Indeed, he was part of a team that built rockets. I even said his role was unclear to me. Can you link to any document detailing his involvement?
Edit: Please don't take this as a diss on his work. Just because one didn't play a role in designing the rockets, doesn't mean they were not crucial to the project.
Have you read Masters of Doom or even Googled the question?
http://bfy.tw/H8Z5