been in loads of green and black choppers, army, no probs. went in one traffic reporting chopper and couldn't see out very well ( they stuck me in the middle seat with no real view of the sceanery ) and pukked me self silly.
the moral of this is get a window seat and make sure it's not to windy when you go up.
if it's a touristy grand canyon type then enjoy , it's fantastic.
take some travel sick tablets hour and a half before you go and if you think you need to, top up just before you fly with one more tablet. (obviously be carefull on the dosage and read the instructions before doing how i said)