1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3 Module: FGAuxiliary.cpp
4 Author: Tony Peden, Jon Berndt
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"
53 #include "FGInertial.h"
54 #include "FGMatrix33.h"
55 #include "FGColumnVector3.h"
56 #include "FGColumnVector4.h"
57 #include "FGPropertyManager.h"
59 static const char *IdSrc = "$Id$";
60 static const char *IdHdr = ID_AUXILIARY;
62 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
64 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
67 FGAuxiliary::FGAuxiliary(FGFDMExec* fdmex) : FGModel(fdmex)
70 vcas = veas = mach = qbar = pt = 0;
74 vPilotAccelN.InitMatrix();
79 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
81 FGAuxiliary::~FGAuxiliary()
86 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
88 bool FGAuxiliary::Run()
92 if (!FGModel::Run()) {
94 if (mach < 1) { //calculate total pressure assuming isentropic flow
95 pt=p*pow((1 + 0.2*mach*mach),3.5);
97 // shock in front of pitot tube, we'll assume its normal and use
98 // the Rayleigh Pitot Tube Formula, i.e. the ratio of total
99 // pressure behind the shock to the static pressure in front
101 B = 5.76*mach*mach/(5.6*mach*mach - 0.8);
103 // The denominator above is zero for Mach ~ 0.38, for which
104 // we'll never be here, so we're safe
106 D = (2.8*mach*mach-0.4)*0.4167;
110 A = pow(((pt-p)/psl+1),0.28571);
111 vcas = sqrt(7*psl/rhosl*(A-1));
112 veas = sqrt(2*qbar/rhosl);
114 // Pilot sensed accelerations are calculated here. This is used
115 // for the coordinated turn ball instrument. Motion base platforms sometimes
116 // use the derivative of pilot sensed accelerations as the driving parameter,
117 // rather than straight accelerations.
119 // The theory behind pilot-sensed calculations is presented:
121 // For purposes of discussion and calculation, assume for a minute that the
122 // pilot is in space and motionless in inertial space. She will feel
123 // no accelerations. If the aircraft begins to accelerate along any axis or
124 // axes (without rotating), the pilot will sense those accelerations. If
125 // any rotational moment is applied, the pilot will sense an acceleration
126 // due to that motion in the amount:
128 // [wdot X R] + [w X (w X R)]
133 // wdot = omegadot, the rotational acceleration rate vector
134 // w = omega, the rotational rate vector
135 // R = the vector from the aircraft CG to the pilot eyepoint
137 // The sum total of these two terms plus the acceleration of the aircraft
138 // body axis gives the acceleration the pilot senses in inertial space.
139 // In the presence of a large body such as a planet, a gravity field also
140 // provides an accelerating attraction. This acceleration can be transformed
141 // from the reference frame of the planet so as to be expressed in the frame
142 // of reference of the aircraft. This gravity field accelerating attraction
143 // is felt by the pilot as a force on her tushie as she sits in her aircraft
144 // on the runway awaiting takeoff clearance.
146 // In JSBSim the acceleration of the body frame in inertial space is given
147 // by the F = ma relation. If the vForces vector is divided by the aircraft
148 // mass, the acceleration vector is calculated. The term wdot is equivalent
149 // to the JSBSim vPQRdot vector, and the w parameter is equivalent to vPQR.
150 // The radius R is calculated below in the vector vToEyePt.
