Ram Recovery A rise in pressure above existing outside atmospheric pressure  at the engine inlet, as a result of the forward velocity of an  aircraft, is referred to as ram pressure. Since any ram effect  causes an increase in compressor entrance pressure over  atmospheric, the resulting pressure rise causes an increase  in the mass airflow and gas velocity, both of which tend to  increase thrust. Although ram effect increases engine thrust,  the thrust being produced by the engine decreases for a given  throttle setting as the aircraft gains airspeed. Therefore, two  opposing trends occur when an aircraft’s speed is increased.  What actually takes place is the net result of these two  different effects. An engine’s thrust output temporarily decreases as aircraft  speed increases from static, but soon ceases to decrease.  Moving toward higher speeds, thrust output begins to increase  again due to the increased pressure of ram recovery. 1-62 0 TAS Increase Airflow (in lb/sec) Specific thrust Total airflow (w a ) Constant rpm, altitude, and OAT Figure 1-87. Effect of airspeed on specific thrust and total engine  airflow.