Lets hear your idea's for cooling a helmet down besides fans which only circulate old air. I had an idea going to use a small cpmouter cool pump that would fit in a pouch and had two hoses one for the helmet and another for the armor under the vest.
I had an idea of using something like that. They have a smaller pump in a computer store at Bestbuy here but its not on there website. It can be run from 2, 9 volts for a few hours according to the salesperson.