A.Weyl Fokker: The Creative Years (Putnam)

The V.8 quintuplane

  Fokker recognized that the triplane fashion had brought him success. The Fok. Dr.I had put him in the lead and his competitors had not been able to catch him up. This gave him a brainwave: if three wings produced such a successful aeroplane, even greater things might be expected from one with more wings.
  On the strength of this aerodynamic misconception he shocked Platz with a request for a quintuplane; he was convinced that five wings ought to ensure resounding success.
  Platz was perturbed by this proposition. The more he thought about the boss’s request in detail, the more his dismay grew. His aerodynamic knowledge at that time was still limited, but he felt instinctively that a quintuplane would be useless as a fighter. It was, of course, an affront to his belief in simplicity, and the complete antithesis of his ideal, the cantilever monoplane.
  Platz argued with Fokker, trying to prove to him that it was scarcely feasible to attach five wings satisfactorily to a single fuselage and that the whole thing would be a mass of struts and wings. But Fokker would not listen; he insisted stubbornly on a quintuplane.
  In 1917, Platz had not had enough experience as a chief designer to feel sure enough of himself in rejecting an absurd request. With extreme distaste he started the unpleasant task of designing the V.8 at Fokker’s behest. Even today he regards the V.8 as such an outrage that he dislikes admitting that he designed it.
  Anyone but Fokker would have conducted model tests or wind-tunnel investigations on stability and control before building such a weird aircraft. Ignoring, as usual, such technical desiderata, Fokker had the contraption built without having the slightest inkling of the kind of properties it was likely to display.
  Platz did his best. He decided on a tandem-wing arrangement, but retained a conventional tail unit on a long fuselage. This was a reasonable feature, giving better fore-and-aft trim possibilities. It may also have saved Fokker’s life. A triplane wing system was mounted at the extreme nose of the aircraft; a pair of biplane wings were attached amidships at a distance of 2-5 times the wing chord behind the triplane structure; neither set of wings was staggered. Balanced control surfaces were fitted to the top wings of both the triplane and biplane systems; those at the front acted as conventional ailerons, those on the midships wings were apparently aligned with the elevators. The centre of gravity was located between the two wing systems; the cockpit was rather far aft, in line with the leading edge of the biplane wings. The engine was a 120-h.p. Mercedes, and a nose radiator was fitted.
  When the V.8 was completed, Fokker made a short hop in it: his intimates dignified this exercise by calling it a flight. He demanded some modifications; when these were completed he made another exploratory hop. After this, Fokker decided to scrap the aircraft. He realized that Platz was right; but he did not tell him so.
  The V.8 was, of course, entirely a private venture: no type-test commission was confronted with the alarming experience of evaluating it.
  Platz confesses that he was immensely relieved when the quintuplane proved such a convincing failure. It if had not been, Fokker would have insisted on aircraft with more and more wings, and Platz would never again have been able to revert to simple and practical aeroplanes.

O.Thetford, P.Gray German Aircraft of the First World War (Putnam)

Fokker V 8
  As may be seen this aircraft, built expressly on Fokker's instructions, utilised mostly V 6 components. It was not a success, and after only two short test hops it was scrapped. Engine was 120 h.p. Mercedes D II.

W.Green, G.Swanborough The Complete Book of Fighters

FOKKER V 8 Germany

  A decidedly bizarre single-seat fighter, the V 8 could be described both as a quintuplane and a tandem-wing aircraft. Powered by a 160 hp Mercedes D III engine, the V 8 had an unstaggered equi-span triplane wing arrangement mounted at the extreme nose and a biplane wing arrangement immediately aft of the pilot’s cockpit and approximately two-and-a-half times the wing chord behind the triplane structure. The top plane of each set of wings incorporated balanced ailerons, and a conventional tail assembly was provided at the end of an inordinately long fuselage, the CG being located between the two wing systems. Anthony Fokker made an abbreviated flight - barely more than a hop - in the V 8 in October 1917, some modifications subsequently being made before a further brief flight was made two weeks later, development then being abandoned. No data for this type were recorded.