The vertical take-off trials were conducted on high ground called the Ochsenkopf at the "Truppenübungsplatz" (military training area) Heuberg near Stetten am kalten Markt, Württemberg. The first successful unmanned vertical take-off from the experimental launch tower occurred on 22 December 1944. The test machine, the M16, was powered only by the Schmidding solid boosters, as were all the early vertical launch trials. Up to and including 1 March 1945, 16 prototypes had been used, eight in glider trials and eight in VTO trials.