Crash and stress damage system
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Inspired and developed from the crash system in the MiG-15 by Slavutinsky Victor, this system is meant to become generic and usable for all aircraft by adding just a few lines. For now you have to add a file with code though.
Features so far
- Impact, crash and explosion detection.
- Tied into the new 3.5+ failure manager.
- Over-G detection for wing stress.
- Sounds.
Planned features
Feel free to suggest some in the forum topic linked to at the end of this article.
Background
See also Failure Manager.
The crash system in the Mig15 also have detection of flying into trees and buildings. That detection is based on random calculation of the chance of hitting something, meaning it will hit trees or building that is not seen in the 3D rendered landscape. I decided that could be confusing for many users, and also it had a big performance hit, therefore that is not a feature present in this system.
How to install the current system on an aircraft
Copy this code into your aircraft's Nasal folder as crash-and-stress.nas file:
#
# A Flightgear crash and stress damage system.
#
# Inspired and developed from the crash system in Mig15 by Slavutinsky Victor. And by Hvengel's formula for wingload stress.
#
# Authors: Slavutinsky Victor, Nikolai V. Chr. (Necolatis)
#
#
# Version 0.18
#
# License:
# GPL 2.0
var TRUE = 1;
var FALSE = 0;
var CrashAndStress = {
# pattern singleton
_instance: nil,
# Get the instance
new: func (gears, stressLimit = nil, wingsFailureModes = nil) {
var m = nil;
if(me._instance == nil) {
me._instance = {};
me._instance["parents"] = [CrashAndStress];
m = me._instance;
m.inService = FALSE;
m.repairing = FALSE;
m.exploded = FALSE;
m.wingsAttached = TRUE;
m.wingLoadLimitUpper = nil;
m.wingLoadLimitLower = nil;
m._looptimer = maketimer(0, m, m._loop);
m.repairTimer = maketimer(10.0, m, CrashAndStress._finishRepair);
m.repairTimer.singleShot = 1;
m.soundWaterTimer = maketimer(3, m, CrashAndStress._impactSoundWaterEnd);
m.soundWaterTimer.singleShot = 1;
m.soundTimer = maketimer(3, m, CrashAndStress._impactSoundEnd);
m.soundTimer.singleShot = 1;
m.explodeTimer = maketimer(3, m, CrashAndStress._explodeEnd);
m.explodeTimer.singleShot = 1;
m.stressTimer = maketimer(3, m, CrashAndStress._stressDamageEnd);
m.stressTimer.singleShot = 1;
m.input = {
# trembleOn: "damage/g-tremble-on",
# trembleMax: "damage/g-tremble-max",
replay: "sim/replay/replay-state",
lat: "position/latitude-deg",
lon: "position/longitude-deg",
alt: "position/altitude-ft",
altAgl: "position/altitude-agl-ft",
elev: "position/ground-elev-ft",
crackOn: "damage/sounds/crack-on",
creakOn: "damage/sounds/creaking-on",
crackVol: "damage/sounds/crack-volume",
creakVol: "damage/sounds/creaking-volume",
wCrashOn: "damage/sounds/water-crash-on",
crashOn: "damage/sounds/crash-on",
detachOn: "damage/sounds/detach-on",
explodeOn: "damage/sounds/explode-on",
simCrashed: "sim/crashed",
wildfire: "environment/wildfire/fire-on-crash",
};
foreach(var ident; keys(m.input)) {
m.input[ident] = props.globals.getNode(m.input[ident], 1);
}
m.fdm = nil;
if(getprop("sim/flight-model") == "jsb") {
m.fdm = jsbSimProp;
} elsif(getprop("sim/flight-model") == "yasim") {
m.fdm = yaSimProp;
} else {
return nil;
}
m.fdm.convert();
m.wowStructure = [];
m.wowGear = [];
m.lastMessageTime = 0;
m._initProperties();
m._identifyGears(gears);
m.setStressLimit(stressLimit);
m.setWingsFailureModes(wingsFailureModes);
m._startImpactListeners();
} else {
m = me._instance;
}
return m;
},
# start the system
start: func () {
me.inService = TRUE;
},
# stop the system
stop: func () {
me.inService = FALSE;
},
# return TRUE if in progress
isStarted: func () {
return me.inService;
},
# accepts a vector with failure mode IDs, they will fail when wings break off.
setWingsFailureModes: func (modes) {
if(modes == nil) {
modes = [];
}
##
# Returns an actuator object that will set the serviceable property at
# the given node to zero when the level of failure is > 0.
# it will also fail additionally failure modes.
var set_unserviceable_cascading = func(path, casc_paths) {
var prop = path ~ "/serviceable";
if (props.globals.getNode(prop) == nil) {
props.globals.initNode(prop, TRUE, "BOOL");
} else {
props.globals.getNode(prop).setBoolValue(TRUE);#in case this gets initialized empty from a recorder signal or MP alias.
