A heat exchange system for use in operating equipment in which a working fluid is utilized in providing selected operations thereof, the heat exchange system providing air and working fluid heat exchanges to cool the working fluid at selectively variable rates in airstreams occurring with uses of the equipment, the system being arranged upstream of a turbofan bypass airstream nozzle, characterized in that the system comprises: a plurality of heat exchangers (14, 24) each having a core with a plurality of passageway structures (15, 25) therein about which air can flow with the passageway structures being connected to an input conduit at one end thereof and connected to an output conduit at an opposite end thereof to enable providing the working fluid to, and removal from, interiors of the passageway structures through interiors of the input and output conduits, a first heat exchanger in the plurality of heat exchangers being mounted stationary in a lower bifurcation structure having at least one movable exit flap so as to permit corresponding portions of the airstreams to pass through the core thereof during at least some such uses of the equipment; a second heat exchanger in the plurality of heat exchangers mounted with respect to the equipment so as to selectively permit corresponding portions of the airstreams to pass through the core thereof during such uses of the equipment; and a core actuator mounted with respect to the second heat exchanger to selectively increase or reduce the passing of those corresponding portions of the airstreams through the core thereof during such uses of the equipment, wherein the core actuator forces the core of the second heat exchanger into selected positions in portions of the airstreams to thereby pass at least in part therethrough during such uses of the equipment; wherein the airstreams include a turbofan airstream and occur on a stream side of a wall provided with the equipment during uses thereof and the second heat exchanger is mounted to be substantially located on a side of the wall opposite the stream side thereof with the core actuator positioned therein so that the core of the second heat exchanger can be moved to selected positions with respect to an opening in the wall such that at least this core is extendable by the core actuator through the opening for selected distances into that region to be occupied by the airstreams on the stream side of the wall during uses of the equipment so that the portions of the airstreams corresponding thereto pass at least in part through this core, and with this core being selectively retractable from those distances. a plurality of heat exchangers (14, 24) each having a core with a plurality of passageway structures (15, 25) therein about which air can flow with the passageway structures being connected to an input conduit at one end thereof and connected to an output conduit at an opposite end thereof to enable providing the working fluid to, and removal from, interiors of the passageway structures through interiors of the input and output conduits, a first heat exchanger in the plurality of heat exchangers being mounted stationary in a lower bifurcation structure having at least one movable exit flap so as to permit corresponding portions of the airstreams to pass through the core thereof during at least some such uses of the equipment; a second heat exchanger in the plurality of heat exchangers mounted with respect to the equipment so as to selectively permit corresponding portions of the airstreams to pass through the core thereof during such uses of the equipment; and a core actuator mounted with respect to the second heat exchanger to selectively increase or reduce the passing of those corresponding portions of the airstreams through the core thereof during such uses of the equipment, wherein the core actuator forces the core of the second heat exchanger into selected positions in portions of the airstreams to thereby pass at least in part therethrough during such uses of the equipment; wherein the airstreams include a turbofan airstream and occur on a stream side of a wall provided with the equipment during uses thereof and the second heat exchanger is mounted to be substantially located on a side of the wall opposite the stream side thereof with the core actuator positioned therein so that the core of the second heat exchanger can be moved to selected positions with respect to an opening in the wall such that at least this core is extendable by the core actuator through the opening for selected distances into that region to be occupied by the airstreams on the stream side of the wall during uses of the equipment so that the portions of the airstreams corresponding thereto pass at least in part through this core, and with this core being selectively retractable from those distances.