Understanding aircraft.cfg files better?

[firefoxa]

Hi all.

New to the forum, but not completely new to FSX
I'm new though to the aircraft.cfg file editing/configuration.
The reason for beeing interested in this is that I use JustFlights Cargo Pilot (CP) for FSX and several of the downloaded aircrafts I wan't to use in it has a .cfg file that CP can't read so I can't use them in CP. The problem is the weight section of the .cfg file. I have figureed out how to make them work with CP, but now that I have started looking in .cfg files I get more and more interested
Many planes have strange weight stations input and several of them are wrong and so on.

What does the different sections reflect, how should I read them and what should I know before doing something with them.

Is there any good links to places wich looks in depth on the aircraft.cfg files? Is there anyone in here that have in depth knowledge?

What I would like to do is to check up the aircraft specs on the net and make sure the .cfg files reflects the real life characteristics as much as possible, but doing this I guess I have to know what to do.

Is like I know fly a DHC6-300 TWIN OTTER. A couple of things disturbs me. The acceleration seems very off (far to fast acceleration) and the power from the engine/props take the aircraft far to fast on 100% (flying with full cargo/fuel leveled out) 210+ knots.

Where should I start looking in the .cfg file and so on..

I hope I was able to explaine myselfe!?

Thx.

Firefoxa.

[lnuss]

The most "in depth" source I know of for the .cfg files would be in the FSX SDK, and it's far from being a tutorial, rather cryptic in fact.

I'd be careful when trying to put real world values into the aircraft.cfg (or at least make sure I saved an original copy), because often many other parameters are affected by changes. FS aircraft are table driven, rather than using real world physics, for the most part, and in all too many cases the values in the .cfg are a result of trial and error to get something that more or less works, since the interactions between various parameters within the file aren't well documented (or aren't documented at all), and few people really understand the interactions. Even some of those who understand a lot are still baffled by certain parts of the file. AND, some parameters are still controlled by the .air files, which are also rather awkward to deal with and even less understood by most (documentation is virtually non-existent).

And no, I'm not an expert on this, but I have a good friend who knows a lot about it and still has to do some really odd things, at times, to get an aircraft to handle well -- it's far from intuitive. As a result, you change something, get what you expect in that area (or maybe not), and eventually discover you've goofed up something else (or maybe several somethings) you thought wasn't related to your change.

It would be nice if there IS someone out there who can provide documentation and tutorials for this area of the sim, but I've not come across anything designed to help a novice, and little even for experts.

[xxmikexx]

firefoxa and lnuss,

The problem is compounded when somebody like me, who does understand most of what's in aircraft.cfg, comes across an aircraft some of whose parameters appear in aircraft.cfg but have no effect when modified. I spent several hours earlier today trying to the get FSX default 737-800 to fly with a lower deck angle in order to improve terrain visibility in climb and cruise when using the 2D panel. I tried EVERYTHING, but NOTHING worked.

So apparently with the advent of FSX there are either a) new rules about when/whether things in aircraft.cfg override things in the .air file, or b) when/whether both aircraft.cfg and .air are ignored and flight model default parameters somehow takes precedence.

But don't ask me about .air files -- I know zero about them.

[ReggieF5421]

Various items.

I'm not sure because I don't have it, but I would expect the Cargo Pilot program to require that different weight stations exist in the aircraft.cfg for varying amounts of cargo. I suspect that's what you have done.

Depending upon the skills of the person doing the flight dynamics - the weights can vary from correct locations to mainly concentrated on the aircraft center of gravity.

I see this a lot in fuel tank locations. Some aircraft will have seven or eight fuel tanks - and all of them located at 0,0,0.

Changing FS aircraft COG with different weights is far from an exact science.

I like FS2004 aircraft because I can use ACM (Aircraft Container Manager) to view the locations of the weight stations, fuel tanks, contact points, etc. in a wireframe view and move them if necessary.

Unfortuntely the program cannot read FSX models, or some with advanced FS2004 XML animations. It is also no longer available in the payware version which allows the complex edits.

Performance as opposed to weight and balance is a better understood subject.

But there are two schools of thought on the subject. One focuses on realistic speeds and such, while the other focuses on realistic engine performance.

i.e. - the speed qroup wants the max speeds to be correct and not too fast at max throttle settings.

The performance group wants x MP to equal x fuel flow and x climb performance - so if you fly a C-46 the way real world pilots fly a C-46 - you get close to real world performance. If the aircraft is flown unrealistically at full throttle, it might be too fast.

You'll notice this is mostly about piston engines. Those seem to be modeled well by the FS flight engine and easy to work with. The same with jets. It's turboprops which seem to be the most tricky/ difficult to hit right in FS based on what I've seen over the years.

