Hello!
I noticed some problems with the T38: first of all, it hovers above ground.
While trying to fix that, I came across the second one: when braking
the gears sometimes go underground. Even the main gears. Taking a
closer look at the 3d model and the fdm config I found that the
distance between the main gears and the nose gear is off by a
significant amount. (6.65m vs 4.95m)
Also, the positions don't match either. The offset here is about 320
inches, which coincides with the aero reference point so I guessed
that the visual reference point should in fact be the same. I updated
the ground contact z values and moved the nose gear towards the front
of the airplane based on the 3d model. I changed the animation to take
gear (oleo strut) compression into account.
Also, I noticed that nose gear deployment is animated in one stage and
therefore the gear passes through the doors. I fixed this by adding a
delay, similar to the main gear animation.
Additionally I fixed a typo in the right_inner_strut animation whereby
the left gear position was used (shouldn't really make any difference
though).
After these modifications I didn't notice any change in the behavior
of the plane, but the visual experience is a lot nicer.
I ask for your comments (especially the original authors' or the
maintainers'), as I am a newbie in this field and also without
documentation. So this is basically guesswork. Hope I didn't make a
big mess (no cerr/cout in it, I double-checked :))
Also, I'd like to have your opinion about a possible canopy issue
visible at the arching piece. It seems as if the glass and the arch
didn't connect properly. Or maybe that's just a strange shadow effect?
(I am using OSG branch, btw)
Greets,
Jester
PS: thanks to the people on IRC for their help.
? T38/t38.diff
Index: T38/T38.xml
===================================================================
RCS file: /var/cvs/FlightGear-0.9/data/Aircraft/T38/T38.xml,v
retrieving revision 1.14
diff -u -r1.14 T38.xml
--- T38/T38.xml 13 Mar 2006 17:36:20 -0000 1.14
+++ T38/T38.xml 5 Mar 2007 03:18:18 -0000
@@ -55,7 +55,7 @@
<z> 36 </z>
</location>
<location name="VRP" unit="IN">
- <x> 0 </x>
+ <x> 320 </x>
<y> 0 </y>
<z> 0 </z>
</location>
@@ -76,9 +76,9 @@
<ground_reactions>
<contact type="BOGEY" name="NOSE_LG">
<location unit="IN">
- <x> 140 </x>
+ <x> 73 </x>
<y> 0 </y>
- <z> -60 </z>
+ <z> -46 </z>
</location>
<static_friction> 0.8 </static_friction>
<dynamic_friction> 0.5 </dynamic_friction>
@@ -93,7 +93,7 @@
<location unit="IN">
<x> 335 </x>
<y> -65 </y>
- <z> -60 </z>
+ <z> -46 </z>
</location>
<static_friction> 0.8 </static_friction>
<dynamic_friction> 0.5 </dynamic_friction>
@@ -108,7 +108,7 @@
<location unit="IN">
<x> 335 </x>
<y> 65 </y>
- <z> -60 </z>
+ <z> -46 </z>
</location>
<static_friction> 0.8 </static_friction>
<dynamic_friction> 0.5 </dynamic_friction>
Index: T38/Models/T38-model.xml
===================================================================
RCS file: /var/cvs/FlightGear-0.9/data/Aircraft/T38/Models/T38-model.xml,v
retrieving revision 1.9
diff -u -r1.9 T38-model.xml
--- T38/Models/T38-model.xml 8 Jan 2006 10:39:53 -0000 1.9
+++ T38/Models/T38-model.xml 5 Mar 2007 03:18:19 -0000
@@ -49,6 +49,26 @@
</condition>
</animation>
+ <!-- oleo hack -->
+ <animation>
+ <condition>
+ <equals>
+ <property>gear/gear[0]/position-norm</property>
+ <value>1</value>
+ </equals>
+ </condition>
+ <type>translate</type>
+ <object-name>nose_wheel</object-name>
+ <object-name>front_lower_strut</object-name>
+ <property>gear/gear[0]/compression-norm</property>
+ <factor>0.3048</factor> <!-- feet to meters -->
+ <axis>
+ <x>0</x>
+ <y>0</y>
+ <z>1</z>
+ </axis>
+ </animation>
+
<animation>
<type>rotate</type>
<object-name>nose_wheel</object-name>
@@ -74,8 +94,10 @@
<object-name>front_upper_strut</object-name>
<object-name>front_fwd_strut</object-name>
<property>gear/gear[0]/position-norm</property>
- <factor>-90</factor>
- <offset-deg>90</offset-deg>
+ <factor>-130</factor>
+ <offset-deg>130</offset-deg>
+ <min-deg>0</min-deg>
+ <max-deg>90</max-deg>
<center>
<x-m>-6.26</x-m>
<y-m>0</y-m>
@@ -201,6 +223,27 @@
</axis>
</animation>
+ <!-- oleo hack -->
+ <animation>
+ <condition>
+ <equals>
+ <property>gear/gear[1]/position-norm</property>
+ <value>1</value>
+ </equals>
+ </condition>
+ <type>translate</type>
+ <object-name>leftgear</object-name>
+ <object-name>left_lower_strut</object-name>
+ <object-name>left_inner_strut</object-name>
+ <property>gear/gear[1]/compression-norm</property>
+ <factor>0.3048</factor> <!-- feet to meters -->
+ <axis>
+ <x>0</x>
+ <y>0</y>
+ <z>1</z>
+ </axis>
+ </animation>
+
<animation>
<type>rotate</type>
<object-name>leftgeardoor</object-name>
@@ -282,7 +325,7 @@
<animation>
<type>rotate</type>
<object-name>right_inner_strut</object-name>
- <property>gear/gear[1]/position-norm</property>
+ <property>gear/gear[2]/position-norm</property>
<factor>-195</factor>
<offset-deg>135</offset-deg>
<min-deg>0</min-deg>
@@ -299,6 +342,27 @@
</axis>
</animation>
+ <!-- oleo hack -->
+ <animation>
+ <condition>
+ <equals>
+ <property>gear/gear[2]/position-norm</property>
+ <value>1</value>
+ </equals>
+ </condition>
+ <type>translate</type>
+ <object-name>rightgear</object-name>
+ <object-name>right_lower_strut</object-name>
+ <object-name>right_inner_strut</object-name>
+ <property>gear/gear[2]/compression-norm</property>
+ <factor>0.3048</factor> <!-- feet to meters -->
+ <axis>
+ <x>0</x>
+ <y>0</y>
+ <z>1</z>
+ </axis>
+ </animation>
+
<animation>
<type>rotate</type>
<object-name>rightgeardoor</object-name>
-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys-and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
_______________________________________________
Flightgear-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/flightgear-devel
