[2.9.7.59263 MT] Engines may be started without airflow below self-sustaining RPM

[Stickler]

As per the Heatblur and RL flight manual, during an engine start using external airflow, one should signal the crew chief to stop flow at 45% RPM. The reason for this figure is not provided in any Air Force manual I'm aware of, but the RF-4B NATOPS manual (NAVAIR 01-245FDC-1) suggests that 45% is usually self-sustaining RPM.

Witness the attached track.

When starting the right engine, I order the crew chief to stop airflow immediately after ignition, which is acknowledged prior to the engine reaching 15% RPM. The engine starts without issues.

When starting the left engine, I order the crew chief to switch external air from the left to the right engine, which is acknowledged at 15% RPM and executed prior to the engine reaching 25% RPM. The engine starts without issues.

I am by no means an expert in the J79 and I cannot prove my position, but it seems implausible that the engine would be able to reach self-sustaining RPM even though airflow is interrupted 20% or more RPM below the relevant threshold.

airflow.trk

[Dominik96]

Tracked

Thank you

[=475FG= Dawger]

The question isn’t whether it would start. Its overtemp. If it is still starting with normal temps, it isn’t modeling the cooling effect of airflow.