How do ride Envelopes keep you safe

Email from Subscriber
I like to ride with my hands up... Is that dangerous? What if someone like Victor Wembenyama did this? How do manufacturers and maintenance staff calculate the clearances of "head chopper" moments on rollercoasters?

TODAY WE WILL BE DISCUSSING HOW RIDE VEHICLES AND PEOPLE FIT WELL WITH THE INSIDE OF THE REACH ENVELOPE OR THE RIDE ENVELOPE AS A TRAIN MOVES AROUND THE TRACK