You are a member of a prestigious flight club based on a secret remote island. To show just how exciting your flying club is, you plan a flight around the world! What makes this flight challenging is that the fuel tanks of your airplanes have enough fuel for only half the trip. What is the minimum number of members you need in your club to successfully complete this trip?

The expected rules apply:
You cannot refuel anywhere except on your secret hidden island base.
You have the tech to do 0-time air refueling (from plane to plane)