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To: old curmudgeon

What they are referring to is called inlet distortion which is a variation in stagnation pressure over the inlet area of the engine. Variations are induced by attitude changes - mainly pitch and yaw - as well as throttling factors that change the near field flow characteristics. Dependent on the robustness of the compressor design and the engine throttling schedule, outlier pressure variations can lead to surge which is mistakenly referred to as compressor stall, which is more often a result rather then a cause of surge.

I don’t know the details of the Hultgren case but it appears that it would be a yaw rate induced surge event leading to engine power loss which she probably tried to counteract with an excessive pitch rate leading to a failed engine side wing stall that then coupled into roll due to asymmetric lift and was unrecoverable due to competing asymmetric thrust moments with the aforementioned yaw rate induced out of balance roll moment.


70 posted on 02/07/2022 1:48:56 PM PST by Regulator (It's fraud, Jim)
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To: Regulator

Thanks. That confirms my guess.

Been retired for so long that the correct terms, pitch and yaw escaped me for the moment I was typing.


74 posted on 02/07/2022 2:02:48 PM PST by old curmudgeon (There is no situation so bad that the federal government can not make worse.)
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To: Regulator; Fury
What they are referring to is called inlet distortion which is a variation in stagnation pressure over the inlet area of the engine. Variations are induced by attitude changes - mainly pitch and yaw - as well as throttling factors that change the near field flow characteristics. Dependent on the robustness of the compressor design and the engine throttling schedule, outlier pressure variations can lead to surge which is mistakenly referred to as compressor stall, which is more often a result rather then a cause of surge.

I don’t know the details of the Hultgren case but it appears that it would be a yaw rate induced surge event leading to engine power loss which she probably tried to counteract with an excessive pitch rate leading to a failed engine side wing stall that then coupled into roll due to asymmetric lift and was unrecoverable due to competing asymmetric thrust moments with the aforementioned yaw rate induced out of balance roll moment.

This is exactly what happened according to several articles I read at the time.

Here you go Fury. Let's dispel some ignorance. You are against ignorance, right?

78 posted on 02/07/2022 2:11:40 PM PST by DiogenesLamp ("of parents owing allegiance to no other sovereignty.")
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