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"
50 #include "FGAircraft.h"
51 #include "FGInertial.h"
52 #include "FGPropertyManager.h"
56 static const char *IdSrc = "$Id$";
57 static const char *IdHdr = ID_AUXILIARY;
59 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
61 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
64 FGAuxiliary::FGAuxiliary(FGFDMExec* fdmex) : FGModel(fdmex)
67 vcas = veas = mach = qbar = pt = tat = 0;
71 vPilotAccelN.InitMatrix();
78 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
80 FGAuxiliary::~FGAuxiliary()
86 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
88 bool FGAuxiliary::Run()
92 if (!FGModel::Run()) {
95 //calculate total temperature assuming isentropic flow
96 tat=sat*(1 + 0.2*mach*mach);
97 tatc=RankineToCelsius(tat);
99 if (mach < 1) { //calculate total pressure assuming isentropic flow
100 pt = p*pow((1 + 0.2*machU*machU),3.5);
102 // shock in front of pitot tube, we'll assume its normal and use
103 // the Rayleigh Pitot Tube Formula, i.e. the ratio of total
104 // pressure behind the shock to the static pressure in front
106 B = 5.76*machU*machU/(5.6*machU*machU - 0.8);
108 // The denominator above is zero for Mach ~ 0.38, for which
109 // we'll never be here, so we're safe
111 D = (2.8*machU*machU-0.4)*0.4167;
115 A = pow(((pt-p)/psl+1),0.28571);
117 vcas = sqrt(7*psl/rhosl*(A-1));
118 veas = sqrt(2*qbar/rhosl);
123 // Pilot sensed accelerations are calculated here. This is used
124 // for the coordinated turn ball instrument. Motion base platforms sometimes
125 // use the derivative of pilot sensed accelerations as the driving parameter,
126 // rather than straight accelerations.
128 // The theory behind pilot-sensed calculations is presented:
130 // For purposes of discussion and calculation, assume for a minute that the
131 // pilot is in space and motionless in inertial space. She will feel
132 // no accelerations. If the aircraft begins to accelerate along any axis or
133 // axes (without rotating), the pilot will sense those accelerations. If
134 // any rotational moment is applied, the pilot will sense an acceleration
135 // due to that motion in the amount:
137 // [wdot X R] + [w X (w X R)]
142 // wdot = omegadot, the rotational acceleration rate vector
143 // w = omega, the rotational rate vector
144 // R = the vector from the aircraft CG to the pilot eyepoint
146 // The sum total of these two terms plus the acceleration of the aircraft
147 // body axis gives the acceleration the pilot senses in inertial space.
148 // In the presence of a large body such as a planet, a gravity field also
149 // provides an accelerating attraction. This acceleration can be transformed
150 // from the reference frame of the planet so as to be expressed in the frame
151 // of reference of the aircraft. This gravity field accelerating attraction
152 // is felt by the pilot as a force on her tushie as she sits in her aircraft
153 // on the runway awaiting takeoff clearance.
155 // In JSBSim the acceleration of the body frame in inertial space is given
156 // by the F = ma relation. If the vForces vector is divided by the aircraft
157 // mass, the acceleration vector is calculated. The term wdot is equivalent
158 // to the JSBSim vPQRdot vector, and the w parameter is equivalent to vPQR.
159 // The radius R is calculated below in the vector vToEyePt.
161 vPilotAccel.InitMatrix();
162 if ( Translation->GetVt() > 1 ) {
163 vPilotAccel = Aerodynamics->GetForces()
164 + Propulsion->GetForces()
165 + GroundReactions->GetForces();
166 vPilotAccel /= MassBalance->GetMass();
167 vToEyePt = MassBalance->StructuralToBody(Aircraft->GetXYZep());
168 vPilotAccel += Rotation->GetPQRdot() * vToEyePt;
169 vPilotAccel += Rotation->GetPQR() * (Rotation->GetPQR() * vToEyePt);
171 vPilotAccel = -1*( State->GetTl2b() * Inertial->GetGravity() );
174 vPilotAccelN = vPilotAccel/Inertial->gravity();
176 earthPosAngle += State->Getdt()*Inertial->omega();
183 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
185 double FGAuxiliary::GetHeadWind(void)
189 psiw = Atmosphere->GetWindPsi();
190 psi = Rotation->Getpsi();
191 vw = Atmosphere->GetWindNED().Magnitude();
193 return vw*cos(psiw - psi);
196 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
198 double FGAuxiliary::GetCrossWind(void)
202 psiw = Atmosphere->GetWindPsi();
203 psi = Rotation->Getpsi();
204 vw = Atmosphere->GetWindNED().Magnitude();
206 return vw*sin(psiw - psi);
209 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
211 void FGAuxiliary::bind(void)
