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Fix for SF bug #3171743 - P-factor does not take into account the thruster pitch and yaw angles

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This commit is contained in:
Erik Hofman 2011-12-23 14:18:38 +01:00
parent 520c002058
commit 05476d0be3
1 changed files with 27 additions and 20 deletions
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47
src/FDM/JSBSim/models/propulsion/FGPropeller.cpp
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@ -194,52 +194,59 @@ FGPropeller::~FGPropeller()
double FGPropeller::Calculate(double EnginePower)
{
FGColumnVector3 localAeroVel = Transform().Transposed() * in.AeroUVW;
double omega, PowerAvailable;
double Vel = in.AeroUVW(eU);
double Vel = localAeroVel(eU);
double rho = in.Density;
double RPS = RPM/60.0;
// Calculate helical tip Mach
double Area = 0.25*Diameter*Diameter*M_PI;
double Vtip = RPS * Diameter * M_PI;
HelicalTipMach = sqrt(Vtip*Vtip + Vel*Vel) / in.Soundspeed;
HelicalTipMach = sqrt(Vtip*Vtip + Vel*Vel) / in.Soundspeed;
PowerAvailable = EnginePower - GetPowerRequired();
if (RPS > 0.0) J = Vel / (Diameter * RPS); // Calculate J normally
else J = Vel / Diameter;
else J = Vel / Diameter;
if (MaxPitch == MinPitch) { // Fixed pitch prop
ThrustCoeff = cThrust->GetValue(J);
ThrustCoeff = cThrust->GetValue(J);
} else { // Variable pitch prop
ThrustCoeff = cThrust->GetValue(J, Pitch);
ThrustCoeff = cThrust->GetValue(J, Pitch);
}
// Apply optional scaling factor to Ct (default value = 1)
ThrustCoeff *= CtFactor;
// Apply optional Mach effects from CT_MACH table
if (CtMach) ThrustCoeff *= CtMach->GetValue(HelicalTipMach);
if (P_Factor > 0.0001) {
// alpha = sin(fdmex->GetAuxiliary()->Getalpha() + FGThruster::GetPitch());
// beta = sin(fdmex->GetAuxiliary()->Getbeta() + FGThruster::GetYaw());
// SetActingLocationY( GetLocationY() + P_Factor*alpha*Sense);
// SetActingLocationZ( GetLocationZ() + P_Factor*beta*Sense);
SetActingLocationY( GetLocationY() + P_Factor*in.Alpha*Sense);
SetActingLocationZ( GetLocationZ() + P_Factor*in.Beta*Sense);
}
Thrust = ThrustCoeff*RPS*RPS*D4*rho;
// From B. W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics"
// first edition, eqn. 6.15 (propeller analysis chapter).
// Induced velocity in the propeller disk area. This formula is obtained
// from momentum theory - see B. W. McCormick, "Aerodynamics, Aeronautics,
// and Flight Mechanics" 1st edition, eqn. 6.15 (propeller analysis chapter).
Vinduced = 0.5 * (-Vel + sqrt(Vel*Vel + 2.0*Thrust/(rho*Area)));
// P-factor is simulated by a shift of the acting location of the thrust.
// The shift is a multiple of the angle between the propeller shaft axis
// and the relative wind that goes through the propeller disk.
if (P_Factor > 0.0001) {
double tangentialVel = localAeroVel.Magnitude(eV, eW);
if (tangentialVel > 0.0001) {
double angle = atan2(tangentialVel, localAeroVel(eU));
double factor = Sense * P_Factor * angle / tangentialVel;
SetActingLocationY( GetLocationY() + factor * localAeroVel(eW));
SetActingLocationZ( GetLocationZ() + factor * localAeroVel(eV));
}
}
omega = RPS*2.0*M_PI;
vFn(1) = Thrust;
vFn(eX) = 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
@ -273,7 +280,7 @@ double FGPropeller::GetPowerRequired(void)
double RPS = RPM / 60.0;
if (RPS != 0.0) J = Vel / (Diameter * RPS);
else J = Vel / Diameter;
else J = Vel / Diameter;
if (MaxPitch == MinPitch) { // Fixed pitch prop
cPReq = cPower->GetValue(J);
@ -320,7 +327,7 @@ double FGPropeller::GetPowerRequired(void)
} else { // Manual Pitch Mode, pitch is controlled externally
}
cPReq = cPower->GetValue(J, Pitch);
}