#include "airspeed_indicator.hxx"
#include <Main/fg_props.hxx>
#include <Main/util.hxx>
+#include <Environment/environment_mgr.hxx>
+#include <Environment/environment.hxx>
// A higher number means more responsive.
_num(node->getIntValue("number", 0)),
_total_pressure(node->getStringValue("total-pressure", "/systems/pitot/total-pressure-inhg")),
_static_pressure(node->getStringValue("static-pressure", "/systems/static/pressure-inhg")),
- _has_barber_pole(node->getBoolValue("has-barber-pole",false))
+ _has_overspeed(node->getBoolValue("has-overspeed-indicator",false)),
+ _pressure_alt_source(node->getStringValue("pressure-alt-source", "/instrumentation/altimeter/pressure-alt-ft")),
+ _ias_limit(node->getDoubleValue("ias-limit", 248.0)),
+ _mach_limit(node->getDoubleValue("mach-limit", 0.48)),
+ _alt_threshold(node->getDoubleValue("alt-threshold", 13200))
{
+ _environmentManager = NULL;
}
AirspeedIndicator::~AirspeedIndicator ()
_static_pressure_node = fgGetNode(_static_pressure.c_str(), true);
_density_node = fgGetNode("/environment/density-slugft3", true);
_speed_node = node->getChild("indicated-speed-kt", 0, true);
+ _tas_node = node->getChild("true-speed-kt", 0, true);
+ _mach_node = node->getChild("indicated-mach", 0, true);
- // barber-pole properties
- _ias_limit_node = node->getNode("ias-limit",0, true);
- _mach_limit_node = node->getNode("mach-limit",0, true);
- _alt_threshold_node = node->getNode("alt-threshold",0, true);
- _airspeed_limit = node->getChild("airspeed-limit-kt", 0, true);
+ // overspeed-indicator properties
+ if (_has_overspeed) {
+ _ias_limit_node = node->getNode("ias-limit",0, true);
+ _mach_limit_node = node->getNode("mach-limit",0, true);
+ _alt_threshold_node = node->getNode("alt-threshold",0, true);
+
+ if (!_ias_limit_node->hasValue()) {
+ _ias_limit_node->setDoubleValue(_ias_limit);
+ }
+
+ if (!_mach_limit_node->hasValue()) {
+ _mach_limit_node->setDoubleValue(_mach_limit);
+ }
+
+ if (!_alt_threshold_node->hasValue()) {
+ _alt_threshold_node->setDoubleValue(_alt_threshold);
+ }
+
+ _airspeed_limit = node->getChild("airspeed-limit-kt", 0, true);
+ _pressure_alt = fgGetNode(_pressure_alt_source.c_str(), true);
+ }
- string paSource = node->getStringValue("pressure-alt-source",
- "/instrumentation/altimeter/pressure-alt-ft");
- _pressure_alt = fgGetNode(paSource.c_str(), true);
- _mach = fgGetNode("/velocities/mach", true);
+ _environmentManager = (FGEnvironmentMgr*) globals->get_subsystem("environment");
}
#ifndef FPSTOKTS
current_speed_kt,
dt * RESPONSIVENESS);
_speed_node->setDoubleValue(filtered_speed);
+ computeMach(filtered_speed);
- if (!_has_barber_pole) {
+ if (!_has_overspeed) {
return;
}
double lmt = _ias_limit_node->getDoubleValue();
if (_pressure_alt->getDoubleValue() > _alt_threshold_node->getDoubleValue()) {
double mmo = _mach_limit_node->getDoubleValue();
- lmt = (filtered_speed/_mach->getDoubleValue())* mmo;
+ lmt = (filtered_speed/_mach_node->getDoubleValue())* mmo;
}
_airspeed_limit->setDoubleValue(lmt);
}
+void
+AirspeedIndicator::computeMach(double ias)
+{
+ if (!_environmentManager) {
+ return;
+ }
+
+ FGEnvironment env(_environmentManager->getEnvironment());
+
+ // derived from http://williams.best.vwh.net/avform.htm#Mach
+ // names here are picked to be consistent with those formulae!
+
+ double oatK = env.get_temperature_degc() + 273.15; // OAT in Kelvin
+ double CS = 38.967854 * sqrt(oatK); // speed-of-sound in knots at altitude
+ double CS_0 = 661.4786; // speed-of-sound in knots at sea-level
+ double P_0 = env.get_pressure_sea_level_inhg();
+ double P = _static_pressure_node->getDoubleValue();
+
+ double DP = P_0 * (pow(1 + 0.2*pow(ias/CS_0, 2), 3.5) - 1);
+ double mach = pow(5 * ( pow(DP/P + 1, 2.0/7.0) -1) , 0.5);
+
+ // publish Mach and TAS
+ _mach_node->setDoubleValue(mach);
+ _tas_node->setDoubleValue(CS * mach);
+}
+
// end of airspeed_indicator.cxx