Specific fuel consumption at altitude will
- decrease.
- remain constant.
- increase.
Explanation
Climbing into colder, less dense air lowers the engine's specific fuel consumption, so for a given thrust less fuel is burned per unit of output. The improvement in thermal efficiency at altitude is a key reason jet aircraft cruise high; SFC does not stay constant or rise with height.
simontay asking:
As I know SFC decreases with altitude.
Community Comments (6)
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dimky Posts: 514 13.04.2012 / 21:26
Hey Simon!
Thrust specific fuel consumption, or just TSFC (SFC) increases with altitude. Here is proof link: http://www.grc.nasa.gov/WWW/K-12/airplane/ngnsim.html
Thrust specific fuel consumption, or just TSFC (SFC) increases with altitude. Here is proof link: http://www.grc.nasa.gov/WWW/K-12/airplane/ngnsim.html
S
simontay Posts: 1 16.04.2012 / 14:34
http://wiki.answers.com/Q/Is_thrust_specific_fuel_consumption_low_at_high_altitude
"Do not confuse TSFC with the efficiency of the engine AND aircraft as a whole. While engines are more efficient at sea level, a jet-powered aircraft as a whole will more efficient (in terms of fuel required to cover a given distance) at an altitude of about 30-35,000 feet."
"Do not confuse TSFC with the efficiency of the engine AND aircraft as a whole. While engines are more efficient at sea level, a jet-powered aircraft as a whole will more efficient (in terms of fuel required to cover a given distance) at an altitude of about 30-35,000 feet."
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dimky Posts: 514 19.04.2012 / 13:56
As I understand, question is about engine, not about aircraft. If I'm right everything is ok. :)
K
kufu Posts: 1 22.09.2013 / 19:40
The question says sfc.....not tsfc....!!!!
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dimky Posts: 514 22.09.2013 / 19:59
Lets put a point on that.
This question is about SFC and about ENGINE, not about aircraft and flight performance.
In open propulsion systems, i.e. jets, at high altitude, fuel consumption increases due to a lack of oxygen in the surrounding air, resulting in incomplete combustion.
This question is about SFC and about ENGINE, not about aircraft and flight performance.
In open propulsion systems, i.e. jets, at high altitude, fuel consumption increases due to a lack of oxygen in the surrounding air, resulting in incomplete combustion.
S
Shawez Posts: 2 16.02.2015 / 07:57
As per what i know, SFC will increase with altitude since its the amount of thrust per pounds of fuel used per hour, since at high altitude the density of air is less, more fuel must be burnt to compensate this decrease in density to produce that same amount of thrust at sea level,hence resulting in an increase in SFC.
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