Kestrel." The range of the machines with the various types of engine should also be noted.
   The D.XVII's ordered by the Dutch Army Air Force are fitted with fully supercharged "Kestrels" and the first production machine with this engine has already been tested. In connection with the accompanying performance tables it should be noted that the weights and performances are guaranteed to within the following margins: 3 per cent, for weight empty, 3 per cent, in speeds and 6 per cent, in climb, providing the engine output and fuel consumption agree with the figures supplied by the engine builders. The wings of the D.XVII are of typical Fokker design, being tapered in thickness and chord and having rounded tips. The two box spars of the upper wing are of silver spruce, and the wing is secured by means of four bolts to a cabane mounted above the fuselage. The lower plane is in two halves, each consisting of two solid spars of laminated spruce. Each half is hinged to the lower longerons. The wings are covered partly with bakelite plywood and partly with fabric. This plywood covering runs from the top of the front wing spar over the leading edge back to the lower surface of the rear spar. The remainder is covered with fabric. The fuselage is a framework of seamless cold-drawn steel tubes welded together and braced by steel wires with turn buckles. The engine mounting, which is an integral part of the fuselage, is separated from the rest of the structure by a fireproof bulkhead. Behind this bulkhead is the main fuel tank, to the rear of which is the pilot's cockpit. The pilot's seat may be adjusted vertically during flight and horizontally while on the ground. For the D.XVII machine being built for the Dutch Air Force a special instrument panel has been produced by Smith's Aircraft Instruments in which the instruments are indirectly lighted from behind the board. All the normal equipment carried in a single-seater fighter is conveniently stowed away. To the left of the pilot is a hand wheel for adjusting the tail plane and the throttle handle, to which are attached the triggers for the twin Vickers machine guns which are mounted in the top of the cowling immediately in front of the pilot. These guns may be either both of 0.303 calibre or one of 0.303 and one of 0.5 calibre. Both guns and their cartridge boxes are secured to a frame which is easily removable from the fuselage.
   The controls are of the conventional "stick" and rudder bar type. Ailerons are provided on the top wing only. They are of wooden construction and are statically balanced.
   The undercarriage consists of two Messier oleo pneumatic struts running from the wheels to the lower longerons. These struts are braced to the rear by means of two streamline tubes, also attached to the lower longerons. The wheels are fitted with independently-operated brakes and the tail skid is sprung with rubber in compression.
   The fuel tank, which holds 57.2 Imp. gallons, is of welded sheet aluminium and is installed in the fuselage near the centre of gravity. The tank may be provided with a bullet-proof covering, in which case its capacity is reduced to 52.8 Imp. gallons. A motor pump feeds the engine, and a hand pump may be installed if desired. The oil tank, also of welded sheet aluminium, holds 4.4 Imp. gallons. A "honeycomb" water radiator of the fixed type is mounted beneath the fuselage between the legs of the undercarriage. Temperature is regulated by shutters operated by the pilot. A Vickers-Potts oil cooler is carried beneath the fuselage forward of the water radiator