Help needed - wing_pos_apex_lon=?

[lykon 0]

Hello guys and best wishes for the new year.

 

I desperately need some help with some issues i am having in order to edit some aircraft commands inside .cfg and .air files. I am currently working to create an airbus a320 FDE and i have all data needed from real charts and i have almost done with my project but i need some extra help with some things i have not cleared them yet.

 

First of all inside aircraft.cfg i want to ask about the command "wing_pos_apex_lon". As far as i know there is no command you can define the length of the aircraft inside aircraft.cfg but i have the real value from the H-arm estimated about 2.5 meters forward from the aircrafts nose. Also i have the length of the wing apex estimated from the aircrafts nose to the wing apex but i don't know for sure that if i put in the command "reference_datum_position" the lenght from the H-arm to the the MAC or to the root chord this would be sufficient but i have did a compromise and i have used both commands:

 

reference_datum_position=0.000, 0.000, 0.000

empty_weight_CG_position=0.000, 0.000, 0.000

 

and after this i have fix a value inside "wing_pos_apex_lon" to give me the model's dry operating weight 25% mac which in my opinion is totally wrong. Any comments or any help in this would be highly appreciated.

 

Also i am having problems in order to calculate inside .air file and particurarly inside the "1101" section the correct values for these commands:

 

 

,Airframe Type, = ?

 

,Fuselage AoA at Min Induced Drag, = ?

 

,CL_adot Lift - AoA rate (?),= ?

,CL_q Lift - Pitch rate (?),= ?

,CL_de Lift - Elevator,= ?

,CL_dh Lift - Horizontal Stabilizer, = ?

 

,Cmo Pitch Moment Coeff at AoA=0 (Trim os), = ?

,Cm_adot Pitch Moment - AoA Rate, = ?

,Cm_h Pitch Moment - Horizontal Stabilizer, = ?

 

 

 

Currently i am using for these values the boeing 737 default values which they are comming from the "TwinEngineCommercialJet" template from inside templates folder from FS9 but while whith these above compromises i did the aircraft is flying well and stable it is not airbus. I would be very greatfull is someone could assist me of how maybe with some formulas or with a quick tutorial help me to estimate these values. Many thanks in advance.

 

Kind regards

Lykon

[Dietmar 8]

Hi,

may be this is a good source for the info you are looking for:

http://www.pafs.wf/

A lot of people with Aibus know how and a lot of models too, where you could look into the air files.

 

Dietmar

[n4gix 4,954]

For general information, the reference_datum_position (RDP) corresponds to an arbitrary point in world space that the engineers have defined as THE reference point for all measurements on real world blueprints/drawings.

 

Typically this RDP is located several feet in front of the fuselage's nose, or the prop spinner of single engine aircraft, centerline, waterline.

 

The hierarcy of the various points are:

VMO - visual model origin (0,0,0)
|___ RDP - reference_datum_position (positive offset from VMO)
 |___EWCG - empty_weight_CG_position (negative offset from RDP)

The beauty of following this convention is that all other measurements in the aircraft.cfg are then defined as negative offsets from the RDP, so you can't get confused about whether they should be positive or negative offsets!

 

Now, that said the sad truth is that most modelers do not use this convention, but simply make the VMO, RDP and EWCG precisely the same point, which to my mind is just plain lazy... :blink:

 

If you wish to PM me an email address, I can send you a very handy utility that will allow you to SEE all of these points as well as all of the other critical points in the sim in real time. Simply unzip Visualizer into any convenient folder (I use ..\FS Tools), then double-click to run Visualizer while FSX is running.

 

Here is a graphic image showing some of the pertinent points on an airframe:

[lykon 0]

Hello guys and many thanks for your effort to help. The above picture is very very helpfull. Also any more help is great appriciated!

 

 

 

Kind regards

Lykon

[Dietmar 8]

Here you get a nice document:

 

http://library.avsim.net/download.php?DLID=170811

 

Dietmar