Active cooling of windward surface of craft

An envelope portion of an airborne craft, the envelope portion comprising:

• a nose;
• a metallic outer wall including a plurality of thru-holes;
• a metallic inner wall arranged interior to the outer wall, the outer and inner walls delimiting an inter-wall volume configured to support a flow of coolant to cool the outer wall during atmospheric heating of the outer wall;
• and
• a plurality of coolant-flow partitions arranged in the inter-wall volume, joining the outer and inner walls, and extending radially and helically about an axis constructed through the nose and aligned to a trajectory of the airborne craft, the plurality of coolant-flow partitions delimiting:
• a plurality of forward-flow channels configured to receive coolant from a coolant reservoir and to conduct the coolant through the inter-wall volume;
• and
• a plurality of reverse-flow channels configured to receive and conduct at last a portion of the coolant through the inter-wall volume,
• wherein the plurality of reverse-flow channels are arranged fluidically downstream of the plurality of forward-flow channels, and
• wherein the plurality of thru-holes of the outer wall extend into the inter-wall volume to release at least a portion of the coolant onto an exterior surface of the outer wall, thereby forming a barrier film on the exterior surface.