1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
5 Date started: 09/12/2000
7 ------------- Copyright (C) 2000 Jon S. Berndt (jon@jsbsim.org) --------------
9 This program is free software; you can redistribute it and/or modify it under
10 the terms of the GNU Lesser General Public License as published by the Free Software
11 Foundation; either version 2 of the License, or (at your option) any later
14 This program is distributed in the hope that it will be useful, but WITHOUT
15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
16 FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
19 You should have received a copy of the GNU Lesser General Public License along with
20 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
21 Place - Suite 330, Boston, MA 02111-1307, USA.
23 Further information about the GNU Lesser General Public License can also be found on
24 the world wide web at http://www.gnu.org.
27 --------------------------------------------------------------------------------
28 09/12/2000 JSB Created
30 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
32 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
37 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
39 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
42 #include "math/FGTable.h"
43 #include "math/FGFunction.h"
45 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
47 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
49 #define ID_ROCKET "$Id: FGRocket.h,v 1.20 2013/11/24 11:40:57 bcoconni Exp $"
51 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
53 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
57 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
59 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
61 /** Models a generic rocket engine.
62 The rocket engine is modeled given the following parameters:
64 <li>Specific Impulse (in sec)</li>
66 Additionally, the following control inputs, operating characteristics, and
67 location are required, as with all other engine types:
69 <li>Throttle setting (in percent, from 0 to 1.0)</li>
70 <li>Maximum allowable throttle setting</li>
71 <li>Minimum working throttle setting</li>
72 <li>Sea level fuel flow at maximum thrust</li>
73 <li>Sea level oxidizer flow at maximum thrust</li>
74 <li>X, Y, Z location in structural coordinate frame</li>
75 <li>Pitch and Yaw</li>
77 The nozzle exit pressure (p2) is returned via a
78 call to FGNozzle::GetPowerRequired(). This exit pressure is used
79 to get the at-altitude thrust level.
81 One can model the thrust of a solid rocket by providing a normalized thrust table
82 as a function of time. For instance, the space shuttle solid rocket booster
83 normalized thrust value looks roughly like this:
86 \<thrust_table name="propulsion/thrust_time" type="internal">
114 The left column is time, the right column is normalized thrust. Inside the
115 FGRocket class code, the maximum thrust is calculated, and multiplied by this
116 table. The Rocket class also tracks burn time. All that needs to be done is
117 for the rocket engine to be throttle up to 1. At that time, the solid rocket
118 fuel begins burning and thrust is provided.
120 @author Jon S. Berndt
121 $Id: FGRocket.h,v 1.20 2013/11/24 11:40:57 bcoconni Exp $
128 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
130 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
132 class FGRocket : public FGEngine
136 @param exec pointer to JSBSim parent object, the FDM Executive.
137 @param el a pointer to the XML Element instance representing the engine.
138 @param engine_number engine number */
139 FGRocket(FGFDMExec* exec, Element *el, int engine_number, struct FGEngine::Inputs& input);
144 /** Determines the thrust.*/
145 void Calculate(void);
147 /** The fuel need is calculated based on power levels and flow rate for that
148 power level. It is also turned from a rate into an actual amount (pounds)
149 by multiplying it by the delta T and the rate.
150 @return Total fuel requirement for this engine in pounds. */
151 double CalcFuelNeed(void);
153 /** The oxidizer need is calculated based on power levels and flow rate for that
154 power level. It is also turned from a rate into an actual amount (pounds)
155 by multiplying it by the delta T and the rate.
156 @return Total oxidizer requirement for this engine in pounds. */
157 double CalcOxidizerNeed(void);
159 /** Gets the total impulse of the rocket.
160 @return The cumulative actual total impulse of the rocket up to this time.*/
161 double GetTotalImpulse(void) const {return It;}
163 /** Gets the total impulse of the rocket.
164 @return The cumulative vacuum total impulse of the rocket up to this time.*/
165 double GetVacTotalImpulse(void) const {return ItVac;}
167 /** Gets the flame-out status.
168 The engine will "flame out" if the throttle is set below the minimum
169 sustainable-thrust setting.
170 @return true if engine has flamed out. */
171 bool GetFlameout(void) {return Flameout;}
173 double GetOxiFlowRate(void) const {return OxidizerFlowRate;}
175 double GetMixtureRatio(void) const {return MxR;}
177 double GetIsp(void) const {return Isp;}
179 void SetMixtureRatio(double mix) {MxR = mix;}
181 void SetIsp(double isp) {Isp = isp;}
183 std::string GetEngineLabels(const std::string& delimiter);
184 std::string GetEngineValues(const std::string& delimiter);
186 /** Sets the thrust variation for a solid rocket engine.
187 Solid propellant rocket motor thrust characteristics are typically
188 defined at 70 degrees F temperature. At any other temperature,
189 performance will be different. Warmer propellant grain will
190 burn quicker and at higher thrust. Total motor impulse is
191 not changed for change in thrust.
192 @param var the variation in percent. That is, a 2 percent
193 variation would be specified as 0.02. A positive 2% variation
194 in thrust would increase the thrust by 2%, and shorten the burn time. */
195 void SetThrustVariation(double var) {ThrustVariation = var;}
197 /** Sets the variation in total motor energy.
198 The total energy present in a solid rocket motor can be modified
199 (such as might happen with manufacturing variations) by setting
200 the total Isp variation.
201 @param var the variation in percent. That is, a 2 percent
202 variation would be specified as 0.02. This variation will
203 affect the total thrust, but not the burn time.*/
204 void SetTotalIspVariation(double var) {TotalIspVariation = var;}
206 /** Returns the thrust variation, if any. */
207 double GetThrustVariation(void) const {return ThrustVariation;}
209 /** Returns the Total Isp variation, if any. */
210 double GetTotalIspVariation(void) const {return TotalIspVariation;}
213 /** Returns the vacuum thrust.
214 @return The vacuum thrust in lbs. */
215 double GetVacThrust(void) const {return VacThrust;}
217 void bindmodel(void);
219 double Isp; // Vacuum Isp
220 double It; // Total actual Isp
221 double ItVac; // Total Vacuum Isp
222 double MxR; // Mixture Ratio
224 double ThrustVariation;
225 double TotalIspVariation;
227 double previousFuelNeedPerTank;
228 double previousOxiNeedPerTank;
229 double OxidizerExpended;
230 double TotalPropellantExpended;
233 double OxidizerFlowRate;
234 double PropellantFlowRate;
237 FGTable* ThrustTable;
238 FGFunction* isp_function;
240 void Debug(int from);
243 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%