Here is my first mod. http://www.nexusmods.com/fallout4/mods/12564/? Kinda does what the others posted do but slows the thrust so you can control and doesn't go as high so you don't reappear back at ground level. I believe jetpacks already drain Fusion Cores just like sprinting in PA but trying to figure how to adjust Fusion core drain while jetpacks are active. If I figure that out I'll update.