1 /*******************************************************************************
3 Module: FGAuxiliary.cpp
6 Purpose: Calculates additional parameters needed by the visual system, etc.
9 ------------- Copyright (C) 1999 Jon S. Berndt (jsb@hal-pc.org) -------------
11 This program is free software; you can redistribute it and/or modify it under
12 the terms of the GNU General Public License as published by the Free Software
13 Foundation; either version 2 of the License, or (at your option) any later
16 This program is distributed in the hope that it will be useful, but WITHOUT
17 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
18 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
21 You should have received a copy of the GNU General Public License along with
22 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
23 Place - Suite 330, Boston, MA 02111-1307, USA.
25 Further information about the GNU General Public License can also be found on
26 the world wide web at http://www.gnu.org.
28 FUNCTIONAL DESCRIPTION
29 --------------------------------------------------------------------------------
30 This class calculates various auxiliary parameters.
33 Anderson, John D. "Introduction to Flight", 3rd Edition, McGraw-Hill, 1989
36 --------------------------------------------------------------------------------
39 ********************************************************************************
41 *******************************************************************************/
43 #include "FGAuxiliary.h"
44 #include "FGTranslation.h"
45 #include "FGRotation.h"
46 #include "FGAtmosphere.h"
48 #include "FGFDMExec.h"
50 #include "FGAircraft.h"
51 #include "FGPosition.h"
55 /*******************************************************************************
56 ************************************ CODE **************************************
57 *******************************************************************************/
59 FGAuxiliary::FGAuxiliary(FGFDMExec* fdmex) : FGModel(fdmex) {
61 vcas = veas = mach = qbar = pt = 0;
66 FGAuxiliary::~FGAuxiliary() {}
70 bool FGAuxiliary::Run() {
73 if (!FGModel::Run()) {
75 if(mach < 1) //calculate total pressure assuming isentropic flow
76 pt=p*pow((1 + 0.2*mach*mach),3.5);
78 // shock in front of pitot tube, we'll assume its normal and use
79 // the Rayleigh Pitot Tube Formula, i.e. the ratio of total
80 // pressure behind the shock to the static pressure in front
82 B = 5.76*mach*mach/(5.6*mach*mach - 0.8);
84 // The denominator above is zero for Mach ~ 0.38, for which
85 // we'll never be here, so we're safe
87 D = (2.8*mach*mach-0.4)*0.4167;
91 A = pow(((pt-p)/psl+1),0.28571);
92 vcas = sqrt(7*psl/rhosl*(A-1));
93 veas = sqrt(2*qbar/rhosl);
95 vPilotAccel = Translation->GetUVWdot() + Aircraft->GetXYZep() * Rotation->GetPQRdot();
106 void FGAuxiliary::GetState(void) {
107 qbar = Translation->Getqbar();
108 mach = Translation->GetMach();
109 p = Atmosphere->GetPressure();
110 rhosl = Atmosphere->GetDensitySL();
111 psl = Atmosphere->GetPressureSL();