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 "FGAerodynamics.h"
45 #include "FGTranslation.h"
46 #include "FGRotation.h"
47 #include "FGAtmosphere.h"
49 #include "FGFDMExec.h"
51 #include "FGAircraft.h"
52 #include "FGPosition.h"
54 #include "FGInertial.h"
55 #include "FGMatrix33.h"
56 #include "FGColumnVector3.h"
57 #include "FGColumnVector4.h"
58 #include "FGPropertyManager.h"
60 static const char *IdSrc = "$Id$";
61 static const char *IdHdr = ID_AUXILIARY;
63 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
65 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
68 FGAuxiliary::FGAuxiliary(FGFDMExec* fdmex) : FGModel(fdmex)
71 vcas = veas = mach = qbar = pt = 0;
75 vPilotAccelN.InitMatrix();
82 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
84 FGAuxiliary::~FGAuxiliary()
89 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
91 bool FGAuxiliary::Run()
95 if (!FGModel::Run()) {
97 if (mach < 1) { //calculate total pressure assuming isentropic flow
98 pt=p*pow((1 + 0.2*mach*mach),3.5);
100 // shock in front of pitot tube, we'll assume its normal and use
101 // the Rayleigh Pitot Tube Formula, i.e. the ratio of total
102 // pressure behind the shock to the static pressure in front
104 B = 5.76*mach*mach/(5.6*mach*mach - 0.8);
106 // The denominator above is zero for Mach ~ 0.38, for which
107 // we'll never be here, so we're safe
109 D = (2.8*mach*mach-0.4)*0.4167;
113 A = pow(((pt-p)/psl+1),0.28571);
114 vcas = sqrt(7*psl/rhosl*(A-1));
115 veas = sqrt(2*qbar/rhosl);
117 // Pilot sensed accelerations are calculated here. This is used
118 // for the coordinated turn ball instrument. Motion base platforms sometimes
119 // use the derivative of pilot sensed accelerations as the driving parameter,
120 // rather than straight accelerations.
122 // The theory behind pilot-sensed calculations is presented:
124 // For purposes of discussion and calculation, assume for a minute that the
125 // pilot is in space and motionless in inertial space. She will feel
126 // no accelerations. If the aircraft begins to accelerate along any axis or
127 // axes (without rotating), the pilot will sense those accelerations. If
128 // any rotational moment is applied, the pilot will sense an acceleration
129 // due to that motion in the amount:
131 // [wdot X R] + [w X (w X R)]
136 // wdot = omegadot, the rotational acceleration rate vector
137 // w = omega, the rotational rate vector
138 // R = the vector from the aircraft CG to the pilot eyepoint
140 // The sum total of these two terms plus the acceleration of the aircraft
141 // body axis gives the acceleration the pilot senses in inertial space.
142 // In the presence of a large body such as a planet, a gravity field also
143 // provides an accelerating attraction. This acceleration can be transformed
144 // from the reference frame of the planet so as to be expressed in the frame
145 // of reference of the aircraft. This gravity field accelerating attraction
146 // is felt by the pilot as a force on her tushie as she sits in her aircraft
147 // on the runway awaiting takeoff clearance.
149 // In JSBSim the acceleration of the body frame in inertial space is given
150 // by the F = ma relation. If the vForces vector is divided by the aircraft
151 // mass, the acceleration vector is calculated. The term wdot is equivalent
152 // to the JSBSim vPQRdot vector, and the w parameter is equivalent to vPQR.
153 // The radius R is calculated below in the vector vToEyePt.
