Militky Brditschka MB-E1
Heinz W. Brditschka also converted an HB-3 airframe in 1973 to have electric power, in which form it was known as the Militky MB-E1; Fred Militky, who designed the installation of the 13hp Bosch electric motor that replaced the piston engine, was an engineer with the Graupner model-building company, and used his experience with electrically powered radio-controlled models to produce this first electric motor glider. This made what is claimed to be the first ever manned electric-powered flight on 21 October 1973.
The silent Militky Brditschka MB El made its 9 minute maiden flight on October 21 1973. Power was provided by a standard Bosch 10kw electric motor and Varta batteries, giving 13 hp.