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Engine power rolls back during takeoff roll


planevan
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When I set takeoff power, (tested with all types of takeoff power) the N1 will increase to an acceptable power, but it will then slowly fall off to around 84% by the time I rotate. This results in longer than expected takeoff roll, and slower climbout. Are there plans to fix this bug? 

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15 hours ago, planevan said:

When I set takeoff power, (tested with all types of takeoff power) the N1 will increase to an acceptable power, but it will then slowly fall off to around 84% by the time I rotate. This results in longer than expected takeoff roll, and slower climbout. Are there plans to fix this bug? 

Are you in the TO Detents?  What did you setup for your performance numbers?

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39 minutes ago, LesOReilly said:

Are you in the TO Detents?  What did you setup for your performance numbers?

"tested with all types of takeoff power" as in I used Max, TOGA, and everything in between. And there's no TO detent. I used the perf numbers from the tablet.

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6 minutes ago, planevan said:

"tested with all types of takeoff power" as in I used Max, TOGA, and everything in between. And there's no TO detent. I used the perf numbers from the tablet.

TOGA is the TO Detent ... so the answer is yes.. I take it you also did not enter a flex temp?

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2 hours ago, LesOReilly said:

TOGA is the TO Detent ... so the answer is yes.. I take it you also did not enter a flex temp?

Tried with and without. I've been consulting a type rated CRJ pilot on the matter. I understand the line of questioning but when an airplane functions fundamentally incorrect, we do not need to be wasting our time with these questions. 

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38 minutes ago, planevan said:

Tried with and without. I've been consulting a type rated CRJ pilot on the matter. I understand the line of questioning but when an airplane functions fundamentally incorrect, we do not need to be wasting our time with these questions. 

No I was trying to understand what you were doing to see if I could also recreate it ..  but I will stop trying also create it in parallel (well once the update to the Marketplace version comes back) hope you get it solved for yourself.. 

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Yes, as you can see it overshoots the target thrust quite badly and then slowly rolls back to it. If you read the linked topic, issue is already confirmed. And to be clear, it does not work like that on the real plane. You might see it go maybe 0,5%N1 over the target, but not 5%. 

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  • CRJ Forum Moderator

@CRJay noted.

I'm not sure if this is the same thing the OP @planevan describes. He states that the N1 constantly falls down to around 84% and settles there.

 

My video actualy shows 2 things:

 

1) N1 overshoots the derated value (in this case 85,7%) by exactly 0,5 --> reaching max. 90,7 then slightly decreasing to the FLX value AND NOT GOING BELOW

 

-and 2 (I saw this only now)-

 

2) just after TO (weight of wheels) you can see FLX changing to TO and the derated value of 85,7 increases to 87,4 --> is this correct (I'm not a RL Pilot)

 

And again, I'm not sure this is the issue the OP describes...

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1 hour ago, GEK_the_Reaper said:

2) just after TO (weight of wheels) you can see FLX changing to TO and the derated value of 85,7 increases to 87,4 --> is this correct (I'm not a RL Pilot)

 

This is not correct. FLX Thrust will remain active until

  • FLX Temp is deleted or FLX Temp < OAT
  • thrust levers are set to CLB or MAX Power
  • WING and/or COWL A/I is ON
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2 hours ago, GEK_the_Reaper said:

@CRJay noted.

I'm not sure if this is the same thing the OP @planevan describes. He states that the N1 constantly falls down to around 84% and settles there.

 

My video actualy shows 2 things:

 

1) N1 overshoots the derated value (in this case 85,7%) by exactly 0,5 --> reaching max. 90,7 then slightly decreasing to the FLX value AND NOT GOING BELOW

 

-and 2 (I saw this only now)-


The 84% N1 value may simply be the max that TO/TO mode should give in the conditions at that time. 
 

And in your video it does not go 0,5 over, but 5. Which is quite significant and depending on conditions may be the difference between FLEX and normal TO thrust.
 

The overall issue sounds the same to me, thrust rolling back during TO roll, something that should not happen. But no telling for sure unless a video is made.  

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