• Which the release of FS2020 we see an explosition of activity on the forun and of course we are very happy to see this. But having all questions about FS2020 in one forum becomes a bit messy. So therefore we would like to ask you all to use the following guidelines when posting your questions:

    • Tag FS2020 specific questions with the MSFS2020 tag.
    • Questions about making 3D assets can be posted in the 3D asset design forum. Either post them in the subforum of the modelling tool you use or in the general forum if they are general.
    • Questions about aircraft design can be posted in the Aircraft design forum
    • Questions about airport design can be posted in the FS2020 airport design forum. Once airport development tools have been updated for FS2020 you can post tool speciifc questions in the subforums of those tools as well of course.
    • Questions about terrain design can be posted in the FS2020 terrain design forum.
    • Questions about SimConnect can be posted in the SimConnect forum.

    Any other question that is not specific to an aspect of development or tool can be posted in the General chat forum.

    By following these guidelines we make sure that the forums remain easy to read for everybody and also that the right people can find your post to answer it.

FS2004 SMS B77L Engine Problem

EK433B77W

EK433B77W

Messages
13
Country
australia
G'day all,

I've just begun using the Simmers Sky Boeing B777-200LR. I've had the aircraft on my system for some time but never really flew her properly. One thing I have noticed compared to the B77W is the difference in engine power. Now, both aircraft are fitted with GE90s but the B77W is a GE90-115BL1 (115,540 lbs of thrust) and the B77L is a GE90-110B1L (110,760 lbs of thrust). When I was executing my approach I noticed to keep the B77L at landing speed I required almost 70% N1, with the B77W it would be more around 40%. Not to mention it almost took the full length on Dubai's RWY 30L to stop her with A.B 2. So, there's also an issue with the Reverse Thrust side of things as well.

So I did a little more digging and found that the B77L would produce 105.90% N1 whereas the B77W on the other hand would produce 115.90% N1. (Note this is simulator data not real-world). Data was found by just pushing the throttles on my quadrant to the full position and waiting for the N1 to stabilize.

I also checked the aircrafts parameters in the aircraft.cfg to see if the engines had been de-rated in the config but both the B77L and the B77W have identical engine data and Turbine Information fields.

So I'm out of ideas on how to fix this issue. If anyone could please assist me in resolving this problem it would be much appreciated.

Thanks in advanced,

Cheers,

EK433B77W!
 
Last edited:
Hi,
The most likely difference is in the .air files sections 1502 through 1507. In particular 1506 thrust scalars.

There is a thread below on that subject which could give some pointers.

The reverse thrust difference could be in the config file [GeneralEngineData]
min_throttle_limit =? Making the value more negative increases reverse thrust.

Roy
 
G'day Roy,

Thanks for your reply, your assistance is much appreciated.

I was able to change the RT settings to get it working to the same degree as the B77W. However, in regards to the .air file for the B77LR when I open it in Notepad all I get is all these symbols?

Just wondering if you could please steer me in the right direction to editing the thrust values in the .air file.

Cheers,

EK433B77W!
 
Hi,
The .air file is binary and you can not easily edit it without using an air file editor. However, all the tables mentioned interact and I would not recommend anyone editing them unless they have had a lot of experience with air files.

It is easier to tune the aircraft in the config file.

I think you may need some more comparative thrust related data points like time to accelerate to climb speed, time to climb to say 10,000 feet. Note the differences between the L and W.

It is just possible that flap drag is different since you have found the difference on the approach. But since you saw different N1 values I think thrust is the problem.

You could play with the thrust_scalar in the config file to increase thrust based on the data points I mentioned above
[jet_engine]
thrust_scalar = 1.0

If that does not get you there, you could use the W air file in the L. If you copy the W air file and paste it next to the L air file and then change the L config file sim=? heading under [fltsim.0] to be the same as the W that should have the L use the W air file. If that works you would need to make the same change in any other [fltsim.n] sections.

Hope this helps.

Roy
 
You must log in or register to reply here.
Back
Top