Question about GE CF6 and rated thrust
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Did a bit of digging:
http://www.airweb.faa.gov....
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf......
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library......
Quoted from that document:
Part 33:
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf...
Interesting requirement of Standard atmosphere there....
http://www.airweb.faa.gov....
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf......
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library......
Quoted from that document:
PART 1--DEFINITIONS AND ABBREVIATIONS
(a) Part 1 Sec. 1.1 is amended as follows:
Sec. 1.1 [Amended]
1. The following new definitions are added:
"Rated takeoff power," with respect to reciprocating, turbopropeller, and turboshaft engine type certification, means the approved brake horsepower that is developed statically under standard sea level conditions, within the engine operating limitations established under Part 33, and limited in use to periods of not over 5 minutes for takeoff operation.
"Rated takeoff thrust," with respect to turbojet engine type certification, means the approved jet thrust that is developed statically under standard sea level conditions, within the engine operating limitations established under Part 33, and limited in use to periods of not over 5 minutes for takeoff operation.
2. The definitions of "maximum continuous power" and "maximum continuous thrust" are amended to read as follows:
"Rated maximum continuous power," with respect to reciprocating, turbopropeller, and turboshaft engines, means the approved brake horsepower that is developed statically or in flight, in standard atmosphere at a specified altitude, within the engine operating limitations established under Part 33, and approved for unrestricted periods of use.
"Rated maximum continuous thrust," with respect to turbojet engines, means the approved jet thrust that is developed statically or in flight, in standard atmosphere at a specified altitude, within the engine operating limitations established under Part 33, and approved for unrestricted periods of use.
(a) Part 1 Sec. 1.1 is amended as follows:
Sec. 1.1 [Amended]
1. The following new definitions are added:
"Rated takeoff power," with respect to reciprocating, turbopropeller, and turboshaft engine type certification, means the approved brake horsepower that is developed statically under standard sea level conditions, within the engine operating limitations established under Part 33, and limited in use to periods of not over 5 minutes for takeoff operation.
"Rated takeoff thrust," with respect to turbojet engine type certification, means the approved jet thrust that is developed statically under standard sea level conditions, within the engine operating limitations established under Part 33, and limited in use to periods of not over 5 minutes for takeoff operation.
2. The definitions of "maximum continuous power" and "maximum continuous thrust" are amended to read as follows:
"Rated maximum continuous power," with respect to reciprocating, turbopropeller, and turboshaft engines, means the approved brake horsepower that is developed statically or in flight, in standard atmosphere at a specified altitude, within the engine operating limitations established under Part 33, and approved for unrestricted periods of use.
"Rated maximum continuous thrust," with respect to turbojet engines, means the approved jet thrust that is developed statically or in flight, in standard atmosphere at a specified altitude, within the engine operating limitations established under Part 33, and approved for unrestricted periods of use.
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf...
Interesting requirement of Standard atmosphere there....
Join Date: Jun 2001
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Give it up Clarence.
These flightsim enthusiasts obviously know it all, and have nothing left to learn.
It's the curse of the internet. Access to everything but understanding.
These flightsim enthusiasts obviously know it all, and have nothing left to learn.
It's the curse of the internet. Access to everything but understanding.
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It would be interesting to get "schooled" on the subject instead of being told to "get lost, you don't get it anyway".
I wan't to know why the FAA documents can't be trusted...
I wan't to know why the FAA documents can't be trusted...
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behind screen-names, raising themself above everyone else.
Fortunately, the other 99% of pilots around here are true gentlemen
M
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It would seem to me that barit1 and Clarence Oveur have provided all the information you need to understand that rated thrust is not confined to ISA conditions.
If you are not prepared to listen to knowledgeable professionals then what is the point?
I am terribly sorry XPMorten, but the best efforts of barit and CO seems to have been wasted on you.
Are you here to learn from professionals who do this for a living, or are you here to tell them how it works?
