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Posted: 8/19/2006 5:48:59 PM EDT
about ms flight sim, the jet engine, how does the n1 and n2 and itt all interact?

why does the n2 turn red at 90?

also, why does the n2 drop as the plane reaches higher altitude, but the throttle never changes?

Link Posted: 8/20/2006 7:29:37 PM EDT
Man thats some hard stuff to remember. I havent worked on aircraft in like 12 years.

itt, do you mean tit, as in turbine inlet tempature>? N1 and N2 I think we sensors in the 1st and 2nd stage of the turbine. they relate to how much compression that stage is producing. As you increase your altitude the air thins out, thus the turbine is over working it self if left at the same throttle setting.

dropping your AOA,( angle of attack) would increase airflow to the n1, but that would also put you in a dive.

I was never good at the mech stuff. If you want to talk radar and navigation, I could help more.
Link Posted: 8/20/2006 10:56:44 PM EDT
[Last Edit: 8/20/2006 10:59:32 PM EDT by Fly-Navy]

Originally Posted By NimmerMehr:
about ms flight sim, the jet engine, how does the n1 and n2 and itt all interact?

why does the n2 turn red at 90?

also, why does the n2 drop as the plane reaches higher altitude, but the throttle never changes?



ITT is Interstage Turbine Temperature, if I have that right. It's basically a reading of the temperature between the turbine stages at the exhaust part of the engine. Gives you a way to monitor engine health and performance. Other similar types you'll see are TIT (Turbine Inlet Temperature) and EGT (Exhaust Gas Temperature).

N1 is the Fan stage RPM measured in percent. The fan stage is the low pressure compressor on the front of the inlet part of the engine.

N2 is the Compressor stage RPM measured in percent. The compressor stage is the high pressure compressor after of the Fan stage, before the combustion chamber.

Why does N2 turn red above 90%? Dunno, guess it's just that aircraft you're flying.

N2 is dropping at altitude because of thinner air. One thing you'll notice the higher you get, is ITT (or TIT or EGT) will increase as well.

Most jets are flown via N2 and Fuel Flow. Some are flown by EPR (Engine Pressure Ratio), which is a ratio of the inlet air and the exhaust air.
Link Posted: 8/21/2006 4:36:47 PM EDT
After 12 years and not even working on the engine instruments I still got it right...lmao!

I remember the beoing 727 types like the KC-135s use EGT, while the F14, and I think the C-130 used TIT. I also remember the KC-135 having and N1 and N2 dials on the center insturment panel, ( I was incharge of a mod where we had to remove the panel to route some wiring behind them), I dont think the F14 had a N1 or N2. As I remember it was a TIT and RPM tape type gage. The C130 I cant even remember.

More to the point, just back off on the throttles when you reach altitude and watch your nose angle and fuel flow.
Link Posted: 8/21/2006 10:22:57 PM EDT

Originally Posted By CWDraco:
After 12 years and not even working on the engine instruments I still got it right...lmao!

I remember the beoing 727 types like the KC-135s use EGT, while the F14, and I think the C-130 used TIT. I also remember the KC-135 having and N1 and N2 dials on the center insturment panel, ( I was incharge of a mod where we had to remove the panel to route some wiring behind them), I dont think the F14 had a N1 or N2. As I remember it was a TIT and RPM tape type gage. The C130 I cant even remember.

More to the point, just back off on the throttles when you reach altitude and watch your nose angle and fuel flow.


That RPM on the F-14 will most likely be N2 RPM if I were a guessing man. N2 is generally what people are referring to when they say "RPM" on a fan-jet.
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