Standard Class High Performance Powered Sailplane (not capable of self-launching)
- Very simple engine control
- " Low weight of power plant
- "Sawtooth"-range approx.190 nm
- good climb rate
An idea is spreading .......... and today there is a world-wide operated and proven alternative to self-launching motorgliders and pure sailplanes: The "Turbo" propulsion system for Schempp-Hirth aircraft (by Prof. Oehler).
Compared with self-launching sailplanes, the greatest advantages are the uncomplicated structure of the power system, the simple control and maintenance, the associated operational reliability and in particular, the considerably lower weight.
The SOLO two-cylinder, two-stroke engine (type 2350, 15.3 kW) is extended and retracted by means of an electrical spindle drive, which is operated by an ILEC control unit, purposely developed for the "Turbo" system. Its LED signals provide information on RPMs, battery voltage, extreme positions of the power plant etc. As no starter motor, choke or throttle is required, the "Turbo" system is extremely simply operated. The engine is started by the windmilling effect of the five-blade propeller at about 62 knots and runs at the preset continuous power.LED signals indicate the normal RPM operating range and also caution of excessive engine speeds. Should the permissible RPMs and the associated flying speed be exceeded though, an ignition cut-off device will prevent the engine from over revving. Stopping it is by switching the ignition off. At a speed of approx. 51 knots the power plant is partly retracted until the rear-vision mirror shows the prop hub just above the fuselage deck. In this attitude the prop stops spinning within a few seconds and can be fully retracted regardless of the position of its blades as they fold up automatically.
The 18m version with about one square meter more wing area than the standard class version allowes even by higher empty mass (caused of the "Turbo" propulsion system) a very low wing load and a exceptional climb rate. In comparison to the 15 m version, the wing span with 18 m wingtips increases the "sawtooth" flight range by about 30 nm, to 190 nm. This "Turbo" propulsion system offers in both wing tips versions a clearly wider flight spectrum as the non motorised version.
Not only may dead-air conditions be overcome and off-field landings safely avoided, the "Turbo" sustainer engine is also well suited for soaring safaris or for instance, exploratory wave flights.