Electric winch
Innovation through tradition
The German Alpensegelflugschule has been known for its pioneering achievements since day one.
A good example, in addition to aero tow with motor gliders and the usage of electric carts for aircraft-recovery, is the world's first four-drum electric winch.
The winch was designed, constructed and built by Rüdiger Ettelbrück, who, with the active assistance of Paul Möller, also mounted the winch in the DASSU workshop.
The construction and development took about 1 year and the assembly time 6 months (all in their spare time).
In October 1995, the first test runs and trial starts were carried out. Since then the winch is successfully in operation and has completed around 272,000 launches until the end of 2017
The winch launch in Germany is still the most common method to get a glider up in the air; DASSU successfully applied the winch starting method since 1954. With the significant increase in takeoff numbers in Unterwössen, however, the capacity of a conventional double drum winch could no longer keep the pace. There were more and more bottlenecks, which could only be solved by using two parallel winches. From experience with the use of two twin-drum winches with internal combustion engines and the resulting problems in terms of operating noise, exhaust gases, maintenance and operating costs, the idea of a stationary constructed four-drum electric winch was born.
The fuel consumption for a tow with the diesel winch is about 0.5 l of diesel. The energy requirement for an electric winch start is on average 1 kWh.
The maintenance costs are below expectations. Wearing parts are essentially the brake pads of the exhaust brake and the potentiometer for the settings of speed and torque. Only the frequency converter had to be changed twice in 23 years of operation.
The cable wear and the number of cable breaks has been reduced to 25% compared to the diesel winch.
In the season of 2003, plastic ropes were used for the first time instead of the usual steel ropes. The advantages of plastic ropes are quit convincing:
Increased towing height (about 10%). Less energy used to pull back.
Better acceleration (lower mass).
Easy splicing, less downtime after a cable break.
Much easier handling when hanging up (weight)