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A320 Family FDM Changes and Improvements

Postby ja sam niko » Thu Mar 27, 2014 8:05 pm

This topic will be used as a place to discuss and work on the fixes and improvements of the FlightGear Airbus A320 Family.

Image

The A320 Family ,by default comes with big problems in it's FDM. The aircraft is making a very annoying ,and when properly loaded,dangerous pitch-dive movements. That behavior starts after enabling the autopilot. When reaching the desired altitude,instead of just leveling off,the aircraft starts to pitch-dive,slowly loose speed,stall and crash.

The problem becomes much more present ,with increase of the speed and weight.

What I did so far was this:

Changes in elevators settings ,lift and CG.

Elevators and lift ,brought some changes in the aircraft's behavior. The pitch-dive was eliminated,but,the nose was still up more than it should be. That made landing of the aircraft,close to impossible.

Changes in the CG ,eliminated the high nose,but,the drawback was that the take off speed is ridiculous... The only aircraft which responded right to some or all changes,was A320-200....why? I have no clue.

So,I will post the xml of the A320 Family ,A318,319,320 and A321.

I hope this topic will lead to solving of the FDM problems.

Cheers
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Re: A320 Family FDM Changes and Improvements

Postby Bjoern » Thu Mar 27, 2014 11:22 pm

Code: Select all
   <axis name="PITCH">


Have you tried altering that section?

The -4.000 in "Pitch_moment_due_to_alpha" look suspicious. What happens when you set this to zero?
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Re: A320 Family FDM Changes and Improvements

Postby hvengel » Thu Mar 27, 2014 11:38 pm

"That behavior starts after enabling the autopilot. "

Sounds like a autopilot tuning issue to me. Does it exhibit this behavior when the autopilot is disengaged? If not then you probably need to look at how the autopilot is setup.
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Re: A320 Family FDM Changes and Improvements

Postby daveculp » Fri Mar 28, 2014 4:11 am

I agree with hvengel. The autopilot is a completely different issue, so don't use it until you have the FDM flying exactly how you want it.
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Re: A320 Family FDM Changes and Improvements

Postby ja sam niko » Fri Mar 28, 2014 8:54 am

Morning.

@Bjoern,I will check that out to see will it make any difference. I will post the changes here.

@hvengel,I don't think it is,cause the A340-600 and older A330 have the same AP like this A320F....and it works great. I will post everything regarding AP here so if there is some error,we could solve it.

@daveculp....agree,if the AP have some errors.


Cheers
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Re: A320 Family FDM Changes and Improvements

Postby scotth1 » Sun Mar 30, 2014 1:16 am

I haven't had a good look the A320, and PID controllers are still more black random magic than science for me, but I agree there is a problem with the A320-family FDM, and the AP doesn't help, but they are separate issues.
I recently used the A320 and found it's rotate speed is much higher than I would have anticipated, and the resulting vertical speed for a given AoA seemed small (ie: it had trouble getting any height), also it can become unstable at cruise alt with just the slightest change in vertical speed, these sound like the pitch moment axis as @Bjoern says and perhaps masspoints need some tuning..
It probably took me 2 years (part time) to get the FDM and AP right for the A380, with a lot of help from JSBsim guys for the FDM, changes to CG point made significant benefits in that case, if you have specific questions try posting on the JSBsim mailing list.
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Re: A320 Family FDM Changes and Improvements

Postby ja sam niko » Sun Mar 30, 2014 9:41 am

Is it possible for you to connect me to those jsbsim guys ?

This A320 Family is present in FG for more then 10 years...so I think it's time fix it.

I will make some changes in the pitch moment axis . The result will be here. I remember that A380 had the same problems,this annoying and (it can get) dangerous pitch-dive behavior. But it's somehow solved....maybe the same solution could be used here.

Cheers
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Re: A320 Family FDM Changes and Improvements

Postby ja sam niko » Sun Mar 30, 2014 10:03 am

The result of the changes in the pitch are catastrophic....

as you can see here... :p


Image



So ,let's make a deal. Here is the A321-200 (231) .xml file,so all of you can make changes to it,and post it back here,and I'll test it. This way ,we can solve this much faster.

Code: Select all
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="http://jsbsim.sourceforge.net/JSBSim.xsl"?>
<fdm_config name="A320-211" version="2.0" release="BETA"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://jsbsim.sourceforge.net/JSBSim.xsd">

<fileheader>
   <author> Unknown </author>
   <filecreationdate> 2003-01-01 </filecreationdate>
   <version> Version </version>
   <description> Airbus A320 </description>
</fileheader>

