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fgdata/Aircraft/c172p/Nasal/engine.nas

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# Manages the engine
#
# Fuel system: based on the Spitfire. Manages primer and negGCutoff
# Hobbs meter
# =============================== DEFINITIONS ===========================================
# set the update period
var UPDATE_PERIOD = 0.3;
# =============================== Hobbs meter =======================================
# this property is saved by aircraft.timer
var hobbsmeter_engine_160hp = aircraft.timer.new("/sim/time/hobbs/engine[0]", 60, 1);
var hobbsmeter_engine_180hp = aircraft.timer.new("/sim/time/hobbs/engine[1]", 60, 1);
var init_hobbs_meter = func(index, meter) {
setlistener("/engines/engine[" ~ index ~ "]/running", func {
if (getprop("/engines/engine[" ~ index ~ "]/running")) {
meter.start();
print("Hobbs system started");
} else {
meter.stop();
print("Hobbs system stopped");
}
}, 1, 0);
};
init_hobbs_meter(0, hobbsmeter_engine_160hp);
init_hobbs_meter(1, hobbsmeter_engine_180hp);
var update_hobbs_meter = func {
# in seconds
var hobbs_160hp = getprop("/sim/time/hobbs/engine[0]") or 0.0;
var hobbs_180hp = getprop("/sim/time/hobbs/engine[1]") or 0.0;
# This uses minutes, for testing
#hobbs = hobbs / 60.0;
# in hours
#hobbs = (hobbs_160hp + hobbs_180hp) / 3600.0;
# tenths of hour
var hobbs = 0;
var current_engine = getprop("controls/engines/active-engine");
if (current_engine == 0) {
hobbs = hobbs_160hp / 3600.0;
} else
if (current_engine == 1) {
hobbs = hobbs_180hp / 3600.0;
}
setprop("/instrumentation/hobbs-meter/digits0", math.mod(int(hobbs * 10), 10));
# rest of digits
setprop("/instrumentation/hobbs-meter/digits1", math.mod(int(hobbs), 10));
setprop("/instrumentation/hobbs-meter/digits2", math.mod(int(hobbs / 10), 10));
setprop("/instrumentation/hobbs-meter/digits3", math.mod(int(hobbs / 100), 10));
setprop("/instrumentation/hobbs-meter/digits4", math.mod(int(hobbs / 1000), 10));
};
setlistener("/sim/time/hobbs/engine[0]", update_hobbs_meter, 1, 0);
setlistener("/sim/time/hobbs/engine[1]", update_hobbs_meter, 1, 0);
setlistener("/controls/engines/active-engine", update_hobbs_meter, 1, 0);
# ========== primer stuff ======================
# Toggles the state of the primer
var pumpPrimer = func {
var push = getprop("/controls/engines/engine/primer-lever") or 0;
if (push) {
var pump = getprop("/controls/engines/engine/primer") or 0;
setprop("/controls/engines/engine/primer", pump + 1);
setprop("/controls/engines/engine/primer-lever", 0);
}
else {
setprop("/controls/engines/engine/primer-lever", 1);
}
};
# Primes the engine automatically. This function takes several seconds
var autoPrime = func {
var p = getprop("/controls/engines/engine/primer") or 0;
if (p < 3) {
pumpPrimer();
settimer(autoPrime, 1);
}
};
# Mixture will be calculated using the primer during 5 seconds AFTER the pilot used the starter
# This prevents the engine to start just after releasing the starter: the propeller will be running
# thanks to the electric starter, but carburator has not yet enough mixture
var primerTimer = maketimer(5, func {
setprop("/controls/engines/engine/use-primer", 0);
# Reset the number of times the pilot used the primer only AFTER using the starter
setprop("/controls/engines/engine/primer", 0);
print("Primer reset to 0");
primerTimer.stop();
});
# ========== oil consumption ======================
# Thanks to HHS81 (Benedikt Hallinger) for more advanced simulation
var service_hours = getprop("/engines/active-engine/oil-service-hours");
var consumption_qps = 0.0;
var rpm_factor = 0.0;
var rpm = 0;
var oil_level = 0;
var oil_full = 0;
var oil_lacking = 0;
var oil_level_limited = 0;
var service_hours_increase_qph = 0;
var service_hours_new = 0;
var low_oil_pressure_factor = 0.0;
var low_oil_temperature_factor = 0.0;
# ======= OIL SYSTEM INIT =======
if (!getprop("/engines/active-engine/oil-service-hours")) {
setprop("/engines/active-engine/oil-service-hours", 0);
}
var oil_consumption = maketimer(1.0, func {
oil_level = getprop("/engines/active-engine/oil-level");
