1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3 Module: FGAtmosphere.cpp
5 Implementation of 1959 Standard Atmosphere added by Tony Peden
7 Purpose: Models the atmosphere
10 ------------- Copyright (C) 1999 Jon S. Berndt (jsb@hal-pc.org) -------------
12 This program is free software; you can redistribute it and/or modify it under
13 the terms of the GNU General Public License as published by the Free Software
14 Foundation; either version 2 of the License, or (at your option) any later
17 This program is distributed in the hope that it will be useful, but WITHOUT
18 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
19 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
22 You should have received a copy of the GNU General Public License along with
23 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
24 Place - Suite 330, Boston, MA 02111-1307, USA.
26 Further information about the GNU General Public License can also be found on
27 the world wide web at http://www.gnu.org.
29 FUNCTIONAL DESCRIPTION
30 --------------------------------------------------------------------------------
31 Models the atmosphere. The equation used below was determined by a third order
32 curve fit using Excel. The data is from the ICAO atmosphere model.
35 --------------------------------------------------------------------------------
37 07/23/99 TP Added implementation of 1959 Standard Atmosphere
38 Moved calculation of Mach number to FGTranslation
39 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
40 COMMENTS, REFERENCES, and NOTES
41 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
42 [1] Anderson, John D. "Introduction to Flight, Third Edition", McGraw-Hill,
43 1989, ISBN 0-07-001641-0
45 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
47 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
49 #include "FGAtmosphere.h"
51 #include "FGFDMExec.h"
53 #include "FGAircraft.h"
54 #include "FGTranslation.h"
55 #include "FGRotation.h"
56 #include "FGPosition.h"
57 #include "FGAuxiliary.h"
59 #include "FGMatrix33.h"
60 #include "FGColumnVector3.h"
61 #include "FGColumnVector4.h"
63 static const char *IdSrc = "$Id$";
64 static const char *IdHdr = ID_ATMOSPHERE;
66 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
68 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
71 FGAtmosphere::FGAtmosphere(FGFDMExec* fdmex) : FGModel(fdmex)
73 Name = "FGAtmosphere";
83 htab[7]=259186.352; //ft.
85 MagnitudedAccelDt = MagnitudeAccel = Magnitude = 0.0;
87 // turbType = ttBerndt; // temporarily disable turbulence until fully tested
90 if (debug_lvl & 2) cout << "Instantiated: " << Name << endl;
93 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
95 FGAtmosphere::~FGAtmosphere()
97 if (debug_lvl & 2) cout << "Destroyed: FGAtmosphere" << endl;
100 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
102 bool FGAtmosphere::InitModel(void)
104 FGModel::InitModel();
107 SLtemperature = temperature;
108 SLpressure = pressure;
110 SLsoundspeed = sqrt(SHRatio*Reng*temperature);
111 rSLtemperature = 1.0/temperature;
112 rSLpressure = 1.0/pressure;
113 rSLdensity = 1.0/density;
114 rSLsoundspeed = 1.0/SLsoundspeed;
120 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
122 bool FGAtmosphere::Run(void)
124 if (!FGModel::Run()) { // if false then execute this Run()
125 //do temp, pressure, and density first
127 h = Position->Geth();
131 pressure = exPressure;
132 temperature = exTemperature;
135 if (turbType != ttNone) {
137 vWindNED += vTurbulence;
140 if (vWindNED(1) != 0.0) psiw = atan2( vWindNED(2), vWindNED(1) );
142 if (psiw < 0) psiw += 2*M_PI;
144 soundspeed = sqrt(SHRatio*Reng*temperature);
146 State->Seta(soundspeed);
148 if (debug_lvl > 1) Debug();
150 } else { // skip Run() execution this time
156 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
160 void FGAtmosphere::Calculate(double altitude)
162 double slope, reftemp, refpress;
166 if (altitude < htab[lastIndex]) {
172 while (htab[i] > altitude) i--;
174 } else if (altitude > htab[lastIndex+1]){
175 if (altitude >= htab[7]){
180 while(htab[i+1] < altitude) i++;
189 //refdens = 0.000706032;
195 //refdens = 0.000171306;
197 case 3: // 104986 ft.
201 //refdens = 1.18422e-05;
203 case 4: // 154199 ft.
207 //refdens = 4.00585e-7;
209 case 5: // 170603 ft.
213 //refdens = 8.17102e-7;
215 case 6: // 200131 ft.
218 refpress = 0.00684986;
219 //refdens = 8.77702e-9;
221 case 7: // 259186 ft.
224 refpress = 0.000122276;
225 //refdens = 2.19541e-10;
228 default: // sea level
229 slope = -0.00356616; // R/ft.
230 reftemp = 518.67; // R
231 refpress = 2116.22; // psf
232 //refdens = 0.00237767; // slugs/cubic ft.
238 temperature = reftemp;
239 pressure = refpress*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
240 //density = refdens*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
241 density = pressure/(Reng*temperature);
243 temperature = reftemp+slope*(altitude-htab[i]);
244 pressure = refpress*pow(temperature/reftemp,-Inertial->SLgravity()/(slope*Reng));
245 //density = refdens*pow(temperature/reftemp,-(Inertial->SLgravity()/(slope*Reng)+1));
246 density = pressure/(Reng*temperature);
249 //cout << "Atmosphere: h=" << altitude << " rho= " << density << endl;
252 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
254 void FGAtmosphere::Turbulence(void)
258 vDirectiondAccelDt(eX) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
259 vDirectiondAccelDt(eY) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
260 vDirectiondAccelDt(eZ) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
262 MagnitudedAccelDt = 1 - 2.0*(((double)(rand()))/RAND_MAX);
263 MagnitudeAccel += MagnitudedAccelDt*rate*State->Getdt();
264 Magnitude += MagnitudeAccel*rate*State->Getdt();
266 vDirectiondAccelDt.Normalize();
267 vDirectionAccel += vDirectiondAccelDt*rate*State->Getdt();
268 vDirectionAccel.Normalize();
269 vDirection += vDirectionAccel*rate*State->Getdt();
270 vDirection.Normalize();
272 vTurbulence = TurbGain*Magnitude * vDirection;
273 vTurbulenceGrad = TurbGain*MagnitudeAccel * vDirection;
275 vBodyTurbGrad = State->GetTl2b()*vTurbulenceGrad;
276 vTurbPQR(eP) = vBodyTurbGrad(eY)/Aircraft->GetWingSpan();
277 if (Aircraft->GetHTailArm() != 0.0)
278 vTurbPQR(eQ) = vBodyTurbGrad(eZ)/Aircraft->GetHTailArm();
280 vTurbPQR(eQ) = vBodyTurbGrad(eZ)/10.0;
282 if (Aircraft->GetVTailArm())
283 vTurbPQR(eR) = vBodyTurbGrad(eX)/Aircraft->GetVTailArm();
285 vTurbPQR(eR) = vBodyTurbGrad(eX)/10.0;
293 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
295 void FGAtmosphere::Debug(void)
298 cout << "vTurbulence(X), vTurbulence(Y), vTurbulence(Z), "
299 << "vTurbulenceGrad(X), vTurbulenceGrad(Y), vTurbulenceGrad(Z), "
300 << "vDirection(X), vDirection(Y), vDirection(Z), "
302 << "vTurbPQR(P), vTurbPQR(Q), vTurbPQR(R), " << endl;
304 cout << vTurbulence << ", " << vTurbulenceGrad << ", " << vDirection << ", " << Magnitude << ", " << vTurbPQR << endl;