<metrics>
   <wingarea  unit="FT2"> 1319.79 </wingarea>
   <wingspan  unit="FT" >  111.26 </wingspan>
   <wing_incidence>          1.03 </wing_incidence>
   <chord     unit="FT" >   13.76 </chord>
   <htailarea unit="FT2">  334.24 </htailarea>
   <htailarm  unit="FT" >   57.88 </htailarm>
   <vtailarea unit="FT2">  248.79 </vtailarea>
   <vtailarm  unit="FT" >   57.33 </vtailarm>
   <location name="AERORP" unit="IN">
   <x> 642.122 </x>
   <y> 0 </y>
   <z> -25.2091 </z>
   </location>
   <location name="EYEPOINT" unit="IN">
   <x> 80 </x>
   <y> -30 </y>
   <z> 70 </z>
   </location>
   <location name="VRP" unit="IN">
   <x> 661.1 </x>
   <y> 0 </y>
   <z> -37 </z>
   </location>
</metrics>

<mass_balance>
   <ixx unit="SLUG*FT2">    611903 </ixx>
   <iyy unit="SLUG*FT2">   1735389 </iyy>
   <izz unit="SLUG*FT2">   2301293 </izz>
   <ixy unit="SLUG*FT2">         0 </ixy>
   <ixz unit="SLUG*FT2">         0 </ixz>
   <iyz unit="SLUG*FT2">         0 </iyz>
   <emptywt unit="LBS" >     87274 </emptywt>
   <location name="CG" unit="IN">
   <x> 642.122 </x>
   <y> 0 </y>
   <z> -41.7398 </z>
   </location>

   <pointmass name="Crew">
      <weight unit="LBS">600</weight>
      <location name="POINTMASS" unit="IN">
         <x>400</x>
         <y>0</y>
         <z>0</z>
      </location>
   </pointmass>
   <pointmass name="PAX">
      <weight unit="LBS">75500</weight>
      <location name="POINTMASS" unit="IN">
         <x>705</x>
         <y>0</y>
         <z>0</z>
      </location>
   </pointmass>
</mass_balance>

<ground_reactions>
   <contact type="BOGEY" name="NOSE_LG">
   <location unit="IN">
      <x> 29.566964</x>
      <y> 0 </y>
      <z> -137.9617 </z>
   </location>
   <static_friction> 0.5 </static_friction>
   <dynamic_friction> 0.8 </dynamic_friction>
   <rolling_friction> 0.02 </rolling_friction>
   <spring_coeff unit="LBS/FT"> 75000 </spring_coeff>
   <damping_coeff unit="LBS/FT/SEC"> 16978.5 </damping_coeff>
   <max_steer unit="DEG"> 75 </max_steer>
   <brake_group> NONE </brake_group>
   <retractable>1</retractable>
   </contact>
   <contact type="BOGEY" name="LEFT_MLG">
   <location unit="IN">
      <x> 699.9243 </x>
      <y> -149.4094 </y>
      <z> -152.6824 </z>
   </location>
   <static_friction> 0.5 </static_friction>
   <dynamic_friction> 0.8 </dynamic_friction>
   <rolling_friction> 0.02 </rolling_friction>
   <spring_coeff unit="LBS/FT"> 180000 </spring_coeff>
   <damping_coeff unit="LBS/FT/SEC"> 33957 </damping_coeff>
   <max_steer unit="DEG"> 0.0 </max_steer>
   <brake_group> LEFT </brake_group>
   <retractable>1</retractable>
   </contact>
   <contact type="BOGEY" name="RIGHT_MLG">
   <location unit="IN">
      <x> 697.3425 </x>
      <y> 149.4094 </y>
      <z> -152.6824</z>
   </location>
   <static_friction> 0.5 </static_friction>
   <dynamic_friction> 0.8 </dynamic_friction>
   <rolling_friction> 0.02 </rolling_friction>
   <spring_coeff unit="LBS/FT"> 180000 </spring_coeff>
   <damping_coeff unit="LBS/FT/SEC"> 33957 </damping_coeff>
   <max_steer unit="DEG"> 0.0 </max_steer>
   <brake_group> RIGHT </brake_group>
   <retractable>1</retractable>
   </contact>

