Complex sentence: The rack contains small explosive cartridges to disengage the suspension hooks and propel the store clear of the aircraft in a consistent manner to aid in accurate aiming of unguided gravity bombs.
Split into simpler sentences: The rack contains small explosive cartridges to open the suspension hooks and push the store clear of the aircraft in a predictable manner. This is necessary both for proper separation of the store from the aircraft, and to aid in accurate aiming of unguided gravity bombs.