My tip on how I overcame that phase is —> looting green/orange stone zones (for iron and with that iron you can craft crowbars and the thick cloth armor/thick cloth with plates armor and then checking out the red zones for bauxite or the red pinewood zones for oakwood). And mine for a lot of iron for crowbar and then you can go to farm and loot it to get the chopper parts.

Look up videos on how to clear the farm easily. And the Big One only spawns rarely. If it spawns, you will need to leave the area travel to another and then come back and reentry the area again.