Help adjusting FDE please?

I wonder if anyone could help me here? I am not a complete novice at this, but of course changing values in the aircraft.cfg can solve one problem only to have a 'knock on' effect and cause new ones. How would I best improve things in this situation....

I have an Embraer 195 (model by JRLucariny, apparently) which has odd approach behaviour. Even with less than 10% fuel, if I don't keep the speed above 150kts, the a/c stalls and falls out of the sky. That's with full flaps, even though in the aircraft.cfg file - "full_flaps_stall_speed = 113.0". The nose is really high at this stage, maybe 15 degs up.. As I add flaps, it doesn't bring the nose down as much as I'd expect from other a/c... It's landable, just: but I don't always make it safely with these characteristics: once a stall starts, I have to slew the a/c up, or crash..

So what do I need to adjust here, so that I can approach 'normally': a reasonable AoA and approach speed? Seems to me that a light E195 should be landing at under 120kts, no? Even my 747s don't insist on landing at 150kts, unless they come in pretty heavy. What parameters can I safely adjust in the aircraft.cfg file (or the air file, come to that? Is that file implicated in this behaviour??).

Many thanks.

please try this:

[flaps.0] //Trailing Edge Flaps

type = 1 // 1 - tail, 2 - lead

span-outboard = 0.8 // 0.0 .. 1.0

extending-time = 20 // seconds

flaps-position.0 = 0 // degrees

flaps-position.1 = 1 // degrees

flaps-position.2 = 2 // degrees

flaps-position.3 = 5 // degrees

flaps-position.4 = 10 // degrees

flaps-position.5 = 15 // degrees

flaps-position.6 = 25 // degrees

flaps-position.7 = 30 // degrees

flaps-position.8 = 40 // degrees

damaging-speed = 250 // KIAS

blowout-speed = 300 // KIAS

lift_scalar = 1.0

drag_scalar = 1.0

pitch_scalar= 0.6

system_type = 1

First, be sure you're flying the aircraft the way its supposed to fly. That sounds obvious, but sometimes designers set up their download to simulate real-world conditions but then they didn't say what those conditions were. :rolleyes:

You could also try to find a similar aircraft and try it out. Does it feel "right" in the pattern? Is it more controllable? Etc. If so, you could do a (usually) quick "hack and slash" dynamics edit. :pilot:

You'll need to edit the aircraft.cfg file of the model you want to use the dynamics of the plane which handles better. For this you'll need a copy of the "good" plane's aircraft.cfg and .air file.

Basically, use the "good" plane's aircraft.cfg and delete the [aircraft.#] sections and general info section. Copy these sections from the plane you want into the .cfg file and save. BE SURE to change the "sim=" line to the name of the "good" aircraft's .air file.

At this point you should test the aircraft. The view point and contact points will probably be wrong but you just want to make sure the plane loads and can fly. If things look good, you can copy the view point and contact point sections (be sure to copy the ALL the data in these two sections and completely over-write the old data).

Test again, you may need to tweak the view point to get it where you want it and the same may be true for the landing gear lengths in the contact point data but they should be close.

This is something that's harder to write about than to actually do ;) - it just takes some experience, if you have specific questions about the contact points or view point let me know and I'll post a reply. The basic idea is to use the cfg. and .air file from something that works better and edit the data for the model, panel, and sound you want to use into the .cfg file. You could do the same thing by copying and paste-ing the data from the better .cfg file into the old .cfg but this takes more time and its easier to screw something up.

Thanks - I have spent some time copying and pasting and trying other air files (latter makes no difference), but not sure of the results yet. I find that reloading a saved flight to test this out doesn't properly reflect how things have been reset - you need to make a proper flight to get a proper result, which takes some time of course.

The main problem seems to be that the pitch of the a/c starts to go up at much higher speeds than I'd imagine, and the aircraft. lightly loaded and with 10% fuel, stalls at speeds of anything much less than 140kts with full flaps (by which time the pitch is almost 20 degrees!). The full flaps stall speed in the cfg file is 113... I'll keep at it for now anyway. I am sure it must be controllable in the aircraft.cfg file.

...

 

The main problem seems to be that the pitch of the a/c starts to go up at much higher speeds than I'd imagine, and the aircraft. lightly loaded and with 10% fuel, stalls at speeds of anything much less than 140kts with full flaps (by which time the pitch is almost 20 degrees!). The full flaps stall speed in the cfg file is 113... I'll keep at it for now anyway. I am sure it must be controllable in the aircraft.cfg file.

