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flightgear/src/Systems/vacuum.cxx

65 lines
1.6 KiB
C++

// vacuum.cxx - a vacuum pump connected to the aircraft engine.
// Written by David Megginson, started 2002.
//
// This file is in the Public Domain and comes with no warranty.
#include "vacuum.hxx"
#include <Main/fg_props.hxx>
VacuumSystem::VacuumSystem( int i )
{
num = i;
}
VacuumSystem::~VacuumSystem ()
{
}
void
VacuumSystem::init()
{
// TODO: allow index of engine to be
// configured.
SGPropertyNode *node = fgGetNode("/systems/vacuum", num, true );
_serviceable_node = node->getChild("serviceable", 0, true);
_rpm_node = fgGetNode("/engines/engine[0]/rpm", true);
_pressure_node = fgGetNode("/environment/pressure-inhg", true);
_suction_node = node->getChild("suction-inhg", 0, true);
}
void
VacuumSystem::bind ()
{
}
void
VacuumSystem::unbind ()
{
}
void
VacuumSystem::update (double dt)
{
// Model taken from steam.cxx
double suction;
if (!_serviceable_node->getBoolValue()) {
suction = 0.0;
} else {
double rpm = _rpm_node->getDoubleValue();
double pressure = _pressure_node->getDoubleValue();
// This magic formula yields about 4 inhg at 700 rpm
suction = pressure * rpm / (rpm + 4875.0);
// simple regulator model that clamps smoothly to about 5 inhg
// over a normal rpm range
double max = (rpm > 0 ? 5.39 - 1.0 / ( rpm * 0.00111 ) : 0);
if ( suction < 0.0 ) suction = 0.0;
if ( suction > max ) suction = max;
}
_suction_node->setDoubleValue(suction);
}
// end of vacuum.cxx