The Delta was built in 1932 by the G. Fieseler Werke in Kassel as the Fieseler F-3 Vespe, the intention being to enter this unorthodox aircraft for the Europa-rundflug held in that year.
The Delta IV alias F-3 was a tandem two-seat monoplane featurig a broad-chord wing with sharply swept-back leading edges and straight trailing edges occupied entirely by flaps and elevons. A small canard foreplane was provided by two 75 hp Pobjoy engines, one mounted in the nose and the other at the rear as a pusher. G. Fieseler himself piloted the aircraft on its flight and crashed. As a result of this accident Fieseler lost interest in the Delta IV, but Lippisch continued development. Flight rials were resumed with the aircraft designated the Delta IVa.
The Delta IVa, was found to posses extermely bad handling
chracteristics and was unstable, crashing during a landing approach. Dr. Walter Georgii of the DFS now came to Lippisch rescue, taking the Delta IV under the wing of the institute and rebuilding it as the Delta IVb. Succesful trials were conducted with the Delta IVb as a single-seater, and a second Delta IV airframe that of the Delta IVb was fitted.The fuselage was also extensively rebuilt, and the second aircraft flew in 1936 as the DFS 39 Delta IVc, testing being peformed by Heini Ditmar.
The handling characteristic of the Delta Ivc were exact antithesis of those of the Delta IV and IVa, and these coupled with the tailless configuration, prompted the request from the construction of a further airframe for testing the R I-203 bi-fuel rocket motor ten being developed by prof. Helmut Walter.