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A320-family/Nasal/Systems/brakesystem.nas

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##########################################################################
# Simple Brake Simulation System
# 2010, Thorsten Brehm
#
# Simple simulation of brake energy absorption and cooling effects.
#
# This module computes (approximates... :-) ) an energy level which
# (faintly) resembles the kinetic energy absorption and cooling effects
# of a brake system. But instead of computing real temperatures, this
# is just meant to distinguish normal energy levels from exceptionally
# high levels. The target is to drive EICAS "brakes overheat" messages
# and gear effects only, to "reward" pilots with exceptionally bad
# landings...
#
# To avoid complicated calculations of different braking effects (roll/air
# drag, reverse thrust etc), we simply assume the brake system to cause a
# fixed deceleration (me.BrakeDecel). With this deceleration we approximate
# the speed difference which would be caused by the brake system alone for
# any given simulation interval. The difference of the kinetic energy level
# at the current speed and the decelerated speed are then added up to the
# total absorbed brake energy.
# Units (knots/lbs/Kg) do not matter much here. Eventually a magic scaling
# divisor is used to scale the output level. Any output > 1 means
# "overheated brakes", any level <=1 means "brake temperature OK".
# No exact science here - but good enough for now :-).
##########################################################################
#
# Added brakes temp calculations and adapted for A320-family
# 2020, Andrea Vezzali
#
##########################################################################
var BrakeSystem =
{
new : func()
{
var m = { parents : [BrakeSystem]};
# deceleration caused by brakes alone (knots/s2)
m.BrakeDecel = 1.0; # kt/s^2
# Higher value means quicker cooling
m.CoolingFactor = 0.000125;
# Scaling divisor. Use this to scale the energy output.
# Manually tune this value: a total energy output
# at "/gear/brake-thermal-energy" > 1.0 means overheated brakes,
# anything below <= 1.0 means energy absorbed by brakes is OK.
#m.ScalingDivisor= 700000*450.0;
m.ScalingDivisor = 0.000000006;
m.LSmokeActive = 0;
m.LSmokeToggle = 0;
m.RSmokeActive = 0;
m.RSmokeToggle = 0;
# m.LnCoolFactor = math.ln(1-m.CoolingFactor);
m.reset();
return m;
},
reset : func()
{
# Initial thermal energy
setprop("gear/gear[1]/Lbrake-thermal-energy",0.0);
setprop("gear/gear[2]/Rbrake-thermal-energy",0.0);
setprop("controls/gear/brake-fans",0);
setprop("gear/gear[1]/Lbrake-smoke",0);
setprop("gear/gear[2]/Rbrake-smoke",0);
setprop("gear/gear[1]/L-Thrust",0);
setprop("gear/gear[2]/R-Thrust",0);
#Introducing a random error on temp sensors (max 5°C)
setprop("gear/gear[1]/L1error-temp-degc", math.round(rand()*(5)));
setprop("gear/gear[1]/L2error-temp-degc", math.round(rand()*(5)));
setprop("gear/gear[2]/R3error-temp-degc", math.round(rand()*(5)));
setprop("gear/gear[2]/R4error-temp-degc", math.round(rand()*(5)));
#var atemp = getprop("environment/temperature-degc") or 0;
#var vmach = getprop("velocities/mach") or 0;
var tatdegc = getprop("/systems/navigation/probes/tat-1/compute-tat") or 0;
var atemp = getprop("environment/temperature-degc") or 0;
