After the Jumo 004 had entered serial production, the Technical Department of the RLM requested Junkers to build a much larger engine capable of powering the heavy jet bombers then under development for the Luftwaffe.
Initially, Junkers proposed modifications of the Jumo 004, specifically the 109-004G and 109-004H.
[1] The engine was to feature an 11-stage axial compressor enclosed in a sheet-steel casing and a 2-stage, air-cooled turbine.
The RLM ordered ten pre-production examples of the 109-012 to be built at Dessau for testing, where several parts for the engines including nine exhaust cones were already completed.
[1] Data from [citation needed]An episode of The Antiques Roadshow filmed at Powis Castle in summer 2022 featured a blueprint of the Junkers 0-12.