if (getprop("/controls/engines/active-engine") == 0)
oil_full = 7;
if (getprop("/controls/engines/active-engine") == 1)
oil_full = 8;
oil_lacking = oil_full - oil_level;
setprop("/engines/active-engine/oil-lacking", oil_lacking);
if (getprop("/engines/active-engine/oil_consumption_allowed")) {
rpm = getprop("/engines/active-engine/rpm");
# Quadratic formula which outputs 1.0 for input 2300 RPM (cruise value),
# 0.6 for 700 RPM (idle) and 1.2 for 2700 RPM (max)
rpm_factor = 0.00000012 * math.pow(rpm, 2) - 0.0001 * rpm + 0.62;
# Consumption rate defined as 0.33 quarts per 1 hour (3600 seconds) (Lycoming Manual 3-6 p27)
# at 2350 RPM (normal cruise)
consumption_qps = 0.33 / 3600;
# Raise consumption when oil level is > 8 quarts (blowout)
if (oil_level > oil_full) {
consumption_qps = consumption_qps * 1.3;
}
# Consumption also raises with oil in service time (lower viscosity => more friction)
# (Oil should be changed at 50 hrs!)
# See: http://www.t-craft.org/Reference/Aircraft.Oil.Usage.pdf
# Hours: 0 | 10 | 25 | 50 | 75
# Add Qts/hr: 0 | 0.02 | 0.125 | 0.5 | 1.125
service_hours = getprop("/engines/active-engine/oil-service-hours");
service_hours_increase_qph = 0.00020 * math.pow(service_hours, 2);
service_hours_increase_qph = std.min(1.5, service_hours_increase_qph); # limit increase to 1.5 (at which point you really should think of changing it)
service_hours_increase_qps = service_hours_increase_qph / 3600;
consumption_qps = consumption_qps + service_hours_increase_qps;
if (getprop("/engines/active-engine/running")) {
oil_level = oil_level - consumption_qps * rpm_factor;
setprop("/engines/active-engine/oil-level", oil_level);
setprop("/engines/active-engine/oil-consume-qps", consumption_qps);
setprop("/engines/active-engine/oil-consume-qph", consumption_qps * 3600);
service_hours_new = (service_hours * 3600 + 1) / 3600; # add one second service time
setprop("/engines/active-engine/oil-service-hours", service_hours_new);
} else {
setprop("/engines/active-engine/oil-consume-qps", 0);
}
low_oil_pressure_factor = 1.0;
low_oil_temperature_factor = 1.0;
# If oil gets low (< 3.0), pressure should drop and temperature should rise
oil_level_limited = std.min(oil_level, 3.0);
# Should give 1.0 for oil_level = 3 and 0.1 for oil_level 1.97,
# which is the min before the engine stops
low_oil_pressure_factor = 0.873786408 * oil_level_limited - 1.621359224;
# Should give 1.0 for oil_level = 3 and 1.5 for oil_level 1.97
low_oil_temperature_factor = -0.485436893 * oil_level_limited + 2.456310679;
setprop("/engines/active-engine/low-oil-pressure-factor", low_oil_pressure_factor);
setprop("/engines/active-engine/low-oil-temperature-factor", low_oil_temperature_factor);
}
else {
# if oil consumption is not allowed, the oil level is set to full and pressure and temp factors are set to 1.0
if (getprop("/controls/engines/active-engine") == 0)
setprop("/engines/active-engine/oil-level", 7);
if (getprop("/controls/engines/active-engine") == 1)
setprop("/engines/active-engine/oil-level", 8);
setprop("/engines/active-engine/low-oil-pressure-factor", 1.0);
setprop("/engines/active-engine/low-oil-temperature-factor", 1.0);
}
});
# Oil Refilling
var oil_refill = func(){
var previous_oil_level = getprop("/engines/active-engine/oil-level");
var service_hours = getprop("/engines/active-engine/oil-service-hours");
var oil_level = getprop("/engines/active-engine/oil-level");
var refilled = oil_level - previous_oil_level;
#print("OIL Refill init: svcHrs=", service_hours, "; oil_level=",oil_level, "; previous_oil_level=",previous_oil_level, "; refilled=",refilled);
if (refilled >= 0) {
# when refill occured, the new oil "makes the old oil younger"
var pct = 0;
if (oil_level > 0) {
pct = previous_oil_level / oil_level;
}
var newService_hours = service_hours * pct;
setprop("/engines/active-engine/oil-service-hours", newService_hours);
#print("OIL Refill: pct=", pct, "; service_hours=",service_hours, "; newService_hours=", newService_hours, "; previous_oil_level=", previous_oil_level, "; oil_level=",oil_level);
}
previous_oil_level = oil_level;
