/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Module: FGAuxiliary.cpp Author: Tony Peden, Jon Berndt Date started: 01/26/99 Purpose: Calculates additional parameters needed by the visual system, etc. Called by: FGSimExec ------------- Copyright (C) 1999 Jon S. Berndt (jsb@hal-pc.org) ------------- This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. Further information about the GNU General Public License can also be found on the world wide web at http://www.gnu.org. FUNCTIONAL DESCRIPTION -------------------------------------------------------------------------------- This class calculates various auxiliary parameters. REFERENCES Anderson, John D. "Introduction to Flight", 3rd Edition, McGraw-Hill, 1989 pgs. 112-126 HISTORY -------------------------------------------------------------------------------- 01/26/99 JSB Created %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% INCLUDES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/ #include "FGAuxiliary.h" #include "FGAerodynamics.h" #include "FGTranslation.h" #include "FGRotation.h" #include "FGAtmosphere.h" #include "FGState.h" #include "FGFDMExec.h" #include "FGFCS.h" #include "FGAircraft.h" #include "FGPosition.h" #include "FGOutput.h" #include "FGInertial.h" #include "FGMatrix33.h" #include "FGColumnVector3.h" #include "FGColumnVector4.h" #include "FGPropertyManager.h" static const char *IdSrc = "$Id$"; static const char *IdHdr = ID_AUXILIARY; /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% CLASS IMPLEMENTATION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/ FGAuxiliary::FGAuxiliary(FGFDMExec* fdmex) : FGModel(fdmex) { Name = "FGAuxiliary"; vcas = veas = mach = qbar = pt = 0; psl = rhosl = 1; earthPosAngle = 0.0; vPilotAccelN.InitMatrix(); bind(); Debug(0); } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% FGAuxiliary::~FGAuxiliary() { unbind(); Debug(1); } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% bool FGAuxiliary::Run() { double A,B,D; if (!FGModel::Run()) { GetState(); if (mach < 1) { //calculate total pressure assuming isentropic flow pt=p*pow((1 + 0.2*mach*mach),3.5); } else { // shock in front of pitot tube, we'll assume its normal and use // the Rayleigh Pitot Tube Formula, i.e. the ratio of total // pressure behind the shock to the static pressure in front B = 5.76*mach*mach/(5.6*mach*mach - 0.8); // The denominator above is zero for Mach ~ 0.38, for which // we'll never be here, so we're safe D = (2.8*mach*mach-0.4)*0.4167; pt = p*pow(B,3.5)*D; } A = pow(((pt-p)/psl+1),0.28571); vcas = sqrt(7*psl/rhosl*(A-1)); veas = sqrt(2*qbar/rhosl); // Pilot sensed accelerations are calculated here. This is used // for the coordinated turn ball instrument. Motion base platforms sometimes // use the derivative of pilot sensed accelerations as the driving parameter, // rather than straight accelerations. // // The theory behind pilot-sensed calculations is presented: // // For purposes of discussion and calculation, assume for a minute that the // pilot is in space and motionless in inertial space. She will feel // no accelerations. If the aircraft begins to accelerate along any axis or // axes (without rotating), the pilot will sense those accelerations. If // any rotational moment is applied, the pilot will sense an acceleration // due to that motion in the amount: // // [wdot X R] + [w X (w X R)] // Term I Term II // // where: // // wdot = omegadot, the rotational acceleration rate vector // w = omega, the rotational rate vector // R = the vector from the aircraft CG to the pilot eyepoint // // The sum total of these two terms plus the acceleration of the aircraft // body axis gives the acceleration the pilot senses in inertial space. // In the presence of a large body such as a planet, a gravity field also // provides an accelerating attraction. This acceleration can be transformed // from the reference frame of the planet so as to be expressed in the frame // of reference of the aircraft. This gravity field accelerating attraction // is felt by the pilot as a force on her tushie as she sits in her aircraft // on the runway awaiting takeoff clearance. // // In JSBSim the acceleration of the body frame in inertial space