152 vPilotAccel.InitMatrix();
153 if( Translation->GetVt() > 1 ) {
154 vToEyePt = Aircraft->GetXYZep() - MassBalance->GetXYZcg();
155 vToEyePt *= inchtoft;
156 vPilotAccel = Aerodynamics->GetForces()
157 + Propulsion->GetForces()
158 + GroundReactions->GetForces();
159 vPilotAccel /= MassBalance->GetMass();
160 vPilotAccel += Rotation->GetPQRdot() * vToEyePt;
161 vPilotAccel += Rotation->GetPQR() * (Rotation->GetPQR() * vToEyePt);
162 //vPilotAccel(2)*=-1;
163 vPilotAccelN = vPilotAccel/Inertial->gravity();
165 earthPosAngle += State->Getdt()*Inertial->omega();
172 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
174 double FGAuxiliary::GetHeadWind(void)
178 psiw = Atmosphere->GetWindPsi();
179 psi = Rotation->Getpsi();
180 vw = Atmosphere->GetWindNED().Magnitude();
182 return vw*cos(psiw - psi);
185 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
187 double FGAuxiliary::GetCrossWind(void)
191 psiw = Atmosphere->GetWindPsi();
192 psi = Rotation->Getpsi();
193 vw = Atmosphere->GetWindNED().Magnitude();
195 return vw*sin(psiw - psi);
198 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
200 void FGAuxiliary::GetState(void)
202 qbar = Translation->Getqbar();
203 mach = Translation->GetMach();
204 p = Atmosphere->GetPressure();
205 rhosl = Atmosphere->GetDensitySL();
206 psl = Atmosphere->GetPressureSL();
209 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
210 // The bitmasked value choices are as follows:
211 // unset: In this case (the default) JSBSim would only print
212 // out the normally expected messages, essentially echoing
213 // the config files as they are read. If the environment
214 // variable is not set, debug_lvl is set to 1 internally
215 // 0: This requests JSBSim not to output any messages
217 // 1: This value explicity requests the normal JSBSim
219 // 2: This value asks for a message to be printed out when
220 // a class is instantiated
221 // 4: When this value is set, a message is displayed when a
222 // FGModel object executes its Run() method
223 // 8: When this value is set, various runtime state variables
224 // are printed out periodically
225 // 16: When set various parameters are sanity checked and
226 // a message is printed out when they go out of bounds
228 void FGAuxiliary::Debug(int from)
230 if (debug_lvl <= 0) return;
232 if (debug_lvl & 1) { // Standard console startup message output
233 if (from == 0) { // Constructor
237 if (debug_lvl & 2 ) { // Instantiation/Destruction notification
238 if (from == 0) cout << "Instantiated: FGAuxiliary" << endl;
239 if (from == 1) cout << "Destroyed: FGAuxiliary" << endl;
241 if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
243 if (debug_lvl & 8 ) { // Runtime state variables
245 if (debug_lvl & 16) { // Sanity checking
247 if (debug_lvl & 64) {
248 if (from == 0) { // Constructor
249 cout << IdSrc << endl;
250 cout << IdHdr << endl;
255 void FGAuxiliary::bind(void){
256 PropertyManager->Tie("velocities/vc-fps", this,
257 &FGAuxiliary::GetVcalibratedFPS);
258 PropertyManager->Tie("velocities/vc-kts", this,
259 &FGAuxiliary::GetVcalibratedKTS);
260 PropertyManager->Tie("velocities/ve-fps", this,
261 &FGAuxiliary::GetVequivalentFPS);
262 PropertyManager->Tie("velocities/ve-kts", this,
263 &FGAuxiliary::GetVequivalentKTS);
264 PropertyManager->Tie("accelerations/a-pilot-x-ft_sec2", this,1,
265 &FGAuxiliary::GetPilotAccel);
266 PropertyManager->Tie("accelerations/a-pilot-y-ft_sec2", this,2,
267 &FGAuxiliary::GetPilotAccel);
268 PropertyManager->Tie("accelerations/a-pilot-z-ft_sec2", this,3,
269 &FGAuxiliary::GetPilotAccel);
270 PropertyManager->Tie("accelerations/n-pilot-x-norm", this,1,
271 &FGAuxiliary::GetNpilot);
272 PropertyManager->Tie("accelerations/n-pilot-y-norm", this,2,
273 &FGAuxiliary::GetNpilot);
274 PropertyManager->Tie("accelerations/n-pilot-z-norm", this,3,
275 &FGAuxiliary::GetNpilot);
276 PropertyManager->Tie("position/epa-rad", this,
277 &FGAuxiliary::GetEarthPositionAngle);
278 /* PropertyManager->Tie("atmosphere/headwind-fps", this,
279 &FGAuxiliary::GetHeadWind,
281 PropertyManager->Tie("atmosphere/crosswind-fps", this,
282 &FGAuxiliary::GetCrossWind,
287 void FGAuxiliary::unbind(void){
288 PropertyManager->Untie("velocities/vc-fps");
289 PropertyManager->Untie("velocities/vc-kts");
290 PropertyManager->Untie("velocities/ve-fps");
291 PropertyManager->Untie("velocities/ve-kts");
292 PropertyManager->Untie("accelerations/a-pilot-x-ft_sec2");
293 PropertyManager->Untie("accelerations/a-pilot-y-ft_sec2");
294 PropertyManager->Untie("accelerations/a-pilot-z-ft_sec2");
295 PropertyManager->Untie("accelerations/n-pilot-x-norm");
296 PropertyManager->Untie("accelerations/n-pilot-y-norm");
297 PropertyManager->Untie("accelerations/n-pilot-z-norm");
298 PropertyManager->Untie("position/epa-rad");
299 /* PropertyManager->Untie("atmosphere/headwind-fps");
300 PropertyManager->Untie("atmosphere/crosswind-fps"); */