Aircraft heat exchangers and plates

A heat exchanger plate for provides heat transfer between a first flow along a first flowpath and a second flow along a second flowpath. The heat exchanger plate comprised a body having: a first face and a second face opposite the first face; a leading edge along the second flowpath and a trailing edge along the second flowpath; a proximal edge having at least one inlet port along the first flowpath and at least one outlet port along the first flowpath; and at least one passageway along the first flowpath. Along a proximal portion, the first face and the second face converge at a first angle. Along a distal portion, the first face and the second face converge at a second angle less than the first angle.