var vmach = getprop("velocities/mach") or 0;
var tatdegc = getprop("systems/navigation/probes/tat-1/compute-tat");
setprop("gear/gear[1]/L1brake-temp-degc",tatdegc+getprop("gear/gear[1]/L1error-temp-degc"));
setprop("gear/gear[1]/L2brake-temp-degc",tatdegc+getprop("gear/gear[1]/L2error-temp-degc"));
setprop("gear/gear[2]/R3brake-temp-degc",tatdegc+getprop("gear/gear[2]/R3error-temp-degc"));
setprop("gear/gear[2]/R4brake-temp-degc",tatdegc+getprop("gear/gear[2]/R4error-temp-degc"));
setprop("sim/animation/fire-services",0);
me.LastSimTime = 0.0;
},
# update brake energy
update : func()
{
var CurrentTime = getprop("sim/time/elapsed-sec");
var dt = CurrentTime - me.LastSimTime;
var LThermalEnergy = getprop("gear/gear[1]/Lbrake-thermal-energy");
var RThermalEnergy = getprop("gear/gear[2]/Rbrake-thermal-energy");
var LBrakeLevel = getprop("fdm/jsbsim/fcs/left-brake-cmd-norm");
var RBrakeLevel = getprop("fdm/jsbsim/fcs/right-brake-cmd-norm");
#var atemp = getprop("environment/temperature-degc") or 0;
#var vmach = getprop("velocities/mach") or 0;
#var tatdegc = atemp * (1 + (0.2 * math.pow(vmach, 2)));
var tatdegc = getprop("/systems/navigation/probes/tat-1/compute-tat") or 0;
var L_thrust_lb = getprop("engines/engine[0]/thrust_lb");
var R_thrust_lb = getprop("engines/engine[1]/thrust_lb");
if (dt<1.0)
{
var OnGround = getprop("gear/gear[1]/wow");
#cooling effect: adjust cooling factor by a value proportional to the environment temp (m.CoolingFactor + environment temp-degc * 0.00001)
var LCoolingRatio = me.CoolingFactor+(tatdegc*0.000001);
var RCoolingRatio = me.CoolingFactor+(tatdegc*0.000001);
if (getprop("controls/gear/brake-fans"))
{
#increase CoolingRatio if Brake Fans are active
LCoolingRatio = LCoolingRatio * 3;
RCoolingRatio = RCoolingRatio * 3;
}
if (getprop("gear/gear[1]/position-norm"))
{
#increase CoolingRatio if gear down according to airspeed
LCoolingRatio = LCoolingRatio * getprop("velocities/airspeed-kt");
} else {
#Reduced CoolingRatio if gear up
LCoolingRatio = LCoolingRatio * 0.1;
}
if (getprop("gear/gear[2]/position-norm"))
{
#increase CoolingRatio if gear down according to airspeed
RCoolingRatio = RCoolingRatio * getprop("velocities/airspeed-kt");
} else {
#Reduced CoolingRatio if gear up
RCoolingRatio = RCoolingRatio * 0.1;
}
if (LBrakeLevel>0)
{
#Reduced CoolingRatio if Brakes used
LCoolingRatio = LCoolingRatio * 0.1 * LBrakeLevel;
}
if (RBrakeLevel>0)
{
#Reduced CoolingRatio if Brakes used
RCoolingRatio = RCoolingRatio * 0.1 * RBrakeLevel;
}
var LnCoolFactor = math.ln(1-LCoolingRatio);
var RnCoolFactor = math.ln(1-RCoolingRatio);
L_thrust_lb = math.abs(getprop("engines/engine[0]/thrust_lb"));
if (L_thrust_lb < 1)
{
L_thrust_lb = 1
}
#Disabling thrust computation on Brakes temperature
#L_Thrust = math.pow((math.log10(L_thrust_lb)),10)*0.0000000002;
L_Thrust = 0;
R_thrust_lb = math.abs(getprop("engines/engine[1]/thrust_lb"));
if (R_thrust_lb < 1)
{
R_thrust_lb = 1
}
#Disabling thrust computation on Brakes temperature
#R_Thrust = math.pow((math.log10(R_thrust_lb)),10)*0.0000000002;
R_Thrust = 0;
if (OnGround)
{
var V1 = getprop("velocities/groundspeed-kt");
var Mass = getprop("fdm/jsbsim/inertia/weight-lbs")*(me.ScalingDivisor);
# absorb some kinetic energy:
# dE= 1/2 * m * V1^2 - 1/2 * m * V2^2)
var V2_L = V1 - me.BrakeDecel * dt * LBrakeLevel;
