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A320 takeoff thrust

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A320 takeoff thrust

Old 11th Feb 2023, 18:42
  #21 (permalink)  

Only half a speed-brake
 
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(10 years on CFM-powered A320, thereafter mixed fleet)

It takes just under 2 sec from stabilized 50% (OEM procedure) to flex/TO/TOGA. J.L.S. most likely refers to the time needed from 18% ground idle to that 50% N1 stabilized, which once in a blue year varies just wildly.

The usual suspects: Dual or singular combustor (different engines), uneven use (asymmetrical thrust taxi), engine state (EGT margins), and a little crosswind seem to play a role. Waiting those 3 seconds for the slower engine to catch up (to 50%) feels like an eternity.

So 3+2 on one, 3+3+2 on the other.
Definitely saw that couple of times, and when the other person didn't, much screaming ensued.

Last edited by FlightDetent; 11th Feb 2023 at 18:55.
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Old 11th Feb 2023, 18:54
  #22 (permalink)  

Only half a speed-brake
 
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2 OP: I understand where that question comes from but after a little insight, it is just plain silly.

Please walk with me, from 50% (1,05) up:
a) If you shoved TLs to TOGA/FLEX in an instant, the actual engine acceleration will follow the FADEC schedule.
b) If you move the TLs in a controlled fashion up, but always staying ahead of the N1 as the engine accelerates, the FADEC schedule is the same as a) above.
c) If you advance too slowly and restrict the acceleration, that's plain wrong.

a) or b) is the same, c) is mishandling. Headwind makes no difference.
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Old 11th Feb 2023, 19:48
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Originally Posted by VariablePitchP
Get back in the sim, it goes 1 straight to 1.2, and that’s only a small part of the scale. Lot easier until you’ve got the muscle memory to set a visual picture than try and gauge 25% of the way of just a small scale graduation.

At least after a couple of hundred goes your hand just does it, surprisingly accurately as well.
The numbers go 1.0 to 1.2 but there is a tick mark at 1.1 and all you need to do to get 1.05 is set the donuts halfway between 1.0 and the 1.1 tick. Easy as.
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Old 12th Feb 2023, 02:20
  #24 (permalink)  

Only half a speed-brake
 
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Originally Posted by AerocatS2A
The numbers go 1.0 to 1.2 but there is a tick mark at 1.1 and all you need to do to get 1.05 is set the donuts halfway between 1.0 and the 1.1 tick. Easy as.
Exactly. Although an untrained eye will be putting it onto 1.1 tickmark which is approximately the same angular location as 50% n1 on the CFM - a common cognitive slip. Why no mark at 1..05 is a bit of a HF puzzle.

The jump from 1.1 to 1.2 probably refers to N1 exclusion zone on the IAE, where fadec refuses to command a setting within a specified vibration zone, resuliting in non-linear thrust control. No FCOM at hand, something like 62-75 N1.


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Old 12th Feb 2023, 05:17
  #25 (permalink)  
 
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Originally Posted by VariablePitchP
Get back in the sim, it goes 1 straight to 1.2, and that’s only a small part of the scale. Lot easier until you’ve got the muscle memory to set a visual picture than try and gauge 25% of the way of just a small scale graduation.

At least after a couple of hundred goes your hand just does it, surprisingly accurately as well.
As I’ve said before we do not and never did operate anything else than CFM over the past 30 years on our 320f fleet, I just happened to be in a IAE sim for other reasons but as others have confirmed below the correct way of setting the required amount of thrust on the IAE does not need any “tricks”.
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