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Fokker M.4

Страна: Германия

Год: 1913

Fokker - M.3 - 1913 - Германия<– –>Fokker - W.1 - 1913 - Германия

A.Weyl Fokker: The Creative Years (Putnam)

The Doeberitz flying centre took a sympathetic view of Fokker’s attempts to produce a practical military monoplane. They suggested that he might be more successful if he were to abandon his two-control system and follow the Zanonia-seed principle of the Taube monoplane.
  Fokker knew he had to produce something fundamentally different from the Spider if he was to stay in business. The profit made by the flying schools was not enough to maintain his growing organization and finance new developments. His Dutch backers wanted to see existing aircraft types making some profit before committing themselves further: they pointed out that other German aircraft manufacturers seemed to be doing well out of the substantial Army orders that were being placed.
  A completely new design was wanted, and Palm was instructed accordingly. The new aircraft was designated M.4, and in it the original and characteristic features of the Fokker-Goedecker design were completely abandoned. The wings had moderate dihedral and no sweep-back; their raked tips and the shoulder-wing arrangement suggested Taube influence, but the Fokker M.4 differed from the Etrich-Wels machine in having ailerons. These control surfaces had oblique hinge lines, and their pronounced wash-out gave them a characteristic upward twist. The mainplanes were braced by cables.
  The wings were made entirely of wood. The main spars were of ash, spindled out for lightness; the front spar was 80 mm. (3-15 inches) aft of the leading edge, along which a pre-formed strip of plywood was placed to preserve the aerofoil section. The wing section had more camber than that of earlier Fokker types. Fokker hoped that this would provide more lift: it may have done so, but only at the expense of longitudinal stability. A gap was left at each wing root to improve downward vision.
  The tailplane was attached to the upper longerons of the fuselage and had two separate elevators. The balanced rudder was somewhat similar to that of contemporary Morane-Saulnier types.
  The M.4 fuselage was a welded steel-tube structure of plain rectangular cross-section. It was of original design and incorporated some detail suggestions made by Platz. The engine was a 100-h.p. six-cylinder Mercedes with a Windhoff overhead radiator. The seats were farther apart than on earlier Fokkers; this gave the observer more room. The pilot occupied the rear cockpit, and had stick control.
  The undercarriage was sprung by rubber rings at the upper ends of the main struts; it incorporated a nose-wheel at the forward end of its central member; and there was a conventional tailskid in place of the primitive and awkward skid amidships that had been fitted to all predecessors of the M.4. The nosewheel had been included at the request of the Army, who regarded it as a better safeguard against nosing-over than the skids of the earlier Fokker types. The lift bracing cables of the mainplanes were attached to the central member of the undercarriage, which was rigidly attached to the fuselage and consequently thought to be immune to the shocks sustained on landing and during taxying. Platz thought this undercarriage rather an impossible structure, and in fact it had to be modified several times.
  Although the M.4’s wings were made entirely of wood, it was given the name Stahltaube. At that time, the Jeannin Stahltaube (which also had all-wood wings) was highly thought of in Army circles and was much sought after by Service pilots.
  The M.4 was built at Schwerin, and its first flights were made during November 1913. It proved to be a disappointment. Various modifications were made in an endeavour to make it acceptable to the Army, but they were unavailing and the M.4 remained unpleasant to handle. Doeberitz detailed Leutnant Muehlig-Hofmann to test the new Fokker. He found it unstable and in performance decidedly inferior to contemporary German aeroplanes. It could not be used as a trainer, and few of the Fokker pilots tried it. It was broken up after a brief existence, and Fokker dismissed Palm its designer.
  It was perhaps regrettable that Fokker acted so hastily, both in demonstrating that he had no use for inferior designers and in having the M.4 scrapped. The aircraft had been a step in the right direction and might have been developed successfully. The gap at the wing roots was a bad feature; the wing camber was excessive and impaired stability; the centre of gravity may have been too far aft (as it often was on Fokker types); the undercarriage needed tidying up. All this could have been put right without disproportionate expense.

A.Weyl - Fokker: The Creative Years /Putnam/
The Fokker M.4, the so-called Stahltaube.
Форум - Breguet's Aircraft Challenge /WWW/
Форум - Breguet's Aircraft Challenge /WWW/
In this rear view of the M.4 the skewed hinge lines of the ailerons can be seen.