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IDG-A32X/Nasal/icing.nas

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#############################################################################
# This file is part of FlightGear, the free flight simulator
# http://www.flightgear.org/
#
# Copyright (C) 2009 Torsten Dreyer, Torsten (at) t3r _dot_ de
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; either version 2 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#############################################################################
#########################################################################################
# this are the helper functions to model structural icing on airplanes
# Maintainer: Torsten Dreyer (Torsten at t3r dot de)
#
# Simple model: we listen to temperature and dewpoint. If the difference (spread)
# is near zero and temperature is below zero, icing may occour.
#
# inputs
# /environment/dewpoint-degc
# /environment/temperature-degc
# /environment/effective-visibility-m
# /velocities/airspeed-kt
# /environment/icing/max-spread-degc default: 0.1
#
# outputs
# /environment/icing/icing-severity numeric value of icing severity
# /environment/icing/icing-severity-name textual representation of icing severity one of
# none,trace,light,moderate,severe
# /environment/icing/icing-factor ammound of ice accumulation per NAM
#########################################################################
# implementation of the global icemachine
#########################################################################
var ICING_NONE = 0;
var ICING_TRACE = 1;
var ICING_LIGHT = 2;
var ICING_MODERATE = 3;
var ICING_SEVERE = 4;
# these are the names for the icing severities
var ICING_CATEGORY = [ "none", "trace", "light", "moderate", "severe" ];
# the ice accumulating factors. Inches per nautical air mile flown
var ICING_FACTOR = [
# none: sublimating 0.3" / 80NM
-0.3/80,
# traces: 0.5" / 80NM
0.5/80.0,
# light: 0.5" / 40NM
0.5/40.0,
# moderate: 0.5" / 20NM
0.5/20.0,
#severe: 0.5" / 10NM
0.5/10
];
# since we don't know the LWC of our clouds, just define some severities
# depending on temperature and a random offset
# format: upper temperatur, lower temperatur, minimum severity, maximum severity
var ICING_TEMPERATURE = [
[ 999, 0, ICING_NONE, ICING_NONE ],
[ 0, -2, ICING_NONE, ICING_MODERATE ],
[ -2, -12, ICING_LIGHT, ICING_SEVERE ],
[ -12, -20, ICING_LIGHT, ICING_MODERATE ],
[ -20, -30, ICING_TRACE, ICING_LIGHT ],
[ -30, -99, ICING_TRACE, ICING_NONE ]
];
var dewpointN = props.globals.getNode( "/environment/dewpoint-degc" );
var temperatureN = props.globals.getNode( "/environment/temperature-degc" );
var speedN = props.globals.getNode( "/velocities/airspeed-kt" );
var icingRootN = props.globals.getNode( "/environment/icing", 1 );
var visibilityN = props.globals.getNode( "/environment/effective-visibility-m" );
var severityN = icingRootN.initNode( "icing-severity", ICING_NONE, "INT" );
var severityNameN = icingRootN.initNode( "icing-severity-name", ICING_CATEGORY[severityN.getValue()] );
var icingFactorN = icingRootN.initNode( "icing-factor", 0.0 );
var maxSpreadN = icingRootN.initNode( "max-spread-degc", 0.1 );
var setSeverity = func {
var value = arg[0];
if( severityN.getValue() != value ) {
severityN.setValue( value );
severityNameN.setValue( ICING_CATEGORY[value] );
}
}
#########################################################################################
# These are objects that are subject to icing
# inputs under /sim/model/icing/iceable (multiple instances allowed)
# ./name # name of this object, more or less useless
# ./salvage-control # name of a boolean property that salvages from ice
# ./output-property # the name of the property where the ice amount is written to
# ./sensitivity # a multiplier for the ice accumulation
#
# outputs
# ./ice-inches # the amount of ice in inches OR
# [property named by output-property] # the amount of ice in inches
#########################################################################################
var IceSensitiveElement = {};
IceSensitiveElement.new = func {
var obj = {};
obj.parents = [IceSensitiveElement];
obj.node = arg[0];
obj.nameN = obj.node.initNode( "name", "noname" );
var n = obj.node.getNode( "salvage-control", 0 );
obj.controlN = nil;
if( n != nil ) {
n = n.getValue();
if( n != nil ) {
obj.controlN = props.globals.initNode( n, 0, "BOOL" );
}
}
obj.sensitivityN = obj.node.initNode( "sensitivity", 1.0 );
obj.iceAmountN = nil;
n = obj.node.getNode( "output-property", 0 );
if( n != nil ) {
