Together with Wilhelm Gundermann he developed a series of experimental engines, including the HeS 3B which powered the world's first jet aircraft, the Heinkel He 178, in 1939.

The RLM or Reichsluftfahrtministerium ("Reich aviation ministry") nationalised his company, and in 1942 it was taken over by Heinkel to form Heinkel-Hirth.

Because of the prohibitions on German aviation in this period, Hirth manufactured small marine and stationary engines, as well as motors for snowmobiles.

[3] In 2011 Gobler-Hirth were developing UAV piston engines to run on heavier jet fuel, because of its higher energy density and ease of handling.

The Skeldar range of UAVs, originally developed by Saab, have introduced Hirth's heavy-fuel piston engines to the marketplace, alongside their established gasoline-fuelled products.