Aircraft heat exchanger

A heat exchanger for heat transfer between an external first flow along a first flowpath and a second flow along an internal second flowpath, the heat exchanger comprising:

• a first manifold;
• a second manifold;
• and
• a plurality of tubes extending from the first manifold to the second manifold and having respective interiors bounding respective legs of the second flowpath, wherein:
• the plurality of tubes comprises a plurality of groups of tubes;
• for each of the groups of the tubes:
• the tubes of the group have first ends mounted to the first manifold at respective first locations;
• the tubes of the group have second ends mounted to the second manifold at respective second locations;
• from the first manifold to the second manifold, each tube has:
• an upstream concave first turn relative to the first flow;
• an upstream convex second turn relative to the first flow;
• and
• an upstream concave third turn relative to the first flow;
• and
• the second locations are offset downstream along the first flowpath from the respective first locations and each tube has no turn other than the first turn, the second turn, and the third turn;
• and
• the tubes are bent so that an internal pressure increase counters stress caused by a temperature increase.

A heat transfer system for heat transfer between an external first flow along a first flowpath and a second flow along an internal second flowpath, the heat transfer system comprising:

• a heat exchanger comprising:
• a first manifold;
• a second manifold;
• and
• a plurality of tubes extending from the first manifold to the second manifold and having respective interiors bounding respective legs of the second flowpath, wherein:
• each of the tubes have first ends mounted to the first manifold at respective first locations;
• each of the tubes have second ends mounted to the second manifold at respective second locations;
• from the first manifold to the second manifold, each tube has:
• an upstream concave first turn relative to the first flow;
• an upstream convex second turn relative to the first flow;
• and
• an upstream concave third turn relative to the first flow;
• and
• the second locations are offset downstream along the first flowpath from the respective first locations and each tube has no turn other than the first turn, the second turn, and the third turn;
• at least one temperature sensor positioned to measure a temperature associated with at least one tube of the plurality of tubes;
• means for controlling pressure within the plurality of tubes;
• and
• a controller coupled to receive input from the at least one temperature sensor and controlling the means so as to increase the pressure responsive to a measured temperature increase.