Total Air Temperature equals ram air temperature when the recovery factor is equal to what percent?

Total Air Temperature is defined as the temperature of the air that results from compressing the air due to the aircraft's forward motion, plus any heat generated by viscous forces. The concept of recovery factor plays a significant role in understanding this relationship.

When the recovery factor reaches 100 percent, it indicates that the total air temperature is equal to the ram air temperature. This means that there is no energy loss in the process of bringing the air to a complete stop (as in a static condition). In a real-world scenario, such a condition is theoretically perfect, where all kinetic energy is converted into thermal energy without any loss.

In practical applications, a recovery factor less than 100 percent would suggest that some of the energy from the kinetic air flow is lost as heat, leading to a total air temperature that is higher than ram air temperature. Conversely, a recovery factor greater than 100 percent is impractical and impossible in standard atmospheric conditions, as it implies that the air is being cooled beyond its starting temperature without any additional energy input.

Hence, a recovery factor of 100 percent reflects the condition where all kinetic energy is transformed into thermal energy, supporting the assertion that total air temperature equals ram air temperature.