c172p: use directional gyro for heading indicator

Also use c172-specific instrumentation list.

Aircraft/c172p/Instruments/panel-only-instrumentation.xml

@@ -51,7 +51,7 @@
 	</marker-beacon>
 
 	<heading-indicator>
-		<name>heading-indicator</name>
+		<name>heading-indicator-dg</name>
 		<number>0</number>
 		<suction>/systems/vacuum/suction-inhg</suction>
 	</heading-indicator>

Aircraft/c172p/Nasal/c172-electrical.nas

@@ -335,9 +335,6 @@ electrical_bus_2 = func() {
     var bus_volts = vbus_volts;
     var load = 0.0;
 
-    # Turn Coordinator Power
-    setprop("/systems/electrical/outputs/turn-coordinator", bus_volts);
-  
     # Map Lights Power
     if ( getprop("/controls/switches/nav-lights" ) ) {
         setprop("/systems/electrical/outputs/map-lights", bus_volts);
@@ -404,6 +401,12 @@ avionics_bus_1 = func() {
         bus_volts = ebus1_volts;
     }
 
+    # Turn Coordinator Power
+    setprop("/systems/electrical/outputs/turn-coordinator", bus_volts);
+
+    # Directional Gyro Power
+    setprop("/systems/electrical/outputs/DG", bus_volts);
+
     # Avionics Fan Power
     setprop("/systems/electrical/outputs/avionics-fan", bus_volts);
 

Aircraft/c172p/Systems/instrumentation.xml

@@ -0,0 +1,125 @@
+<?xml version="1.0"?>
+
+<!--
+**********************************************************************
+instrumentation.xml
+
+c172p instrumentation configuration. This file selects the
+instrumentation modules that should be available.
+
+You can have several instances of the same instrument type.
+The value inside the name tag becomes the node in the property tree.
+If two instruments have the same name you must use the number tag
+to separate them. They become name[number] in the property tree.
+Some instruments have additional configuration tags like static-port
+and pitot-port. The static- and pitot-ports (and any other system that
+an instrument depend on) have to be configured in the systems
+configuration file: generic-systems.xml
+
+The values in this file are the default values. If any configuration
+tags are omitted in an aircraft specific version of this configuration
+file, these values will be used (they are hardcoded).
+
+**********************************************************************
+-->
+
+<PropertyList>
+
+  <adf>
+    <name>adf</name>
+    <number>0</number>
+  </adf>
+
+  <airspeed-indicator>
+    <name>airspeed-indicator</name>
+    <number>0</number>
+    <total-pressure>/systems/pitot/total-pressure-inhg</total-pressure>
+    <static-pressure>/systems/static/pressure-inhg</static-pressure>
+  </airspeed-indicator>
+
+  <altimeter>
+    <name>altimeter</name>
+    <number>0</number>
+    <static-pressure>/systems/static/pressure-inhg</static-pressure>
+    <quantum>0</quantum>
+    <tau>0</tau>
+  </altimeter>
+
+  <attitude-indicator>
+    <name>attitude-indicator</name>
+    <number>0</number>
+    <suction>/systems/vacuum/suction-inhg</suction>
+  </attitude-indicator>
+
+  <clock>
+    <name>clock</name>
+    <number>0</number>
+  </clock>
+
+  <dme>
+    <name>dme</name>
+    <number>0</number>
+  </dme>
+
+  <altimeter>
+    <name>encoder</name>
+    <number>0</number>
+    <static-pressure>/systems/static/pressure-inhg</static-pressure>
+    <quantum>10</quantum>
+    <tau>0.1</tau>
+  </altimeter>
+
+  <marker-beacon>
+    <name>marker-beacon</name>
+    <number>0</number>
+  </marker-beacon>
+
+  <heading-indicator-dg>
+    <name>heading-indicator</name>
+    <number>0</number>
+    <suction>/systems/vacuum/suction-inhg</suction>
+  </heading-indicator-dg>
+
+  <KT-70>
+    <name>kt-70</name>
+    <number>0</number>
+  </KT-70>
+
+  <magnetic-compass>
+    <name>magnetic-compass</name>
+    <number>0</number>
+  </magnetic-compass>
+
+  <nav-radio>
+    <name>nav</name>
+    <number>0</number>
+  </nav-radio>
+
+  <nav-radio>
+    <name>nav</name>
+    <number>1</number>
+  </nav-radio>
+
+  <slip-skid-ball>
+    <name>slip-skid-ball</name>
+    <number>0</number>
+  </slip-skid-ball>
+
+  <transponder>
+    <name>transponder</name>
+    <number>0</number>
+    <mode-c-altitude>/instrumentation/encoder/mode-c-alt-ft</mode-c-altitude>
+  </transponder>
+
+  <turn-indicator>
+    <name>turn-indicator</name>
+    <number>0</number>
+  </turn-indicator>
+
+  <vertical-speed-indicator>
+    <name>vertical-speed-indicator</name>
+    <number>0</number>
+    <static-pressure>/systems/static/pressure-inhg</static-pressure>
+  </vertical-speed-indicator>
+
+</PropertyList>

Aircraft/c172p/c172-electrical.xml

@@ -104,6 +104,11 @@
 
   <!-- Electrical Bus 2 Outputs -->
 
+  <output>
+    <name>Directional Gyro</name>
+    <prop>/systems/electrical/outputs/DG</prop>
+  </output>
+
   <output>
     <name>Turn Coordinator Power</name>
     <prop>/systems/electrical/outputs/turn-coordinator</prop>
@@ -341,6 +346,14 @@
 
   <!-- connect bus 2 outputs -->
 
+  <connector>
+    <input>Electrical Bus 2</input>
+    <output>Directional Gyro</output>
+    <switch>
+      <prop>/controls/circuit-breakers/directional-gyro</prop>
+    </switch>
+  </connector>
+
   <connector>
     <input>Electrical Bus 2</input>
     <output>Turn Coordinator Power</output>

Aircraft/c172p/c172p-set.xml

@@ -128,7 +128,9 @@ Started October 23 2001 by John Check, fgpanels@rockfish.net
   </flight-recorder>
 
   <menubar include="Dialogs/c172p-menu.xml"/>
-
+  <instrumentation n="0">
+    <path>Aircraft/c172p/Systems/instrumentation.xml</path>
+  </instrumentation>
  </sim>
 
  <!-- trim for level cruise -->