   <contact type="STRUCTURE" name="NOSE_1">
   <location unit="IN">
      <x> 205.905536 </x>
      <y> 0 </y>
      <z> -38.1374 </z>
   </location>
   <static_friction> 1.0 </static_friction>
   <dynamic_friction> 1.4 </dynamic_friction>
   <rolling_friction> 1.0 </rolling_friction>
   <spring_coeff unit="LBS/FT"> 1.5e+06 </spring_coeff>
   <damping_coeff unit="LBS/FT/SEC"> 50000 </damping_coeff>
   <max_steer unit="DEG"> 0.0 </max_steer>
   <brake_group> NONE </brake_group>
   <retractable>0</retractable>
   </contact>
   <contact type="STRUCTURE" name="NOSE_2">
   <location unit="IN">
      <x> 296.220436 </x>
      <y> 0 </y>
      <z> -55.0271 </z>
   </location>
   <static_friction> 1.0 </static_friction>
   <dynamic_friction> 1.4 </dynamic_friction>
   <rolling_friction> 1.0 </rolling_friction>
   <spring_coeff unit="LBS/FT"> 1.5e+06 </spring_coeff>
   <damping_coeff unit="LBS/FT/SEC"> 50000 </damping_coeff>
   <max_steer unit="DEG"> 0.0 </max_steer>
   <brake_group> NONE </brake_group>
   <retractable>0</retractable>
   </contact>
   <contact type="STRUCTURE" name="CENTER_1">
   <location unit="IN">
      <x> 274.0157 </x>
      <y> 0 </y>
      <z> -60.0665 </z>
   </location>
   <static_friction> 1.0 </static_friction>
   <dynamic_friction> 1.4 </dynamic_friction>
   <rolling_friction> 1.0 </rolling_friction>
   <spring_coeff unit="LBS/FT"> 1.5e+06 </spring_coeff>
   <damping_coeff unit="LBS/FT/SEC"> 50000 </damping_coeff>
   <max_steer unit="DEG"> 0.0 </max_steer>
   <brake_group> NONE </brake_group>
   <retractable>0</retractable>
   </contact>
   <contact type="STRUCTURE" name="CENTER_2">
   <location unit="IN">
      <x> 930 </x>
      <y> 0 </y>
      <z> -60.0665 </z>
   </location>
   <static_friction> 1.0 </static_friction>
   <dynamic_friction> 1.4 </dynamic_friction>
   <rolling_friction> 1.0 </rolling_friction>
   <spring_coeff unit="LBS/FT"> 1.5e+06 </spring_coeff>
   <damping_coeff unit="LBS/FT/SEC"> 50000 </damping_coeff>
   <max_steer unit="DEG"> 0.0 </max_steer>
   <brake_group> NONE </brake_group>
   <retractable>0</retractable>
   </contact>
   <contact type="STRUCTURE" name="TAIL_1">
   <location unit="IN">
      <x> 992.87399 </x>
      <y> 0 </y>
      <z> -44.7722 </z>
   </location>
   <static_friction> 1.0 </static_friction>
   <dynamic_friction> 1.4 </dynamic_friction>
   <rolling_friction> 1.0 </rolling_friction>
   <spring_coeff unit="LBS/FT"> 1.5e+06 </spring_coeff>
   <damping_coeff unit="LBS/FT/SEC"> 50000 </damping_coeff>
   <max_steer unit="DEG"> 0.0 </max_steer>
   <brake_group> NONE </brake_group>
   <retractable>0</retractable>
   </contact>
   <contact type="STRUCTURE" name="TAIL_2">
   <location unit="IN">
      <x> 1119.88189 </x>
      <y> 0 </y>
      <z> -18.8067 </z>
   </location>
   <static_friction> 1.0 </static_friction>
   <dynamic_friction> 1.4 </dynamic_friction>
   <rolling_friction> 1.0 </rolling_friction>
   <spring_coeff unit="LBS/FT"> 1.5e+06 </spring_coeff>
   <damping_coeff unit="LBS/FT/SEC"> 50000 </damping_coeff>
   <max_steer unit="DEG"> 0.0 </max_steer>
   <brake_group> NONE </brake_group>
   <retractable>0</retractable>
   </contact>
   <contact type="STRUCTURE" name="TAIL_3">
   <location unit="IN">
      <x> 1236.49609 </x>
      <y> 0 </y>
      <z> -10.2599 </z>
   </location>
   <static_friction> 1.0 </static_friction>
   <dynamic_friction> 1.4 </dynamic_friction>
   <rolling_friction> 1.0 </rolling_friction>
   <spring_coeff unit="LBS/FT"> 1.5e+06 </spring_coeff>
   <damping_coeff unit="LBS/FT/SEC"> 50000 </damping_coeff>
   <max_steer unit="DEG"> 0.0 </max_steer>
   <brake_group> NONE </brake_group>
   <retractable>0</retractable>
   </contact>
   <contact type="STRUCTURE" name="TAIL_4">
   <location unit="IN">
      <x> 232.59841 </x>
      <y> 0 </y>
      <z> 47.4138 </z>
   </location>
   <static_friction> 1.0 </static_friction>
   <dynamic_friction> 1.4 </dynamic_friction>
   <rolling_friction> 1.0 </rolling_friction>
   <spring_coeff unit="LBS/FT"> 1.5e+06 </spring_coeff>
   <damping_coeff unit="LBS/FT/SEC"> 50000 </damping_coeff>
   <max_steer unit="DEG"> 0.0 </max_steer>
   <brake_group> NONE </brake_group>
   <retractable>0</retractable>
   </contact>
   <contact type="STRUCTURE" name="WING_TIP_1">
   <location unit="IN">
      <x> 838.8898 </x>
      <y> -667.5197 </y>
      <z> 35.7926 </z>
   </location>
   <static_friction> 1.0 </static_friction>
   <dynamic_friction> 1.4 </dynamic_friction>
   <rolling_friction> 1.0 </rolling_friction>
   <spring_coeff unit="LBS/FT"> 1.5e+06 </spring_coeff>
   <damping_coeff unit="LBS/FT/SEC"> 50000 </damping_coeff>
   <max_steer unit="DEG"> 0.0 </max_steer>
   <brake_group> NONE </brake_group>
   <retractable>0</retractable>
   </contact>
   <contact type="STRUCTURE" name="WING_TIP_2">
   <location unit="IN">
      <x> 838.8898 </x>
      <y> 667.5197 </y>
      <z> 35.7926 </z>
   </location>
   <static_friction> 1.0 </static_friction>
   <dynamic_friction> 1.4 </dynamic_friction>
   <rolling_friction> 1.0 </rolling_friction>
   <spring_coeff unit="LBS/FT"> 1.5e+06 </spring_coeff>
   <damping_coeff unit="LBS/FT/SEC"> 50000 </damping_coeff>
   <max_steer unit="DEG"> 0.0 </max_steer>
   <brake_group> NONE </brake_group>
   <retractable>0</retractable>
   </contact>
</ground_reactions>