}
# ======= Oil temperature jsbsim compensator =======
# Currently, jsbsim oil temperature always initializes at 60°F.
# We want an temperature that initialize to environment temperature until first start
# and then gradually switch over to the real jsbsim value after some time.
var calculate_real_oiltemp = maketimer(0.5, func {
if (!getprop("/engines/active-engine/already-started-in-session")) {
# engine is still cold
var temp_env = getprop("/environment/temperature-degf") or 60;
var temp_jsbsim_oil = getprop("/engines/active-engine/oil-temperature-degf") or 60;
current_temp_diff = temp_jsbsim_oil - temp_env;
setprop("/engines/active-engine/oil-temperature-env-diff", current_temp_diff);
} else {
# engine has been started at least one time:
# gradually remove the difference as jsbsim adapts to real environment temperature
calculate_real_oiltemp.stop();
interpolate("/engines/active-engine/oil-temperature-env-diff", 0, 180); # hand over to jsbsim caluclation gradually over 2 minutes
}
});
# ========== carburetor icing ======================
var carb_icing_function = maketimer(1.0, func {
if (getprop("/engines/active-engine/carb_icing_allowed")) {
var rpm = getprop("/engines/active-engine/rpm");
var dewpointC = getprop("/environment/dewpoint-degc");
var dewpointF = dewpointC * 9.0 / 5.0 + 32;
var airtempF = getprop("/environment/temperature-degf");
var oil_temp = getprop("/engines/active-engine/oil-temperature-degf");
var egt_degf = getprop("/engines/active-engine/egt-degf");
var engine_running = getprop("/engines/active-engine/running");
var carb_ice = getprop("/engines/active-engine/carb_ice");
# the formula below attempts to model the graph found in the POH which relates air temperature, dew point and RPM to icing
# conditions. The outputs of carb_icing_formula ranges from 0.65 to -0.35 (positive means ice is accumulating, negative
# means that ice is melting)
var factorX = 13.2 - 3.2 * math.atan2 ( ((rpm - 2000.0) * 0.008), 1);
var factorY = 7.0 - 2.0 * math.atan2 ( ((rpm - 2000.0) * 0.008), 1);
var carb_icing_formula = (math.exp( math.pow((0.6 * airtempF + 0.3 * dewpointF - 42.0),2) / (-2 * math.pow(factorX,2))) * math.exp( math.pow((0.3 * airtempF - 0.6 * dewpointF + 14.0),2) / (-2 * math.pow(factorY,2))) - 0.35) * engine_running;
