My Dad worked for Hughes Aircraft briefly in 1946 before being appointed engineering project manager at Douglas on the DC-6. He mentioned that Howard was at the plant at least three days per week "supervising" the construction. Also a man could walk upright on a cat-walk behind the engines until just past the outboard engine. A very LARGE wing.
We had a table at home for years that was made from the 28-ply spar cap birch plywood.
A truly amazing aircraft which, I suspect needed at least 4 more engines. Clearly, Howard Hughes was...."one of a kind".