[HELP] Green Goblin Glider v1.1

I wanted to make green goblin hovercraft with touch tilting of rocket (1st step of construction then I'll add horizontal stabilizer and velocity) but since yesterday I don't find how to make a good recognition of my finger on the screen to indicate the good way of the rocket vector. Can I get help please?

Update: improved after ZardOz hints. Is it better? I still don't understanding how to make better angle recognition