1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3 Module: FGPropeller.cpp
6 Purpose: Encapsulates the propeller object
8 ------------- Copyright (C) 2000 Jon S. Berndt (jsb@hal-pc.org) -------------
10 This program is free software; you can redistribute it and/or modify it under
11 the terms of the GNU General Public License as published by the Free Software
12 Foundation; either version 2 of the License, or (at your option) any later
15 This program is distributed in the hope that it will be useful, but WITHOUT
16 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
17 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
20 You should have received a copy of the GNU General Public License along with
21 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
22 Place - Suite 330, Boston, MA 02111-1307, USA.
24 Further information about the GNU General Public License can also be found on
25 the world wide web at http://www.gnu.org.
27 FUNCTIONAL DESCRIPTION
28 --------------------------------------------------------------------------------
31 --------------------------------------------------------------------------------
34 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
36 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
38 #include "FGPropeller.h"
40 static const char *IdSrc = "$Id$";
41 static const char *IdHdr = ID_PROPELLER;
43 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
45 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
48 FGPropeller::FGPropeller(FGFDMExec* exec, FGConfigFile* Prop_cfg) : FGThruster(exec)
53 MaxPitch = MinPitch = P_Factor = Sense = 0.0;
55 Name = Prop_cfg->GetValue("NAME");
56 Prop_cfg->GetNextConfigLine();
57 while (Prop_cfg->GetValue() != "/FG_PROPELLER") {
61 } else if (token == "DIAMETER") {
62 *Prop_cfg >> Diameter;
64 } else if (token == "NUMBLADES") {
65 *Prop_cfg >> numBlades;
66 } else if (token == "MINPITCH") {
67 *Prop_cfg >> MinPitch;
68 } else if (token == "MAXPITCH") {
69 *Prop_cfg >> MaxPitch;
70 } else if (token == "P_FACTOR") {
71 *Prop_cfg >> P_Factor;
72 } else if (token == "SENSE") {
74 } else if (token == "EFFICIENCY") {
75 *Prop_cfg >> rows >> cols;
76 if (cols == 1) Efficiency = new FGTable(rows);
77 else Efficiency = new FGTable(rows, cols);
78 *Efficiency << *Prop_cfg;
79 } else if (token == "C_THRUST") {
80 *Prop_cfg >> rows >> cols;
81 if (cols == 1) cThrust = new FGTable(rows);
82 else cThrust = new FGTable(rows, cols);
83 *cThrust << *Prop_cfg;
84 } else if (token == "C_POWER") {
85 *Prop_cfg >> rows >> cols;
86 if (cols == 1) cPower = new FGTable(rows);
87 else cPower = new FGTable(rows, cols);
89 } else if (token == "EOF") {
90 cerr << " End of file reached" << endl;
93 cerr << "Unhandled token in Propeller config file: " << token << endl;
98 cout << "\n Propeller Name: " << Name << endl;
99 cout << " IXX = " << Ixx << endl;
100 cout << " Diameter = " << Diameter << " ft." << endl;
101 cout << " Number of Blades = " << numBlades << endl;
102 cout << " Minimum Pitch = " << MinPitch << endl;
103 cout << " Maximum Pitch = " << MaxPitch << endl;
104 if (P_Factor > 0.0) cout << " P-Factor = " << P_Factor << endl;
106 cout << " Rotation Sense = CW (viewed from pilot looking forward)" << endl;
107 } else if (Sense < 0.0) {
108 cout << " Rotation Sense = CCW (viewed from pilot looking forward)" << endl;
110 cout << " Rotation Sense = indeterminate" << endl;
112 cout << " Efficiency: " << endl;
114 cout << " Thrust Coefficient: " << endl;
116 cout << " Power Coefficient: " << endl;
123 if (debug_lvl & 2) cout << "Instantiated: FGPropeller" << endl;
126 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
128 FGPropeller::~FGPropeller()
130 if (Efficiency) delete Efficiency;
131 if (cThrust) delete cThrust;
132 if (cPower) delete cPower;
133 if (debug_lvl & 2) cout << "Destroyed: FGPropeller" << endl;
136 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
138 // We must be getting the aerodynamic velocity here, NOT the inertial velocity.
139 // We need the velocity with respect to the wind.
141 // Note that PowerAvailable is the excess power available after the drag of the
142 // propeller has been subtracted. At equilibrium, PowerAvailable will be zero -
143 // indicating that the propeller will not accelerate or decelerate.
144 // Remembering that Torque * omega = Power, we can derive the torque on the
145 // propeller and its acceleration to give a new RPM. The current RPM will be
146 // used to calculate thrust.
148 // Because RPM could be zero, we need to be creative about what RPM is stated as.
150 float FGPropeller::Calculate(float PowerAvailable)
152 float J, C_Thrust, omega;
153 float Vel = (fdmex->GetTranslation()->GetvAero())(1);
154 float rho = fdmex->GetAtmosphere()->GetDensity();
155 float RPS = RPM/60.0;
159 J = Vel / (Diameter * RPM / 60.0);
164 if (MaxPitch == MinPitch) { // Fixed pitch prop
165 C_Thrust = cThrust->GetValue(J);
166 } else { // Variable pitch prop
167 C_Thrust = cThrust->GetValue(J, Pitch);
170 if (P_Factor > 0.0001) {
171 alpha = fdmex->GetTranslation()->Getalpha();
172 beta = fdmex->GetTranslation()->Getbeta();
173 SetLocationY(P_Factor*alpha*fabs(Sense)/Sense);
174 SetLocationZ(P_Factor*beta*fabs(Sense)/Sense);
175 } else if (P_Factor < 0.000) {
176 cerr << "P-Factor value in config file must be greater than zero" << endl;
179 Thrust = C_Thrust*RPS*RPS*Diameter*Diameter*Diameter*Diameter*rho;
181 omega = RPS*2.0*M_PI;
183 // Must consider rotated axis for propeller (V-22, helicopter case)
185 vH(eX) = Ixx*omega*fabs(Sense)/Sense;
189 if (omega <= 5) omega = 1.0;
191 Torque = PowerAvailable / omega;
192 RPM = (RPS + ((Torque / Ixx) / (2.0 * M_PI)) * deltaT) * 60.0;
193 return Thrust; // return thrust in pounds
196 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
198 float FGPropeller::GetPowerRequired(void)
200 if (RPM <= 0.10) return 0.0; // If the prop ain't turnin', the fuel ain't burnin'.
202 float cPReq, RPS = RPM / 60.0;
204 float J = (fdmex->GetTranslation()->GetvAero())(1) / (Diameter * RPS);
205 float rho = fdmex->GetAtmosphere()->GetDensity();
207 if (MaxPitch == MinPitch) { // Fixed pitch prop
208 cPReq = cPower->GetValue(J);
209 } else { // Variable pitch prop
210 cPReq = cPower->GetValue(J, Pitch);
213 PowerRequired = cPReq*RPS*RPS*RPS*Diameter*Diameter*Diameter*Diameter
215 return PowerRequired;
218 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
220 void FGPropeller::Debug(void)
222 //TODO: Add your source code here