[Jared Smith]

I am wondering how reenactors and jousters pad the inside of their great helms? Given potential frontal impact, does anyone add padding around the chin, cheeks, or to protect eye glasses?

I am hoping there is something a little more elaborate than just gluing foam inside. (I have to believe historical men at arms had the same concerns. They must have done something other than foam and rubber glue!)

[Peter Lyon]

when I made my great helm in the late 80s, I made pads from carpet underfelt with a casing of light canvas, and glued them into the sides and back of the helm, and made a thick donut to go into the top, which allowed some air flow but separated my head from the top and sides of the helmet. This was worn over a padded coif, so there was a lot of padding. I used it a lot for foot combat, and later for jousting. In one case I saw in a video that a lance had hit the side of the helmet and knocked my head sideways, but at the time I was unaware of the hit, so clearly the padding (and a bit of adrenaline) worked.
I am cautious about using modern foams for padding, as some can crush down to almost nothing under impact, and give very little protection. A firmer foam might seem less protective, but is much better for the times when the helmet gets a big hit (EG falling of a horse). I prefer underfelt or raw wool.