Jump to content

CFM engines not immediately responding to slight thrust increase


Meyerflyer

Recommended Posts

Hello,

 

this is a behaviour I also noticed in the old bus. The CFM engines (on all A31x/A32x models) are running at idle for example after pushing back. I increase the thrust levers to about 30-35% N1 to start taxi, but the engines either do not respond at all or only after 5-10 seconds. When I increase the thrust levers a bit more or get to > 40% out of idle, they respond quickly. The IAE engines increase speed immediately in all conditions. Is this an issue or is this a normal CFM engines behaviour?

Link to comment
Share on other sites

It can be quite normal for engines to respond rather late when they are in ground IDLE. Sometimes even a couple of seconds, maybe even 5. 10 seconds sounds quite long though, is this a number you guesstimated or you measured? 5 would sound normal, 10 a bit too much.

Link to comment
Share on other sites

Emanuel, thanks for your reply. I can try to measure it soon. I felt like sometimes the engines are not even responding at all or only well behind 10 seconds. I was wondering, because the IAE engines always respond immediately, while the CFMs don't.

Link to comment
Share on other sites

I can only comment from my real life experience with the CFM56, not on an A320 though.

In my airline we do a takeoff config check before we start taxiing where we push the thrust levers all the way to the forward stop and pull them back again in order to trigger the takeoff config warning to find out if we forgot anything. Doing this in other CFM56 simulations I always see the engine running up to about 40%, in real life they will hardly start to react, mostly not even react at all.

 

Jet engines are very responsive at low altitude and thrust settings typically seen during approach, usually they react almost instant (say around 60%N1).

In ground IDLE or at very high altitudes and lower thrust settings (below about 70% N1) you get almost no reactions though.

I am yet to see an addon which would represent this behaviour really well. The stable call at 40/50% N1 is really a lot more meaningful in real life than it is in flight sim at the moment, even considering the highest end addons currently on the market.

Link to comment
Share on other sites

vor 1 hour , Mathijs Kok sagte:

There are limitations in the simulator in this aspect.

 

Can you explain this a bit more? Why do the IAEs respond immediately out of ground IDLE, and the CFMs do not behave the same, if it is a simulator limitation?

Link to comment
Share on other sites

Hi , 

I would like to share my impressions Aerosoft support forum, especially regarding Mr. Kok's approaches. I think M. Kok is an executive (or owner AS company) who have technical experience  and administrator forum. I frequently see M. Kok answers the topics aspect a businessman when customers look for a technical solution and sometimes customers get imperfect and misleading knowledge.

Sorry for my unpleasant comment but these are my impressions who follows the forum for several years, regarding AS Forum .

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. Privacy Policy & Terms of Use