Konstantin Tsiolkovsky and what American credited with creating and building the world's first liquid-fueled rocket, made  theoretical and practical breakthroughs for spaceflight?
Robert H. Goddard: Robert Hutchings Goddard (October 5, 1882 – August 10, 1945) was an American engineer, professor, physicist, and inventor who is credited with creating and building the world's first liquid-fueled rocket.
i don't know