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Allow a single vacuum system to be driven by multiple pumps. This allows

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modeling of a simple single vacuum system with a pump source on each engine
in a multiengine aircraft.  The highest rpm engine takes priority for driving
the vacuum system.
This commit is contained in:
curt 2005-10-15 20:03:17 +00:00
parent 5c0dbf7b65
commit 330024e0b7
2 changed files with 24 additions and 9 deletions
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22
src/Systems/vacuum.cxx
View file

@ -11,10 +11,10 @@ VacuumSystem::VacuumSystem ( SGPropertyNode *node )
: :
name("vacuum"), name("vacuum"),
num(0), num(0),
rpm("/engines/engine[0]/rpm"),
scale(1.0) scale(1.0)
{ {
rpms.clear();
int i; int i;
for ( i = 0; i < node->nChildren(); ++i ) { for ( i = 0; i < node->nChildren(); ++i ) {
SGPropertyNode *child = node->getChild(i); SGPropertyNode *child = node->getChild(i);
@ -25,7 +25,7 @@ VacuumSystem::VacuumSystem ( SGPropertyNode *node )
} else if ( cname == "number" ) { } else if ( cname == "number" ) {
num = child->getIntValue(); num = child->getIntValue();
} else if ( cname == "rpm" ) { } else if ( cname == "rpm" ) {
rpm = cval; rpms.push_back(cval);
} else if ( cname == "scale" ) { } else if ( cname == "scale" ) {
scale = child->getDoubleValue(); scale = child->getDoubleValue();
} else { } else {
@ -41,7 +41,7 @@ VacuumSystem::VacuumSystem( int i )
{ {
name = "vacuum"; name = "vacuum";
num = i; num = i;
rpm = "/engines/engine[0]/rpm"; rpms.clear();
scale = 1.0; scale = 1.0;
} }
@ -52,12 +52,16 @@ VacuumSystem::~VacuumSystem ()
void void
VacuumSystem::init() VacuumSystem::init()
{ {
unsigned int i;
string branch; string branch;
branch = "/systems/" + name; branch = "/systems/" + name;
SGPropertyNode *node = fgGetNode(branch.c_str(), num, true ); SGPropertyNode *node = fgGetNode(branch.c_str(), num, true );
_serviceable_node = node->getChild("serviceable", 0, true); _serviceable_node = node->getChild("serviceable", 0, true);
_rpm_node = fgGetNode(rpm.c_str(), true); for ( i = 0; i < rpms.size(); i++ ) {
SGPropertyNode_ptr _rpm_node = fgGetNode(rpms[i].c_str(), true);
_rpm_nodes.push_back( _rpm_node );
}
_pressure_node = fgGetNode("/environment/pressure-inhg", true); _pressure_node = fgGetNode("/environment/pressure-inhg", true);
_suction_node = node->getChild("suction-inhg", 0, true); _suction_node = node->getChild("suction-inhg", 0, true);
} }
@ -78,11 +82,19 @@ VacuumSystem::update (double dt)
// Model taken from steam.cxx // Model taken from steam.cxx
double suction; double suction;
unsigned int i;
if (!_serviceable_node->getBoolValue()) { if (!_serviceable_node->getBoolValue()) {
suction = 0.0; suction = 0.0;
} else { } else {
double rpm = _rpm_node->getDoubleValue() * scale; // select the source with the max rpm
double rpm = 0.0;
for ( i = 0; i < _rpm_nodes.size(); i++ ) {
double tmp = _rpm_nodes[i]->getDoubleValue() * scale;
if ( tmp > rpm ) {
rpm = tmp;
}
}
double pressure = _pressure_node->getDoubleValue(); double pressure = _pressure_node->getDoubleValue();
// This magic formula yields about 4 inhg at 700 rpm // This magic formula yields about 4 inhg at 700 rpm
suction = pressure * rpm / (rpm + 4875.0); suction = pressure * rpm / (rpm + 4875.0);

11
src/Systems/vacuum.hxx
View file

@ -11,6 +11,7 @@
# error This library requires C++ # error This library requires C++
#endif #endif
#include <simgear/math/sg_types.hxx>
#include <simgear/props/props.hxx> #include <simgear/props/props.hxx>
#include <simgear/structure/subsystem_mgr.hxx> #include <simgear/structure/subsystem_mgr.hxx>
@ -18,11 +19,13 @@
/** /**
* Model a vacuum-pump system. * Model a vacuum-pump system.
* *
* This first, simple draft is hard-wired to engine #1. * Multiple pumps (i.e. for a multiengine aircraft) can be specified.
* *
* Input properties: * Input properties:
* *
* "rpm" * "rpm1"
* "rpm2"
* "..."
* /environment/pressure-inhg * /environment/pressure-inhg
* /systems/"name"/serviceable * /systems/"name"/serviceable
* *
@ -48,10 +51,10 @@ private:
string name; string name;
int num; int num;
string rpm; string_list rpms;
double scale; double scale;
SGPropertyNode_ptr _serviceable_node; SGPropertyNode_ptr _serviceable_node;
SGPropertyNode_ptr _rpm_node; vector<SGPropertyNode_ptr> _rpm_nodes;
SGPropertyNode_ptr _pressure_node; SGPropertyNode_ptr _pressure_node;
SGPropertyNode_ptr _suction_node; SGPropertyNode_ptr _suction_node;