In the closing years of the Second World War, German aeronautical engineering produced some of its most radical and visionary concepts — none more extraordinary than the Lippisch P 13a. Conceived by Dr. Alexander Lippisch, the P 13a was a tailless delta-wing ramjet interceptor designed to fly on coal dust — one of the most unconventional propulsion ideas ever seriously pursued in aviation history.
The Concept
By 1944, Germany faced a critical shortage of aviation fuel. Lippisch's response was audacious: design a high-speed interceptor powered by a ramjet burning granulated coal. The P 13a was conceived as a point-defence interceptor capable of reaching speeds exceeding 1,650 km/h — supersonic performance that would have placed it far ahead of any Allied fighter of the era.
The airframe was a pure delta configuration, with no horizontal tail surfaces. A wire mesh basket in the centre of the ramjet intake would hold the burning coal charge, sustained by the ram air forced through the duct at high speed. The pilot sat in a prone position to withstand the anticipated g-forces.
The DM-1 Glider
To validate the aerodynamics of the delta configuration, Lippisch's team constructed the DM-1 — a full-scale unpowered glider testbed. Captured by American forces in 1945 before it ever flew in Germany, the DM-1 was shipped to the United States and tested at NACA Langley. Its data directly influenced post-war American delta-wing research, including the Convair XF-92 — the grandfather of the F-102 Delta Dagger.
Legacy
The P 13a never flew in powered form. Yet its influence on post-war aerodynamics — particularly in the United States and France — was profound. Lippisch's delta-wing philosophy lived on in the Convair family, in the Mirage series, and in every supersonic delta that followed.
At Online Aviation Library, we don't teach — we tell stories. The Lippisch P 13a is one of the most compelling stories in the history of aviation engineering: a coal-burning interceptor that never flew, yet shaped the supersonic age.
Watch: Silvio's Story of the Lippisch P 13a
In this video, Silvio walks through the history, engineering, and legacy of the P 13a — from Lippisch's drawing board to the NACA wind tunnels of post-war America.