From 7dfd9f15ff8e92c7da71f0046d77fdcb869aa1cc Mon Sep 17 00:00:00 2001
From: Jonathan Redpath <legoboyvdlp@gmail.com>
Date: Thu, 30 Dec 2021 13:46:35 +0000
Subject: [PATCH] APU: make the code shutting down the APU after 0.2 seconds of
 power loss more resilient, uisng JSBSim

---
 Nasal/Systems/APU.nas |  31 ++---
 Systems/a320-apu.xml  | 275 +++++++++++++++++++++++-------------------
 2 files changed, 161 insertions(+), 145 deletions(-)

diff --git a/Nasal/Systems/APU.nas b/Nasal/Systems/APU.nas
index 0ec3635c..919c9cf6 100644
--- a/Nasal/Systems/APU.nas
+++ b/Nasal/Systems/APU.nas
@@ -273,24 +273,6 @@ var APU = {
 				me.autoStop();
 			}
 			
-			if (systems.ELEC.Bus.dcBat.getValue() < 25) {	
-				if (!me._powerLost) {
-					me._powerLost = 1;
-					settimer(func() {
-						if (me._powerLost) {
-							if (me.GenericControls.starter.getValue()) {
-								me.GenericControls.starter.setValue(0);
-							}
-							if (me.state != 0) {
-								me.autoStop();
-							}
-						}
-					}, 0.2);
-				}
-			} else {
-				me._powerLost = 0;
-			}
-			
 			if (systems.ELEC.EmerElec.getValue() == 1 and (systems.ELEC.EmerElec45.getValue() != 1 and systems.ELEC.Source.EmerGen.voltsRelay.getValue() < 110)) {
 				me.inhibitEMERELEC = 1;
 			} else {
@@ -316,6 +298,19 @@ var APUController = {
 	}
 };
 
+setlistener("/systems/apu/shutdown-power-loss", func(val) {
+	if (APUController.APU != nil) {
+		if (val.getBoolValue()) {
+			if (APUController.APU.GenericControls.starter.getValue()) {
+				APUController.APU.GenericControls.starter.setValue(0);
+			}
+			if (APUController.APU.state != 0) {
+				APUController.APU.autoStop();
+			}
+		}
+	}
+}, 0, 0);
+
 var _masterTime = 0;
 setlistener("/controls/apu/master", func() {
 	if (APUController.APU != nil) {
diff --git a/Systems/a320-apu.xml b/Systems/a320-apu.xml
index f6ad2161..f4ae5c9c 100644
--- a/Systems/a320-apu.xml
+++ b/Systems/a320-apu.xml
@@ -7,52 +7,52 @@
     <channel name="APU" execrate="8">
         <!-- bleed 1.8 kg / sec @ 42 psig -->
         <!-- fuel 148 kg/hr -->
-		<!-- generator 24034 rpm, 10129 rpm fuel ctl, 32045 rpm starter, 51965 rpm cooling, 4137rpm oil pump -->
+        <!-- generator 24034 rpm, 10129 rpm fuel ctl, 32045 rpm starter, 51965 rpm cooling, 4137rpm oil pump -->
 
