Originally Posted by
beardy
This was supplied on the tech log forum :
Windmilling drag
So when practicing a turnback be aware that in the real case a windmilling engine is high drag, higher than idle thrust or a seized engine.
The study considers internal drag of the engine only and acknowledges that overspill of air from the intake can affect airframe drag. As airflow through the windmilling engine is reported as 3x greater than the seized engine, that’s potentially a lot of air to redirect. In a podded engine with aerodynamically shaped lips I can quite imagine that a ‘blob’ of slower air in the intake would act as quite an effective fairing to divert surplus airflow around the nacelle in streamlined fashion. What I know from experience is that the angular, aerodynamically-complex maw of the Tornado didn’t like having a seized engine inside it... probably not helped by most of the spilled air immediately colliding with the external stores and landing gear (admittedly not as much of a problem for the Hawk, but probably still more than for a podded type).