}
return {
parents: [FailureMgr.FailureActuator],
mode_paths: casc_paths,
set_failure_level: func(level) {
setprop(prop, level > 0 ? 0 : 1);
foreach(var mode_path ; me.mode_paths) {
FailureMgr.set_failure_level(mode_path, level);
}
},
get_failure_level: func { getprop(prop) ? 0 : 1 }
}
}
me.prop = me.fdm.wingsFailureID;
me.actuator_wings = set_unserviceable_cascading(me.prop, modes);
FailureMgr.add_failure_mode(me.prop, "Main wings", me.actuator_wings);
},
# set the stresslimit for the main wings
setStressLimit: func (stressLimit = nil) {
if (stressLimit != nil) {
me.wingloadMax = stressLimit['wingloadMaxLbs'];
me.wingloadMin = stressLimit['wingloadMinLbs'];
me.maxG = stressLimit['maxG'];
me.minG = stressLimit['minG'];
me.weight = stressLimit['weightLbs'];
if(me.wingloadMax != nil) {
me.wingLoadLimitUpper = me.wingloadMax;
} elsif (me.maxG != nil and me.weight != nil) {
me.wingLoadLimitUpper = me.maxG * me.weight;
}
if(me.wingloadMin != nil) {
me.wingLoadLimitLower = me.wingloadMin;
} elsif (me.minG != nil and me.weight != nil) {
me.wingLoadLimitLower = me.minG * me.weight;
} elsif (me.wingLoadLimitUpper != nil) {
me.wingLoadLimitLower = -me.wingLoadLimitUpper * 0.4;#estimate for when lower is not specified
}
me._looptimer.start();
} else {
me._looptimer.stop();
}
},
# repair the aircaft
repair: func () {
me.failure_modes = FailureMgr._failmgr.failure_modes;
me.mode_list = keys(me.failure_modes);
foreach(var failure_mode_id; me.mode_list) {
FailureMgr.set_failure_level(failure_mode_id, 0);
}
me.wingsAttached = TRUE;
me.exploded = FALSE;
me.lastMessageTime = 0;
me.repairing = TRUE;
me.input.simCrashed.setBoolValue(FALSE);
me.repairTimer.restart(10.0);
},
_finishRepair: func () {
me.repairing = FALSE;
},
_initProperties: func () {
me.input.crackOn.setBoolValue(FALSE);
me.input.creakOn.setBoolValue(FALSE);
me.input.crackVol.setDoubleValue(0.0);
me.input.creakVol.setDoubleValue(0.0);
me.input.wCrashOn.setBoolValue(FALSE);
me.input.crashOn.setBoolValue(FALSE);
me.input.detachOn.setBoolValue(FALSE);
me.input.explodeOn.setBoolValue(FALSE);
},
_identifyGears: func (gears) {
me.contacts = props.globals.getNode("/gear").getChildren("gear");
foreach(var contact; me.contacts) {
me.index = contact.getIndex();
me.isGear = me._contains(gears, me.index);
me.wow = contact.getChild("wow");
if (me.isGear == TRUE) {
append(me.wowGear, me.wow);
} else {
append(me.wowStructure, me.wow);
}
}
},
_isStructureInContact: func () {
foreach(var structure; me.wowStructure) {
if (structure.getBoolValue() == TRUE) {
return TRUE;
}
}
return FALSE;
},
_isGearInContact: func () {
foreach(var gear; me.wowGear) {
if (gear.getBoolValue() == TRUE) {
return TRUE;
}
}
return FALSE;
},
_contains: func (vector, content) {
foreach(var vari; vector) {
if (vari == content) {
return TRUE;
}
}
return FALSE;
},
_startImpactListeners: func () {
ImpactStructureListener.crash = me;
foreach(var structure; me.wowStructure) {
setlistener(structure, func {call(ImpactStructureListener.run, nil, ImpactStructureListener, ImpactStructureListener)},0,0);
