Into a Motor Glider
The fs26 represents the Akaflieg Stuttgart’s first foray into the field of motor gliders and it can be described in three points:
- Pusher configuration
- Tailless design
- Separate elevator
It was decided however to keep the construction of the aircraft as conventional as possible. As an example of this, the forward fuselage was taken over from the Phoebus sailplane. The already tight space inside the aircraft was made even tighter as the addition of an engine necessitated the addition of seven levers and three display instruments. Nevertheless, it was possible to make even the nose wheel retractable. Due to the lack of space inside the fuselage, exacerbated by the addition of a propeller and the length of the main undercarriage, the decision was made to make the undercarriage operate hydraulically. The Hirth F 10A engine was chosen to power the plane. When gliding, standard procedure is to feather the propellers and close all air inlets. In addition to being an experimental motor glider, the fs26 was also used to test the feasibility of cooling pusher engines using regular methods.
While designing the connections for the three-piece wings, a point of consideration was that the fs26 should still be easily road transportable and that unnecessary weight should be dispensed with. On the fs26, the forces on the wing spars are transferred via bolts from one flange to the other. This connection was extensively tested to check its feasibility. A weight reduction of 23% was achieved using this connection when compared to a tongue-fork connection.
The fs26 can be found at the Sailplane Museum at the Wasserkuppe.
|Construction||1969 – 1970|
|First flight||25 September 1970|
|Construction method||GRP-Balsa Sandwich|
|Wing area||13,2 m²|
|Wing sweep||0° (t/4)|
|Aileron area||0,464 m²|
|Tailplane area||1,32 m²|
|Vertical stabilizer area||2 x 1,13 m²|
|Empty weight||250 kg|