#include <iostream>
#include <sstream>
#include "FGRocket.h"
-#include "FGState.h"
#include "models/FGPropulsion.h"
#include "FGThruster.h"
#include "FGTank.h"
namespace JSBSim {
-static const char *IdSrc = "$Id$";
+static const char *IdSrc = "$Id: FGRocket.cpp,v 1.23 2011/01/24 13:01:56 jberndt Exp $";
static const char *IdHdr = ID_ROCKET;
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
FGRocket::FGRocket(FGFDMExec* exec, Element *el, int engine_number)
: FGEngine(exec, el, engine_number)
{
+ Type = etRocket;
Element* thrust_table_element = 0;
ThrustTable = 0L;
BurnTime = 0.0;
previousFuelNeedPerTank = 0.0;
previousOxiNeedPerTank = 0.0;
PropellantFlowRate = 0.0;
- FuelFlowRate = 0.0;
- OxidizerFlowRate = 0.0;
- SLOxiFlowMax = 0.0;
+ FuelFlowRate = FuelExpended = 0.0;
+ OxidizerFlowRate = OxidizerExpended = 0.0;
+ SLOxiFlowMax = SLFuelFlowMax = 0.0;
+ BuildupTime = 0.0;
It = 0.0;
+ ThrustVariation = 0.0;
+ TotalIspVariation = 0.0;
+ Flameout = false;
// Defaults
MinThrottle = 0.0;
if (el->FindElement("isp"))
Isp = el->FindElementValueAsNumber("isp");
+ if (el->FindElement("builduptime"))
+ BuildupTime = el->FindElementValueAsNumber("builduptime");
if (el->FindElement("maxthrottle"))
MaxThrottle = el->FindElementValueAsNumber("maxthrottle");
if (el->FindElement("minthrottle"))
if (el->FindElement("sloxiflowmax"))
SLOxiFlowMax = el->FindElementValueAsNumberConvertTo("sloxiflowmax", "LBS/SEC");
+ // If there is a thrust table element, this is a solid propellant engine.
thrust_table_element = el->FindElement("thrust_table");
if (thrust_table_element) {
ThrustTable = new FGTable(PropertyManager, thrust_table_element);
+ Element* variation_element = el->FindElement("variation");
+ if (variation_element) {
+ if (variation_element->FindElement("thrust")) {
+ ThrustVariation = variation_element->FindElementValueAsNumber("thrust");
+ }
+ if (variation_element->FindElement("total_isp")) {
+ TotalIspVariation = variation_element->FindElementValueAsNumber("total_isp");
+ }
+ }
}
bindmodel();
Debug(0);
-
- Type = etRocket;
- Flameout = false;
-
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-double FGRocket::Calculate(void)
+void FGRocket::Calculate(void)
{
- double dT = State->Getdt()*Propulsion->GetRate();
- double thrust;
+ if (FDMExec->IntegrationSuspended()) return;
+
+ double dT = FDMExec->GetDeltaT()*Propulsion->GetRate();
+
+ RunPreFunctions();
if (!Flameout && !Starved) ConsumeFuel();
if (ThrustTable != 0L) { // Thrust table given -> Solid fuel used
if ((Throttle == 1 || BurnTime > 0.0 ) && !Starved) {
- BurnTime += State->Getdt();
double TotalEngineFuelBurned=0.0;
for (int i=0; i<(int)SourceTanks.size(); i++) {
FGTank* tank = Propulsion->GetTank(i);
}
}
- VacThrust = ThrustTable->GetValue(TotalEngineFuelBurned);
+ VacThrust = ThrustTable->GetValue(TotalEngineFuelBurned)
+ * (ThrustVariation + 1)
+ * (TotalIspVariation + 1);
+ if (BurnTime <= BuildupTime && BuildupTime > 0.0) {
+ VacThrust *= sin((BurnTime/BuildupTime)*M_PI/2.0);
+ // VacThrust *= (1-cos((BurnTime/BuildupTime)*M_PI))/2.0; // 1 - cos approach
+ }
+ BurnTime += FDMExec->GetDeltaT(); // Increment burn time
} else {
VacThrust = 0.0;
}
} // End thrust calculations
- thrust = Thruster->Calculate(VacThrust);
- It += thrust * dT;
+ It += Thruster->Calculate(VacThrust) * dT;
- return thrust;
+ RunPostFunctions();
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
double Fshortage=0, Oshortage=0, TanksWithFuel=0, TanksWithOxidizer=0;
if (FuelFreeze) return;
- if (TrimMode) return;
+ if (FDMExec->GetTrimStatus()) return;
// Count how many assigned tanks have fuel for this engine at this time.