<propulsion>
   <engine file="v2533_a5">
   <location unit="IN">
      <x> 589.735 </x>
      <y> -226.575 </y>
      <z> -45.567 </z>
   </location>
   <orient unit="DEG">
      <roll> 0.0 </roll>
      <pitch> 2.2 </pitch>
      <yaw> 1 </yaw>
   </orient>
   <feed>0</feed>
   <feed>1</feed>
   <feed>3</feed>
   <feed>4</feed>
   <feed>5</feed>
   <thruster file="direct">
      <location unit="IN">
      <x> 589.735 </x>
      <y> -226.575 </y>
      <z> -45.567 </z>
      </location>
      <orient unit="DEG">
      <roll> 0.0 </roll>
      <pitch> 2.2 </pitch>
      <yaw> 1 </yaw>
      </orient>
   </thruster>
   </engine>
   <engine file="v2533_a5">
   <location unit="IN">
      <x> 589.735 </x>
      <y> 226.575 </y>
      <z> -45.567 </z>
   </location>
   <orient unit="DEG">
      <roll> 0.0 </roll>
      <pitch> 2.2 </pitch>
      <yaw> -1 </yaw>
   </orient>
   <feed>0</feed>
   <feed>1</feed>
   <feed>3</feed>
   <feed>4</feed>
   <feed>5</feed>
   <thruster file="direct">
      <location unit="IN">
      <x> 589.735 </x>
      <y> 226.575 </y>
      <z> -45.567 </z>
      </location>
      <orient unit="DEG">
      <roll> 0.0 </roll>
      <pitch> 2.2 </pitch>
      <yaw> -1 </yaw>
      </orient>
   </thruster>
   </engine>
   <tank type="FUEL">    <!-- Left Tank (Inner) -->
      <location unit="IN">
         <x> 630.6588 </x>
         <y> -236.2992 </y>
         <z> -33.9470 </z>
      </location>
      <capacity unit="LBS"> 12186.9 </capacity>
      <contents unit="LBS"> 2437.38 </contents>
   </tank>
   <tank type="FUEL">    <!-- Left Tank (Outer) -->
      <location unit="IN">
         <x> 737.4190 </x>
         <y> -457.4259 </y>
         <z> -8.0898 </z>
      </location>
      <capacity unit="LBS"> 1548.8 </capacity>
      <contents unit="LBS"> 154.88 </contents>
   </tank>
   <tank type="FUEL">    <!-- Left Tank (Surge) -->
      <location unit="IN">
         <x> 788.4322 </x>
         <y> -574.4148 </y>
         <z> 3.1080 </z>
      </location>
      <capacity unit="LBS"> 328.13 </capacity>
      <contents unit="LBS"> 0 </contents>
   </tank>
   <tank type="FUEL">    <!-- Center Tank -->
      <location unit="IN">
         <x> 580.9955 </x>
         <y> 0 </y>
         <z> -47.0 </z>
      </location>
      <capacity unit="LBS"> 14520 </capacity>
      <contents unit="LBS"> 0 </contents>
   </tank>
   <tank type="FUEL">    <!-- Right Tank (Inner) -->
      <location unit="IN">
         <x> 630.6588 </x>
         <y> 236.2992 </y>
         <z> -33.9470 </z>
      </location>
      <capacity unit="LBS"> 12186.9 </capacity>
      <contents unit="LBS"> 2437.38 </contents>
   </tank>
   <tank type="FUEL">    <!-- Right Tank (Outer) -->
      <location unit="IN">
         <x> 737.4190 </x>
         <y> 457.4259 </y>
         <z> -8.0898 </z>
      </location>
      <capacity unit="LBS"> 1548.8 </capacity>
      <contents unit="LBS"> 154.88 </contents>
   </tank>
   <tank type="FUEL">    <!-- Right Tank (Surge) -->
      <location unit="IN">
         <x> 788.4322 </x>
         <y> 574.4148 </y>
         <z> 3.1080 </z>
      </location>
      <capacity unit="LBS"> 328.13 </capacity>
      <contents unit="LBS"> 0 </contents>
   </tank>
</propulsion>