If you are not prepared to listen to knowledgeable professionals then what is the point?
I am terribly sorry XPMorten, but the best efforts of barit and CO seems to have been wasted on you.
Are you here to learn from professionals who do this for a living, or are you here to tell them how it works?
Last edited by Techman; 14th Sep 2006 at 19:31. Reason: XPMorten post above.
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Please don't lump me into the category of a "flightsim enthusiast who knows it all" because I started this thread wanting to learn and I am still learning.
This thread was civil but some people took it a little personal so if we can keep it confined to the topic at hand I think we can all continue learning. :-)
My next question is, can max continuous thrust (I've seen it quoted as 46000lbs or so) be maintained all the way to to cruise? At what altitude does the engine start losing the ability to create 46000lbs? I know the thinning air planes a big role in the engine's reduction of power.
This thread was civil but some people took it a little personal so if we can keep it confined to the topic at hand I think we can all continue learning. :-)
My next question is, can max continuous thrust (I've seen it quoted as 46000lbs or so) be maintained all the way to to cruise? At what altitude does the engine start losing the ability to create 46000lbs? I know the thinning air planes a big role in the engine's reduction of power.
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Techman:
I understand that. It's the primary qualification run to achieve the FAA acceptance which is interesting to me.
The manufacturer states that we have a 50000 lbs engine here. How does he prove that? He sets it up in a rig and lets it run through the FAA approved qualification (rating) process.
If the mfg of the engine could choose test conditions himself he would set it up in a more favourable condition. That's my understanding of why set (ISA) conditions are needed to validate test results. Can't compare apples and oranges...
I understand that. It's the primary qualification run to achieve the FAA acceptance which is interesting to me.
The manufacturer states that we have a 50000 lbs engine here. How does he prove that? He sets it up in a rig and lets it run through the FAA approved qualification (rating) process.
If the mfg of the engine could choose test conditions himself he would set it up in a more favourable condition. That's my understanding of why set (ISA) conditions are needed to validate test results. Can't compare apples and oranges...
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I happen to have a degree in combustion engineering which gives me the
right to an opinion.
signing off this thread.
M
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Given that the fan airflow creates most of the thrust in a high-bypass machine like CF6, the rated thrust is a matter of pushing a specified airflow (about 1400 lbs/sec) through a geometrically-specified fan nozzle annulus.
To pump this much airflow on a standard day, it takes about 3800 rpm. If a hotter day (lower air density), more rpm is needed, and if a colder day, less rpm to achieve rated thrust. Similarly with altitude.
In the engine development testing, enough data are acquired over a range of temperatures & pressure altitudes that the shape (slope, etc.) of the power management curves is well verified. The net result is that the left-hand side of the chart essentially contains lines of constant fan airflow, and thus constant thrust.
To pump this much airflow on a standard day, it takes about 3800 rpm. If a hotter day (lower air density), more rpm is needed, and if a colder day, less rpm to achieve rated thrust. Similarly with altitude.
In the engine development testing, enough data are acquired over a range of temperatures & pressure altitudes that the shape (slope, etc.) of the power management curves is well verified. The net result is that the left-hand side of the chart essentially contains lines of constant fan airflow, and thus constant thrust.
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XPMorten,
What does it matter? You seem not wanting to listen anyway.
(BTW. What PM? Please do tell)
chksix,
Where do you find a test cell that is at ISA conditions?
barit1 has explained it well.
What does it matter? You seem not wanting to listen anyway.
(BTW. What PM? Please do tell)
chksix,
Where do you find a test cell that is at ISA conditions?
barit1 has explained it well.
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The "IF" is superfluous - I was in the business 33 years and NOT ONCE encountered SL ISA:
15.0 C
14.696 PSIA (1013.25 Mb, if you prefer)
ZERO humidity
15.0 C
14.696 PSIA (1013.25 Mb, if you prefer)
ZERO humidity