# the efficacy of carb heat depends on the EGT. With a typical EGT of ~1500, the carb_heat_rate will be around -1.5.
# This value is an educated guess of the RL effect, and should melt ice regardless of the icing rate
if (getprop("/controls/engines/current-engine/carb-heat"))
var carb_heat_rate = -0.001 * egt_degf;
else
var carb_heat_rate = 0.0;
# a warm engine will accumulate less ice than a cold one, which is what oil temp factor is used for. oil_temp_factor
# ranges from 0 to aprox -0.2 (at 250 oF). These values are educated guesses of the RL effect
var oil_temp_factor = oil_temp / -1250;
# the final rate of icing or melting is then calculated by all these effects together
var carb_icing_rate = carb_icing_formula + carb_heat_rate + oil_temp_factor;
# since the carb_icing_rate gives an arbitrary final value, the rate is then scaled down by 0.00001 to ensure ice
# accumulates as slowly as expected
carb_ice = carb_ice + carb_icing_rate * 0.00001;
carb_ice = std.max(0.0, std.min(carb_ice, 1.0));
# this property is used to lower the RPM of the engine as ice accumulates (more ice in the carburator == less power)
var vol_eff_factor = std.max(0.0, 0.85 - 1.72 * carb_ice);
setprop("/engines/active-engine/carb_ice", carb_ice);
setprop("/engines/active-engine/carb_icing_rate", carb_icing_rate);
setprop("/engines/active-engine/volumetric-efficiency-factor", vol_eff_factor);
setprop("/engines/active-engine/oil_temp_factor", oil_temp_factor);
}
else {
setprop("/engines/active-engine/carb_ice", 0.0);
setprop("/engines/active-engine/carb_icing_rate", 0.0);
setprop("/engines/active-engine/volumetric-efficiency-factor", 0.85);
setprop("/engines/active-engine/oil_temp_factor", 0.0);
};
});
# ========== engine coughing ======================
var engine_coughing = func(){
var coughing = getprop("/engines/active-engine/coughing");
var running = getprop("/engines/active-engine/running");
if (coughing and running) {
# the code below kills the engine and then brings it back to life after 0.25 seconds, simulating a cough
setprop("/engines/active-engine/kill-engine", 1);
settimer(func {
setprop("/engines/active-engine/kill-engine", 0);
}, 0.25);
};
# basic value for the delay (interval between consecutive coughs), in case no fuel contamination nor carb ice are present
var delay = 2;
# if coughing due to fuel contamination, then cough interval depends on quantity of water
var water_contamination0 = getprop("/consumables/fuel/tank[0]/water-contamination");
var water_contamination1 = getprop("/consumables/fuel/tank[1]/water-contamination");
var total_water_contamination = std.min((water_contamination0 + water_contamination1), 0.4);
if (total_water_contamination > 0) {
# if contamination is near 0, then interval is between 17 and 20 seconds, but if contamination is near the
# engine stopping value of 0.4, then interval falls to around 0.5 and 3.5 seconds
delay = 3.0 * rand() + 17 - 41.25 * total_water_contamination;
};
# if coughing due to carb ice melting, then cough depends on quantity of ice in the carburettor
var carb_ice = getprop("/engines/active-engine/carb_ice");
if (carb_ice > 0) {
# if carb_ice is near 0, then interval is between 17 and 20 seconds, but if carb_ice is near the
# engine stopping value of 0.3, then interval falls to around 0.5 and 3.5 seconds
delay = 3.0 * rand() + 17 - 41.25 * carb_ice;
};
coughing_timer.restart(delay);
}
var coughing_timer = maketimer(1, engine_coughing);
# ====== Engine starting actions ======
var engine_starting = props.globals.initNode("/engines/engine/starting", 0, "BOOL");
setlistener("/engines/engine/running", func(ngn){
if (ngn.getValue() and !getprop("/engines/engine[0]/coughing")) {
engine_starting.setValue(1);
var timer = maketimer(1, func(){
engine_starting.setValue(0);
});
timer.singleShot = 1; # timer will only be run once
timer.start();
} else {
engine_starting.setValue(0);
}
},0,0);
setlistener("/engines/engine/starting", func(ngn){
# Eye-candy: when engine starts, let the view shake a bit
if (ngn.getValue() and getprop("/sim/current-view/internal")) {
var curX = getprop("/sim/current-view/x-offset-m");
var xtimer = maketimer(0.05, func(){
interpolate("/sim/current-view/x-offset-m", curX-0.0015+rand()*0.003, 0.05);
});
xtimer.start();
var curY = getprop("/sim/current-view/y-offset-m");
