What affect will altitude have on compressor stall
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What affect will altitude have on compressor stall
In a turbine engine will an increase in altitude cause a higher or lower propensity to experience compressor stall?
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It could cause a higher propensity to have a compressor stall, especially if you exceed the engine rated altitude or you do not keep the spool speed up. See the the attached report to see what can happen:
http://www.ntsb.gov/ntsb/GenPDF.asp?...05MA003&rpt=fa
http://www.ntsb.gov/ntsb/GenPDF.asp?...05MA003&rpt=fa
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Certainly used to be a consideration on the Canberra during high altitude cruise. The Pilot's Notes, IIRC, referred to the relationship N / Square root of OAT, which could (and did) cause surge and/or flameout.
Higher altitudes = less pressure and less bang, also less flow reversal and less yaw rate.
The cause effect complicates the good and bad. Less bang and less yaw rate have resulted in missed cues by the crew until aircraft upset. Low pressure at altitude make it more difficult to recover if the engine runs-down, although you have lots of time to think about it on the way down
.... follow the manuals and you should recover.
The stalls at lower altitudes increase the pucker factor due to noise and yaw and most of the significant errors are due to excessively quick pilot repsonses on the throttles (wrong engine or multiple engines at once) Most of the serious problems at altitude are failure to recognize an engine malfunction and subsequent attitude change in the aircraft until upset (night, clouds, no horrizon etc.)
Certain types of engine internal stall conditions are more prevalent at high altitudes so the initiating cause is subjective to the good vs bad comparisons.
The cause effect complicates the good and bad. Less bang and less yaw rate have resulted in missed cues by the crew until aircraft upset. Low pressure at altitude make it more difficult to recover if the engine runs-down, although you have lots of time to think about it on the way down
.... follow the manuals and you should recover. The stalls at lower altitudes increase the pucker factor due to noise and yaw and most of the significant errors are due to excessively quick pilot repsonses on the throttles (wrong engine or multiple engines at once) Most of the serious problems at altitude are failure to recognize an engine malfunction and subsequent attitude change in the aircraft until upset (night, clouds, no horrizon etc.)
Certain types of engine internal stall conditions are more prevalent at high altitudes so the initiating cause is subjective to the good vs bad comparisons.
To answer the question, as density altitude increases stall margin decreases.
The early P&W JT9-3A engines had a throttle bar - a simple sliding blocker - slid into place when operating above F290 to prevent closing the thrust levers all the way. Sometimes when the gas path was a bit buggered up they would simply surge in cruise when the air density changed by flying into a different parcel of air. Kept the FEs awake!! You did, however, become very adept at running the engine failure checklist followed by the inflight start checklist. With luck you could get a relight without needing to descend.
The early P&W JT9-3A engines had a throttle bar - a simple sliding blocker - slid into place when operating above F290 to prevent closing the thrust levers all the way. Sometimes when the gas path was a bit buggered up they would simply surge in cruise when the air density changed by flying into a different parcel of air. Kept the FEs awake!! You did, however, become very adept at running the engine failure checklist followed by the inflight start checklist. With luck you could get a relight without needing to descend.
