Maximum card: Hermann Oberth, one of the three founding fathers of rocketry and astronautics

Hermann Oberth...Tsiolkovsky...Goddard.
Sometimes, it takes more than 1 father.

"Hermann Julius Oberth (25 June 1894 – 28 December 1989), born in Transylvania, România, then part of Austria-Hungary, was a (Transylvanian Saxon) physicist and engineer, who along with the Russian Konstantin Tsiolkovsky and the American Robert H. Goddard, was one of the Founding Fathers of rocketry and astronautics. The three never were active collaborators, and in fact, never knew one another: instead, their parallel achievements occurred independently of one another."
"In the autumn of 1929, Oberth conducted a static firing of his first liquid-fueled rocket motor, which he named the Kegeldüse. He was helped in this experiment by his students at the Technical University of Berlin, one of whom was Wernher von Braun, who would later become a giant in both German and American rocket engineering from the 1940s onward, culminating with the gigantic Saturn V rockets that made it possible for men to land on the Moon in 1969 and in several following years."
http://en.wikipedia.org/wiki/Hermann_Oberth