<system file="pushback" />

<flight_control name="FCS: A320">
   <channel name="Pitch">
   <summer name="Pitch Trim Sum">
      <input>fcs/elevator-cmd-norm</input>
      <input>fcs/pitch-trim-cmd-norm</input>
      <clipto>
      <min>-1</min>
      <max>1</max>
      </clipto>
   </summer>

   <aerosurface_scale name="Elevator Control">
      <input>fcs/pitch-trim-sum</input>
      <gain>0.018</gain>
      <range>
      <min>-30</min>
      <max>15</max>
      </range>
      <output>fcs/elevator-pos-rad</output>
   </aerosurface_scale>

   <aerosurface_scale name="Elevator position normalized">
      <input>fcs/elevator-pos-deg</input>
      <domain>
      <min>-30</min>
      <max>15</max>
      </domain>
      <range>
      <min>-1</min>
      <max>1</max>
      </range>
      <output>fcs/elevator-pos-norm</output>
   </aerosurface_scale>
   </channel>
   <channel name="Roll">
   <summer name="Roll Trim Sum">
      <input>fcs/aileron-cmd-norm</input>
      <input>fcs/roll-trim-cmd-norm</input>
      <clipto>
      <min>-1</min>
      <max>1</max>
      </clipto>
   </summer>

   <aerosurface_scale name="Left Aileron Control">
      <input>fcs/roll-trim-sum</input>
      <gain>0.02</gain>
      <range>
      <min>-25</min>
      <max>25</max>
      </range>
      <output>fcs/left-aileron-pos-rad</output>
   </aerosurface_scale>

   <aerosurface_scale name="Right Aileron Control">
      <input>-fcs/roll-trim-sum</input>
      <gain>0.02</gain>
      <range>
      <min>-25</min>
      <max>25</max>
      </range>
      <output>fcs/right-aileron-pos-rad</output>
   </aerosurface_scale>

   <aerosurface_scale name="Left Aileron position normalized">
      <input>fcs/left-aileron-pos-deg</input>
      <domain>
      <min>-25</min>
      <max>25</max>
      </domain>
      <range>
      <min>-0.75</min>
      <max>1</max>
      </range>
      <output>fcs/left-aileron-pos-norm</output>
   </aerosurface_scale>

   <aerosurface_scale name="Right Aileron position normalized">
      <input>fcs/right-aileron-pos-deg</input>
      <domain>
      <min>-25</min>
      <max>25</max>
      </domain>
      <range>
      <min>-0.75</min>
      <max>1</max>
      </range>
      <output>fcs/right-aileron-pos-norm</output>
   </aerosurface_scale>
   </channel>
   <channel name="Yaw">
   <pure_gain name="Yaw Damper Rate">
      <input>velocities/r-rad_sec</input>
      <gain>2</gain>
   </pure_gain>

   <pure_gain name="Yaw Damper Beta">
      <input>aero/beta-rad</input>
      <gain>-5</gain>
   </pure_gain>

   <summer name="Yaw Trim Sum">
      <input>fcs/rudder-cmd-norm</input>
      <input>fcs/yaw-trim-cmd-norm</input>
      <clipto>
      <min>-1</min>
      <max>1</max>
      </clipto>
   </summer>

   <summer name="Rudder Sum">
      <input>fcs/yaw-trim-sum</input>
      <input>fcs/yaw-damper-rate</input>
      <input>fcs/yaw-damper-beta</input>
      <clipto>
      <min>-1</min>
      <max>1</max>
      </clipto>
   </summer>

   <aerosurface_scale name="Rudder Control">
      <input>fcs/rudder-sum</input>
      <gain>0.01745</gain>
      <range>
      <min>-25</min>
      <max>25</max>
      </range>
      <output>fcs/rudder-pos-rad</output>
   </aerosurface_scale>

   <aerosurface_scale name="Rudder position normalized">
      <input>fcs/rudder-pos-deg</input>
      <domain>
      <min>-25</min>
      <max>25</max>
      </domain>
      <range>
      <min>-1</min>
      <max>1</max>
      </range>
      <output>fcs/rudder-pos-norm</output>
   </aerosurface_scale>
   </channel>
   <channel name="Flaps">
   <kinematic name="Flaps Control">
      <input>fcs/flap-cmd-norm</input>
      <traverse>
      <setting>
         <position>0</position>
         <time>0</time>
      </setting>
      <setting>
         <position>40</position>
         <time>40</time>
      </setting>
      </traverse>
      <output>fcs/flap-pos-deg</output>
   </kinematic>