213 typedef double (FGAuxiliary::*PMF)(int) const;
214 PropertyManager->Tie("velocities/vc-fps", this,
215 &FGAuxiliary::GetVcalibratedFPS);
216 PropertyManager->Tie("velocities/vc-kts", this,
217 &FGAuxiliary::GetVcalibratedKTS);
218 PropertyManager->Tie("velocities/ve-fps", this,
219 &FGAuxiliary::GetVequivalentFPS);
220 PropertyManager->Tie("velocities/ve-kts", this,
221 &FGAuxiliary::GetVequivalentKTS);
222 PropertyManager->Tie("velocities/machU", this,
223 &FGAuxiliary::GetMachU);
224 PropertyManager->Tie("velocities/tat-r", this,
225 &FGAuxiliary::GetTotalTemperature);
226 PropertyManager->Tie("velocities/tat-c", this,
227 &FGAuxiliary::GetTAT_C);
228 PropertyManager->Tie("velocities/pt-lbs_sqft", this,
229 &FGAuxiliary::GetTotalPressure);
231 PropertyManager->Tie("accelerations/a-pilot-x-ft_sec2", this,1,
232 (PMF)&FGAuxiliary::GetPilotAccel);
233 PropertyManager->Tie("accelerations/a-pilot-y-ft_sec2", this,2,
234 (PMF)&FGAuxiliary::GetPilotAccel);
235 PropertyManager->Tie("accelerations/a-pilot-z-ft_sec2", this,3,
236 (PMF)&FGAuxiliary::GetPilotAccel);
237 PropertyManager->Tie("accelerations/n-pilot-x-norm", this,1,
238 (PMF)&FGAuxiliary::GetNpilot);
239 PropertyManager->Tie("accelerations/n-pilot-y-norm", this,2,
240 (PMF)&FGAuxiliary::GetNpilot);
241 PropertyManager->Tie("accelerations/n-pilot-z-norm", this,3,
242 (PMF)&FGAuxiliary::GetNpilot);
243 PropertyManager->Tie("position/epa-rad", this,
244 &FGAuxiliary::GetEarthPositionAngle);
245 /* PropertyManager->Tie("atmosphere/headwind-fps", this,
246 &FGAuxiliary::GetHeadWind,
248 PropertyManager->Tie("atmosphere/crosswind-fps", this,
249 &FGAuxiliary::GetCrossWind,
253 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
255 void FGAuxiliary::unbind(void)
257 PropertyManager->Untie("velocities/vc-fps");
258 PropertyManager->Untie("velocities/vc-kts");
259 PropertyManager->Untie("velocities/ve-fps");
260 PropertyManager->Untie("velocities/ve-kts");
261 PropertyManager->Untie("velocities/machU");
262 PropertyManager->Untie("velocities/tat-r");
263 PropertyManager->Untie("velocities/tat-c");
264 PropertyManager->Untie("accelerations/a-pilot-x-ft_sec2");
265 PropertyManager->Untie("accelerations/a-pilot-y-ft_sec2");
266 PropertyManager->Untie("accelerations/a-pilot-z-ft_sec2");
267 PropertyManager->Untie("accelerations/n-pilot-x-norm");
268 PropertyManager->Untie("accelerations/n-pilot-y-norm");
269 PropertyManager->Untie("accelerations/n-pilot-z-norm");
270 PropertyManager->Untie("position/epa-rad");
271 /* PropertyManager->Untie("atmosphere/headwind-fps");
272 PropertyManager->Untie("atmosphere/crosswind-fps"); */
276 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
278 void FGAuxiliary::GetState(void)
280 qbar = Translation->Getqbar();
281 mach = Translation->GetMach();
282 machU= Translation->GetMachU();
283 p = Atmosphere->GetPressure();
284 rhosl = Atmosphere->GetDensitySL();
285 psl = Atmosphere->GetPressureSL();
286 sat = Atmosphere->GetTemperature();
289 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
290 // The bitmasked value choices are as follows:
291 // unset: In this case (the default) JSBSim would only print
292 // out the normally expected messages, essentially echoing
293 // the config files as they are read. If the environment
294 // variable is not set, debug_lvl is set to 1 internally
295 // 0: This requests JSBSim not to output any messages
297 // 1: This value explicity requests the normal JSBSim
299 // 2: This value asks for a message to be printed out when
300 // a class is instantiated
301 // 4: When this value is set, a message is displayed when a
302 // FGModel object executes its Run() method
303 // 8: When this value is set, various runtime state variables
304 // are printed out periodically
305 // 16: When set various parameters are sanity checked and
306 // a message is printed out when they go out of bounds
308 void FGAuxiliary::Debug(int from)
310 if (debug_lvl <= 0) return;
312 if (debug_lvl & 1) { // Standard console startup message output
313 if (from == 0) { // Constructor
317 if (debug_lvl & 2 ) { // Instantiation/Destruction notification
318 if (from == 0) cout << "Instantiated: FGAuxiliary" << endl;
319 if (from == 1) cout << "Destroyed: FGAuxiliary" << endl;
321 if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
323 if (debug_lvl & 8 ) { // Runtime state variables
325 if (debug_lvl & 16) { // Sanity checking
327 if (debug_lvl & 64) {
328 if (from == 0) { // Constructor
329 cout << IdSrc << endl;
330 cout << IdHdr << endl;
335 } // namespace JSBSim