}
},
_isRunning: func () {
if (me.inService == FALSE or me.input.replay.getBoolValue() == TRUE or me.repairing == TRUE) {
return FALSE;
}
me.time = me.fdm.input.simTime.getValue();
if (me.time != nil and me.time > 1) {
return TRUE;
}
return FALSE;
},
_calcGroundSpeed: func () {
me.realSpeed = me.fdm.getSpeedRelGround();
return me.realSpeed;
},
_impactDamage: func () {
me.lat = me.input.lat.getValue();
me.lon = me.input.lon.getValue();
me.info = geodinfo(me.lat, me.lon);
me.solid = me.info == nil?TRUE:(me.info[1] == nil?TRUE:me.info[1].solid);
me.speed = me._calcGroundSpeed();
if (me.exploded == FALSE) {
me.failure_modes = FailureMgr._failmgr.failure_modes;
me.mode_list = keys(me.failure_modes);
me.probability = (me.speed * me.speed) / 40000.0;# 200kt will fail everything, 0kt will fail nothing.
me.hitStr = "something";
if(me.info != nil and me.info[1] != nil) {
me.hitStr = me.info[1].names == nil?"something":me.info[1].names[0];
foreach(infoStr; me.info[1].names) {
if(find('_', infoStr) == -1) {
me.hitStr = infoStr;
break;
}
}
}
# test for explosion
if(me.probability > 0.766 and me.fdm.input.fuel.getValue() > 2500) {
# 175kt+ and fuel in tanks will explode the aircraft on impact.
me.input.simCrashed.setBoolValue(TRUE);
me._explodeBegin("Aircraft hit "~me.hitStr~".");
return;
}
foreach(var failure_mode_id; me.mode_list) {
if(rand() < me.probability) {
FailureMgr.set_failure_level(failure_mode_id, 1);
}
}
me.str = "Aircraft hit "~me.hitStr~".";
me._output(me.str);
} elsif (me.solid == TRUE) {
# The aircraft is burning and will ignite the ground
if(me.input.wildfire.getValue() == TRUE) {
me.pos= geo.Coord.new().set_latlon(me.lat, me.lon);
wildfire.ignite(me.pos, 1);
}
}
if(me.solid == TRUE) {
me._impactSoundBegin(me.speed);
} else {
me._impactSoundWaterBegin(me.speed);
}
},
_impactSoundWaterBegin: func (speed) {
if (speed > 5) {#check if sound already running?
me.input.wCrashOn.setBoolValue(TRUE);
me.soundWaterTimer.restart(3);
}
},
_impactSoundWaterEnd: func () {
me.input.wCrashOn.setBoolValue(FALSE);
},
_impactSoundBegin: func (speed) {
if (speed > 5) {
me.input.crashOn.setBoolValue(TRUE);
me.soundTimer.restart(3);
}
},
_impactSoundEnd: func () {
me.input.crashOn.setBoolValue(FALSE);
},
_explodeBegin: func(str) {
me.input.explodeOn.setBoolValue(TRUE);
me.exploded = TRUE;
me.failure_modes = FailureMgr._failmgr.failure_modes;
me.mode_list = keys(me.failure_modes);
foreach(var failure_mode_id; me.mode_list) {
FailureMgr.set_failure_level(failure_mode_id, 1);
}
me._output(str~" and exploded.", TRUE);
me.explodeTimer.restart(3);
},
_explodeEnd: func () {
me.input.explodeOn.setBoolValue(FALSE);
},
_stressDamage: func (str) {
me._output("Aircraft damaged: Wings broke off, due to "~str~" G forces.");
me.input.detachOn.setBoolValue(TRUE);
FailureMgr.set_failure_level(me.fdm.wingsFailureID, 1);
me.wingsAttached = FALSE;
me.stressTimer.restart(3);
},
_stressDamageEnd: func () {
me.input.detachOn.setBoolValue(FALSE);
},
_output: func (str, override = FALSE) {
me.time = me.fdm.input.simTime.getValue();