   <aerosurface_scale name="Flap position normalized">
      <input>fcs/flap-pos-deg</input>
      <domain>
      <min>0</min>
      <max>40</max>
      </domain>
      <range>
      <min>0</min>
      <max>1</max>
      </range>
      <output>fcs/flap-pos-norm</output>
   </aerosurface_scale>
   </channel>
   <channel name="Landing Gear">
   <kinematic name="Gear Control">
      <input>gear/gear-cmd-norm</input>
      <traverse>
      <setting>
         <position>0</position>
         <time>0</time>
      </setting>
      <setting>
         <position>1</position>
         <time>10</time>
      </setting>
      </traverse>
      <output>gear/gear-pos-norm</output>
   </kinematic>
   </channel>
   <channel name="Speedbrake">
   <kinematic name="Speedbrake">
      <input>fcs/speedbrake-cmd-norm</input>
      <traverse>
      <setting>
         <position>0</position>
         <time>0</time>
      </setting>
      <setting>
         <position>1</position>
         <time>2</time>
      </setting>
      </traverse>
      <output>fcs/speedbrake-pos-norm</output>
   </kinematic>
   </channel>
</flight_control>
<aerodynamics>

   <axis name="DRAG">
   <function name="aero/coefficient/CDo">
      <description>Drag_at_zero_lift</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <value>0.016</value>
      </product>
   </function>
   <function name="aero/coefficient/CDalpha">
      <description>Drag_due_to_alpha</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <table>
         <independentVar lookup="row">aero/alpha-rad</independentVar>
         <independentVar lookup="column">fcs/flap-pos-deg</independentVar>
         <tableData>
            0.0000   1.0000   25.0000   40.0000
         -0.0873   0.0041   0.0000   0.0005   0.0014
         -0.0698   0.0013   0.0004   0.0025   0.0041
         -0.0524   0.0001   0.0023   0.0059   0.0084
         -0.0349   0.0003   0.0057   0.0108   0.0141
         -0.0175   0.0020   0.0105   0.0172   0.0212
         0.0000   0.0052   0.0168   0.0251   0.0399
         0.0175   0.0099   0.0248   0.0346   0.0502
         0.0349   0.0162   0.0342   0.0457   0.0621
         0.0524   0.0240   0.0452   0.0583   0.0755
         0.0698   0.0334   0.0577   0.0724   0.0904
         0.0873   0.0442   0.0718   0.0881   0.1068
         0.1047   0.0566   0.0874   0.1053   0.1248
         0.1222   0.0706   0.1045   0.1240   0.1443
         0.1396   0.0860   0.1232   0.1442   0.1654
         0.1571   0.0962   0.1353   0.1573   0.1790
         0.1745   0.1069   0.1479   0.1708   0.1930
         0.1920   0.1180   0.1610   0.1849   0.2075
         0.2094   0.1298   0.1746   0.1995   0.2226
         0.2269   0.1424   0.1892   0.2151   0.2386
         0.2443   0.1565   0.2054   0.2323   0.2564
         0.2618   0.1727   0.2240   0.2521   0.2767
         0.2793   0.1782   0.2302   0.2587   0.2835
         0.2967   0.1716   0.2227   0.2507   0.2753
         0.3142   0.1618   0.2115   0.2388   0.2631
         0.3316   0.1475   0.1951   0.2214   0.2451
         0.3491   0.1097   0.1512   0.1744   0.1966
         </tableData>
      </table>
      </product>
   </function>
   <function name="aero/coefficient/CDde">
      <description>Drag_due_to_elevator_Deflection</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>fcs/mag-elevator-pos-rad</property>
      <value>0.0500</value>
      </product>
   </function>
   <function name="aero/coefficient/CDbeta">
      <description>Drag_due_to_sideslip</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>aero/mag-beta-rad</property>
      <value>0.2000</value>
      </product>
   </function>
   <function name="aero/coefficient/CDgear">
      <description>Drag_due_to_landing_gear</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>gear/gear-pos-norm</property>
      <value>0.0400</value>
      </product>
   </function>
   <function name="aero/coefficient/CDspeedbrake">
      <description>Drag_due_to_speedbrake</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>fcs/speedbrake-pos-norm</property>
      <value>0.0400</value>
      </product>
   </function>
   </axis>

   <axis name="SIDE">
   <function name="aero/coefficient/CYb">
      <description>Side_force_due_to_beta</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <table>
         <independentVar>aero/beta-rad</independentVar>
         <tableData>
         -0.3500   0.5000
         0.0000   0.0000
         0.3500   -0.5000
         </tableData>
      </table>
      </product>
   </function>
   </axis>

