ORIGINAL: Espresso-Outfitters
In the 3 blade prop area, you have broken up the air with the previous prop a bit more so, the thicker the air, the more effiecient the prop, it's kind of like putting 2 motors and props operating independantly just behind each other, the rear prop only has the left overs from the front one -----
That does not actually happen in flight & only occurs under particular conditions on a test bench.