Researching the history of
the design of helmets, I can only find a few things online.

It appears the post WW II
plastics industry recognized a potential market in replacing the
"labor intensive" hand stitched football helmet . Using
less then $ 5.00 of injection molded plastic they could make a helmet
shell, and then simply glue some padding inside.

First marketing move was
toward the "NFL", who after trials rejected it. ...  With
continued effort a few NFL teams began wearing them , leading the way into the High School and College markets .

I have yet to find any
records of testing done in the 1940 -  50 s...to evaluate the
concussion causing potential of introducing hard helmets to contact sports.

We do find numerous recent
scientific studies online indicating that helmet to helmet hits are dangerous and harmful , often effecting long term quality
of life .

 ---  Please ask your readers
for any early test information , other than marketing numbers or the
durability testing that checked helmets for strength and hardness .

Millions of football
players and future players may also be interested , along with their
parents , coaches and doctors .

Thanks again for your work and this forum.

G. Malcolm Brown