   <axis name="LIFT">
   <function name="aero/coefficient/CLalpha">
      <description>Lift_due_to_alpha</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <table>
         <independentVar lookup="row">aero/alpha-rad</independentVar>
         <independentVar lookup="column">fcs/flap-pos-deg</independentVar>
         <tableData>
            0.0000   1.0000   9.0000   10.0000   40.0000
         -0.0900   -0.2200   -0.2200   -0.1200   -0.1200   0.3200
         0.0000   0.2500   0.2500   0.3500   0.3500   0.7500
         0.0900   0.7300   0.7300   0.8300   0.8300   1.2300
         0.1000   0.8300   0.8300   0.9300   0.9300   1.3300
         0.1200   0.9200   0.9200   1.0200   1.0200   1.4200
         0.1400   1.0200   1.0200   1.1200   1.1200   1.5200
         0.1600   1.0800   1.0800   1.1800   1.1800   1.5800
         0.1700   1.1300   1.1300   1.2300   1.2300   1.6300
         0.1900   1.1900   1.1900   1.2900   1.2900   1.6900
         0.2100   1.2500   1.2500   1.3500   1.3500   1.7700
         0.2400   1.3500   1.3700   1.4700   1.4800   1.9300
         0.2600   1.4400   1.4700   1.5700   1.6200   2.1200
         0.2800   1.4700   1.5100   1.6100   1.7800   2.4000
         0.3000   1.5000   1.5600   1.6600   1.9000   2.3000
         0.3200   1.4700   1.6100   1.6000   1.7000   2.0300
         0.3400   1.3500   1.5000   1.4100   1.5000   1.5300
         0.3600   1.1500   1.2000   1.2000   1.2000   1.2000
         </tableData>
      </table>
      </product>
   </function>
   <function name="aero/coefficient/CLDe">
      <description>Lift_due_to_Elevator_Deflection</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>fcs/elevator-pos-rad</property>
      <value>0.1930</value>
      </product>
   </function>
   </axis>

   <axis name="ROLL">
   <function name="aero/coefficient/Clb">
      <description>Roll_moment_due_to_beta</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>metrics/bw-ft</property>
      <table>
         <independentVar>aero/beta-rad</independentVar>
         <tableData>
         -0.3500   0.0100
         0.0000   0.0000
         0.3500   -0.0100
         </tableData>
      </table>
      </product>
   </function>
   <function name="aero/coefficient/Clp">
      <description>Roll_moment_due_to_roll_rate_(roll_damping)</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>metrics/bw-ft</property>
      <property>aero/bi2vel</property>
      <property>velocities/p-aero-rad_sec</property>
      <value>-0.5000</value>
      </product>
   </function>
   <function name="aero/coefficient/Clr">
      <description>Roll_moment_due_to_yaw_rate</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>metrics/bw-ft</property>
      <property>aero/bi2vel</property>
      <property>velocities/r-aero-rad_sec</property>
      <value>0.0050</value>
      </product>
   </function>
   <function name="aero/coefficient/Clda">
      <description>Roll_moment_due_to_aileron</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>metrics/bw-ft</property>
      <property>fcs/left-aileron-pos-rad</property>
      <value>0.2000</value>
      </product>
   </function>
   <function name="aero/coefficient/Cldr">
      <description>Roll_moment_due_to_rudder</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>metrics/bw-ft</property>
      <property>fcs/rudder-pos-rad</property>
      <value>0.0050</value>
      </product>
   </function>
   </axis>

   <axis name="PITCH">
   <function name="aero/coefficient/Cmo">
      <description>Pitching_moment_at_zero_alpha</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>metrics/cbarw-ft</property>
      <table>
         <independentVar>fcs/flap-pos-deg</independentVar>
         <tableData>
         0.0000   0.0400
         40.0000   -0.1000
         </tableData>
      </table>
      </product>
   </function>
   <function name="aero/coefficient/Cmalpha">
      <description>Pitch_moment_due_to_alpha</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>metrics/cbarw-ft</property>
      <property>aero/alpha-rad</property>
      <value>-4.0000</value>
      </product>
   </function>
   <function name="aero/coefficient/CmDe">
      <description>Pitch_moment_due_to_elevator_Deflection</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>metrics/cbarw-ft</property>
      <property>fcs/elevator-pos-rad</property>
      <value>-1.5000</value>
      </product>
   </function>
   <function name="aero/coefficient/Cmq">
      <description>Pitch_moment_due_to_pitch_rate</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>metrics/cbarw-ft</property>
      <property>aero/ci2vel</property>
      <property>velocities/q-aero-rad_sec</property>
      <value>-10.0000</value>
      </product>
   </function>
   <function name="aero/coefficient/Cmadot">
      <description>Pitch_moment_due_to_alpha_rate</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>metrics/cbarw-ft</property>
      <property>aero/ci2vel</property>
      <property>aero/alphadot-rad_sec</property>
      <value>-12.0000</value>
      </product>
   </function>
   </axis>

   <axis name="YAW">
   <function name="aero/coefficient/Cnr">
      <description>Yaw_moment_due_to_yaw_rate</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>metrics/bw-ft</property>
      <property>aero/bi2vel</property>
      <property>velocities/r-aero-rad_sec</property>
      <value>-0.0400</value>
      </product>
   </function>
   <function name="aero/coefficient/Cnb">
      <description>Yaw_moment_due_to_beta</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>metrics/bw-ft</property>
      <property>aero/beta-rad</property>
      <value>0.2000</value>
      </product>
   </function>
   <function name="aero/coefficient/Cndr">
      <description>Yaw_moment_due_to_rudder</description>
      <product>
      <property>aero/qbar-psf</property>
      <property>metrics/Sw-sqft</property>
      <property>metrics/bw-ft</property>
      <property>fcs/rudder-pos-rad</property>
      <value>-0.5000</value>
      </product>
   </function>
   </axis>
</aerodynamics>

