Flex takeoffs only on Airbus?
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Joined: Dec 2006
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From: aussie land
Flex takeoffs only on Airbus?
Excuse my ignorance, but is the flex takeoff technique only used on Airbus series aircraft? How about the Boeing 777 and 787? Do they use similar reduced power takeoffs or do Boeings always use TOGA power?
Joined: Apr 2010
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From: Home soon
Hello,
FLEX is a term used by Airbus, Boeing uses Assume Temperature whch is the same.Fool the computer that its warmer outside to reduce takeoff thrust,saving engine life by reducing egt up to 56c using max assum temp(25%).(b737).
Boeing also uses variable derate tomreducemtake off thrust when assume temp is not possible,assum temp can be used in conjunctionmwith derate.
Excuse my ipad typing
FLEX is a term used by Airbus, Boeing uses Assume Temperature whch is the same.Fool the computer that its warmer outside to reduce takeoff thrust,saving engine life by reducing egt up to 56c using max assum temp(25%).(b737).
Boeing also uses variable derate tomreducemtake off thrust when assume temp is not possible,assum temp can be used in conjunctionmwith derate.
Excuse my ipad typing
Joined: Dec 2011
Posts: 52
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From: Paris, London and New York
Question:
I understand we reduce thrust due to warmer then standard temps or higher then standard density altitude in order to limit I guess ITT and preserve this way engine life. But N1 is reduced also when temp are colder then standard. Is it because of stractural limits or what.... ??
I understand we reduce thrust due to warmer then standard temps or higher then standard density altitude in order to limit I guess ITT and preserve this way engine life. But N1 is reduced also when temp are colder then standard. Is it because of stractural limits or what.... ??
Joined: May 2004
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From: Europe
No, i think your missing the point...
We still limit the n1 power for takeoff even if it is colder then standard (ISA) because we can still further preserve engine life... the power req for takeoff from performance calculations tells us we need say 84.5% N1, where the full power takeoff gives us an N1 limit of say 89% So then using the flex temp, we tell the fadec to limit the N1 to that minimum req from calcs, and engine life is preserved, company saves another dollar....
Feel free to correct or add anything boys and girls
We still limit the n1 power for takeoff even if it is colder then standard (ISA) because we can still further preserve engine life... the power req for takeoff from performance calculations tells us we need say 84.5% N1, where the full power takeoff gives us an N1 limit of say 89% So then using the flex temp, we tell the fadec to limit the N1 to that minimum req from calcs, and engine life is preserved, company saves another dollar....
Feel free to correct or add anything boys and girls
