After takeoff, what supplies cooling air to the heat exchanger?

The correct answer highlights the role of ram air in the cooling system of the T-6 aircraft. After takeoff, the ram air inlet uses the aircraft's forward motion to draw in ambient air. This air then passes over the heat exchanger, which is crucial for regulating the temperature of various components, particularly the engine and other systems that require effective cooling.

This process is particularly effective during flight, as the faster the aircraft moves through the air, the greater the volume of air that can be utilized for cooling. Ram air is essential because it ensures that the heat exchanger operates efficiently, helping to maintain optimal engine performance and prevent overheating.

In contrast, options like the exhaust air inlet, environmental control inlet, and cabin air inlet do not primarily facilitate the cooling process in this context. The exhaust air inlet is more related to expelling waste gases, while the environmental control inlet and cabin air inlet are focused on providing conditioned air for cabin pressure and temperature regulation rather than cooling the engine or heat exchanger directly after takeoff.