it's called onomatopoeia, child
use google chrome, it has a built-in spelling corrector
there are dozens of things you could use for a flying object such as that of a flying... paintball
but
an onomatopoeia is based off of a sound that the object in question makes
does a flying paintball really make a sound
do they even have to be real
sometimes i doubt this
flying -
zoomed
whizzed
whooshed
hitting a barrel (why does the barrel have any importance)
splat
pow
squish
boom
also I haven't looked it up but there's bound to be some sort of website dedicated to more extensive real onomatopoeia
whatever