Derived from his Arado Ar 79, the basic design shared by all models was that of a conventional low-wing cantilever monoplane with retractable tricycle undercarriage and all-metal construction.

The Bl.500 prototype was built for Blume at the Focke-Wulf plant and was powered by a Lycoming O-320 engine of 112 kW (150 hp).

This led to a modified version, the Bl.502 that achieved German type certification and was offered for sale alongside the generally similar Bl.503 with a more powerful engine.

However, no orders were forthcoming and Blume abandoned the project.

Data from Jane's All The World's Aircraft 1961–62[1]General characteristics Performance