%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
#include "FGPropeller.h"
+#include "FGFCS.h"
-static const char *IdSrc = "$Header$";
+static const char *IdSrc = "$Id$";
static const char *IdHdr = ID_PROPELLER;
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CLASS IMPLEMENTATION
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
+// This class currently makes certain assumptions when calculating torque and
+// p-factor. That is, that the axis of rotation is the X axis of the aircraft -
+// not just the X-axis of the engine/propeller. This may or may not work for a
+// helicopter.
-FGPropeller::FGPropeller(FGFDMExec *FDMExec) : FGThruster(FDMExec)
+FGPropeller::FGPropeller(FGFDMExec* exec, FGConfigFile* Prop_cfg) : FGThruster(exec)
{
+ string token;
+ int rows, cols;
+ MaxPitch = MinPitch = P_Factor = Sense = Pitch = 0.0;
+
+ Name = Prop_cfg->GetValue("NAME");
+ Prop_cfg->GetNextConfigLine();
+ while (Prop_cfg->GetValue() != string("/FG_PROPELLER")) {
+ *Prop_cfg >> token;
+ if (token == "IXX") {
+ *Prop_cfg >> Ixx;
+ } else if (token == "DIAMETER") {
+ *Prop_cfg >> Diameter;
+ Diameter /= 12.0;
+ } else if (token == "NUMBLADES") {
+ *Prop_cfg >> numBlades;
+ } else if (token == "MINPITCH") {
+ *Prop_cfg >> MinPitch;
+ } else if (token == "MAXPITCH") {
+ *Prop_cfg >> MaxPitch;
+ } else if (token == "MINRPM") {
+ *Prop_cfg >> MinRPM;
+ } else if (token == "MAXRPM") {
+ *Prop_cfg >> MaxRPM;
+ } else if (token == "C_THRUST") {
+ *Prop_cfg >> rows >> cols;
+ if (cols == 1) cThrust = new FGTable(rows);
+ else cThrust = new FGTable(rows, cols);
+ *cThrust << *Prop_cfg;
+ } else if (token == "C_POWER") {
+ *Prop_cfg >> rows >> cols;
+ if (cols == 1) cPower = new FGTable(rows);
+ else cPower = new FGTable(rows, cols);
+ *cPower << *Prop_cfg;
+ } else if (token == "EOF") {
+ cerr << " End of file reached" << endl;
+ break;
+ } else {
+ cerr << "Unhandled token in Propeller config file: " << token << endl;
+ }
+ }
+
+ Type = ttPropeller;
+ RPM = 0;
+ vTorque.InitMatrix();
+
+ Debug(0);
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+FGPropeller::~FGPropeller()
+{
+ if (cThrust) delete cThrust;
+ if (cPower) delete cPower;
+ Debug(1);
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+//
+// We must be getting the aerodynamic velocity here, NOT the inertial velocity.
+// We need the velocity with respect to the wind.
+//
+// Note that PowerAvailable is the excess power available after the drag of the
+// propeller has been subtracted. At equilibrium, PowerAvailable will be zero -
+// indicating that the propeller will not accelerate or decelerate.
+// Remembering that Torque * omega = Power, we can derive the torque on the
+// propeller and its acceleration to give a new RPM. The current RPM will be
+// used to calculate thrust.
+//
+// Because RPM could be zero, we need to be creative about what RPM is stated as.
+
+double FGPropeller::Calculate(double PowerAvailable)
+{
+ double J, C_Thrust, omega;
+ double Vel = fdmex->GetTranslation()->GetAeroUVW(eU);
+ double rho = fdmex->GetAtmosphere()->GetDensity();
+ double RPS = RPM/60.0;
+ double alpha, beta;
+
+ if (RPM > 0.10) {
+ J = Vel / (Diameter * RPS);
+ } else {
+ J = 0.0;
+ }
+
+ if (MaxPitch == MinPitch) { // Fixed pitch prop
+ C_Thrust = cThrust->GetValue(J);
+ } else { // Variable pitch prop
+ C_Thrust = cThrust->GetValue(J, Pitch);
+ }
+
+ if (P_Factor > 0.0001) {
+ alpha = fdmex->GetTranslation()->Getalpha();
+ beta = fdmex->GetTranslation()->Getbeta();
+ SetActingLocationY( GetLocationY() + P_Factor*alpha*Sense);
+ SetActingLocationZ( GetLocationZ() + P_Factor*beta*Sense);
+ } else if (P_Factor < 0.000) {
+ cerr << "P-Factor value in config file must be greater than zero" << endl;
+ }
+
+ Thrust = C_Thrust*RPS*RPS*Diameter*Diameter*Diameter*Diameter*rho;
+ omega = RPS*2.0*M_PI;
+
+ // Check for windmilling.
+ double radius = Diameter * 0.375; // 75% of radius
+ double windmill_cutoff = tan(Pitch * 1.745329E-2) * omega * radius;
+ if (Vel > windmill_cutoff)
+ Thrust = -Thrust;
+
+ vFn(1) = Thrust;
+
+ // The Ixx value and rotation speed given below are for rotation about the
+ // natural axis of the engine. The transform takes place in the base class
+ // FGForce::GetBodyForces() function.