155 vPilotAccel.InitMatrix();
156 if ( Translation->GetVt() > 1 ) {
157 vToEyePt = Aircraft->GetXYZep() - MassBalance->GetXYZcg();
158 vToEyePt *= inchtoft;
159 vPilotAccel = Aerodynamics->GetForces()
160 + Propulsion->GetForces()
161 + GroundReactions->GetForces();
162 vPilotAccel /= MassBalance->GetMass();
163 vPilotAccel += Rotation->GetPQRdot() * vToEyePt;
164 vPilotAccel += Rotation->GetPQR() * (Rotation->GetPQR() * vToEyePt);
165 //vPilotAccel(2)*=-1;
166 vPilotAccelN = vPilotAccel/Inertial->gravity();
168 earthPosAngle += State->Getdt()*Inertial->omega();
175 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
177 double FGAuxiliary::GetHeadWind(void)
181 psiw = Atmosphere->GetWindPsi();
182 psi = Rotation->Getpsi();
183 vw = Atmosphere->GetWindNED().Magnitude();
185 return vw*cos(psiw - psi);
188 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
190 double FGAuxiliary::GetCrossWind(void)
194 psiw = Atmosphere->GetWindPsi();
195 psi = Rotation->Getpsi();
196 vw = Atmosphere->GetWindNED().Magnitude();
198 return vw*sin(psiw - psi);
201 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
203 void FGAuxiliary::bind(void)
205 typedef double (FGAuxiliary::*PMF)(int) const;
206 PropertyManager->Tie("velocities/vc-fps", this,
207 &FGAuxiliary::GetVcalibratedFPS);
208 PropertyManager->Tie("velocities/vc-kts", this,
209 &FGAuxiliary::GetVcalibratedKTS);
210 PropertyManager->Tie("velocities/ve-fps", this,
211 &FGAuxiliary::GetVequivalentFPS);
212 PropertyManager->Tie("velocities/ve-kts", this,
213 &FGAuxiliary::GetVequivalentKTS);
214 PropertyManager->Tie("accelerations/a-pilot-x-ft_sec2", this,1,
215 (PMF)&FGAuxiliary::GetPilotAccel);
216 PropertyManager->Tie("accelerations/a-pilot-y-ft_sec2", this,2,
217 (PMF)&FGAuxiliary::GetPilotAccel);
218 PropertyManager->Tie("accelerations/a-pilot-z-ft_sec2", this,3,
219 (PMF)&FGAuxiliary::GetPilotAccel);
220 PropertyManager->Tie("accelerations/n-pilot-x-norm", this,1,
221 (PMF)&FGAuxiliary::GetNpilot);
222 PropertyManager->Tie("accelerations/n-pilot-y-norm", this,2,
223 (PMF)&FGAuxiliary::GetNpilot);
224 PropertyManager->Tie("accelerations/n-pilot-z-norm", this,3,
225 (PMF)&FGAuxiliary::GetNpilot);
226 PropertyManager->Tie("position/epa-rad", this,
227 &FGAuxiliary::GetEarthPositionAngle);
228 /* PropertyManager->Tie("atmosphere/headwind-fps", this,
229 &FGAuxiliary::GetHeadWind,
231 PropertyManager->Tie("atmosphere/crosswind-fps", this,
232 &FGAuxiliary::GetCrossWind,
236 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
238 void FGAuxiliary::unbind(void)
240 PropertyManager->Untie("velocities/vc-fps");
241 PropertyManager->Untie("velocities/vc-kts");
242 PropertyManager->Untie("velocities/ve-fps");
243 PropertyManager->Untie("velocities/ve-kts");
244 PropertyManager->Untie("accelerations/a-pilot-x-ft_sec2");
245 PropertyManager->Untie("accelerations/a-pilot-y-ft_sec2");
246 PropertyManager->Untie("accelerations/a-pilot-z-ft_sec2");
247 PropertyManager->Untie("accelerations/n-pilot-x-norm");
248 PropertyManager->Untie("accelerations/n-pilot-y-norm");
249 PropertyManager->Untie("accelerations/n-pilot-z-norm");
250 PropertyManager->Untie("position/epa-rad");
251 /* PropertyManager->Untie("atmosphere/headwind-fps");
252 PropertyManager->Untie("atmosphere/crosswind-fps"); */
256 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
258 void FGAuxiliary::GetState(void)
260 qbar = Translation->Getqbar();
261 mach = Translation->GetMach();
262 p = Atmosphere->GetPressure();
263 rhosl = Atmosphere->GetDensitySL();
264 psl = Atmosphere->GetPressureSL();
267 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
268 // The bitmasked value choices are as follows:
269 // unset: In this case (the default) JSBSim would only print
270 // out the normally expected messages, essentially echoing
271 // the config files as they are read. If the environment
272 // variable is not set, debug_lvl is set to 1 internally
273 // 0: This requests JSBSim not to output any messages
275 // 1: This value explicity requests the normal JSBSim
277 // 2: This value asks for a message to be printed out when
278 // a class is instantiated
279 // 4: When this value is set, a message is displayed when a
280 // FGModel object executes its Run() method
281 // 8: When this value is set, various runtime state variables
282 // are printed out periodically
283 // 16: When set various parameters are sanity checked and
284 // a message is printed out when they go out of bounds
286 void FGAuxiliary::Debug(int from)
288 if (debug_lvl <= 0) return;
290 if (debug_lvl & 1) { // Standard console startup message output
291 if (from == 0) { // Constructor
295 if (debug_lvl & 2 ) { // Instantiation/Destruction notification
296 if (from == 0) cout << "Instantiated: FGAuxiliary" << endl;
297 if (from == 1) cout << "Destroyed: FGAuxiliary" << endl;
299 if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
301 if (debug_lvl & 8 ) { // Runtime state variables
303 if (debug_lvl & 16) { // Sanity checking
305 if (debug_lvl & 64) {
306 if (from == 0) { // Constructor
307 cout << IdSrc << endl;
308 cout << IdHdr << endl;