is given // by the F = ma relation. If the vForces vector is divided by the aircraft // mass, the acceleration vector is calculated. The term wdot is equivalent // to the JSBSim vPQRdot vector, and the w parameter is equivalent to vPQR. // The radius R is calculated below in the vector vToEyePt. vPilotAccel.InitMatrix(); if ( Translation->GetVt() > 1 ) { vPilotAccel = Aerodynamics->GetForces() + Propulsion->GetForces() + GroundReactions->GetForces(); vPilotAccel /= MassBalance->GetMass(); vToEyePt = Aircraft->GetXYZep() - MassBalance->GetXYZcg(); vToEyePt *= inchtoft; vPilotAccel += Rotation->GetPQRdot() * vToEyePt; vPilotAccel += Rotation->GetPQR() * (Rotation->GetPQR() * vToEyePt); } else { vPilotAccel = -1*( State->GetTl2b() * Inertial->GetGravity() ); } vPilotAccelN = vPilotAccel/Inertial->gravity(); earthPosAngle += State->Getdt()*Inertial->omega(); return false; } else { return true; } } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% double FGAuxiliary::GetHeadWind(void) { double psiw,vw,psi; psiw = Atmosphere->GetWindPsi(); psi = Rotation->Getpsi(); vw = Atmosphere->GetWindNED().Magnitude(); return vw*cos(psiw - psi); } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% double FGAuxiliary::GetCrossWind(void) { double psiw,vw,psi; psiw = Atmosphere->GetWindPsi(); psi = Rotation->Getpsi(); vw = Atmosphere->GetWindNED().Magnitude(); return vw*sin(psiw - psi); } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAuxiliary::bind(void) { typedef double (FGAuxiliary::*PMF)(int) const; PropertyManager->Tie("velocities/vc-fps", this, &FGAuxiliary::GetVcalibratedFPS); PropertyManager->Tie("velocities/vc-kts", this, &FGAuxiliary::GetVcalibratedKTS); PropertyManager->Tie("velocities/ve-fps", this, &FGAuxiliary::GetVequivalentFPS); PropertyManager->Tie("velocities/ve-kts", this, &FGAuxiliary::GetVequivalentKTS); PropertyManager->Tie("accelerations/a-pilot-x-ft_sec2", this,1, (PMF)&FGAuxiliary::GetPilotAccel); PropertyManager->Tie("accelerations/a-pilot-y-ft_sec2", this,2, (PMF)&FGAuxiliary::GetPilotAccel); PropertyManager->Tie("accelerations/a-pilot-z-ft_sec2", this,3, (PMF)&FGAuxiliary::GetPilotAccel); PropertyManager->Tie("accelerations/n-pilot-x-norm", this,1, (PMF)&FGAuxiliary::GetNpilot); PropertyManager->Tie("accelerations/n-pilot-y-norm", this,2, (PMF)&FGAuxiliary::GetNpilot); PropertyManager->Tie("accelerations/n-pilot-z-norm", this,3, (PMF)&FGAuxiliary::GetNpilot); PropertyManager->Tie("position/epa-rad", this, &FGAuxiliary::GetEarthPositionAngle); /* PropertyManager->Tie("atmosphere/headwind-fps", this, &FGAuxiliary::GetHeadWind, true); PropertyManager->Tie("atmosphere/crosswind-fps", this, &FGAuxiliary::GetCrossWind, true); */ } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAuxiliary::unbind(void) { PropertyManager->Untie("velocities/vc-fps"); PropertyManager->Untie("velocities/vc-kts"); PropertyManager->Untie("velocities/ve-fps"); PropertyManager->Untie("velocities/ve-kts"); PropertyManager->Untie("accelerations/a-pilot-x-ft_sec2"); PropertyManager->Untie("accelerations/a-pilot-y-ft_sec2"); PropertyManager->Untie("accelerations/a-pilot-z-ft_sec2"); PropertyManager->Untie("accelerations/n-pilot-x-norm"); PropertyManager->Untie("accelerations/n-pilot-y-norm"); PropertyManager->Untie("accelerations/n-pilot-z-norm"); PropertyManager->Untie("position/epa-rad"); /* PropertyManager->Untie("atmosphere/headwind-fps"); PropertyManager->Untie("atmosphere/crosswind-fps"); */ } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAuxiliary::GetState(void) { qbar = Translation->Getqbar(); mach = Translation->GetMach(); p = Atmosphere->GetPressure(); rhosl = Atmosphere->GetDensitySL(); psl = Atmosphere->GetPressureSL(); } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% // 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 FGAuxiliary::Debug(int from) { if (debug_lvl <= 0) return; if (debug_lvl & 1) { // Standard console startup message output if (from == 0) { // Constructor } } if (debug_lvl & 2 ) { // Instantiation/Destruction notification if (from == 0) cout << "Instantiated: FGAuxiliary" << endl; if (from == 1) cout << "Destroyed: FGAuxiliary" << 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; } } }