+
+ vH(eX) = Ixx*omega*Sense;
+ vH(eY) = 0.0;
+ vH(eZ) = 0.0;
+
+ if (omega <= 5) omega = 1.0;
+
+ ExcessTorque = PowerAvailable / omega;
+ RPM = (RPS + ((ExcessTorque / Ixx) / (2.0 * M_PI)) * deltaT) * 60.0;
+
+ // The friction from the engine should
+ // stop it somewhere; I chose an
+ // arbitrary point.
+ if (RPM < 5.0)
+ RPM = 0;
+
+ vMn = fdmex->GetRotation()->GetPQR()*vH + vTorque*Sense;
+
+ return Thrust; // return thrust in pounds
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+double FGPropeller::GetPowerRequired(void)
+{
+ if (RPM <= 0.10) return 0.0; // If the prop ain't turnin', the fuel ain't burnin'.
+
+ double cPReq, RPS = RPM / 60.0;
+
+ double J = fdmex->GetTranslation()->GetAeroUVW(eU) / (Diameter * RPS);
+ double rho = fdmex->GetAtmosphere()->GetDensity();
+
+ if (MaxPitch == MinPitch) { // Fixed pitch prop
+ Pitch = MinPitch;
+ cPReq = cPower->GetValue(J);
+ } else { // Variable pitch prop
+ double advance = fdmex->GetFCS()->GetPropAdvance(ThrusterNumber);
+
+ if (MaxRPM != MinRPM) { // fixed-speed prop
+ double rpmReq = MinRPM + (MaxRPM - MinRPM) * advance;
+ double dRPM = rpmReq - RPM;
+
+ Pitch -= dRPM / 10;
+
+ if (Pitch < MinPitch) Pitch = MinPitch;
+ else if (Pitch > MaxPitch) Pitch = MaxPitch;
+
+ } else {
+ Pitch = MaxPitch - (MaxPitch - MinPitch) * advance;
+ }
+ cPReq = cPower->GetValue(J, Pitch);
+ }
+
+ PowerRequired = cPReq*RPS*RPS*RPS*Diameter*Diameter*Diameter*Diameter
+ *Diameter*rho;
+ vTorque(eX) = -Sense*PowerRequired / (RPS*2.0*M_PI);
+
+ return PowerRequired;
}
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-void FGPropeller::Calculate(void)
+FGColumnVector3 FGPropeller::GetPFactor()
{
- FGThruster::Calculate();
+ double px=0.0, py, pz;
+
+ py = Thrust * Sense * (GetActingLocationY() - GetLocationY()) / 12.0;
+ pz = Thrust * Sense * (GetActingLocationZ() - GetLocationZ()) / 12.0;
+ return FGColumnVector3(px, py, pz);
}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+// The bitmasked value choices are as follows:
+// unset: In this case (the default) JSBSim would only print
+// out the normally expected messages, essentially echoing
+// the config files as they are read. If the environment
+// variable is not set, debug_lvl is set to 1 internally
+// 0: This requests JSBSim not to output any messages
+// whatsoever.
+// 1: This value explicity requests the normal JSBSim
+// startup messages
+// 2: This value asks for a message to be printed out when
+// a class is instantiated
+// 4: When this value is set, a message is displayed when a
+// FGModel object executes its Run() method
+// 8: When this value is set, various runtime state variables
+// are printed out periodically
+// 16: When set various parameters are sanity checked and
+// a message is printed out when they go out of bounds
+
+void FGPropeller::Debug(int from)
+{
+ if (debug_lvl <= 0) return;
+
+ if (debug_lvl & 1) { // Standard console startup message output
+ if (from == 0) { // Constructor
+ cout << "\n Propeller Name: " << Name << endl;
+ cout << " IXX = " << Ixx << endl;
+ cout << " Diameter = " << Diameter << " ft." << endl;
+ cout << " Number of Blades = " << numBlades << endl;
+ cout << " Minimum Pitch = " << MinPitch << endl;
+ cout << " Maximum Pitch = " << MaxPitch << endl;
+ cout << " Thrust Coefficient: " << endl;
+ cThrust->Print();
+ cout << " Power Coefficient: " << endl;
+ cPower->Print();
+ }
+ }
+ if (debug_lvl & 2 ) { // Instantiation/Destruction notification
+ if (from == 0) cout << "Instantiated: FGPropeller" << endl;
+ if (from == 1) cout << "Destroyed: FGPropeller" << endl;
+ }
+ if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
+ }
+ if (debug_lvl & 8 ) { // Runtime state variables
+ }
+ if (debug_lvl & 16) { // Sanity checking
+ }
+ if (debug_lvl & 64) {
+ if (from == 0) { // Constructor
+ cout << IdSrc << endl;
+ cout << IdHdr << endl;
+ }
+ }
+}
+
projects / flightgear.git / blobdiff