The Lippisch P.12, P.13a and P.13b were related design projects for a ramjet-powered delta wing interceptor aircraft studied in 1944 by German designer Alexander Lippisch. The P.12 and P.13a were unarmed, relying on reinforced wings to ram its opponent. The P.13a and b were to be powered by producer gas made in-flight from powdered coal. The DM-1 was a full-size glider, flown to test the P.12/13a low-speed aerodynamics.
The resulting design was initially assumed to use conventional liquid fuel and designated the P.12. But Lippisch had also become convinced of the benefits of solid fuel for short-duration high-speed flight and adopted this power source as the P.13. The design of both types then proceeded in parallel.
From autumn 1944, Alexander Lippisch had opened his own development office at the Aviation Research Institute Vienna (LFW) in Wiener Neustadt together with his mathematician from Messerschmitt Hermann Behrbohm on half-time (who still on half time worked for Messerschmitt in the underground facility of the Oberbayerische Forschungsanstalt in Oberammergau
The P.13a had reached a stage where full-scale aerodynamic trials would be possible. A glider with the same general design and wingspan, but with the intake and exhaust faired in, was built as the DM-1. Lippisch however took little interest; having moved on from the design, he set up the glider project only to keep students of Darmstadt and Munich Universities from being drafted into a by-then hopeless war. and lessons learned were incorporated into NASA's research aircraft of the 1950s and on.
P.13b
thumb|Modern drawing of the P.13b
Before the DM.10 was begun, in December 1944 Lippisch's attention moved to a revised design similar in some respects to the earlier P.11 / Delta VI but keeping the P.13a's sharp sweep angle and solid-fuel ramjet with rotating burner.
The wing was essentially that of the P.12/13 but larger at span and cut short at the front for unswept air intakes at the roots. Like the P.11 it had a conventional nose nacelle and cockpit with small twin tail fins either side of a centre section inset on the straight wing trailing edge. The landing skid was moved further back and refined, with a return of the early P.12's small downturned winglets or fins on the wingtips to act as outrigger bumpers when landing.
Wind tunnel tests had just begun by the time the Russians arrived in Vienna and Lippisch had to flee.