Daimler-Benz DB 007

The Daimler-Benz DB 007, called ZTL 109-007 by the German Air Ministry and ZTL 6001 inside the company, was an early German jet engine design that grew out of work begun by Karl Leist in 1939. It combined contra-rotating compressor stages with a ducted bypass fan, which makes it one of the earliest turbofan designs to reach the hardware stage. The mechanics were demanding: seventeen compressor stages were split between two drums turning in opposite directions, and a three-stage fan sat outside them with a bypass ratio of roughly 2.45 to 1. Bench testing began on 27 May 1943, but the Air Ministry stopped the programme in May 1944 because of the low performance expected, the complexity, and the good results of much simpler jet designs. Only bench testing was ever achieved.