-		<fcs_function name="/systems/apu/bleed-load-kw">
-			<function>
-				<ifthen>
-					<eq>
-						<property>/controls/pneumatics/switches/apu</property>
-						<value>1</value>
-					</eq>
-					<value>252</value>
-					<value>0</value>
-				</ifthen>
-			</function>
-		</fcs_function>
-		
-		
-		<fcs_function name="/systems/apu/electrical-load-kw">
-			<function>
-				<ifthen>
-					<gt>
-						<property>/systems/electrical/relay/apu-glc/output</property>
-						<value>110</value>
-					</gt>
-					<value>132</value>
-					<value>0</value>
-				</ifthen>
-			</function>
-		</fcs_function>
-		
-		<fcs_function name="/systems/apu/apu-load-cmd">
-			<function>
-				<quotient>
-					<sum>
-						<property>/systems/apu/electrical-load-kw</property>
-						<property>/systems/apu/bleed-load-kw</property>
-					</sum>
-					<value>400</value>
-				</quotient>
-			</function>
-		</fcs_function>
-		
-		<actuator name="/systems/apu/apu-load">
-			<input>/systems/apu/apu-load-cmd</input>
-			<rate_limit>0.01</rate_limit> <!-- 60 seconds cooling period for bleed which is ~ 60% -->
-		</actuator>
-		
+        <fcs_function name="/systems/apu/bleed-load-kw">
+            <function>
+                <ifthen>
+                    <eq>
+                        <property>/controls/pneumatics/switches/apu</property>
+                        <value>1</value>
+                    </eq>
+                    <value>252</value>
+                    <value>0</value>
+                </ifthen>
+            </function>
+        </fcs_function>
+        
+        
+        <fcs_function name="/systems/apu/electrical-load-kw">
+            <function>
+                <ifthen>
+                    <gt>
+                        <property>/systems/electrical/relay/apu-glc/output</property>
+                        <value>110</value>
+                    </gt>
+                    <value>132</value>
+                    <value>0</value>
+                </ifthen>
+            </function>
+        </fcs_function>
+        
+        <fcs_function name="/systems/apu/apu-load-cmd">
+            <function>
+                <quotient>
+                    <sum>
+                        <property>/systems/apu/electrical-load-kw</property>
+                        <property>/systems/apu/bleed-load-kw</property>
+                    </sum>
+                    <value>400</value>
+                </quotient>
+            </function>
+        </fcs_function>
+        
+        <actuator name="/systems/apu/apu-load">
+            <input>/systems/apu/apu-load-cmd</input>
+            <rate_limit>0.01</rate_limit> <!-- 60 seconds cooling period for bleed which is ~ 60% -->
+        </actuator>
+        
         <washout_filter name="/systems/apu/dn-dt">
             <input>/engines/engine[2]/n1</input>
             <c1>1</c1>
@@ -60,60 +60,60 @@
         
         <fcs_function name="/systems/apu/egt-degC">
             <function>
-				<sum>
-					<product>
-						<property>/systems/apu/apu-load</property>
-						<value>50</value>
-					</product>
-					<ifthen>
-						<or>
-							<lt>
-								<property>/engines/engine[2]/n1</property>
-								<value>0.5</value>
-							</lt>
-							<gt>
-								<property>/systems/apu/dn-dt</property>
-								<value>0</value>
-							</gt>
-						</or>
-						<table>
-							<independentVar lookup="row">/engines/engine[2]/n1</independentVar>
-							<tableData>
-								5.0     20.0
-								8.0     45.0
-								10.0    120.0
-								12.0    225.0
-								18.0    430.0
-								25.0    500.0
-								27.0    560.0
-								30.0    720.0
-								35.0    785.0
-								40.0    800.0
-								45.0    795.0
-								50.0    785.0
-								60.0    755.0
-								75.0    645.0
-								90.0    520.0
-								100.0   415.0
-							</tableData>
-						</table>
-						<table>
-							<independentVar lookup="row">/engines/engine[2]/n1</independentVar>
-							<tableData>
-								2.0     200.0
-								8.0     220.0
-								12.0    225.0
-								18.0    240.0
-								30.0    250.0
-								50.0    265.0
-								60.0    295.0
-								75.0    380.0
-								90.0    410.0
-								100.0   415.0
-							</tableData>
-						</table>
-					</ifthen>
-				</sum>
+                <sum>
+                    <product>
+                        <property>/systems/apu/apu-load</property>
+                        <value>50</value>
+                    </product>
+                    <ifthen>
+                        <or>
+                            <lt>
+                                <property>/engines/engine[2]/n1</property>
+                                <value>0.5</value>
+                            </lt>
+                            <gt>
+                                <property>/systems/apu/dn-dt</property>
+                                <value>0</value>
+                            </gt>
+                        </or>
+                        <table>
+                            <independentVar lookup="row">/engines/engine[2]/n1</independentVar>
+                            <tableData>
+                                5.0     20.0
+                                8.0     45.0
+                                10.0    120.0
+                                12.0    225.0
+                                18.0    430.0
+                                25.0    500.0
+                                27.0    560.0
+                                30.0    720.0
+                                35.0    785.0
+                                40.0    800.0
+                                45.0    795.0
+                                50.0    785.0
+                                60.0    755.0
+                                75.0    645.0
+                                90.0    520.0
+                                100.0   415.0
+                            </tableData>
+                        </table>
+                        <table>
+                            <independentVar lookup="row">/engines/engine[2]/n1</independentVar>
+                            <tableData>
+                                2.0     200.0
+                                8.0     220.0
+                                12.0    225.0
+                                18.0    240.0
+                                30.0    250.0
+                                50.0    265.0
+                                60.0    295.0
+                                75.0    380.0
+                                90.0    410.0
+                                100.0   415.0
+                            </tableData>
+                        </table>
+                    </ifthen>
+                </sum>
             </function>
         </fcs_function>
         
