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DHC-6 Twin Otter development

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DHC-6 Twin Otter development

Postby mpbartram » Fri Jan 31, 2014 3:20 pm

Hi everyone. I'm new to the Flightear community and development, and new-ish to Flightgear (tried various times in the past; always my computer couldn't cope). I've been flying the DHC-6 in particular recently, and amongst other things that need work discovered the reverse thrust does very-nearly nothing.

There's a forum thread up till early last year implying development is still in progress, but little else I can find. The maintainer, Syd Adams, doesn't seem very public on the internet, and the version on flightgearcanada.ca seems older and less complete than the one on Flightgear's download page.

So anyway, I wondered about tweaking the plane for my own use - and if that, perhaps getting involved in development of it. I have some coding experience (Haskell, Python, C) and experience flying in but not piloting the DHC-6. Any thoughts? Anyone know about development of this particular aeroplane?

Thanks

M
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Re: DHC-6 Twin Otter development

Postby sa7k » Fri Jan 31, 2014 4:39 pm

The french forum guys are making improvements to the DHC6 here:
http://equipe-flightgear.forumactif.com/t1195-dhc-6-300-twin-otter
I'm sure one of them will reply as they are active in this forum too.
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Re: DHC-6 Twin Otter development

Postby F-JJTH » Fri Jan 31, 2014 5:15 pm

We have done some improvements, but we didn't touched the FDM at all.
I invit you to contact Secret_hamster because he is looking at the DHC6's FDM.

Syd has been informed of the work done on the french forum and he is free to commit it in FGData.

For information the work done by french forum is available on GIT: https://gitorious.org/paf/fgdata
Feel you free to contribute ;)

Regards,
Clément
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Re: DHC-6 Twin Otter development

Postby erik » Sat Feb 01, 2014 2:14 pm

FYI, I just updated the DHC-6 JSBSim FDM at:
http://jsbsim.cvs.sourceforge.net/viewv ... raft/DHC6/

This uses data gathered for icing conditions (but without the icing data) and hence has a fairly high out of normal ranges (-20 to 40 degrees alpha and -20 to 20 degrees beta). I used all the data I could find for the aircraft.

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Re: DHC-6 Twin Otter development

Postby clrCoda » Sat Feb 01, 2014 7:17 pm

mpbartram wrote in Fri Jan 31, 2014 3:20 pm: and amongst other things that need work discovered the reverse thrust does very-nearly nothing.


Be sure to run the condition levers all the way back to get thrust reverse. The over head, center pair of levers controlled by keyboard shift-n. Then Hit the DELETE key to change the direction of the Thrust levers to get reverse thrust.

Best of luck
Ray St. Marie
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Re: DHC-6 Twin Otter development

Postby mpbartram » Sat Feb 01, 2014 11:21 pm

Thanks those of you who posted about development. I'll try setting up cloning the git and cvs repositories in the next few days, hopefully. Erik I'm not quite sure what you mean by "a high out of normal ranges" - high power, or aerodynamic performance or something? Anyway, sounds interesting. I wonder how it compares to the current YASim model.

cirCoda: I'm pretty sure (not that I have any great experience!) the condition levers want to be full forward, as that puts the prop angles closest to 0deg, able to go to -ve deg for reverse thrust. Blue condition/prop levers back puts props to feather, at high positive angle, for gliding or perhaps taxiing. On the other hand the throttles *do* need pulling back, i.e. setting to 0, first, because that makes the continuous lever action in this cockpit.
But I tried as you said, and it makes no difference. Brakes off, throttle full reverse, does nothing regardless of whether I set the condition levers forward/backward/central first - or fiddle with them afterwards.
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Re: DHC-6 Twin Otter development

Postby clrCoda » Sun Feb 02, 2014 7:15 am

It works for me, but then I am using the 2.0 version of the dhc6-300 in fg2.12.1 because more things work on the 2.0 version of the plane than the more recent one.

I might suggest getting a copy of the 2.0 version of the plane and migrating the things that work in each version of the plane into a more complete version.

I'd be really interested in the end result of such a project.
Ray St. Marie
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Re: DHC-6 Twin Otter development

Postby Buckaroo » Sun Feb 02, 2014 8:04 am

On the reverse thrust issue, it looks like the more recent YASim FDM uses a rather small thrust value. Older versions had a maximum reverse thrust value 2.5 times greater. That might account for what some folks are noticing.

