On the Gravitron, a centrifuge carnival ride in the shape of a flying saucer, riders experience 3Gs for minutes. Best carnival ride as a kid, we rode it continuously for ages.
Oh god, I will never forget that ride. I was at a carnival when I was around 13 or 14 and rode that ride, and midway through it had a malfunction. They stopped it to address the issue, and then decided to give us an extra long ride to compensate for the problem. When it was finally over and I was about ready to stagger off of it, the operator got on the mic and said, “who wants more?!?” Seemingly everyone but me screamed for more. At that point I was too sick to make any sounds at all.
That night, hours later, as I lay on the floor of my friend’s bedroom (it was a sleepover), trying to fall asleep, I still remember feeling like the room was spinning. I never went back on that ride.
Funny, something really similar happened to me! 14 years old, at a friend's birthday party at Magic Mountain. The Superman ride was new. That's where you get into a bullet shaped gondola and get shot up a vertical tower, with a giant statue of Superman at its apex, go briefly weightless and then freefall backwards until you curve flat and brake to a stop. Never big on roller coasters, I got peer pressured into this one.
I didn't like it all that much. But what scared the hell out of me was when, on descent, the brakes malfunctioned. This caused the gondola to go screaming backwards past the platform where the next riders were lined up, fly through some butcher curtains and go crashing into a padded wall in a hidden cinder block cell at the end of the track.
We all sat there for a minute pretty stunned, and then some goofy employee came running out and jumped up on the front of the car. "Whoops! That wasn't supposed to happen!" He said. "But I have some great news for you! Who wants to go again??"
My brother and me tried this ~4 years ago (we are adults, but still, carnival is fun). I handled it well, but my brother was traumatized. I think you ought to check each future passenger if the sensation of being compressed and having troubles breathing won't trigger a phobia.