@@ -137,31 +137,31 @@
                 </table>
             </function>
         </fcs_function>
-		
-		<fcs_function name="/systems/apu/oil/oil-temperature-degC">
+        
+        <fcs_function name="/systems/apu/oil/oil-temperature-degC">
             <function>
-				<product>
-					<sum>
-						<value>1.0</value> <!-- tune -->
-						<product>
-							<property>/systems/apu/apu-load</property>
-							<value>0.3</value>
-						</product>
-					</sum>
-					<table>
-						<independentVar lookup="row">/systems/apu/oil/oil-pressure-psi</independentVar>
-						<tableData>
-							0   0
-							25  135
-							35  105
-							55  85
-						</tableData>
-					</table>
-					<quotient>
-						<property>/engines/engine[2]/n1</property>
-						<value>100</value>
-					</quotient>
-				</product>
+                <product>
+                    <sum>
+                        <value>1.0</value> <!-- tune -->
+                        <product>
+                            <property>/systems/apu/apu-load</property>
+                            <value>0.3</value>
+                        </product>
+                    </sum>
+                    <table>
+                        <independentVar lookup="row">/systems/apu/oil/oil-pressure-psi</independentVar>
+                        <tableData>
+                            0   0
+                            25  135
+                            35  105
+                            55  85
+                        </tableData>
+                    </table>
+                    <quotient>
+                        <property>/engines/engine[2]/n1</property>
+                        <value>100</value>
+                    </quotient>
+                </product>
             </function>
         </fcs_function>
         
@@ -170,10 +170,10 @@
                 <sum>
                     <property>/systems/apu/oil/level-l</property>
                     <product>
-						<quotient>
-							<property>/engines/engine[2]/n1</property>
-							<value>100</value>
-						</quotient>
+                        <quotient>
+                            <property>/engines/engine[2]/n1</property>
+                            <value>100</value>
+                        </quotient>
                         <property>/systems/apu/oil/allow-oil-consumption</property>
                         <value>-0.00000131437</value>
                         <property>simulation/channel-dt</property>
@@ -182,6 +182,27 @@
             </function>
             <output>/systems/apu/oil/level-l</output>
         </fcs_function>
+        
+        <switch name="/systems/apu/shutdown-power-loss-cmd">
+            <default value="0"/>
+            <test logic="AND" value="1">
+                /systems/electrical/bus/dc-bat lt 25
+            </test>
+        </switch>
+        
+        <actuator name="/systems/apu/shutdown-power-loss-timer">
+			<input>/systems/apu/shutdown-power-loss-cmd</input>
+            <rate_limit sense="incr">5</rate_limit>
+            <rate_limit sense="decr">100</rate_limit>
+        </actuator>
+        
+        <switch name="/systems/apu/shutdown-power-loss">
+            <default value="0"/>
+            <test logic="AND" value="1">
+                /systems/apu/shutdown-power-loss-timer eq 1
+            </test>
+        </switch>
+        
 		
     </channel>