NATIONAL HARBOR, Md. – The Marines’ RQ-21A Blackjack small tactical unmanned aerial system will finish its testing this summer and begin workups with a Marine Expeditionary Unit this fall, as contractor Insitu continues to improve the system’s endurance and develop new payloads for the Marines and international customers. The group-3 UAV recently finished its land-based initial operational test and evaluation at Twentynine Palms, Calif., and is almost done with its ship-based developmental testing on the USS New York (LPD-21), Col.…