var ytimer = maketimer(0.05, func(){
interpolate("/sim/current-view/y-offset-m", curY-0.0015+rand()*0.003, 0.05);
});
ytimer.start();
var stoptimer = maketimer(0.8, func(){
xtimer.stop();
ytimer.stop();
interpolate("/sim/current-view/x-offset-m", curX, 0.1);
interpolate("/sim/current-view/y-offset-m", curY, 0.1);
});
stoptimer.singleShot = 1;
stoptimer.start();
}
}, 0, 0);
# ========== Main loop ======================
var update = func {
#this block should be moved out of nasal and into jsbsim or autopilot logic
var leftTankUsable = 0;
var rightTankUsable = 0;
if (getprop("/consumables/fuel/tank[0]/selected") and getprop("/consumables/fuel/tank[0]/level-gal_us") > 0) leftTankUsable = 1;
if (getprop("/consumables/fuel/tank[1]/selected") and getprop("/consumables/fuel/tank[1]/level-gal_us") > 0) rightTankUsable = 1;
if (getprop("/consumables/fuel/tank[2]/selected") and getprop("/consumables/fuel/tank[2]/level-gal_us") > 0) leftTankUsable = 1;
if (getprop("/consumables/fuel/tank[3]/selected") and getprop("/consumables/fuel/tank[3]/level-gal_us") > 0) rightTankUsable = 1;
var outOfFuel = !(leftTankUsable or rightTankUsable);
# We use the mixture to control the engines, so set the mixture
var usePrimer = getprop("/controls/engines/engine/use-primer") or 0;
if(getprop("/controls/panel/glass")) usePrimer = 0;
var engine_running = getprop("/engines/active-engine/running");
if (outOfFuel and (engine_running or usePrimer)) {
print("Out of fuel!");
gui.popupTip("Out of fuel!");
}
elsif (usePrimer and !engine_running and getprop("/engines/active-engine/oil-temperature-degf") <= 75) {
# Mixture is controlled by start conditions
var primer = getprop("/controls/engines/engine/primer");
if (!getprop("/fdm/jsbsim/fcs/mixture-primer-cmd") and getprop("/controls/switches/starter") and getprop("/controls/switches/master-bat")) {
if (primer < 3) {
print("Use the primer!");
gui.popupTip("Use the primer!");
}
elsif (primer > 6) {
print("Flooded engine!");
gui.popupTip("Flooded engine!");
}
else {
print("Check the throttle!");
gui.popupTip("Check the throttle!");
}
}
}
var active_engine = getprop("/controls/engines/active-engine");
var rpm = getprop("/engines/engine", active_engine, "rpm");
# sorry - had to hack this to prevent coughing on startup due to the oil pressure simulation. Maybe this can be used elsewhere
if (rpm < 900 and getprop("/controls/switches/starter") == 1) { # make sure it is not triggered if you accidentally hit s in the air
setprop("/engines/active-engine/ready-oil-press-checker", 1); # 0 = off, 1 = checker is armed, 2 = engine is running and ready
}
if (getprop("/engines/active-engine/ready-oil-press-checker") == 1 and getprop("/engines/active-engine/rpm") > 900) {
setprop("/engines/active-engine/ready-oil-press-checker", 2); # engine is ready for use
}
};
setlistener("/controls/switches/starter", func {
var v = getprop("/controls/switches/starter") or 0;
if (v == 0) {
print("Starter off");
# notice the starter will be reset after 5 seconds
primerTimer.restart(5);
}
else {
print("Starter on");
if(getprop("/controls/panel/glass"))
setprop("/controls/engines/engine/use-primer", 0);
else
setprop("/controls/engines/engine/use-primer", 1);
if (primerTimer.isRunning) {
primerTimer.stop();
}
}
}, 1, 0);
# ================================ Initalize ======================================
# Make sure all needed properties are present and accounted
# for, and that they have sane default values.
setprop("/engines/active-engine/rpm", 0);
setprop("/engines/active-engine/ready-oil-press-checker", 0);
# =============== Variables ================
controls.incThrottle = func {
var delta = arg[1] * controls.THROTTLE_RATE * getprop("/sim/time/delta-realtime-sec");
var old_value = getprop("/controls/engines/current-engine/throttle");
var new_value = std.max(0.0, std.min(old_value + delta, 1.0));
setprop("/controls/engines/current-engine/throttle", new_value);
};
controls.throttleMouse = func {
if (!getprop("/devices/status/mice/mouse[0]/button[1]")) {
return;
}
var delta = cmdarg().getNode("offset").getValue() * -4;
var old_value = getprop("/controls/engines/current-engine/throttle");
var new_value = std.max(0.0, std.min(old_value + delta, 1.0));
setprop("/controls/engines/current-engine/throttle", new_value);
};
