Why can't I slide the throttle all the way up?
When you first start using your Helo TC app, you'll notice that the throttle slider only seems to go about halfway up the "Lift Off" controls on the left of the HELO TC app. This is a limiter to help new pilots ease into controlling HELO TC without taking an unplanned flight to the wall or ceiling.
After you've logged enough flight time, you'll get an in-app option to turn off that limiter. If you feel that you're a bit ahead of the game and would like to turn off the limiter early, just tap the gear icon to go to HELO TC's settings and turn Expert Mode to "On". This will remove the limiter.