That is why I suggest :

pitch_scalar= 0.6

and a little less lift scalar (0.9) as my tests of aurigny_embraer_195.zip and upd. showed.

But perhaps we test different aircrafts?

A few thoughts...

Yes, it's possible that changing one value in the aircraft.cfg will solve one problem but lead to another. I'm always sensitive to this when tinkering with the cfg.

Also, some of the lines in the aircraft.cfg have little or no effect on how the aircraft flies. I believe full_flaps_stall_speed is one of them. So don't read too much into this line.

As to making the airplane approach more realistically, a few things to look for:

*Is the gross weight of the airplane reasonable? You said the fuel load is light, great, but if the empty weight is high it won't matter. Try it with a lot less empty weight or payload and see what happens.

*Look at the flap settings. Is max trailing edge flaps about 40 degrees or so? Are the leading edge flaps disabled? Certainly check the line for lift_scalar = xxx for each flap section. Try it with about 50% more flap lift and see what happens.

*Is it possible that you're retracting the flaps after take off, or extending them before landing, while too fast? This would cause the sim to consider them 'broken', even though you think you've extended them. Set values for damaging-speed and blowout-speed high enough to not be a problem.

Once you find something that helps your problem you can refine the changes and look out for side effects. Don't forget to back up your original cfg file!

Nadlzfw

Thanks for all the comments...

I did change the pitch_scalar= as you suggested, but I am not sure it had any great effect in the sim. After reading the Aircraft SDK again,in [Flaps.0] I changed the value of lift_scalar from 0.0 to 1.0 - this seems to have helped a bit. I also changed a few drag_scalar values slightly (yes, I have all my files backed up multiple times).

I am still testing these settings and I'll post back with any definitive results. Meanwhile, many thanks for all the comments and suggestions.

How did you get to "lift_scalar=0.0"???

Do we test rides on the same aircraft?

Please check my pictures, especially the panel at final approach.

In between I had some fine landings with "lift_scalar=0.9" and "pitch_scalar=0.4" (120 KIAS, 10 percent fuel). I believe it is a god idea not to go to the limit of 113 KIAS!

Starting with 98% fuel was also okay.

:pilot:

Nobody in this thread has mentioned it yet but have you tried moving the COG towards the rear in the plane's aircraft.cfg by, e.g. one foot at a time. Your problem certainly sounds like a COG position problem.

Hans

Martin, if the original value of the lift_scalar was zero, that means the flaps were doing nothing to bring the nose down to prevent a stall. Increasing the value to 1.0 helped, so you should keep increasing the lift_scalar until the approach seems normal.

The lift_scalar is just a multiplier to a value in the .air file that may be way too low. It's easier to increase the lift_scalar than to guess at a better value for the .air file. You may have to set it to 3.0 or more to get the results that you're expecting.

Give it a try and good luck.

Regards, JerryH

Hi,

Note that the flaps section in the aircraft.cfg file can be in several parts, and one of those should have the lift_scalar higher than 0. This is the one I would increase, until the behavior is what you want.

Not all RW aircraft react the same, but AFAIK most flap deflections will give a nose down pitch moment. Slats will do the reverse, not sure about Kreugers.

Anyway in the .air file, table 1101 Primary aerodynamics, in the Pitch section there is Cm_df Pitch moment flaps, a positive value will give a nose down pitch. The value just has to be experimented with to get the desired result.

I think the config value of pitch scalar gives a percentage of that value, so if its in the wrong direction to start with.....

Good luck

As long we don't know which specific aircraft is meant, these very fine ideas are like stiring in the mud. I used for my test flights aurigny_embraer_195.zip and aurigny_embraer_195_update.zip. It has an aircraft.cfg with a flaps section that does not have a "lift_scalar=0.0" (nonsense in my mind).

With this ac my suggestions work, all other is unknown for me.

Lets hope Martin will tell us, what we are discussing....

How did you get to "lift_scalar=0.0"???

It must have been like that, I didn't edit it that way. I used InfoRapid to search all my FS9 aircraft.cfg files for 'lift_scalar' and there were quite a few set at zero.

I believe it is a good idea not to go to the limit of 113 KIAS!

Agreed!! :o I stay around 135 minimum, with c.15% fuel left (and about 1/3 capacity cargo/baggage load) - the a/c tends to be near to a stall much below that, with full flaps, but 135kts is fine. Better than the minimum VRef of 155-160 I had to use before (and even then the angle of the nose was frightening!).

