This is a Skywalker Sound sound effect that is only available on Sound Ideas Canada Ltd.'s Soundstorm Sound Effects Library as Sound Ideas, Explosions - Incoming Artillery - C U - Very Good, Explosions With Incoming Whoosh Of Shell, Large Concussive Whumps From Explosion, Some Whistles An. It may be considered as a stock sound effect. Links: https://soundeffects.fandom.com/wiki/SKYWALKER,_WHOOSH_-_ARTILLERY_FALL_01#Audio_Samples