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Re: DHC-6 Twin Otter development

Postby erik » Mon Feb 03, 2014 11:51 am

mpbartram wrote in Sat Feb 01, 2014 11:21 pm:Erik I'm not quite sure what you mean by "a high out of normal ranges" - high power, or aerodynamic performance or something? Anyway, sounds interesting. I wonder how it compares to the current YASim model.


"high out of normal ranges" is my unscientific way of saying that it can handle crabbed landings (high beta) and high angle approaches (high alpha). During normal flight alpha and beta both are normally close to 0 degrees but in some situations you need to fly with the aircraft nose pointing in a different direction than the direction you're flying to.

Anyway I'm quite convinced about the JSBSim FDM although it would be good to give it some testing by someone who does know how the DHC-6 handles in real life. But id does include flapperon in the aerodynamics for instance.

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Re: DHC-6 Twin Otter development

Postby mpbartram » Tue Feb 04, 2014 11:45 pm

I tried your JSBSim FDM, but am not quite sure how to make it work. I put it in my dhc-6 folder as dhc6-jsbsim.xml, and copied the dhc6-set.xml to dhc6-jsbsim-set.xml changing file references and FDM engine name accordingly. But when I try loading it I get:
Code: Select all
Aircraft propulsion element has problems in file C:/... dhc6/dhc6-jsbsim.xml
Unknown exception in the main loop. Aborting...
Possible cause: No such file or directory

Any ideas what's going on? Bug? My wrong way of using the FDM?
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Re: DHC-6 Twin Otter development

Postby erik » Wed Feb 05, 2014 8:42 am

I got it to work by extracting this archive in Aircraft/dhc6 and by commenting out the systems.nas file from dhc6-base.xml (there seems to be something YASim specific in it:
Code: Select all
diff --git a/Aircraft/dhc6/dhc6-base.xml b/Aircraft/dhc6/dhc6-base.xml
index 9283b8e..5be3ea2 100644
--- a/Aircraft/dhc6/dhc6-base.xml
+++ b/Aircraft/dhc6/dhc6-base.xml
@@ -400,7 +400,7 @@ Jan 2008 Syd Adams
     <nasal>
         <dhc6>
             <file>Aircraft/dhc6/Nasal/Electrical.nas</file>
-            <file>Aircraft/dhc6/Nasal/systems.nas</file>
+<!--        <file>Aircraft/dhc6/Nasal/systems.nas</file> -->
         </dhc6>
     <dialogs><file>Aircraft/dhc6/Nasal/dialogs.nas</file></dialogs>
         <m877>

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Re: DHC-6 Twin Otter development

Postby mpbartram » Thu Mar 06, 2014 11:44 pm

Thanks Erik. That works for me, mostly. And I got it to work with systems.nas by commenting out the Shudown() line in the fdm-initialiser listener. I guess some difference between how engine control works in yasim and jsb is the issue. Also the attitude indicator still doesn't work...
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Re: DHC-6 Twin Otter development

Postby abassign » Sat Nov 01, 2014 6:04 pm

Image

The cabin light is too bright, I think is possible to have a better effect by this modify:

File .../Aircraft/dhc6/Models/Lights/cabin-light.xml
Code: Select all
<?xml version="1.0" encoding="UTF-8" ?>
<!--
2014    
    -->

<PropertyList>
   <path>lightcone-central.ac</path>

   <animation>
      <type>select</type>
      <condition>
         <and>
            <property>controls/lighting/cabin-lights</property>
            <property>/sim/rendering/rembrandt/enabled</property>
         </and>
      </condition>
   </animation>
   
   <!--Spot lights-->
   <animation>
      <type>light</type>
      <light-type>spot</light-type>
      <object-name>Cone</object-name>
      <nopreview/>
      <position>
         <x>-3</x>
         <y>-0.1</y>
         <z>0.700</z>
      </position>
      <direction>
         <x>-1</x>
         <y>0</y>
         <z>0</z>
      </direction>
      <ambient>
         <r>0.8</r>
         <g>0.8</g>
         <b>0.8</b>
         <a>1.0</a>
      </ambient>
      <diffuse>
         <r>0.7</r>
         <g>0.7</g>
         <b>0.5</b>
         <a>1.0</a>
      </diffuse>
      <specular>
         <r>0.7</r>
         <g>0.7</g>
         <b>0.7</b>
         <a>1.0</a>
      </specular>
      <attenuation>
         <c>1.0</c>
         <l>0.2</l>
         <q>0.05</q>
      </attenuation>
      <exponent>30.0</exponent>
      <near-m>0.2</near-m>
      <far-m>1.30</far-m>
      <cutoff>120</cutoff>
   </animation>
   
