F.V.D. Doris

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Doris
Role Single-seat glider
National origin Germany
Manufacturer Flugtechnischer Verein Dresden (F.V.D.)
Designer Horst Muttray and Reinhold Seiferth
First flight 1922
Number built 1

The F.V.D. Doris or Dresden Doris, later known as the Akaflieg Dresden D-B2 Doris, was a monoplane glider built in Germany in 1922. It was unusual in having wings which could independently adjust their angles of attack, a feature intended to increase the energy acquired from gusts of wind.

Design and development

After the collaboration between the Technical High School Dresden (TH Dresden) and the local flying club, the Flugtechnischer Verein Dresden (F.V.D.), that led to the quite successful 1921

UK at least, as the F.V.D. monoplane,[2] it was later incorporated retrospectively into the Akaflieg Dresden's design list as the D-B2 Doris. Most notably, it had wings which could adjust their relative angles of attack independently both of each other and of the pilot.[1]

The idea of such wings came from the poor understanding of

ailerons for roll control became standard on gliders.[1][2]

The Doris was a

chord, where the wing was thickest. The spars were mounted over the fuselage on a narrow central faired column. The wing was largely fabric covered but from the spar forward it was plywood skinned around the leading edge on the upper side, though the ply did not extend as far aft on the underside. The extreme tips were also ply covered.[1]

The fuselage of the Doris had a wooden frame girder structure with a rectangular cross section, tapering aft to a horizontal wedge. Forward of the wing

aspect ratio, all-moving tailplane was nearly rectangular in plan apart from angled tips and was fabric covered behind its leading edge. The Doris was a short aircraft and its vertical tail was therefore large, with a quadrant shaped fin and a near rectangular rudder which had a small cut-away at its base for tailplane movement. The vertical tail surfaces were fabric covered. Like the Stehaufchen, the Doris had a pair of horizontal landing skids. These were fixed to the fuselage at the nose and mounted on the ends of a pair of transverse, arched ash brackets on rubber shock absorbers.[1]

Operational history

The Doris took part in the 1922 Rhön contest, though Flight noted that it "does not appear to have accomplished very much".[2] It remained on the Wasserkuppe after the competition but crashed, injuring Muttray. The accident, which badly damaged the Doris, was partially ascribed to the unfamiliar control column mounted tailplane trim lever, so when the glider was rebuilt this control was relocated further back in the cockpit. After the rebuild, completed in November 1922, the Doris flew from the Dresden club's airfield at Geising in the Ore Mountains. Some decent but unexceptional flights were made.[1]

Specifications

Data from Historische Deutsche Flugzeuge bis 1945[1]

General characteristics

  • Crew: One
  • Length: 5.30 m (17 ft 5 in)
  • Wingspan: 12.20 m (40 ft 0 in)
  • Wing area: 15.5 m2 (167 sq ft)
  • Aspect ratio: 9.5
  • Airfoil: Göttingen 441
  • Empty weight: 118.5 kg (261 lb)
  • Gross weight: 195 kg (430 lb)
  • Wing loading: 12.6 kg/m2 (2.6 lb/sq ft)

Performance

  • Maximum glide ratio: 14.5


References

  1. ^
    ISBN 978-3-923142-39-2
    .
  2. ^ a b c "German gliders". Flight. Vol. XIV, no. 38. 21 September 1922. pp. 546–9.
  3. ^ K. D. Jones, C. M. Dohring, and M. F. Platzer. "Experimental and Computational Investigation of the Knoller-Betz Effect", AIAA Journal, Vol. 36, No. 7 (1998), pp. 1240-1246.
  4. ^ Kens (2011). Historische Deutsche Flugzeuge bis 1945. pp. 121–5.

External links

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