Technical expertise, training and beautful illustrations / diagrams by Fred Freeman:
It is a shame that it doesn’t seem to exist a single website dedicated to Fred Freeman works. Not even a Wiki article, for god’s sake!
The only I could find are some illustrations here and there:
Collier’s Space Flight Series
The incredible Fred Fremann
The book via the always amazing: Paleofuture. Keep reading it for further illustrations by the same author.