Perhaps you should try some spelling variations:
unmanned arterial » unmanned arial, skinned arterial, unmanned area
arterial vehicle » aerial vehicle, lateral vehicle, criteria vehicle
damaged arterial » damaged bacterial, damaged material, damaged materials

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((( unmanned arterial vehicle ) OR ( damaged arterial vehicle ))) OR ( unmanned aerial vehicles )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(((( unmanned arterial vehicle ) OR ( damaged arterial vehicle ))) or ( unmanned aerial vehicles ))".
• Adding a wildcard symbol may retrieve word variants: (((( unmanned arterial vehicle ) OR ( damaged arterial vehicle ))) or ( unmanned aerial vehicles ))*.