I wanted to know if Goddard and vonBraun knew each other, and yes, they were friends.
https://www.famousscientists.org/robert-goddard/
Von Braun would not have existed without Goddard.
It was Hermann Oberth’s earlier correspondence with Goddard when he and Von Braun started the Vereinigung fur Raumschifahrt (VfR) in 1929 that allowed Oberth and Von Braun to move forward so quickly.
When he was questioned about the V2 design by OSS in 1945, he asked them why they didn’t just talk to their own guy Goddard...since it was basically his design.
Oberth had independently derived the relevant equations for powered flight but lacked the practical capabilities like designing a turbopump. Goddard didn’t tell him everything because as the years went on, cooperating with Germany became increasingly dangerous. But their exchanges in the ‘20s had a tremendous impact on the Von Braun and the others in the VfR (like Hohmann, Riedel and the famous Willy Ley).