The First Retractable Undercarriage
The fs18 arose from experience gained from the Rhön Gliding Competition. It was designed to be able to thermal tightly with as little sink rate as possible. Six months were available for the construction of the plane.
The fs18 has a high-wing configuration. Its wings are square in the innerside with trapezoid outer panels. There’s a kink at the 4 m span, where the two-piece aileron begins. The wings are also equipped with flaps, with a depth of 30%. They are attached perpendicularly to the fuselage to reduce interference drag at the wing root as much as possible.
The fs18 was the first sailplane to receive a retractable undercarriage. The wheel is in its retracted configuration fully covered inside the fuselage contour, with the wheel well being covered by the undercarriage doors. As with the F.1 and fs16, the fuselage behind the wing is raised upwards.
On the 7th December 1938, the fs18 was destroyed in a plane crash which killed its pilot, Ernst Scheible.
Specifications
Construction | 1938 |
First flight | 21 July 1938 |
Method of construction | Wood |
Wingspan | 18 m |
Wing area | 18 m² |
Aspect ratio | 18 |
Profile | NACA 23012 thickened to 23018 between 1,5 – 0m |
Dihedral angle | 5° |
Wing sweep | 5° |
Aileron area | 4,9 m² |
Flap area | 3,5 m² |
Elevator area | 1,425 m² |
Rudder area | 1,0 m² |
Length | 8,7 m |
Height | 1,75 m |
Empty weight | 215 kg |
MTOW | 315 kg |
Glide ratio | 26,9 |
Best glide speed | 78 km/h |
Min. sink speed | 53 km/h |
Landing speed | 37 km/h |
Ultimate load factor | 10g |