if (override == TRUE or (me.time - me.lastMessageTime) > 3) {
me.lastMessageTime = me.time;
print(str);
screen.log.write(str, 0.7098, 0.5372, 0.0);# solarized yellow
}
},
_loop: func () {
me._testStress();
me._testWaterImpact();
},
_testWaterImpact: func () {
if(me.input.altAgl.getValue() < 0) {
me.lat = me.input.lat.getValue();
me.lon = me.input.lon.getValue();
me.info = geodinfo(me.lat, me.lon);
me.solid = me.info==nil?TRUE:(me.info[1] == nil?TRUE:me.info[1].solid);
if(me.solid == FALSE) {
me._impactDamage();
}
}
},
_testStress: func () {
if (me._isRunning() == TRUE and me.wingsAttached == TRUE) {
me.gForce = me.fdm.input.Nz.getValue() == nil?1:me.fdm.input.Nz.getValue();
me.weight = me.fdm.input.weight.getValue();
me.wingload = me.gForce * me.weight;
me.broken = FALSE;
if(me.wingload < 0) {
me.broken = me._testWingload(-me.wingload, -me.wingLoadLimitLower);
if(me.broken == TRUE) {
me._stressDamage("negative");
}
} else {
me.broken = me._testWingload(me.wingload, me.wingLoadLimitUpper);
if(me.broken == TRUE) {
me._stressDamage("positive");
}
}
} else {
me.input.crackOn.setBoolValue(FALSE);
me.input.creakOn.setBoolValue(FALSE);
#me.input.trembleOn.setValue(0);
}
},
_testWingload: func (wingloadCurr, wingLoadLimit) {
if (wingloadCurr > (wingLoadLimit * 0.5)) {
#me.input.trembleOn.setValue(1);
me.tremble_max = math.sqrt((wingloadCurr - (wingLoadLimit * 0.5)) / (wingLoadLimit * 0.5));
#me.input.trembleMax.setDoubleValue(1);
if (wingloadCurr > (wingLoadLimit * 0.75)) {
#me.tremble_max = math.sqrt((wingloadCurr - (wingLoadLimit * 0.5)) / (wingLoadLimit * 0.5));
me.input.creakVol.setDoubleValue(me.tremble_max);
me.input.creakOn.setBoolValue(TRUE);
if (wingloadCurr > (wingLoadLimit * 0.90)) {
me.input.crackOn.setBoolValue(TRUE);
me.input.crackVol.setDoubleValue(me.tremble_max);
if (wingloadCurr > wingLoadLimit) {
me.input.crackVol.setDoubleValue(1);
me.input.creakVol.setDoubleValue(1);
#me.input.trembleMax.setDoubleValue(1);
return TRUE;
}
} else {
me.input.crackOn.setBoolValue(FALSE);
}
} else {
me.input.creakOn.setBoolValue(FALSE);
}
} else {
me.input.crackOn.setBoolValue(FALSE);
me.input.creakOn.setBoolValue(FALSE);
#me.input.trembleOn.setValue(0);
}
return FALSE;
},
};
var ImpactStructureListener = {
crash: nil,
run: func () {
if (crash._isRunning() == TRUE) {
var wow = crash._isStructureInContact();
if (wow == TRUE) {
crash._impactDamage();
}
}
},
};
# static class
var fdmProperties = {
input: {},
convert: func () {
foreach(var ident; keys(me.input)) {
me.input[ident] = props.globals.getNode(me.input[ident], 1);
}
},
fps2kt: func (fps) {
return fps * FPS2KT;
},
getSpeedRelGround: func () {
return 0;
},
wingsFailureID: nil,
};
var jsbSimProp = {
parents: [fdmProperties],
input: {
weight: "fdm/jsbsim/inertia/weight-lbs",
fuel: "fdm/jsbsim/propulsion/total-fuel-lbs",
simTime: "fdm/jsbsim/simulation/sim-time-sec",
northFps: "velocities/speed-north-fps",
eastFps: "velocities/speed-east-fps",
downFps: "velocities/speed-down-fps",
Nz: "fdm/jsbsim/accelerations/Nz",
},
getSpeedRelGround: func () {
