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

11
src/Systems/vacuum.hxx
View file

@ -11,6 +11,7 @@
# error This library requires C++
#endif
#include <simgear/math/sg_types.hxx>
#include <simgear/props/props.hxx>
#include <simgear/structure/subsystem_mgr.hxx>
@ -18,11 +19,13 @@
/**
* 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:
*
* "rpm"
* "rpm1"
* "rpm2"
* "..."
* /environment/pressure-inhg
* /systems/"name"/serviceable
*
@ -48,10 +51,10 @@ private:
string name;
int num;
string rpm;
string_list rpms;
double scale;
SGPropertyNode_ptr _serviceable_node;
SGPropertyNode_ptr _rpm_node;
vector<SGPropertyNode_ptr> _rpm_nodes;
SGPropertyNode_ptr _pressure_node;
SGPropertyNode_ptr _suction_node;