A couple places where people get into this indepth are:

www.calclassic.com - Tom Gibson's excellent site and some really good folks

www.sim-outhouse.com - their Flight Dynamics section on their forums - a lot of the SOH folks come from Combat Flight Simulator and have been working for years on getting those models to work right in FS2002, FS2004 & now FSX.

A lot of folks use AirWrench - Jerry Beckwith's tool set to create flight dynamics entries and .AIR files. www.mudpond.org

One last thing - in general FS is going farther away from the .AIR file being customizable and toward the aircraft.cfg having all the changeable items. FSX increases this importance of aircraft.cfg settings over .AIR file settings.

[earthdog]

Try this..i just found it

http://forums.frugalsworld.com/vbb/s....php?p=1522389

Elias

[xxmikexx]

earthdog,

That's an excellent lengthy article, one that at least shows what most of the major issues are. I've made a copy of it for my own reference, along with the link you provided -- many thanks.

I will add that as long as people make backups of aircraft.cfg there is no reason in the world not to experiment, though a commonsense knowledge of basic aerodynamics should be sufficient to make educated guesses about which parameters to try twiddling.

Very often, instead of making a backup at any given step in the process I will instead simply comment out an old variable value and replace it with a new one, as in the following completely made up example. (I'm not even sure the variable name is correct) ...

;;;;;pitch_stability=1.0000
pitch_stability=2.0

The use of five consecutive semicolons makes it very clear which variables I've changed as well as what their pre-change values were.

[n4gix]

earthdog,

That's an excellent lengthy article, one that at least shows what most of the major issues are.

In general, the entries in the aircraft.cfg that have a corresponding entry in the .air file are scalar values which are primarily used to "fine tune" the FDE. That is why the typical entry is 1.0 (100% of the .air file's value).

Having to artifically "pump up" the .air file's values by400% such as shown in that referenced article simply tells me that the basic .air file is crap:

pitch stability = 4.0
roll stability = 2.0
yaw stability = 4.0

The correct approach would be to edit the .air file's parameters so that the scalars in the aircraft.cfg approach 1.0...

...rarely should these entries exceed +/- 0.3

[NikeHerk67]

In general, the entries in the aircraft.cfg that have a corresponding entry in the .air file are scalar values which are primarily used to "fine tune" the FDE. That is why the typical entry is 1.0 (100% of the .air file's value).

Having to artifically "pump up" the .air file's values by400% such as shown in that referenced article simply tells me that the basic .air file is crap:

pitch stability = 4.0
roll stability = 2.0
yaw stability = 4.0

The correct approach would be to edit the .air file's parameters so that the scalars in the aircraft.cfg approach 1.0...

...rarely should these entries exceed +/- 0.3

Bill,

Thanks for confirming what I've been saying for quite some time.
Inuss articulated it quite well. Any slight change in the configuration files and or air files can affect a multitude of parameters.

It's obvious by reading the article that the author was not exactly the best FS pilot. When he refers to aircraft as having such poor flight dynamics that "they drop out of the sky" flags go up here.

I'd guess his resulting aircraft might have a glide ratio of a soar plane, which is why I quit flying combat simulators years ago.

[llivaudais]

Mike,

There are very few AC that I haven't edited in some fashion or other. So frequent are my edits now that the first thing EVERY new AC gets is a copy "orig_aircraft.cfg".

First, as to your 2D cockpit issue, I found that the FS8/FS9 additions to the panel.cfg worked in FSX to set a different 2D view angle, and a toggle with Ctrl+Space seemed to snap to the new view angle and make it a new "reference/default" view (as best I recall.)

Second, making the 2D pan-able simplifies the whole view-angle issue in the 2D view.

Thirdly, I fought an A4 some years ago that wanted to fly about 10°-15° nose up. Maybe the real aircraft does but I doubt it. My solution was to adjust the angle of incidence of both wings and horizontal stab' to give them some of what they seemed to want. The flight surfaces AoA matter a whole lot more than the fuselage AoA. It may not have been perfect, but it made flying it enjoyable - and I doubt if I ever ran into problems from exceeding the max AoA.

--------------------------------------------------
A-4 skyhawk edit: VIEW_FORWARD_DIR=14.5, 0.0, 0.0
wow, that thing did/does fly nose up!

wing_incidence=-0.659180
htail_incidence=-3.300000
-not sure if these are original or edited A-4 parameters

* panning the 2D camera with tophat, mouse or keys
PanPbhAdjust = Swivel
PanPbhReturn = False
PitchPanRate=8 ;; for 8°/sec pan speed
PanAcceleratorTime=0
---------------------------------------------------

Just a few thoughts.

Loyd

[navigatre]

When I try to change the Aircraft.cfg file in FSX I get a "Denied" response (unlike FS9 when I could add aircraft "addons". What's going on?

Gary at golson33@gmail.com

Thanks