# 2018.2 introduces new "all" properties for throttle, mixture and prop pitch.
# this is the correct way to interface with the axis based controls - use a listener
# on the *-all property
setlistener("/controls/engines/throttle-all", func{
var value = (1 - getprop("/controls/engines/throttle-all")) / 2;
var new_value = std.max(0.0, std.min(value, 1.0));
setprop("/controls/engines/current-engine/throttle", new_value);
}, 0, 0);
setlistener("/controls/engines/mixture-all", func{
var value = (1 - getprop("/controls/engines/mixture-all")) / 2;
var new_value = std.max(0.0, std.min(value, 1.0));
setprop("/controls/engines/current-engine/mixture", new_value);
}, 0, 0);
# backwards compatibility only - the controls.throttleAxis should not be overridden like this. The joystick binding Throttle (all) has
# been replaced and controls.throttleAxis will not be called from the controls binding - so this is to
# maintain compatibility with existing joystick xml files.
controls.throttleAxis = func {
var value = (1 - cmdarg().getNode("setting").getValue()) / 2;
var new_value = std.max(0.0, std.min(value, 1.0));
setprop("/controls/engines/current-engine/throttle", new_value);
};
controls.adjMixture = func {
var delta = arg[0] * controls.THROTTLE_RATE * getprop("/sim/time/delta-realtime-sec");
var old_value = getprop("/controls/engines/current-engine/mixture");
var new_value = std.max(0.0, std.min(old_value + delta, 1.0));
setprop("/controls/engines/current-engine/mixture", new_value);
};
# backwards compatibility only - the controls.throttleAxis should not be overridden like this. The joystick binding Throttle (all) has
# been replaced and controls.throttleAxis will not be called from the controls binding - so this is to
# maintain compatibility with existing joystick xml files.
controls.mixtureAxis = func {
var value = (1 - cmdarg().getNode("setting").getValue()) / 2;
var new_value = std.max(0.0, std.min(value, 1.0));
setprop("/controls/engines/current-engine/mixture", new_value);
};
var _axisMode = {
0: controls.perIndexAxisHandler("/controls/engines/current-engine[",
"]/throttle"),
1: controls.perIndexAxisHandler("/controls/engines/current-engine[",
"]/mixture"),
2: controls.perIndexAxisHandler("/controls/engines/current-engine[",
"]/propeller-pitch")
};
controls.perEngineSelectedAxisHandler = func(mode) {
return _axisMode[mode];
};
controls.stepMagnetos = func {
var old_value = getprop("/controls/switches/magnetos");
var new_value = std.max(0, std.min(old_value + arg[0], 3));
setprop("/controls/switches/magnetos", new_value);
};
# key 's' calls to this function when it is pressed DOWN even if I overwrite the binding in the -set.xml file!
# fun fact: the key UP event can be overwriten!
controls.startEngine = func(v = 1) {
# Only operate in non-walker mode ('s' is also bound to walk-backward)
var view_name = getprop("/sim/current-view/name");
if (view_name == getprop("/sim/view[110]/name") or view_name == getprop("/sim/view[111]/name")) {
return;
}
if (getprop("/engines/active-engine/running"))
{
setprop("/controls/switches/starter", 0);
return;
}
else {
setprop("/controls/switches/magnetos", 3);
setprop("/controls/switches/starter", v);
}
};
var engine_timer = maketimer(UPDATE_PERIOD, func { update(); });
coughing_timer.singleShot = 1;
oil_consumption.simulatedTime = 1;
setlistener("/sim/signals/fdm-initialized", func {
engine_timer.start();
carb_icing_function.start();
coughing_timer.start();
if (oil_consumption.isRunning) {
oil_consumption.stop();
}
oil_consumption.start();
calculate_real_oiltemp.start();
});
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