Multi-Stage Rockets Have Been Exactly Depicted In This 16th-Century Book

The Sibiu Manuscripts That Defy Time:

The 450-page document, famous for mentioning liquid fuel and multi-stage rockets, together with the building methods, was discovered in Romania roughly 60 years ago by Doru Todericiu, a professor of Science and Technology at the University of Buchares, who retrieved it from the archives of the city of Sibiu (Sibiu public records Varia II 374), in 1961.
Writings and drawings illustrating medieval artillery, ballistics and multistage rockets were revealed, and some experts even doubt that it could date back even further than the 16^th century. The credits are given to a military engineer named Conrad Haas, hailed for being the initial individual in conceptualizing multistage rockets.

The Life Of Conrad Haas:

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Conrad Haas (1509–1576) was an Austrian or a Transylvanian Saxon military engineer from the Kingdom of Hungary, Transylvania. A pioneer of rocket propulsion, Haas has designed a 3-stage and a manned rocket, which was absolutely remarkable considering the era he was living in.
Haas was believed to have originated from Dornbach, now part of Hernals, Vienna, holding the post of Arsenal Master of the Imperial Habsburg army under Ferdinand I. He was invited to Hermannstadt, Eastern Hungarian Kingdom (now Sibiu, Romania) to be a weapons engineer and teacher at Klausenburg.

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There, Conrad Haas composed a German-language treatise on rocket technology, including the combination of fireworks and other weapon technologies. His work also involved the theory of motion of multi-stage rockets, different fuel mixtures using liquid fuel, and introduced delta-shape fins and bell-shaped nozzles.
In the last paragraph of his chapter on the military use of rockets, he wrote in German: "But my advice is for more peace and no war, leaving the rifles calmly in storage, so the bullet is not fired, the gunpowder is not burned or wet, so the prince keeps his money, the arsenal master his life; that is the advice Conrad Haas gives."

The Sibiu Manuscript And The Experiment Of Johann Schmidlap:

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Johann Schmidlap of Schorndorf was a 16th-century Bavarian fireworks maker and rocket pioneer. He published a book on fireworks, “Künstliche und rechtschaffene Fewrwerck zum Schimpff,” firstly printed in Nuremberg in 1561.
Schmidlap is believed to be the first to successfully fly staged rockets. It is said that he built his rocket based on the concept discussed in the work of Conrad Haas. He experimented with staging in 1590, using a design he called “step rockets.”
Before discovery of Haas’ manuscript, the first description of the three-stage rocket was in Poland credited to the Polish artillery specialist Kazimierz Siemienowicz in his 1650 work, “Artis Magnae Artilleriae Pars Prima.”