me.northSpeed = me.input.northFps.getValue();
me.eastSpeed = me.input.eastFps.getValue();
me.horzSpeed = math.sqrt((me.eastSpeed * me.eastSpeed) + (me.northSpeed * me.northSpeed));
me.vertSpeed = me.input.downFps.getValue();
me.realSpeed = me.fps2kt(math.sqrt((me.horzSpeed * me.horzSpeed) + (me.vertSpeed * me.vertSpeed)));
return me.realSpeed;
},
wingsFailureID: "fdm/jsbsim/structural/wings",
};
var yaSimProp = {
parents: [fdmProperties],
input: {
weight: "yasim/gross-weight-lbs",
fuel: "consumables/fuel/total-fuel-lbs",
simTime: "sim/time/elapsed-sec",
northFps: "velocities/speed-north-fps",
eastFps: "velocities/speed-east-fps",
downFps: "velocities/speed-down-fps",
Nz: "accelerations/n-z-cg-fps_sec",
},
getSpeedRelGround: func () {
me.northSpeed = me.input.northFps.getValue();
me.eastSpeed = me.input.eastFps.getValue();
me.horzSpeed = math.sqrt((me.eastSpeed * me.eastSpeed) + (me.northSpeed * me.northSpeed));
me.vertSpeed = me.input.downFps.getValue();
me.realSpeed = me.fps2kt(math.sqrt((me.horzSpeed * me.horzSpeed) + (me.vertSpeed * me.vertSpeed)));
return me.realSpeed;
},
wingsFailureID: "structural/wings",
};
# TODO:
#
# Loss of inertia if impacting/sliding? Or should the jsb groundcontacts take care of that alone?
# If gears hit something at too high speed the gears should be damaged?
# Make property to control if system active, or method enough?
# Explosion depending on bumpiness and speed when sliding?
# Tie in with damage from Bombable?
# Use galvedro's UpdateLoop framework when it gets merged
# example uses:
#
# var crashCode = CrashAndStress.new([0,1,2]);
#
# var crashCode = CrashAndStress.new([0,1,2], {"weightLbs":30000, "maxG": 12});
#
# var crashCode = CrashAndStress.new([0,1,2,3], {"weightLbs":20000, "maxG": 11, "minG": -5});
#
# var crashCode = CrashAndStress.new([0,1,2], {"wingloadMaxLbs": 90000, "wingloadMinLbs": -45000}, ["controls/flight/aileron", "controls/flight/elevator", "controls/flight/flaps"]);
#
# var crashCode = CrashAndStress.new([0,1,2], {"wingloadMaxLbs":90000}, ["controls/flight/aileron", "controls/flight/elevator", "controls/flight/flaps"]);
#
# Gears parameter must be defined.
# Stress parameter is optional. If minimum wing stress is not defined it will be set to -40% of max wingload stress if that is defined.
# The last optional parameter is a list of failure mode IDs that shall fail when wings detach. They must be defined in the FailureMgr.
#
#
# Remember to add sounds and to add the sound properties as custom signals to the replay recorder.
# example use:
var crashCode = nil;
var crash_start = func {
removelistener(lsnr);
crashCode = CrashAndStress.new([0,1,2], {"weightLbs":30000, "maxG": 12}, ["controls/flight/aileron", "controls/flight/elevator"]);
crashCode.start();
}
var lsnr = setlistener("sim/signals/fdm-initialized", crash_start);
var repair = func {
if (crashCode != nil) {
crashCode.repair();
}
};
var lsnr = setlistener("/sim/signals/reinit", repair);Notice that you should edit the line underneath # example use to fit your aircraft requirements.