...have you tried moving the COG towards the rear

No, I thought of it but haven't tried - the balance looks good in the FS9 fuel menu, but that may be wrong.

you should keep increasing the lift_scalar until the approach seems normal

Yes, with the lift_scalar value altered in [Flaps.0] and [Flaps.1], things are much better now. I haven't tried changing the value in [Flaps.0] only...

in the .air file, table 1101 Primary aerodynamics, in the Pitch section there is Cm_df Pitch moment flaps, a positive value will give a nose down pitch

I'll have a look at this too, thanks.

As long we don't know which specific aircraft is meant..

I think it must be the same as yours - I have been testing with an E195 Aurigny livery - as I said at the start, the model is by a 'JR Lucariny', which should identify the a/c, no?

I might just add that, although I am marked 'Junior Member' here with few posts, I have been posting over on A***M since 2002, with some 4000 posts there (as far as I recall: I won't ever go there again due to a certain moderator and the general policy these days. But I won't get started on that!) and have spent 15 years now enjoying and tweaking FS in this way. That doesn't mean I don't have areas of doubts and even of gross ignorance of course! I've never pretended to be a guru...

Thanks again.

M.

Flap pitch alone won't cure anything. It will only give you one other thing to worry about. Locoriny's FDEs are always messed up (and he does Payware?-cheesh!).

You need a complete makeover (both cfg and air files need to be tweaked). Plus trial & error flying. Having that much nose pitch on approach when everything is 'minimums' speaks of a crap FDE. Will I work on it? Not if the 'garbage' is from you know who. I don't like thiefs.

Chuck B

Napamule

How right you are Chuck!

I compared E195FBe.air and Boeing737-400.air (fs9 supplied) byte by byte, no difference!

I compared the aircraft.cfgs too, only few differences (lights, contact points, static_cg_height, and so on).

So it is ridiculous...

:mad:

The same plane often gets changed and reuploaded. If you want others to look at the files you must post name of .zip -file that you downloaded to get the aircraft.

Either save the .zip files and keep them and in a textfile write down where you got them. Or if you don't have the drivespace, place a textfile in the aircraft's folder with the information.

(or better yet, do both).

Then post that info when asking.

"i installed Johnny Bravo's A737" is really not enough.

I have saved every zip file I have ever downloaded for FS over the past 15 years - I'll check and give the zip file name when I get home to the PC... I didn't give it at first as I was asking a general question about editing the aircraft.cfg file (for any aircraft). It's now become specific...

EDIT: It's E195Be.zip (from the library here).

Ok, no worries, I did not mean to cause (personal) offense. Good on you saving the .zip's.:) always a good idea.

I just needed to get it off my chest I guess. Way too many threads without a filename, that's all.

Happy Flights,

il.

I click on 'Name', or 'Date Modified', or 'Size', or 'Type', to 'organize', and then use 'Ctrl'+'Mouse Wheel' to view.

Chuck B

Napamule

BTW, just out of curiosity, has the OP checked the calibration of their controller recently?

Some FS aircraft are more "twitchy" to controller inputs than others. Several months ago, I was chasing what I thought were problems in an aircraft's dynamics. As it turned out, my joystick's rudder sensor had become loose (actually, I found out it had not been installed correctly when the joystick was manufactured after I figured out how to take it apart and re assemble it :rolleyes: ).

You should be able to access your controller calibration through the FS pull down menu. Depending on what you use, you should see a display that shows the X/Y position of the yoke or joystick and sliders that show the position of the rudder pedals and throttle. These displays should show the rudder and X/Y positions fairly centered if you're not touching them.

Joysticks and yokes can drift over time. Sometimes a re-cal can eliminate a lot of problems. :cool:

BTW, just out of curiosity, has the OP checked the calibration of their controller recently?

Yes, thanks, I do check that from time to time (because of other issues with my X52), and it's OK.

I think changing the lift_scalar value in [Flaps.0] has more or less solved the issue. The past few flights I have had no problems with speeds or pitch, but I will fly some more with this a/c to make sure.

Quote: '..That is why I suggest : pitch_scalar= 0.6'

That flap pitch is momemtary and does not last long enough to be there when you land a minute later. Bogus suggestion. Not relevant.

What is needed is elevator pitch trim on approach to help with ac attitude (which changes when you lower gear, add flaps, or reduce power) in order to land on main wheels. Simple as that. PITCH TRIM. OK? OK!

Chuck B

Napamule