Flex To Temp/TOGA!
 

Good morning,
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I was reading about flex to temp on the bus.
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Basically, as air get's cold, more it get's denser (more air molecules).
So if air is hot, less you have air molecules so you won't be able to get the required thrust (so the turbine will not turn).
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So you basically tell the plane that the outside temperature is very hot (not true), so the plane will think that as the outside temperature is already very hot, if you add to much fuel (and compress a lot), the temperature will get to high and the air (+ fuel) won't be able to turn the turbine to get thrust.
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FLEX TEMP = TOGA with the selected temperature.
So if you enter 50°, it means that if the outside temperature would have really been of 50° and if you would have used TOGA, then you would have got the Flex temp.*
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At a certain temperature, air + fuel won't be able to produce thrust (mostly no air molecules).*
If the outside air temperature is very cold, we will be able to use more fuel and get a higher RPM.
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1) Am I right?
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2) So with TOGA, you won't get 0,001% thrust more. So does FADEC use the outside temperature to calculate the required amount of fuel to turn the turbine/fan at the highest RPM possible? So the temperature and the weight of the plane is very important...am I right?*

Thanks a lot!

Flex To Temp/TOGA!
 

My brain exploded

You have some correct information and you're mixing it in with some not so correct.

For every takeoff, performance data is calculated that includes the highest temperature the aircraft can safely takeoff on a specific runway under the current conditions. If that temperature is higher than the actual OAT, it becomes the assumed temperature. Sometimes it's very high, like the 50C you mentioned, other times it's lower (but still more than actual).

Jet engines produce reduced thrust as the ambient air temperature increases. The flex temp is the highest air temperature at which the engines would produce the required takeoff thrust. The crew enters it into the flight management system (FMS) — which, as you said, tells the aircraft to assume the specified air temperature instead of the actual temperature. When flex (FLX) thrust is selected during takeoff, the engine controller produces maximum thrust for the assumed (flex) temperature.

Thanks a lot!!!!

What isthe max flex temp possible for an A330? A320?
I don't think you can enter 300°....

It's been a while since I flew the A320, so I don't remember what the max possible number that can be put into the flex field. I think it was 50 degrees, but that may just have been the max temperature used at my company.

That's the highest assumed temperature I've ever seen used in any performance calculation (50C / 122 F) on any aircraft I've flown.

Are you a pilot? Serious question.

Looking at your post history, you ask detailed questions about aircraft that you apparently lack the background to understand and apply. If you're a pilot in training, for your own benefit, please stick to the basics. If you are an Airbus pilot, don't you have a training department to use as a resource?

http://www.airlinepilotforums.com/se...archid=5698745

"For his own benefit"??? :rolleyes: Good grief, lighten up. He's obviously an enthusiast. Maybe he flies the A320 sim on his computer or he's just getting into light aircraft. Whatever the case, let him ask his questions if he wants.

Ha ha ha! ;)
Thanks for your replies! ;)

So 50°C....

No! I am 14 years old and not at all a pilot! That's my dream!

Thanks a lot

I didn't say "don't ask questions", just that the axiom "you need to learn to walk before you run" seems to apply. To grasp complex concepts and ideas in most disciplines, a fundamental level of knowledge is helpful (if not mandatory).

Do you think the max/reduced thrust discussion would be easier with a firm grasp of density altitude? There's a good reason that training programs use the building block technique.

Good for you for asking, but I suggest you do some reading to get the most out of your time on the subject. Read the FAA (free) publication "The Pilots Handbook of Aeronautical Knowledge"
https://www.faa.gov/regulations_poli...ilot_handbook/

It's free, and will fill-in a lot of gaps you have. Good luck!

I know it's at least 55C.

The rule of thumb on the airbus is that TOGA is always TOGA!

Flex temp is a lower detent on the thrust lever and is just an artificially reduced power to save engine wear. If you need more power, you can move it forward into the TOGA detent for maximum power.