On Monday, June 3, 2013 11:17:28 AM UTC-5, wrote:
On Sunday, June 2, 2013 10:30:54 AM UTC-7, Sean F (F2) wrote:

http://youtu.be/o0twY9cWOUg



What was the effect of the blades upon performance?

Here is a copy from Wikipedia on Idaflieg:

After the war, the Akafliegs re-formed in 1951, co-ordinated by Interessengemeinschaft Deutscher Akademischer Fliegergruppen e.V. (Idaflieg – interest group for German academic flying groups), with ten groups formed by 2009.
The aim of the Akafliegs is scientific research into flight development, as well as design and construction of aeroplanes, especially gliders. Much of the practical work is done at the summer meetings of the 'Idaflieg' in co-operation with the German Aerospace Center (DLR), while the results of the research are presented at the winter meetings. The 'Idaflieg' also offers many events and courses to its members such as the specification, design and certification of aeroplanes.
Test results are presented at specific scheduled events, written reports are not normally available. Results are mostly shared only with the manufacturer of the tested equipment.
Herb