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