1944 proved a critical year for Germany and its fabled Luftwaffe. Once a master of the skies, advanced products fielded by the Allies in number soon began to remove the German initiative. The Allied reach had expanded to unacceptable lengths, able to target all German-held territories and even German soil itself - no part of the Reich in Europe was safe now. This brought into question the levels of defense for Germany and, in particular, what was being done to counter the threat of American heavy bombers during the day and British heavy bombers during the night. As such, various programs were enacted - primarily through the "Emergency Fighter Program" born on July 3rd, 1944 - to find viable defensive-minded interceptors capable of reacting swiftly to incoming enemy flight groups and engaging bombers with appropriate armament.
Ernst Heinkel headed the Heinkel AG concern which was best known for its He 111 Medium bomber of Battle of Britain fame. The German Air Ministry (RLM) charged any interested German aviation firm with submitting a proposal for an inexpensive single-seat, turbojet-powered interceptor. Four companies responded with varying designs including Heinkel, Messerschmitt, Bachem and Junkers. The Heinkel submission - P.1077 - was selected ahead of the others. However, the Bachem P.20 went on to be evolved into the operational Ba 349A "Natter" ("Viper") along another avenue. Design of the P.1077 originated with Wilhelm Benz and was given the program name of "Julia".
The P.1077 "Julia" was developed along two lines: in one form, the pilot was fitted in a prone position, the intent being to keep the fuselage as slim (and profile small) and aerodynamic as possible under the thrust of rocket power; in the other form, the pilot sat upright in the traditional manner. The former design trend was ultimately selected for further development - engineers convinced of the layout's benefits. To further simplify manufacture, the Julia would not be fitted with a conventional undercarriage - instead it would be launched from guide rails and glide down to land onto provided integral skids under the fuselage. The cockpit would include only the most basic of instrumentation to keep manufacturing/procurement costs down and ease training of potential pilots.
Key to the success of the Julia was its intended powerplant based on rocket propulsion. In question was the Walter HWK 509C series dual-chambered, liquid bi-fuel rocket motor promising a thrust output of 3,750lb. As take-off was required to commence at quickly as possible (in the hopes of intercepting incoming bomber formations in time), the airframe was further outfitted with 4 x Schmidding 533 series booster rockets with 2,650lb thrust each to be used during launch, jettisoned only after their fuel supply had been spent.