In your aircraft-set.xml file under nasal tags add
<crash>
<file>Aircraft/[aircraft name here]/Nasal/crash-and-stress.nas</file>
</crash>
Add this to your sounds file, remember to replace JA37, with your aircraft folder name:
<?xml version="1.0" encoding="UTF-8"?>
<PropertyList>
<fx>
<!-- ... -->
<aircraft-explode>
<name>aircraft-explode</name>
<path>Aircraft/JA37/Sounds/aircraft-explode.wav</path>
<mode>once</mode>
<condition>
<equals>
<property>damage/sounds/explode-on</property>
<value>1</value>
</equals>
</condition>
<position>
<x>0.01</x>
<y>0.01</y>
<z>0.01</z>
</position>
<volume>
<factor>3</factor>
<max>3</max>
</volume>
</aircraft-explode>
<aircraft-detach>
<name>aircraft-detach</name>
<path>Aircraft/JA37/Sounds/aircraft-wings-detach.wav</path>
<mode>once</mode>
<condition>
<equals>
<property>damage/sounds/detach-on</property>
<value>1</value>
</equals>
</condition>
<position>
<x>0.01</x>
<y>0.01</y>
<z>0.01</z>
</position>
<volume>
<factor>1</factor>
</volume>
</aircraft-detach>
<aircraft-crash>
<name>aircraft-impact</name>
<path>Sounds/aircraft-crash.wav</path>
<mode>once</mode>
<condition>
<equals>
<property>damage/sounds/crash-on</property>
<value>1</value>
</equals>
</condition>
<position>
<x>0.01</x>
<y>0.01</y>
<z>0.01</z>
</position>
<volume>
<factor>1</factor>
</volume>
</aircraft-crash>
<aircraft-water-crash>
<name>aircraft-water-crash</name>
<path>Aircraft/JA37/Sounds/aircraft-water-crash.wav</path>
<mode>once</mode>
<condition>
<equals>
<property>damage/sounds/water-crash-on</property>
<value>1</value>
</equals>
</condition>
<position>
<x>0.01</x>
<y>0.01</y>
<z>0.01</z>
</position>
<volume>
<factor>1</factor>
</volume>
</aircraft-water-crash>
<aircraft-crack>
<name>aircraft-crack</name>
<path>Aircraft/JA37/Sounds/aircraft-crack.wav</path>
<mode>once</mode>
<condition>
<property>sim/current-view/internal</property>
<equals>
<property>damage/sounds/crack-on</property>
<value>1</value>
</equals>
</condition>
<position>
<x>0.01</x>
<y>0.01</y>
<z>0.01</z>
</position>
<volume>
<property>damage/sounds/crack-volume</property>
<factor>1</factor>
</volume>
</aircraft-crack>
<aircraft-creaking>
<name>aircraft-creaking</name>
<path>Aircraft/JA37/Sounds/aircraft-creaking.wav</path>
<mode>looped</mode>
<condition>
<property>sim/current-view/internal</property>
<equals>
<property>damage/sounds/creaking-on</property>
<value>1</value>
</equals>
</condition>
<position>
<x>0.01</x>
<y>0.01</y>
<z>0.01</z>
</position>
<volume>
<property>damage/sounds/creaking-volume</property>
<factor>1</factor>
</volume>
</aircraft-creaking>
<!-- ... -->
</fx>
</PropertyList>
Add some sounds to the aircraft sound folder that corresponds to the file names used in the above. (you can eventually use those in the Mig15 or JA-37 folders, depending what kind of sounds you prefer.)
Optionally add these signals to the replay recorder:
<signal>
<type>bool</type>
<property type="string">damage/sounds/explode-on</property>
</signal>
<signal>
<type>bool</type>
<property type="string">damage/sounds/crash-on</property>
</signal>
<signal>
<type>bool</type>
<property type="string">damage/sounds/water-crash-on</property>
</signal>
<signal>
<type>bool</type>
<property type="string">damage/sounds/crack-on</property>
</signal>
<signal>
<type>bool</type>
<property type="string">damage/sounds/creaking-on</property>
</signal>
<signal>
<type>float</type>
<property type="string">damage/sounds/crack-volume</property>
</signal>
<signal>
<type>float</type>
<property type="string">damage/sounds/creaking-volume</property>
</signal>
<signal>
<type>bool</type>
<property type="string">fdm/jsbsim/structural/wings/serviceable</property>
</signal>
Notice that the last signal is JSBSim specific, the corresponding YASim signal is:
<signal>
<type>bool</type>
<property type="string">structural/wings/serviceable</property>
</signal>That property is also what you would use to animate wings being detached and/or changes in the aerodynamics.
Performance
As it is now you should feel no performance degradation at all from using it.
Aircrafts that use this system
FGAddon
Soon
- Mig21bis (In development by Pinto)
- P47 (In development by swampthing)
- Grumman F-14 Tomcat (Development version by Richard)
- McDonnell Douglas F-15 Eagle (Development version by Richard)
Related content
- Generic crash system for JSBSim aircraft – Forum topic on the official FlightGear forum.