Passive sickness is fairly common, I had it during the first batch of contact rides in texans. I am grateful I went thru T-6s and not 37s, or I am fairly certain that I would have had active airsickness in a sortie. The T-6 A/C works as advertised, the Tweet, well it's a Cessna and those of us prior civi types know the Cessna experience lol.

At any rate, I hadn't been passive airsick since steep turns during my PPL training and my CFI checkride. This tells you being dehydrated (4 hr checkride) and being new to airplane motion (PPL training) will cause you to have airsickness. The problem is accentuated by the fact that UPT is an accelerated program and your diet during the day at UPT is sub-par at best (no time to sit back and enjoy a decent meal). Assuming you are not one of the types that will absolutely have a hard time and will need time off-base to fix it, and rather have an average predisposition to airsickness: drink a ton of water, keep yourself as cool as possible in the plane, pace yourself in the flight (it comes with time) and lastly...take GINGER PILLS before the flight. Man that was my little secret in contact and brother they worked like a champ! I went from having to fight passive airsickness (you know when you are when the sweating floodgates open, you start salivating like crazy, [salivating induces vomiting]) at the end of the sorties, to flying solid the whole sortie. There was a little placebo effect, knowing beforehand the pills had worked phsycologically helped me get through the inner ear acclimating sorties that is contact phase. Later on, the pills were not as necessary. Good luck and drink lots of water!