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richtemark

Engines Spooling

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Hello Captains:

 

Sorry if it had been asked before, but I did not find an answer to my following question: I often see aircrafts parked at an airport with either one or both of their engines spooling, although the plane is parked and the engines are not started. Since this also occurs while there is practically no wind, I ask myself whether it is possible to simulate such spooling with the 737NGX? And what is the purpose of it? 

 

Cheers,

Markus

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Can't answer the first part,as to weather you can simulate spooling,but it does not take much wind at all to get engines to rotate whilst on the ground ,a small breeze up the jet pipe is enough to start one rotating as to the purpose I would say that there is none

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Hello Captains:

 

Sorry if it had been asked before, but I did not find an answer to my following question: I often see aircrafts parked at an airport with either one or both of their engines spooling, although the plane is parked and the engines are not started. Since this also occurs while there is practically no wind, I ask myself whether it is possible to simulate such spooling with the 737NGX? And what is the purpose of it? 

 

Cheers,

Markus

It does take a bit of wind, and that's why we call it, in English, "windmilling." It serves no purpose, unless you're trying to restart an engine at altitude!

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I ask myself whether it is possible to simulate such spooling with the 737NGX? And what is the purpose of it? 

I'm sure it would be possible for PMDG to simulate this, if they chose to.  As for purpose, it's not something done deliberately, it's just that the fan acts like a windmill, as Matt said above, and will rotate in the wind.  The point from a simulation is that it will affect the way the engine starts.  A tailwind will cause the fan to rotate in the wrong direction, but this will still show as positive indicated N1 on the flightdeck.  Attempting to start an engine in this condition can result in a hot start (EGT rising rapidly towards the red line).  So before you turn the fuel on you need to be sure there is N1 rotation in the correct direction.  

 

If this was modelled, together with a high EGT if you tried to start with no N1 rotation, it would add an extra layer of realism to the engine start process.

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I think the NGX does windmill on the ground...

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Thanks for your replies. So it is sheer wind that keeps the fans spinning.

 

 

I think the NGX does windmill on the ground...

 

Are you sure of that? I have never seen it with the 737NGX, any other PMDG plane (or any FSX-plane at all), although I always take a look around the aircraft when it is grounded.

 

Cheers,

Markus

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It is modelled on many addons, perhaps PMDG left it out to save animations on more important features.

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