   <effect>
      <name>REMBRANDT transparency</name>
      <inherits-from>Effects/model-transparent</inherits-from>
      <object-name>Light</object-name>
   </effect>

</PropertyList>


File: .../Aircraft/dhc6/Models/Lights/L-oh-light.xml

Code: Select all
<?xml version="1.0" encoding="UTF-8" ?>
<!--
2014    
    -->

<PropertyList>
   <path>L-lightcone-oh.ac</path>

   <animation>
      <type>select</type>
      <condition>
         <and>
            <property>controls/lighting/cabin-lights</property>
            <property>/sim/rendering/rembrandt/enabled</property>
         </and>
      </condition>
   </animation>
   
   <!--Spot lights-->
   <animation>
      <type>light</type>
      <light-type>point</light-type>
      <object-name>Cone</object-name>
      <nopreview/>
      <position>
         <x>-3.44</x>
         <y>-0.28</y>
         <z>0.84</z>
      </position>
      <direction>
         <x>0</x>
         <y>0</y>
         <z>0</z>
      </direction>
      <ambient>
         <r>0.8</r>
         <g>0.8</g>
         <b>0.8</b>
         <a>1.0</a>
      </ambient>
      <diffuse>
         <r>0.7</r>
         <g>0.7</g>
         <b>0.6</b>
         <a>1.0</a>
      </diffuse>
      <specular>
         <r>0.7</r>
         <g>0.7</g>
         <b>0.7</b>
         <a>1.0</a>
      </specular>
      <attenuation>
         <c>5.0</c>
         <l>0.2</l>
         <q>0.005</q>
      </attenuation>
      <exponent>8.0</exponent>
      <near-m>0.5</near-m>
      <far-m>0.23</far-m>
      <cutoff>120</cutoff>
   </animation>
   
   <effect>
      <name>REMBRANDT transparency</name>
      <inherits-from>Effects/model-transparent</inherits-from>
      <object-name>Light</object-name>
   </effect>

</PropertyList>


File: .../Aircraft/dhc6/Models/Lights/oh-light.xml

Code: Select all
<?xml version="1.0" encoding="UTF-8" ?>
<!--
2014    
    -->

<PropertyList>
   <path>lightcone-oh.ac</path>


   <animation>
      <type>select</type>
      <condition>
         <and>
            <property>controls/lighting/cabin-lights</property>
            <property>/sim/rendering/rembrandt/enabled</property>
         </and>
      </condition>
   </animation>
   
   <!--Spot lights-->
   <animation>
      <type>light</type>
      <light-type>point</light-type>
      <object-name>Cone</object-name>
      <nopreview/>
      <position>
         <x>-3.02</x>
         <y>0</y>
         <z>0.52</z>
      </position>
      <direction>
         <x>0</x>
         <y>0</y>
         <z>-0.8</z>
      </direction>
      <ambient>
         <r>0.8</r>
         <g>0.8</g>
         <b>0.7</b>
         <a>1.0</a>
      </ambient>
      <diffuse>
         <r>0.7</r>
         <g>0.7</g>
         <b>0.6</b>
         <a>1.0</a>
      </diffuse>
      <specular>
         <r>0.7</r>
         <g>0.7</g>
         <b>0.7</b>
         <a>1.0</a>
      </specular>
      <attenuation>
         <c>5.0</c>
         <l>0.002</l>
         <q>0.00005</q>
      </attenuation>
      <exponent>8.0</exponent>
      <near-m>0.5</near-m>
      <far-m>0.55</far-m>
      <cutoff>120</cutoff>
   </animation>
   
   <effect>
      <name>REMBRANDT transparency</name>
      <inherits-from>Effects/model-transparent</inherits-from>
      <object-name>Light</object-name>
   </effect>

</PropertyList>
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Re: DHC-6 Twin Otter development

Postby primtala2 » Thu Nov 06, 2014 12:48 am

This twin otter model is very solid. However, a crucial instrument is missing from the cockpit. The DME !.
So i borrowed the dme instrument from the cessna 172 and added it in the otter like so.