var V2_R = V1 - me.BrakeDecel * dt * RBrakeLevel;
LThermalEnergy += (Mass * getprop("gear/gear[1]/compression-norm") * (math.pow(V1, 2) - math.pow(V2_L, 2)) / 2);
if (getprop("services/chocks/left"))
{
if (!getprop("controls/gear/brake-parking"))
{
# cooling effect: reduce thermal energy by (LnCoolFactor) * dt
LThermalEnergy = LThermalEnergy * math.exp(LnCoolFactor * dt);
} else {
#LThermalEnergy += L_Thrust;
# cooling effect: reduce thermal energy by (LnCoolFactor) * dt
LThermalEnergy = (LThermalEnergy * math.exp(LnCoolFactor * dt)) + (L_Thrust * dt);
}
} else {
if (!getprop("controls/gear/brake-parking"))
{
if (LBrakeLevel>0)
{
if (V2_L>0)
{
#LThermalEnergy += (Mass * (math.pow(V1, 2) - math.pow(V2_L, 2)) / 2) + L_thrust;
# cooling effect: reduce thermal energy by (LnCoolFactor) * dt
LThermalEnergy = LThermalEnergy * math.exp(LnCoolFactor * dt);
} else {
#LThermalEnergy += math.abs(L_Thrust);
# cooling effect: reduce thermal energy by (LnCoolFactor) * dt
LThermalEnergy = (LThermalEnergy * math.exp(LnCoolFactor * dt)) + (L_Thrust * dt);
}
} else {
# cooling effect: reduce thermal energy by (LnCoolFactor) * dt
LThermalEnergy = LThermalEnergy * math.exp(LnCoolFactor * dt);
}
} else {
#LThermalEnergy += math.abs(L_Thrust);
# cooling effect: reduce thermal energy by (LnCoolFactor) * dt
LThermalEnergy = (LThermalEnergy * math.exp(LnCoolFactor * dt)) + (L_Thrust * dt);
}
}
RThermalEnergy += (Mass * getprop("gear/gear[2]/compression-norm") * (math.pow(V1, 2) - math.pow(V2_R, 2)) / 2);
if (getprop("services/chocks/right"))
{
if (!getprop("controls/gear/brake-parking"))
{
# cooling effect: reduce thermal energy by (RnCoolFactor) * dt
RThermalEnergy = RThermalEnergy * math.exp(RnCoolFactor * dt);
} else {
#RThermalEnergy += math.abs(R_Thrust);
# cooling effect: reduce thermal energy by (RnCoolFactor) * dt
RThermalEnergy = (RThermalEnergy * math.exp(RnCoolFactor * dt)) + (R_Thrust * dt);
}
} else {
if (!getprop("controls/gear/brake-parking"))
{
if (RBrakeLevel>0)
{
if (V2_R>0)
{
#RThermalEnergy += (Mass * (math.pow(V1, 2) - math.pow(V2_R, 2)) / 2) + R_thrust;
# cooling effect: reduce thermal energy by (RnCoolFactor) * dt
RThermalEnergy = RThermalEnergy * math.exp(RnCoolFactor * dt);
} else {
#RThermalEnergy += math.abs(R_Thrust);
# cooling effect: reduce thermal energy by (RnCoolFactor) * dt
RThermalEnergy = (RThermalEnergy * math.exp(RnCoolFactor * dt)) + (R_Thrust * dt);
}
} else {
# cooling effect: reduce thermal energy by (RnCoolFactor) * dt
RThermalEnergy = RThermalEnergy * math.exp(RnCoolFactor * dt);
}
} else {
#RThermalEnergy += math.abs(R_Thrust);
# cooling effect: reduce thermal energy by (RnCoolFactor) * dt
RThermalEnergy = (RThermalEnergy * math.exp(RnCoolFactor * dt)) + (R_Thrust * dt);
}
}
} else {
LThermalEnergy = LThermalEnergy * math.exp(LnCoolFactor * dt);
RThermalEnergy = RThermalEnergy * math.exp(RnCoolFactor * dt);
}
if (LThermalEnergy < 0) {
LThermalEnergy = 0
}
if (LThermalEnergy > 3) {
LThermalEnergy = 3
}
if (RThermalEnergy < 0) {
RThermalEnergy = 0
}
if (RThermalEnergy > 3) {
RThermalEnergy = 3
}
setprop("gear/gear[1]/L-Thrust",L_Thrust);
setprop("gear/gear[2]/R-Thrust",R_Thrust);
setprop("gear/gear[1]/Lbrake-thermal-energy",LThermalEnergy);
setprop("gear/gear[2]/Rbrake-thermal-energy",RThermalEnergy);
