Standard Class High Performance Powered Sailplane (not capable of self-launching)
- Very simple engine control
- Low weight of power plant
- "Sawtooth"-range approx. 160 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 lighter weight.
Even a comparison with pure sailplanes comes out in favour of the "Turbo" propulsion system, since the penalties in performance and handling are virtually non-existent. Their utilization spectrum, however, is widely surpassed:
Not only may dead-air conditions be overcome and off-field landings safely avoided, the "Turbo" sustainer engine is also well suited for iosoaring safarislg or for instance, exploratory wave flights (thanks to its acknowledged fine airfoil section the approx. 0.8 lb/ft 2 higher wing loading is taken with ease).
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 multi-function control unit, purposely developed for the "Turbo" system. Its LED signals provide information on RPMs, battery voltage, extreme positions of the power plant etc.
The only engine controls are ignition switch, fuel shut-off valve and decompression handle. Starter, choke or throttle are not needed.
The engine is started by the windmilling effect of the multi-blade folding propeller at about 70 knots and is preset to operate at full power. It is stopped by switching the igniton to "OFF" and reducing the speed to about 49 to 54 knots. Once the windmilling propeller has stopped, the power plant is retracted regardless of the position of the propeller blades - they fold up automatically.
For sanctioned contests, the DISCUS-2T can be quickly restored to a sailplane complying with the Standard Class rules, as the engine, propeller and battery are quickly removable (thus giving a weight saving of almost 66 lb).
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