Image
Fits nicely there.

But i have a problem. I does not work !. The power comes on becouse i can see the "miles" marking lighting up. But it does not show any distance do the dme like it should. Here is my procedure.

I started by simply copying the dme folder from the cessna instruments folder to the otter instruments folder. Then i added this code to flightdeck.xml (otter instruments folder)

Image
That made the dme instrument visible in the otter.


And then i read in the ki266.xml file (otter instruments dme folder) which said

<!--
This is the ki266 3d instrument.
Modeled after King KI266 DME Indicator

This instrument needs the file
Aircraft/Instruments-3d/ki266/ki266.nas
to be included in your -set.xml nasal section
like this:

<nasal>
<YourAircraft>
<file>Aircraft/Instruments-3d/ki266/ki266.nas</file>
</YourAircraft>
</nasal>

and at least one instance of the ki266 class to be created
in your aircraft nasal code like this:
ki266.new(0); # for your first dme at /instrumentation/dme[0]
ki266.new(1); # if you have another at /instrumentation/dme[1]
Maintainer: Torsten Dreyer
-->


So that's what i did. Like this. See the code i added in green. Made no other changes.

The dhc6-set.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--
************************************************************************
de Havilland Twin Otter
Jan 2008 Syd Adams
************************************************************************
-->

<PropertyList include="dhc6-base.xml">
<sim>
<description>Twin Otter (wheels)</description>
<status>developement</status>
<author>Syd Adams</author>
<flight-model>yasim</flight-model>
<aero>dhc6</aero>
<fuel-fraction>0.5</fuel-fraction>
<startup>
<splash-texture>Aircraft/dhc6/splash.png</splash-texture>
</startup>
<model>
<path>Aircraft/dhc6/Models/DHC6.xml</path>
<blunt-nose type="bool">0</blunt-nose>
</model>


<hitches>
<aerotow>
<tow>
<length type="float">60</length>
<elastic-constant type="float">10000</elastic-constant>
<weight-per-m-kg-m type="float">1</weight-per-m-kg-m>
<dist type="float">1</dist>
<connected-to-property-node type="bool"></connected-to-property-node>
<brake-force type="float">100000</brake-force>
<connected-to-ai-or-mp-callsign type ="string">*</connected-to-ai-or-mp-callsign>
<end-force-x type ="float">0</end-force-x>
<end-force-y type ="float">0</end-force-y>
<end-force-z type ="float">0</end-force-z>
</tow>
<speed-in-tow-direction type="float">0</speed-in-tow-direction>
<open type="bool">true</open>
<local-pos-x type="float">0</local-pos-x>
<local-pos-y type="float">0</local-pos-y>
<local-pos-z type="float">0</local-pos-z>
<is-slave type="bool">false</is-slave>
</aerotow>
</hitches>



</sim>

<controls>
<gear>
<brake-parking>1</brake-parking>
</gear>
</controls>



<hitch name="aerotow" x="-6.2" y="0" z="-0.12" force-is-calculated-by-other="1">
<tow length="60" weight-per-meter="0.035" elastic-constant="9000" break-force="10000" mp-auto-connect-period="1.0"/>
<winch max-tow-length="1000" min-tow-length="60" initial-tow-length="60"/>
</hitch>

Code (): Select all
<nasal>
<dhc6>
<file>dhc6/Models/Instruments/dme/ki266.nas</file>
<script><![CDATA[
ki266.new(0);
aircraft.data.add( "engines/engine[0]/egt-bug-norm" );
]]></script>
</dhc6>
</nasal>


</PropertyList>


That's all what i thought was needed to make this work. What am i doing wrong ?. Any ideas would be apprieciated.
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Re: DHC-6 Twin Otter development

Postby tauchergreg » Sun Nov 09, 2014 3:04 pm

hi primtala2,

has the DME power from the Electrical.nas ?

append(serv_list,"instrumentation/dme/serviceable");
append(servout_list,"dme");

regrads
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C160 Transall , Twin Otter DHC6, both with small modification
EF2000
ETMN under development
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