Onomatopoeia:
* Whap!
* Whack!
* Whip!
* Crack!
* Snap!
Descriptive:
* The sound of a whip cracking.
* A sharp, sudden sound.
* A loud, resonant sound.
* A cutting, piercing sound.
Literary:
* The air hissed as the whip cut through it.
* A sound like a thousand tiny explosions.
* The sound of power unleashed.
The best way to spell out a whipping sound is to choose a word or phrase that best captures the sound's specific quality and the context in which it occurs.