Over in 72 Land Kevin Callahan has finished his Special Hobby Sack AS 6. I happened to see this at the same time as Tom GF was reviewing Stephen Ransom's brief history of Brandis airfield "Zwischen Leipzig und der Mulde" at his German Aviation 1919-1945 blog Like all of Tom's recommendations this little booklet is well worth tracking down - especially as amazon.de re-sellers have copies on offer for under 10 euros. The connection is Ransom's treatment of the Sack AS 6 on page 61 of his Brandis history. He provides some fascinating information..
Circular wing aircraft planforms were all the rage in America in the 1930s and for a time post war. In fact the American "flying flapjack" flew well enough, but these designs were ultimately no more than aeronautical cul-de-sacs. The Luftwaffe 'sponsored' a similar concept - although their machine was dreamt up in his barn by a farmer, Arthur Sack from Mackern in Saxony (north-east of Leipzig). Sack was an aero-modeller who had entered his flying model in a contest in Leipzig in 1939 and where he had apparently met Ernst Udet who had encouraged him to continue his 'design' work. By early 1944 Sack had built his first piloted Kreisflügler circular wing design 'aircraft', since designated the Sack AS 6 (or the Sack AS 6 V1 according to Special Hobby). Sack then apparently persuaded the Kommandant of his local airfield to allow some developmental work to go on at his airfield - only in this case the local airfield was Flugplatz Brandis, where later that year highly secret and state-of-the-art designs such as the rocket-powered Messerschmitt Me 163 point interceptor and the amazing forward-swept wing Junkers Ju 287 jet bomber were being test flown and operated!