Simply Jetpacks Energy and Charging

• Jetpacks store energy (FE) and drain it while flying; the drain rate scales with the throttle.
• Each tier has its own capacity - higher tiers hold more energy and fly faster.
• Charge a jetpack in any machine or device that outputs energy into items.
• Fluxpacks work the other way around: worn in the chest slot, they discharge their stored energy into the equipment you are wearing, keeping energy-using gear topped up in the field.
• The creative jetpack ignores energy entirely - infinite flight with no charging.

An empty jetpack will not fly - the engine simply produces no lift until the pack is recharged.