Delta says a personal item is a purse, briefcase, camera bag or diaper bag. Or something similar on size. I'd say the hardshell is bigger than those items. You could try but I think you'd run the risk of them telling you no and charging for an extra bag. I have only taken my drone on as a carry on, not as a personal item in addition to a carry on. When the flight is full they get very picky about these things.