// If there is/are fuel tanks but no oxidizer tanks, this indicates
// a solid rocket is being modeled.
for (i=0; i<SourceTanks.size(); i++) {
- Tank = Propulsion->GetTank(SourceTanks[i]);
+ Tank = Propulsion->GetTank(i);
switch(Tank->GetType()) {
case FGTank::ttFUEL:
- if (Tank->GetContents() > 0.0 && Tank->GetSelected()) ++TanksWithFuel;
+ if (Tank->GetContents() > 0.0 && Tank->GetSelected() && SourceTanks[i] > 0) ++TanksWithFuel;
break;
case FGTank::ttOXIDIZER:
- haveOxTanks = true;
- if (Tank->GetContents() > 0.0 && Tank->GetSelected()) ++TanksWithOxidizer;
+ if (Tank->GetSelected() && SourceTanks[i] > 0) {
+ haveOxTanks = true;
+ if (Tank->GetContents() > 0.0) ++TanksWithOxidizer;
+ }
break;
}
}
// Expend fuel from the engine's tanks if the tank is selected as a source
// for this engine.
- double fuelNeedPerTank = CalcFuelNeed()/TanksWithFuel;
- double oxiNeedPerTank = CalcOxidizerNeed()/TanksWithOxidizer;
+ double fuelNeedPerTank = 0;
+ double oxiNeedPerTank = 0;
+
+ if (TanksWithFuel > 0) fuelNeedPerTank = CalcFuelNeed()/TanksWithFuel;
+ if (TanksWithOxidizer > 0) oxiNeedPerTank = CalcOxidizerNeed()/TanksWithOxidizer;
for (i=0; i<SourceTanks.size(); i++) {
- Tank = Propulsion->GetTank(SourceTanks[i]);
- if ( ! Tank->GetSelected()) continue; // If this tank is not selected as a source, skip it.
+ Tank = Propulsion->GetTank(i);
+ if ( ! Tank->GetSelected() || SourceTanks[i] == 0) continue; // If this tank is not selected as a source, skip it.
switch(Tank->GetType()) {
case FGTank::ttFUEL:
Fshortage += Tank->Drain(2.0*fuelNeedPerTank - previousFuelNeedPerTank);
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+//
+// The FuelFlowRate can be affected by the TotalIspVariation value (settable
+// in a config file or via properties). The TotalIspVariation parameter affects
+// thrust, but the thrust determines fuel flow rate, so it must be adjusted
+// for Total Isp Variation.
double FGRocket::CalcFuelNeed(void)
{
- double dT = State->Getdt()*Propulsion->GetRate();
+ double dT = FDMExec->GetDeltaT()*Propulsion->GetRate();
if (ThrustTable != 0L) { // Thrust table given - infers solid fuel
FuelFlowRate = VacThrust/Isp; // This calculates wdot (weight flow rate in lbs/sec)
+ FuelFlowRate /= (1 + TotalIspVariation);
} else {
FuelFlowRate = SLFuelFlowMax*PctPower;
}
double FGRocket::CalcOxidizerNeed(void)
{
- double dT = State->Getdt()*Propulsion->GetRate();
+ double dT = FDMExec->GetDeltaT()*Propulsion->GetRate();
OxidizerFlowRate = SLOxiFlowMax*PctPower;
OxidizerExpended = OxidizerFlowRate*dT;
return OxidizerExpended;
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-// This funciton should tie properties to rocket engine specific properties
+// This function should tie properties to rocket engine specific properties
// that are not bound in the base class (FGEngine) code.
//
void FGRocket::bindmodel()
property_name = base_property_name + "/total-impulse";
PropertyManager->Tie( property_name.c_str(), this, &FGRocket::GetTotalImpulse);
- property_name = base_property_name + "/oxi-flow-rate-pps";
- PropertyManager->Tie( property_name.c_str(), this, &FGRocket::GetOxiFlowRate);
property_name = base_property_name + "/vacuum-thrust_lbs";
PropertyManager->Tie( property_name.c_str(), this, &FGRocket::GetVacThrust);
+
+ if (ThrustTable) { // Solid rocket motor
+ property_name = base_property_name + "/thrust-variation_pct";
+ PropertyManager->Tie( property_name.c_str(), this, &FGRocket::GetThrustVariation,
+ &FGRocket::SetThrustVariation);
+ property_name = base_property_name + "/total-isp-variation_pct";
+ PropertyManager->Tie( property_name.c_str(), this, &FGRocket::GetTotalIspVariation,
+ &FGRocket::SetTotalIspVariation);
+ } else { // Liquid rocket motor
+ property_name = base_property_name + "/oxi-flow-rate-pps";
+ PropertyManager->Tie( property_name.c_str(), this, &FGRocket::GetOxiFlowRate);
+ }
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
cout << " Minimum Throttle = " << MinThrottle << endl;
cout << " Fuel Flow (max) = " << SLFuelFlowMax << endl;
cout << " Oxidizer Flow (max) = " << SLOxiFlowMax << endl;
- cout << " Mixture ratio = " << SLOxiFlowMax/SLFuelFlowMax << endl;
+ if (SLFuelFlowMax > 0)
+ cout << " Mixture ratio = " << SLOxiFlowMax/SLFuelFlowMax << endl;
}
}
if (debug_lvl & 2 ) { // Instantiation/Destruction notification
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