A tiltrotor aircraft has a vertical takeoff and landing flight mode and a forward flight mode. The aircraft includes an airframe having at least one wing. First and second oppositely disposed booms extend longitudinally from the at least one wing. Forward rotors are coupled to the forward ends of the booms and aft rotors are coupled to the aft ends of the booms. The forward rotors are reversibly tiltable between a vertical lift orientation, wherein the forward rotors are above the booms, and a forward thrust orientation, wherein the forward rotors are forward of the booms. The aft rotors are reversibly tiltable between a vertical lift orientation, wherein the aft rotors are below the booms, and a forward thrust orientation, wherein the aft rotors are aft of the booms.