A scale model of the P12/13 configuration was successfully tested at Spitzerberg Airfield, near Vienna in Austria, in 1944.
The P.13a had reached a stage where full-scale aerodynamic trials would be possible. A glider with the same general design and 6.7m wingspan, but with the intake and exhaust faired in, was built as the DM-1. The DM-1 had not been finished when it was captured by American forces. The Americans ordered Lippisch's team to complete the glider, and it was then shipped to the United States where it was test-flown.

(Artist's view)