What is the correct starting sequence for a turbojet engine?

The correct starting sequence for a turbojet engine involves initiating airflow before igniting the fuel. This sequence is crucial because it ensures that there is sufficient air passing through the engine to mix with the fuel and support combustion. When the airflow is established first, it creates the necessary conditions for ignition to occur more effectively. The engine's compressor begins to spin, drawing in ambient air. After airflow is established, starting the ignition system then introduces the spark or flame, igniting the fuel that is subsequently introduced.

The reason for this order emphasizes the importance of having a stable airflow to prevent unburned fuel from accumulating in the combustion chamber, which could lead to a failure to ignite or even engine damage. Following this, once the fuel flow is established, the engine can successfully transition to combustion, leading to thrust generation.

Other sequences, such as initiating fuel flow before establishing airflow, could lead to challenges in ignition and could risk operational safety. Therefore, the proper sequence of airflow, ignition, and then fuel flow is essential for the reliable starting of a turbojet engine.