   <external_reactions>
      <force name="pushback" frame="BODY">
         <location unit="IN">
            <x>294</x>
            <y>0</y>
            <z>-149</z>
         </location>
         <direction>
            <x>1</x>
            <y>0</y>
            <z>0</z>
         </direction>
      </force>
   </external_reactions>
</fdm_config>


Cheers
The worst floods in the Balkans ever,follow these links to learn more how to help. Thank you.
http://www.google.org/crisisresponse/2014-balkans-floods

http://www.mvp.gov.ba/HTML/eng-help.pdf
ja sam niko
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Re: A320 Family FDM Changes and Improvements

Postby Bjoern » Sun Mar 30, 2014 3:10 pm

I'm not going to feed you. It's either collaborative cooking or death by starvation.
Do a barrel roll!
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Re: A320 Family FDM Changes and Improvements

Postby daveculp » Sun Mar 30, 2014 4:02 pm

First step is to verify the x location of the main wheels. You will base the CG, ARP, VRP, fuel tanks, cargo and passenger loads based on this. Put the CG about 20 inches forward of the wheels. Locate the ARP, passenger position and VRP at the CG. Put the center fuel tank a foot in front of the CG and the wing tanks a foot behind.

Keep in mind that you can't make the balance problem "user proof". The user can easily mis-load the airplane, making it unflyable.
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Re: A320 Family FDM Changes and Improvements

Postby buster » Sun Mar 30, 2014 4:36 pm

Hallo ja sam niko,

according to my experience in creating autopilots, this pitch-dive behaviour seems to me to be an issue of the autopilot.
If you are capable to fly the aircraft correcty by hand with a given FDM, it should be Ok. Then it's up to you to adjust the
autopilot to this FDM, in a way it will be able to control the aircraft in all situations of load, COG, speed and altitude.
In case you cannot find one fitting set of parameters for the PID-controllers, you have to make those parameters dynamically
changing due to the flight situation mentioned above, e.g. you can do this by Nasal.
As the PID-controllers are very sensitive to the FDM and the above flight-parameters, you cannot take an existing AP from
other aircraft without adopting it to your specific new aircraft. So you cannot reuse the AP from A340-600 or A330 for your A320 without retuning parameters of the PID-controllers. If the same AP works fine for e.g. the A340-600, that doesn't mean
it will work in the same way for other aircrafts too.
So I highly recommend to face on the AP (and not on the FDM) to fix the pitch-dive-behaviour when AP is enabled.
I know well it can be a very annoying and time-consuming work to find suitable PID-controller-parameters, but to fix this
problem you have to exercise patience.

Cheers,
Markus
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Re: A320 Family FDM Changes and Improvements

Postby ja sam niko » Sun Mar 30, 2014 8:06 pm

I'm not going to feed you. It's either collaborative cooking or death by starvation.


OK ,then I will gladly die,than to be treated like this.

That's it from me forever.
The worst floods in the Balkans ever,follow these links to learn more how to help. Thank you.
http://www.google.org/crisisresponse/2014-balkans-floods

http://www.mvp.gov.ba/HTML/eng-help.pdf
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Re: A320 Family FDM Changes and Improvements

Postby daveculp » Fri Apr 04, 2014 6:25 pm

I took note of a data point yesterday in the A3
19. This could help tune the lift curve, i.e. the curve has to go through this point.

Altitude: 25000 ft
KIAS: 250
GW: 119,600 lbs
SAT: -27C
AOA: 2.6 degrees
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Re: A320 Family FDM Changes and Improvements

Postby ja sam niko » Fri Apr 04, 2014 6:46 pm

I'm enough of this aircraft,which means that I'm not working on it any more. The aircraft is simply hopeless and I don't want to waste any more time on it.



Cheers
The worst floods in the Balkans ever,follow these links to learn more how to help. Thank you.
http://www.google.org/crisisresponse/2014-balkans-floods

http://www.mvp.gov.ba/HTML/eng-help.pdf
ja sam niko
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Re: A320 Family FDM Changes and Improvements

Postby Rick Ace » Fri Apr 04, 2014 7:11 pm

ja sam niko wrote in Fri Apr 04, 2014 6:46 pm:I'm enough of this aircraft,which means that I'm not working on it any more. The aircraft is simply hopeless and I don't want to waste any more time on it.



Cheers

No one is going to work with you, if you keep abandoning a project. It usually takes several months of active development until you gather a strong community of volunteers. If you show people that you are dedicated to a project, then they will slowly start arriving.

And this aircraft is not hopeless. It has a decent FDM, and a lot of features were put into it. I remember that Skyop continuously made improvements and releases. There are a lot of things that you can build upon. ;) We're lucky that this is GPL.
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