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serviceceiling

Compressor Stall

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A few hours ago I took the -600 for a test flight, where I performed slow-flight and did some steep turns to test the flight dynamics of the NGX in every aspect and situation. During a stall I noticed a popping sound that came from the engines, they stuttered. I guess this was a compressor stall. I found it really amazing that PMDG actually modeled this occurance and included sounds for it, if it's the case.

 

Cheers from Frankfurt.

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They're not listed in the failure options. Would be a nice addition if possible. Somehow I don't think so.

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I'm hesitant to believe compressor stalls are in the sim if only because in the NG it's fairly difficult to cause with the invention of FADEC and engine software.

 

Some programs like FSCaptain will give you an engine flameout in extremely wet weather, but that's as far as I'm sure it'll go.

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Are you sure that you're not hearing the stick-shaker? Stalling an aircraft doesn't mean that the engines will suffer a compressor stall at the same time.

 

Depending on the quality of sound system you have, it could be that the sound of the stick shaker along with the engines is creating an irregular sound. I had some cheap speakers that couldn't adequately handle a range of sounds all at once and this created such an effect.

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It was not the stick shaker. Before the test flight I turned off all the warning and safety systems to have full control over the aircraft.

 

I heard the engines stutter. BTW: I did about 3 stalls and this only happended during the third.

I am using REX essential and its weather engine, maybe it has something to do with that.

 

EDIT: I don't have speakers, I run FSX on a HP G62 notebook and I never experienced any sound issues at all.

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If it is true it is a great feature, but, can you post a video?

How did you disabled the stall warning/shaker? Through FMC?

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It was not the stick shaker. Before the test flight I turned off all the warning and safety systems to have full control over the aircraft.

 

Maybe I'm wrong, but I don't know stick shaker turn off button. You can see stick shaker in action by pressing STALL WARNING TEST buttons on after overhead panel while on ground with AC power available. Also 737 is not Airbus with its normal law and flight envelope protection. Just turn off AP, A/T and you will have full control of the aircraft with aural and visual warnings working.

Video would be very appreciated.

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In the real plane the stick shaker can be excluded only by pulling the CBs, however in NGX the fmc menus (failures) could help.

I just finished to test this compressor stall, I was able to have a near to 90° pitch up, with airplane falling down but nothing other than stick shaker and winds. I also searched how to disable stick shaker from menus and I've not found either in the MISC, flt cont or other menus.

I think that more clarification is needed to help us how to replicate or to understand what it was.

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We did not model compressor stalls in the NGX - no idea what you saw/heard...

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It is called placebo. You were siting in the best fsx airliner which is 99.995% realistic. Your brain added the remaining 0.005%.

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Bogdan, do you have Accu-Feel? That's the only other thing I can think of that might be responsible for the sounds you heard.

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No I don't have Accufeel.

Well, looks like it was indeed just a sound issue.

I'll try it again tonight and see what it was and if it occurs again.

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