n = n.getValue();
if( n != nil ) {
obj.iceAmountN = props.globals.initNode( n, 0.0 );
}
}
if( obj.iceAmountN == nil ) {
obj.iceAmountN = obj.node.initNode( "ice-inches", 0.0 );
}
return obj;
};
#####################################################################
# this gets called from the icemachine on each update cycle
# arg[0] is the time in seconds since last update
# arg[1] is the number of NAM traveled since last update
# arg[2] is the ice-accumulation-factor for the current severity
#####################################################################
IceSensitiveElement.update = func {
if( me.controlN != nil and me.controlN.getBoolValue() ) {
if( me.iceAmountN.getValue() != 0.0 ) {
me.iceAmountN.setDoubleValue( 0.0 );
}
return;
}
var deltat = arg[0];
var dist_nm = arg[1];
var factor = arg[2];
var v = me.iceAmountN.getValue() + dist_nm * factor * me.sensitivityN.getValue();
if( v < 0.0 ) {
v = 0.0;
}
if( me.iceAmountN.getValue() != v ) {
me.iceAmountN.setValue( v );
}
};
#####################################################################
# read the ice sensitive elements from the config file
#####################################################################
var iceSensitiveElements = nil;
var icingConfigN = props.globals.getNode( "/sim/model/icing", 0 );
if( icingConfigN != nil ) {
iceSensitiveElements = [];
var iceableNodes = icingConfigN.getChildren( "iceable" );
foreach( var iceable; iceableNodes ) {
append( iceSensitiveElements, IceSensitiveElement.new( iceable ) );
}
};
#####################################################################
# the time triggered loop
#####################################################################
var elapsedTimeNode = props.globals.getNode( "/sim/time/elapsed-sec" );
var lastUpdate = 0.0;
var icing = func {
var temperature = temperatureN.getValue();
var severity = ICING_NONE;
icingFactorN.setDoubleValue( ICING_FACTOR[severity] );
var visibility = 0;
if( visibilityN != nil ) {
visibility = visibilityN.getValue();
}
# check if we should create some ice
var spread = temperature - dewpointN.getValue();
if( spread < maxSpreadN.getValue() and visibility < 1000 ) {
for( var i = 0; i < size(ICING_TEMPERATURE); i = i + 1 ) {
if( ICING_TEMPERATURE[i][0] > temperature and
ICING_TEMPERATURE[i][1] <= temperature ) {
var s1 = ICING_TEMPERATURE[i][2];
var s2 = ICING_TEMPERATURE[i][3];
var ds = s2 - s1 + 1;
severity = s1 + int(rand()*ds);
icingFactorN.setDoubleValue( ICING_FACTOR[severity] );
break;
}
}
} else {
# clear air
# melt ice if above freezing temperature
# the warmer, the faster. Lets guess that at 10degc
# 0.5 inch goes in 10miles
if( temperature > 0.0 ) {
icingFactorN.setDoubleValue( factor = -0.05 * temperature / 10.0 );
}
# if temperature below zero, sublimating factor is initialized
}
setSeverity( severity );
# update all sensitive areas
var now = elapsedTimeNode.getValue();
var dt = now - lastUpdate;
foreach( var iceable; iceSensitiveElements ) {
iceable.update( dt, dt * speedN.getValue()/3600.0, icingFactorN.getValue() );
}
lastUpdate = now;
settimer( icing, 2 );
}
#####################################################################
# start our icemachine
# don't care if there is nothing to put ice on
#####################################################################
if( iceSensitiveElements != nil ) {
lastUpdate = elapsedTimeNode.getValue();
icing();
}
#####################################################################
# OHP button
#####################################################################
setprop("/controls/switches/windowprobeheat", 0);
setprop("/controls/switches/windowprobeheatfault", 0);
setlistener("/controls/switches/windowprobeheat", func {
var windowprb = getprop("/controls/switches/windowprobeheat");
var fault = getprop("/controls/switches/windowprobeheatfault");
if (windowprb == 0.5) { # if in auto
var wowl = getprop("/gear/gear[1]/wow");
var wowr = getprop("/gear/gear[2]/wow");
var stateL = getprop("/engines/engine[0]/state");
var stateR = getprop("/engines/engine[1]/state");
var fault = getprop("/controls/switches/windowprobeheatfault");
if (!wowl or !wowr and !fault) {
setprop("/controls/deice/windowprobeheat", 1);
} else if (stateL == 3 or stateR == 3 and !fault) {
setprop("/controls/deice/windowprobeheat", 1);
}
} else if (windowprb == 1 and !fault) { # if in ON
setprop("/controls/deice/windowprobeheat", 1);
} else if (fault) {
setprop("/controls/deice/windowprobeheat", 0);
} else {
setprop("/controls/deice/windowprobeheat", 0);
}
});
#####################################################################