Flight, August 1923

GOTHENBURG International Aero Exhibition 1923

The Dutch Section

   HOLLAND was represented at I.L.U.G. by one firm only, the N.V. Nederlandsche Vliegtuigenfabriek of Amsterdam. In addition to two complete aeroplanes and the all-Duralumin hull of a new Fokker flying boat, a number of scale models of the long series of Fokker machines produced during recent years were exhibited. Some of these models represented types to which we hope to make detailed reference at a future date. At present we must confine ourselves to the two types exhibited full scale.
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   Developed from the famous Fokker D.VII, although a much smaller machine, the new Fokker D.XI, exhibited at Gothenburg, is chiefly remarkable for the very small bottom plane which, the designer claims, not only gives an exceptionally good view, but which also combines the aerodynamic efficiency of the parasol monoplane with the rigidity of the biplane. The lower plane, in the D.XI, is quite small, and is heavily staggered in relation to the top plane, to which it is braced by a single pair of V struts on each side. On the machine exhibited it was not possible to ascertain the exact spar arrangement of the lower plane, but it appears probable that the spars are arranged in the form of a V, coming to a point at the lower wing tip. In that case the V interplane strut would seem to be satisfactory. Both upper and lower planes of the D.XI are covered with ply-wood, as in the well-known Fokker commercial monoplanes. The fuselage, on the other hand, is built of welded steel tubing and is fabric covered.
   The Fokker D.XI can be fitted with either 300 h.p. Hispano-Suiza or 375 h.p. Curtiss engine. Side radiators similar to those on the C.IV are fitted, and the same gear is used for drawing them into the fuselage. In general construction the D.XI follows usual Fokker practice, but an innovation has been made in the steel tube undercarriage, in which the axle is so mounted (see sketch) that it can move not only up and down but also fore and aft and laterally to a certain extent. This arrangement, it is claimed, will save ripping off a tyre when landing with a certain amount of side drift.
   Following is a brief specification of the Fokker D.XI. Length, o.a., 7.2m. (23ft. 7 ins.); span, 11.5m. (37 ft. 9 ins.). The machine is supplied with wings of different areas, ranging from 18 sq.m. (194 sq. ft.) to 24 sq. m. (258 sq.ft.). According to the size of wings fitted, the useful load varies from 250 kgs. (550 lbs.) to 400 kgs. (880 lbs.). The speed varies, according to engine and wings fitted, from 240 km. (149 m.p.h.) to 260 km. (161 m.p.h.). The climb is given as 5,000 m. (16,400 ft.) in 12 minutes, but it is not stated with what size wings this figure is attained.