[GH85Carrera]

The engines on the SR 71 .
The geniuses at the Skunk Works had to figure out a way an air breathing J 58 engine could handle supersonic airflow.
By using the inlet spike in the engine And the bypass doors, they were able to change the airflow from supersonic to subsonic. The front of the engine there is a sharp spike. The shape is not random. It sets up the shockwave in front of the inlet to protect it from the full impact of the air ahead. It also sets up the shockwaves inside the inlet, to slow the air down to subsonic speeds before it hits the compressor.