Propeller shape affects the load on motor

Hi I’m looking for a theoretical explanation for my test results. I did bench test with 4 different carbon fiber propellers. 15x6.5, 16x5.5, 17x5.5 version 1 and 17x5.5 version 2.
17’’ v1 and v2 are different in design and shape.

With 15’’ prop, 70% throttle I got 2550g thrust at 16amps,
with 16’’ prop, 70% throttle I got 2950g thrust at 20amps
with 17’’ version 1, 70% throttle, 3400g thrust at 25amps
with 17’’ version 2, 70% throttle, 3400g thrust at 19amps…

Both 17’’ props give me the exact same thrust but with different amount amps drawed. weight difference is only few grams, so I would say that is not the issue. 15’’ prop at maximum throttle gives me 3700g thrust at 28amps and 17’’ version 2 gives me 4800g thrust at only 25amps… Logically propeller with bigger diameter and pitch draws more amps. This test proved otherwise…

How to theoretically explain how the shape of propeller affects the load on motor? Is it bound to drag? Or maybe how the weight is shared on the propeller?

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