#Calculating Brakes temperature
setprop("gear/gear[1]/L1brake-temp-degc",tatdegc+getprop("gear/gear[1]/L1error-temp-degc")+(LThermalEnergy * (300-tatdegc-getprop("gear/gear[1]/L1error-temp-degc"))));
setprop("gear/gear[1]/L2brake-temp-degc",tatdegc+getprop("gear/gear[1]/L2error-temp-degc")+(LThermalEnergy * (300-tatdegc-getprop("gear/gear[1]/L2error-temp-degc"))));
setprop("gear/gear[2]/R3brake-temp-degc",tatdegc+getprop("gear/gear[2]/R3error-temp-degc")+(RThermalEnergy * (300-tatdegc-getprop("gear/gear[2]/R3error-temp-degc"))));
setprop("gear/gear[2]/R4brake-temp-degc",tatdegc+getprop("gear/gear[2]/R4error-temp-degc")+(RThermalEnergy * (300-tatdegc-getprop("gear/gear[2]/R4error-temp-degc"))));
if ((LThermalEnergy>1)and(!me.LSmokeActive))
{
# start smoke processing
me.LSmokeActive = 1;
settimer(func { BrakeSys.Lsmoke(); },0);
}
if ((RThermalEnergy>1)and(!me.RSmokeActive))
{
# start smoke processing
me.RSmokeActive = 1;
settimer(func { BrakeSys.Rsmoke(); },0);
}
}
me.LastSimTime = CurrentTime;
# 5 updates per second are good enough
settimer(func { BrakeSys.update(); },0.2);
},
# smoke processing
Lsmoke : func()
{
if ((me.LSmokeActive)and(getprop("gear/gear[1]/Lbrake-thermal-energy")>1))
{
# make density of smoke effect depend on energy level
var LSmokeDelay=0;
var LThermalEnergy = getprop("gear/gear[1]/Lbrake-thermal-energy");
if (LThermalEnergy < 1.5)
LSmokeDelay=(1.5-LThermalEnergy);
# No smoke when gear retracted
var LSmokeValue = (getprop("gear/gear[1]/position-norm")>0.5);
# toggle smoke to interpolate different densities
if (LSmokeDelay>0.05)
{
me.LSmokeToggle = !me.LSmokeToggle;
if (!me.LSmokeToggle)
LSmokeValue = 0;
else
LSmokeDelay = 0;
}
setprop("gear/gear[1]/Lbrake-smoke",LSmokeValue);
settimer(func { BrakeSys.Lsmoke(); },LSmokeDelay);
}
else
{
# stop smoke processing
setprop("gear/gear[1]/Lbrake-smoke",0);
setprop("sim/animation/fire-services",0);
me.LSmokeActive = 0;
}
if (getprop("gear/gear[1]/Lbrake-thermal-energy") > 1.5)
setprop("sim/animation/fire-services",1);
else
setprop("sim/animation/fire-services",0);
},
# smoke processing
Rsmoke : func()
{
if ((me.RSmokeActive)and(getprop("gear/gear[2]/Rbrake-thermal-energy")>1))
{
# make density of smoke effect depend on energy level
var RSmokeDelay=0;
var RThermalEnergy = getprop("gear/gear[2]/Rbrake-thermal-energy");
if (RThermalEnergy < 1.5)
RSmokeDelay=(1.5-RThermalEnergy);
# No smoke when gear retracted
var RSmokeValue = (getprop("gear/gear[2]/position-norm")>0.5);
# toggle smoke to interpolate different densities
if (RSmokeDelay>0.05)
{
me.RSmokeToggle = !me.RSmokeToggle;
if (!me.RSmokeToggle)
RSmokeValue = 0;
else
RSmokeDelay = 0;
}
setprop("gear/gear[2]/Rbrake-smoke",RSmokeValue);
settimer(func { BrakeSys.Rsmoke(); },RSmokeDelay);
}
else
{
# stop smoke processing
setprop("gear/gear[2]/Rbrake-smoke",0);
me.RSmokeActive = 0;
}
if (getprop("gear/gear[2]/Rbrake-thermal-energy") > 1.5)
setprop("sim/animation/fire-services",1);
else
setprop("sim/animation/fire-services",0);
},
};
var BrakeSys = BrakeSystem.new();
setlistener("sim/signals/fdm-initialized",
# executed on _every_ FDM reset (but not installing new listeners)
func(idle) { BrakeSys.reset(); },
0,0);
settimer(func()
{
BrakeSys.update();
}, 5);
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