im shooting gold tip 5575 xt hunters ,in the past my arrows were just straight fletched the ones i just bought are fletched with a helicle ,the helicle arrows never shoot the same spot twice so i went and shot the straight fletched it was a bullseye everytime whats the difference?COULD SOME ONE ELABORATE ON THIS FOR ME?

question 1, why wont these arrows fly like the others?

question 2,does the arrow with helicle slow down my speed?