A.Weyl Fokker: The Creative Years (Putnam)

The light aeroplanes V.39 and V.40

   Soon after the unrest of the early days of November 1918 Platz completed two new designs. Both were low-power single-seat monoplanes intended for sporting flying. Platz built them in the belief that there were people who liked to fly for fun. What he forgot was that people who are so inclined usually lack the money needed to buy aeroplanes.
   The two new aircraft were scaled-down Fok. D.VIII single-seaters. In both, however, the wing was fabric-covered. This meant that torsional loads had to be resisted entirely by differential bending of the spars. These were designed accordingly. The ailerons were simplified, being no longer inset but extending to the wing tips; their hinge lines were slightly skewed, and they had no horn balance. The elevator was also a plain surface; the rudder was balanced, but there was no fin.
   Although basically similar, the V.39 and V.40 differed in size and power units. V.39 was the larger of the two, with a wing area of about 9 sq. m. (97 sq. ft.); its engine was a Gnome of 50 or 80 h.p., cowled in the same way as the engine of the Fok. D.VIII.
   The V.40 was the smallest aeroplane ever built by the Fokker Works. Its wing span was only 5-9 m. (19-5 ft.), the area 7 sq. m. (75-5 sq. ft.); its length was 3-94 m. (13 ft.). The V.40 was powered by an old 35-h.p. Anzani inverted-Y air-cooled engine, and had a top speed of 111 km./hr. (69 m.p.h.).
   Both aircraft flew well, and were liked by all pilots who tried them. The flight tests were done by Parge. Fokker seems never to have flown them, and it is doubtful whether they ever went to Holland. They failed to find a market and did not go into production.
   A somewhat similar attempt to build a small edition of the Fok. D.VIII was made by Gabriel at Bromberg a year or so later. This aircraft, the Gabriel P.5, had a plywood-covered wing but had a plywood fuselage instead of the steel-tube structure of the Fok. D.VIII. It had a 30-h.p. Haacke two-cylinder engine and was even smaller than the Fokker V.40: its wing span was only 5 m. (16-5 ft.) and the length 4 m. (13-2 ft.). The empty weight was stated to be a mere 125 kg. (275 lb.).